Class XI, Principles of Commerce, "Debentures "

INTRODUCTION
A trading company has an implied power to borrow money as an incidental part of its day to day business. In the case of Joint Stock Company the memorandum of association may fix limits to the borrowing powers and in such case borrowing in excess of he limit will be ultra virus to the company. A company therefore generally borrows money by means of issuing documents or bonds which are know as debentures.
It may be regarded as written acknowledgment of a loan by the company conditioning for the promise of repayment of interest and the principle after the specified time, if the loan is redeemable. A debenture must be distinguished from share. While debenture creates a loan a share creates an ownership. A debenture holder is thus creditor and he is entitled to a fixed rate of interest irrespective of profit while the shareholder is the owner who is entitled to receive profits, if there are any.
CLASSES OF DEBENTURES
1. NAKED DEBENTURES
These are without any security i.e have no charge on any assets of the company. For practical purpose these are merely promissory notes. In the event of liquidation of the company the holders are ranked as unsecured creditors.
2. MORTGAGE DEBENTURES
These have certain specific rights against the assets of the company in other words the company pledges its assets to the lenders.
3. REGISTERED DEBENTURE
These are recorded in the books of company and are payable only to those who are written against them as holders. These can be transferred only by the proper transfer executed deeds.
4. BEARER DEBENTURES
The names of the holder of debentures are not registered and they are payable to those who present them. They can be transferred by means of redelivery by one person to another
5. REDEEMABLE DEBENTURES
These are repaid by the company after a specific number of years after giving the prescribed notice of redemption to the debenture holder.
6. IRREDEEMABLE DEBENTURES
These are the debentures which are not paid during life of the company but on the liquidation of company the debenture holder gets their amount back.

Class XI, Principles of Commerce, "Joint Stock Company"

Joint Stock Company

DEFINITION
In the modern times the business and industry has been developed on a large scale the capital required for such industry and trade is huge which cannot be accumulated either in a sole proprietorship or a partnership organization. As a result of this change, a new form of organization has become quite popular in modern times which are known as Joint Stock Company. It is normally defined as;

“An association of many person who contribute money or money’s worth to common stock or employ it in some trade and business, and who share profit or loss arising from there.”

It means the joint stock company is a voluntary association of individual who contribute their money or profit to a common stock for carrying on a particular business. The money or money’s worth contributed by the member known as ‘share holders’ forms the capital of the company. The capital is divided into numbers of unit called share. Each share carries definite face value and is transferable in the market without any restriction or formalities.
A company as soon as incorporated takes a legal entity distinct from the share holder who composes it. It is managed by a group of persons known as directors. Directors are the representatives of share holders.
FORMATION OF JOINT STOCK COMPANY
All the joint stock companies whether public or private are governed by the company’s ordinance 1984 and must be formed according to the procedures laid down in that act. For the formulation of Joint Stock Company the following document must be submitted to the registrar, joint stock Company;
1. The list of directors along with their address.
2. the memorandum of association on which at least 7 person, who are promoters should sign in case of public limited company and two in case of private limited company. In addition of this it is also essential for the, to purchase the qualification share.
3. Articles of association duly signed as memorandum of association.
4. The consent of all the directors to act as directors.
5. A formal declaration by the secretary that all the formalities are duly completed.
6. A statement of normal capital.
Along with the above documents, registration fees, which varies with the amount of share capital is paid off to the treasury.
When the registrar of the joint stock companies is satisfied from all the formalities he will enter the name of the company in the register and will issue a certificate of incorporation. Now the company will have its separate existence.
CLASSES OF COMPANIES
There are following classes of Joint Stock Company:
1.CHARTERED COMPANY
2.STATUTORY COMPANY
3. REGISTERED COMPANY
…………(A) LIMITED COMPANY
………………….(I) PRIVATE LIMITED COMPANY
………………….(II)PUBLIC LIMITED COMPANY
……………………………….. * COMPANY LIMITED BY GUARANTEE
……………………………….. * COMPANY LIMITED BY SHARES
………..(B) UNLIMITED COMPANY
1. CHARTERED COMPANY
This type of company was formed in England and many other European countries before the passing of company acts. They are called chartered companies because they created by the royal charter of sovereign of a country. Such companies are rarely formed in present days. The chartered bank of England, the chartered mercantile of India, the imperial bank of east India Company has been formed under such chartered. In such companies the share holder are not responsible for the debt of the company. It can be dissolved by the king. After the passing of the companies Act such companies began to register under companies Act.
2. STATUTORY COMPANY
They are formed under the special act of the legislature. These are not regulated by the companies act. The special act of the legislature under which they are formed gives them monopolistic power to trade in the particular field of operation. Government took the initiative and created national bank of Pakistan, P.I.B.C and state bank of Pakistan etc. its functioning is more or less the same as the registered companies. Government controls more of the share than the public. Other example of this company are P.I.A etc.
3. REGISTERED COMPANY
This is most common form which is created under companies act. Before a registered company can be formed certain legal formalities are required to be completed and documents are to be filled with the registrar of the joint stock companies of the providence. In Pakistan these companies are incorporated under the company’s ordinance. It is of two types.
a) UNLIMITED COMPANIES
These companies are registered under the companies act. The labializes of share holder of such companies is unlimited. An unlimited company can take numerous members. It has a separate entity and is managed by the board of directors and its share is freely transferable.
b) LIMITED COMPANIES
The liabilities of the members of limited company is limited by the total value of the share they hold or by the amount they have promised to contribute in the event of liquidation of the company. It is of two types.
i) PRIVATE LIMITED COMPANY
It is composed of at least two members and in no case can the number of its member exceed 50. It cannot issues share or debenture. It share cannot be transferred to other.
ii) PUBLIC LIMITED COMPANY
It is formed by at least 7 members but there is no limited to the number of people. It can issue prospectus in order to sell its share in the market. Its share is transferable to others
It has two types:
i) Company Limited by Share The liability of the shareholder of the company limited by the share is limited to the extend of the face value of the share held by them.
ii) Company Limited By Guarantee The members of such company undertake to shoulder a definite amount of extra liability over and above the total value of the share they hold.
MEMORANDUM OF ASSOCIATION
The first thing in the formation of joint stock company is the preparation of memorandum of association. It is the document which sets out the constitution of the company and as such is really the foundation on which the structure of company rests. That is why this document has often being called the charter of the company in its relation to the outside world. The document is prepared by the promoters of the company. It must contain the following clauses.
1. NAME CLAUSE
In this clause the full name of the company is shown and the last word of the name of the company must be limited. The company can adopt any name but there are certain restriction and the words like “ROYAL, IMPERIAL, EMPIRE, ESTATE’ etc cannot be used without the special permission of the government.
2. OBJECT CLAUSE
This clause is very important one must be very carefully drafted as it determines the activities of the company. Here each and every detail of activities of the business to be carried out must be laid down. Once the object clause is completed it becomes very difficult to make any amendments. The value of the share the utmost money must be given in detail.
3. SITUATION CLAUSE
This act provides that the company must have a registered office so that registrar may be able to send notice etc. to the company at the registered office.
4. LIABILITY CLAUSE
A declaration that the share holder liability is limited.
5. CAPITAL CLAUSE
This clause must contain a statement as to the amount of capital with which the company proposes to be registered and the division therefore into share at certain fixes amounts.
ARTICLES OF ASSOCIATION
This is an important document which must be prepared and filled with the registrar of the company. It contains rule and regulation regarding the internal work and management of the company. It defines the power, rights, and duties of directors, share holders and other officer of the company. The purpose of this document is to carry out the object set out in the memorandum. The memorandum limits the jurisdiction beyond which the article of association cannot go. It states how general meeting are to be held, how the voting is to be done. How the shares are to be transferred, and how they are to be forfeited, how accounts are to be kept. If the company does not prepare the article of association than it can adopt its table A of company ordinance.
The article must be seriously drafted, seriously numbered and printed and then filed with the registrar of Joint Stock Company. The article must be signed by the subscriber and witness as in the case of memorandum. It is usual to print memorandum and article in one booklet, as the company required to provide the copies to members on request.
DIFFERENCE BETWEEN MEMORANDUM AND ARTICLE OF ASSOCIATION
MEMORANDUM OF ASSOCIATION……………………………………………………………ARTICLES OF ASSOCIATION
1.It is charter of company which defines the powers objects of the company…… 1. It contains rule and regulation regarding the internal work and management of the company. It defines the power, rights, and duties of directors, share holder.
2.It is difficult to alter. Its alteration requires confirmation of the court…………….. 2. It can be altered by passing special resolution in a general meeting.
3.It must be signed by at least 7 subscribers………………………………………….. 3. It must be signed by at least 2 subscribers.
4. It must be registered before incorporation of the company………………………..4. It may or may not t be registered before incorporation of the company.
5. It is not subjected to article…………………………………………………………….. 5.It is subjected to memorandum.
6. It governess the relationship of the company with outside world……………….. 6. It governs the them. Relationship of members among.
DIFFERENCE BETWEEN PRIVATE AND PUBLIC LIMITED COMPANIES
1. NUMBER OF SHAREHOLDERS
In private limited company minimum number of share holder is 2 and maximum is 50 but in a public limited company the minimum number of share holder is 7 and there is no limitation on the maximum number which may increase to thousand.
2. SUBSCRIPTION OF SHARES
A private limited company cannot invite the general public for the purchase of share and debentures. But a public limited company can invite the general public for the purchase of share and debentures.
3. DIRECTORS
A private limited company may or may not have directors; there is no restriction on it. But in case of public limited company there must be at least three directors. There is no limitation fixed for the appointment of directors.
4. CONSENT PARTNER
If there is partner in private company his written consents are not required but in case of Public limited company, his written consents are required.
5. CERTIFICATE OF INCORPORATION
A private limited company can start the business without registration or incorporation certificate but public limited company cannot start without registration.
6. PROSPECTUS
A private limited company can issue a prospectus or statement in lieu of prospectus. But it is necessary for the public limited company to issue a prospectus or statement in lieu of prospectus.
7. AUDIT OF ACCOUNT
The account of private limited company may be checked by any person, or by the body of the company. But the accounts of public limited company must be audit by chartered accountants or registered accounts.
8. ADVERTISING ACCOUNTS
It is not necessary for the private limited company to advertise the copy of balance sheet and profit or loss account every year. But for public limited company it is necessary to advertise the copy of balance sheet and profit or loss account every year.
9. STATUTORY MEETINGS
It is not necessary for the private limited company to call a statutory meeting. But statutory meeting must be called within 6 months from the commencement of the business in public limited company.
10. APPOINTMENT OF MANAGING AGENTS
Managing agent in private limited company can be appointed for a period, but managing agent in the public limited company can be appointed for the 20 years at-most.
11. QUALIFICATION OF SHARE FOR DIRECTORS
In private limited company there is no qualification of shares for directors but in public limited company a person will have to purchase qualification share for becoming the director of company.
12. CONDITION OF MINIMUM SUBSCRIPTION
The condition of minimum subscription is not applicable for private limed company. But for the public limited company the minimum subscription must be raised before the almost of shares of the general public.
ADVANTAGES OF JOINT STOCK COMPANY
1. HUGE AMMOUNT OF CAPITAL
It is in position to raise large amount of capital required for big business. The reason is the limitation of liabilities and ease of transferability of share. A small value of share allows charge number of people to invest. Therefore large capital can be raised by Joint Stock Company.
2. ALL PEOPLE CAN INVEST
The shares are of different kinds and they are purchased by person of different temperaments. The small value of share allows the poor people to also purchase it. Besides the company can also raise fiancé by the issue of debentures and bonds.
3. LIMITED LIABILITIES OF SHAREHOLDERS
The liabilities are limited. It means that the risk is spread over a large number of share holders and possibility of hardship on few is reduced. Secondly if the business is lost the shareholder are not going to loose anything from their private properties.
4. EFFICIENT MANAGEMENT
The management is carried out by the people who are able, experienced and trustees of share holders. It is thus in the hand of few exporters.secondly the company can also hire efficient and qualified staff since it can pay their wages.
5. STABILITY OF BUSINESS
The success of business also depends upon the life of the business. The joint stock company is more suited in this respect, for a company is a legal person having a perpetual succession.
6. EASE OF EXPANSION:
In joint stock Company if it is desirable to expand the business it can be easily done by the issue of more and more shares.
7. EASY TRANSFERABILITY OF SHARE:
The share of company are easily bought and sold in stock exchange market like ordinary commodities, and the shareholder can withdraw his money when ever required by selling his shares to others. This fact encourages the public to invest money.
8. LEGAL ENTITY
The company has legal entity distinct from the shareholders. The company can enter into any contract with any person on behalf of the company’s name.
9. TAX CONCESSIONS
The income tax has provided special concession to joint stock companies which are not available to sole proprietorship or partnership organization.
10. MASS PRODUCTION
The greatest benefit of the joint stock companies is that it has made possible production on larger scale. Modern and mass production needs huge capital which can be accumulated in such a form to business organization.
DISADVANTAGES OF JOINT STOCK COMPANY
1. DIFFICULTY IN FORMATION
The promoters has to under go under certain legal formalities to create the business. They have to prepare and file the necessary documents and pay the registration fee.
2. SEPARATION OF OWNERSHIP FROM CONTROL
The management of the company is entirely in the hands of directors and the shareholder, who are the actual owners have no say in it. The directors may be dishonest and may deceive the public.
3. LACK OF PERSONAL INTEREST
As compared to other forms of business such organization lacks personnel interest, because the management knows that they will be paid in any condition and secondly the directors know the profit will be divided into number of share holders. This situation leads to the absence of personal interest.
4. LACK OF SECRECY
A successful requires secrecy sometimes in certain matters. Secrecy cannot be maintained here because each and every formula or terms are exposed to all the shareholders regarding the volumes at sales margin of profits etc.
5. MONOPOLY
Another danger lies in a tendency for the joint stock company to form themselves into a combination exercising monopolistic powers and monopoly is against public interest.
6. CORRUPTION
The share being easily sale able, shrewd directors sell them whenever they suspect any danger in the business and shift the loss of the company on general public.
7. DIVIDED RESPONSIBILITIES
The work of company is divided among various departments and the in charge of the company is quite independent. This sometimes causes much hardship and result in- Efficiency
8. SOURCE OF DECEIVING INVESTORS
By forming bogus companies the promoters can deceive the general public.

Class XI, Principles of Commerce, "TYPES OF ORGANIZATION"

Types of Organization

1) Sole Proprietorship
2) Partnership
1. SOLE PROPRIETORSHIP
It is the form of business organization in which an individual introduces his own capital, uses his own skills and intelligence in the management of its affairs and is solely responsible for the result of its operations. He may run the business alone or obtain assistance of employees. It is the easiest to form and is also the simplest in organization. The sole proprietor may borrow or use other people‘s money in doing his business.
The individual proprietor is the supreme judge of all matters pertaining to his business, subject only to the general laws of the land and to such special legislation a may effect his particular business.
ADVANTAGES OF SOLE PROPRIETORSHIP
1. EASY TO START
The formation of sole proprietorship is quite easy than partnership and joint stock company. There are no legal formalities for the starting this business, like agreement, memorandum of association, or articles of associations.
2. EASY TO DISSOLVE
It is easy to dissolve because the sole trader is not required to take permission for the dissolution either from share holder in the general meeting as in the case of joint stock companies or consult all the partners in the case of partnership.
3. FREEDOM OF ACTION
A sole trader has maximum freedom to take decision at his own end. His decision is final he may expand his business by adding new products or can discontinue old ones. He can wind up his business or he can change his business place from one place to another.
4. FREEDOM OF GOVERNMENT CONTROL
He is free from government control to a great extent than any other form of organization. A sole trader is not required to send his periodical balance sheet to the government.
5. OWNERS OF ALL PROFIT
No other organization permits to retain cent percent profit they earn. But in sole proprietorship the sole trader is the master of his business and is entitled to retain the entire profit of the business.
6. LOW TAXES
He has to pay minimum income tax and other taxes than in partnership and Joint Stock Company. In this manner he saves much out of his profit.
7. SECRECY
Secrecy is base of a business and it should not be disclosed. Success of business depends upon secrecy. A sole trader can maintain secrets of his business but it is not possible to keep secret in partnership or Joint Stock Company.
8. LOW COST ORGANIZATION
A sole trader is not required to pay registration fees as paid by stock company and legal fees in the formation of partnership.
9. FULL CONTROL
He has got full control over his planning. Nobody is there to interfere in his business.
10. IMMEDIATE ACTION AND QIUCK DECISION
In business it becomes very essential to take decision on particular times and for that purpose immediate action is required. Sole trader can take immediate action and decision but in partnership and joint stock companies actions cannot be taken without permission of owners and meetings should be called for this purpose. In this way business cannot take proper advantage of time.
11. FLEXIBILITY OF ORGANIZATION
If any change is business is called of the sole proprietor has a right to bring about the change. A good number of giant sized concerns fall on account of their inability to change their policies promptly with a change in situation.
12. SOCIAL DIS-LIABILITIES
From the social point of view
i) Continuity of individual proprietorship ensures that too much wealth does not get concentrated in a few hands.
ii) The unlimited liability ensures sufficient responsibilities to the society.
iii) It brings into full play the qualities of self confidence, diligence and tact among business people.
iv) The growing number of sole proprietorships firms contributes to the commercial development of the country.
13. PERSONAL INCENTIVES
A man in business for him has everything lose if his efforts are not successful to earn profits. This fact makes him willing to devote maximum time, thought and energy to the successful prosecution of the activities of business ha has organized.
14. CREDIT WORTHINESS
Sole proprietor’s liabilities are unlimited as the creditor can even recover his amount from the personal belongings of the trader. Therefore this fact makes a sole proprietor credit worthy.
DISADVANTAGES OF SOLE PROPRIETORSHIP
The sole proprietorship has some disadvantages which are as follows:
1. LIMITED FINANCE
The sole proprietorship can face financial problems. He can depend only his own resources. It is neither safe nor easy for him to borrow large amount of money from banks or other financial institutions.
2. DIFFICULTIES IN MANAGEMENT
Each individual has particular attitude or ability in particular respects. Modern business is full of complications airing especially from the changing nature of market and the various laws that are being enacted. An individual may not be expert in all matters. Therefore sometimes his decision may be unbalances and would lend to the failure of the business.
3. LIMITED SPAN OF SUPERVISION
A sole proprietor however qualified and clever will find it hard to supervise the work of his sub ordinate beyond a certain limit e.g. in ease of large general store owned by single person, it will be difficult for the owner to keep an eye on all the departments and employee and to ensure that the customers are treated nicely. The problems will be more acute if store has its branches in other places.
4. LIMITATION ON SIZE
Because of limitation of finance, managerial skills and span of supervision a sole proprietor has to manger the size of the business up to a certain limit. This deprives the firm of the opportunity of reaping the economic of large scale production.
5. UNLIMITED LIABILITY
He has great risks. It is true that he receives all the profits of the business but likewise he has to face the entire losses. Not only the assets of the business but also his private assets will be used to pay off the firm’s debts and losses. Unlimited liability also discourages the expansion of business.
6. LACK OF CONTINUITY
Any personal problem or illness which is affecting the sole proprietor has direct effect on his business. It ends with the retirement, death or bankrupt of the owner. If the business is rendering useful services to the society the closure of such a business will be social loss. Similarly with the death of the proprietor, the business may pass on to his successors who may not possess the same degree of self-reliance, ability and intelligence.
7. EASE OF FORMATION
The very ease and cheapness of entering business as a proprietor may be disadvantages. Many people go into business with too little capital and training and are dashed by the competition of the business. As a result a number of business failures are proprietorships.
SUITABILITY OF SOLE PROPRIETORSHIP
One man control over the business would be most efficient and profitable. If only that one man has the capability of managing everything indefinitely. Unfortunately such a person does not exist. This form of organization is therefore suitable for the following cases.
a) Where the capital required is small and risk is not heavy since merchandise and services of one kind are sold. E.g. magazine and newspaper stand, bakeries teashops, rental libraries etc.
b) Where quickness in decision is needed i.e. Bullion dealers, share brokers etc.
c) Where services are sold and customer requires personnel attention egg. Patient, lawyers, dentist, cobblers, accountant.
d) Where special regard has to be shown to the tastes of the customers egg. Tailoring, restaurant, managing etc.
e) Where market is limited eg. Retail trade.
Thus sole proprietorship has its own scope of activities and continuous to exist in spite of development of bigger organizations like partnership and joint stock companies.
2. PARTNERSHIP
It is rare that person combines in himself all that is essential to make him successful businessman. Beside to reap the economies of large scale operation sole proprietor may fail to cope up with demands of expansion. He may possess adequate capital but he may be handicapped by the lack of experience. Skills and managerial ability. Or it may be the other way round. Therefore a combination of two or more or more persons, some having capital and others having skill or experience proves to be beneficial.
According to section 4 of the Indian partnership Act of 1932, partnership is defined as “the relating between persons, who having agreed to share profits of a business carried on by all or any one of them acting for all”
The above definition reveals that:
1. An agreement between partners is necessary.
2. The agreement must be in regard to the sharing of the profit of the business.
3. The business must be carried by all or any one of them acting for all.
The individual who constitute the partnership are called partners and they collectively form the firm. The name in which there business is carried on is called the firm name.
FEATURES OR ELEMENTS OR CHARACTERISTICS OF PARTNERSHIP
Partnership is the result of contract between two or more person who has agreed to carry out on a business with the object of earning profit. The followings are the main features of partnership.
1. AGREEMENT
The most important element without which partnership cannot be formed is the agreement between the partners. It is immaterial whether the agreement is written or oral but its existence is essential. Besides, the agreement must be done in carrying the business and sharing of profit.
2. NUMBERS OF PARTNERS
There must be an association of two or more person to constitute a partnership. The maximum number of partners is 10 for banking business and 20 for general business.
3. BUSINESS PURPOSE
The main idea of partnership is to do business and distribute the share of profit earn during the course of business among the partners. The aim of business must be earring of money.
4. SHARING OF PROFIT
The partners carry out business with the view to earn profit which is distributed among them in agreed ratio. In similar way, if there is a loss all partners are going to bear it.
5. CAPITAL
The partners provide capital from there own pockets but they can also borrow money at their own risk. One can become partner of a firm even without contributing any money towards the business. In that case, his time, energy and intelligence will be regarded as capital for which he will take a share of profit. If the partners devote the maximum amount of his time in business he would also be paid a salary.
6. MUTUAL TRUST, CONFIDENCE AND UTMOST FAITH
All the partners must trust each other. They work in closed cooperation to make the enterprise a success. The partnership agreement is made on utmost trust and faith. The partners must disclose every information and must present true accounts to one another.
7. PRESENCE OF AGENCY
The other most important element of partnership is the presence of agency between partners. Each partner is liable for the act of other partner. It may possible that one partner transact whole business on behalf of other partner with their consents.
8. BUSINESS IN WIDER SENSE
The term business is very wide and it includes every kind of trade. Profession and occupation. Thus the partnership is not confined to a particular kind of trade or profession. Thus partnership has no limitation of duration and it may be formed for a single transation.
9. UNLIMITED LIABILITIES
Every partner has unlimited liabilities toward the firm’s debt. The creditors can recover debt from the personnel property of the partners.
10. NO SEPARATE LEGAL ENTITY
Generally partnership has no legal status as entity. The assets are used and liabilities are owned by the partners collectively.
11. EFFECTS OF PARTNER’S DEATH
Unless the partnership agreement provides otherwise the death of partner automatically dissolve the partnership business.
12. RESTRICTION ON RETIREMENT OF PARTNERS
The partner cannot retire without the consent of the co-partners.
The partnership organization has following types of partners.
TYPES OF PARTNERSHIP
1. ACTIVE OR WORKING PARTNER
These are those members of partnership who contribute to the capital of the firm and taken the active part in the conduct and administration of the business. He is considered as agent of the firm by other partners.
2. DORMANT OR SLEEPING PARTNER
They contribute to the capital of the firm but do not take any part in management. Their names dose not appears any where as partners but in reality they are partners. They also share profit. They are liable to the third parties on behalf of the firm. He has every right to inspect and copy the books of accounts.
3. NOMINAL PARTNER
He is the one who neither contribute any capital t the firm nor takes any active part in conduct and administration of the business he only lends the use of his name to the firm. He is not entitled to share the profit. He is liable for all acts of firm.
4. QUASI PARTNER
A quasi partner is a retired partner who has left his capitols with the firm as loans. He gets interest on his loan at the rate varying with the profit of the firm.
5. LIMITED PARTNER
The liability of the limited partner is limited to the extend of his investment in the business. Such a partner is not allowed to take part in the management of the firm. In case of falier he cannot lose anything from his private property.
6. MINOR PARTNER
With the consent of all partners a minor person can be admitted to the benefits of the firms only. Such a partner cannot be held liable for the firm’s debts.
7. SELF STYLED PARTNER
Any person who calls himself by his gesture and posture or conduct or by his words of mouth or by written expression to be the partner of the firm is know as self styled partner.
8. SALARIED PARTNER
Generally in professions, it is not seen that some person is admitted as a partner who invested his capital in the business nor has interest in goodwill of the firm such a partner is remunerated in different way.
ADVANTAGES OF PARTNERSHIP
1. LARGE AMOUNT OF CAPITAL
In sole proprietary ship the amount of capital is limited to personal fortune and credit of one individual. In a partnership the capital can easily be raised according to requirements by bringing additional workers.
2. COMBINED JUDGEMENTS AND MANAGERIAL SKILLS
In partnership business there are more than one owner, it is therefore possible to combine the abilities and knowledge of every partner to the best interest of the business. With combine decision and judgment business is greatly benefited and more profit is possibly earned.
3. PERSONAL INTEREST
Since each general partner is responsible not only for his acts but also for the acts of his partners, he shall devote his personal attention and interest to the activities of the firm and this will enable a firm to attain maximum efficiency.
4. HIGH CREDIT STANDING
A partnership has little difficulty in obtaining credit. Especially if the partners have their personal wealth. If there are several partners and one of them has several extensive private means, creditors have little reason to doubt that the debt of partnership will be paid in fall.
5. EASE OF FORMATION
A partnership business is easy to start with as it is free from all legal formalities. It does not suffer the legal handicaps. The business can be easily increased or decreased to the suitable condition.
6. RETAINING OF VALUABLE PERSON/ PROVISION OF NEW BLOOD TO THE BUSINESS
New blood can be infused into the business by admitting new partners. Then the business can utilize the genius of an enterprising young man.
7. CO-ORDINATED DECISION
The decisions which take place in the partner ship are the coordinated decision i.e. the decision which are jointly take by all the partners.
8. LIGHTER RISK
Risk is spread here over several persons who are the partners. All the partners pool together their abilities and their income.
9. UNLIMITED LIABILITIES
Each partner has an unlimited liability towards the firm debt. The creditors can recover the debts from the personal property of the partners.
10. FLEXIBILITY OF THE ORGANIZATION
A partnership organization is extremely mobile, flexible and elastic. The partners are at ease to carry on any legal business.
DISADVANTAGES OF PARTNERSHIP
1. POSSIBILITY OF DISAGREEMENT BETWEEN THE PARTNERS
Two or more men start out together as close friends or as relatives. However they may develop difference over a year that will make for unpleasantness and inability to work together for the best interest of their firm.
2. UNLIMITED LIABILITIES
The greatest disadvantage is that of unlimited liability of the partners. At general partners are liable personally for the partnership debts. Where there are heavy losses the partner having much property will have to sustain the entire loss.
3. DIVIDED CONTROL/ DELAY IN DECISION MAKING
In the partnership more than one person is involved in every decision reached. If partner are not active in the operations it may be necessary to delay the making of an important decision. Therefore divided control leads to delay in decision.
4. FROZEN OR BLOCK INVESTMENT
For an individual who wishes to invest some money in a business, the partnership form may prove to be a poor investment from the view point of liquidity and transferability. It is correct to say that it is easy to invest money but is difficult to withdraw it, because it would mean the termination of business
5. LIMITATION ON SIZE
Since maximum number of partners is 20, it might ne possible that at some time the capital becomes short. If it happens the business has to be converted into a joint stock company. Therefore a big business cannot be started even if they get a chance to expand it, because the capital of 20 people may not be sufficient.
6. NO LEGAL ENTITY
Law does not recognize a partnership as an organization having an entity existence separate from the partners who comprises it.
7. LACK OF SECRECY
Secrecy in business is necessary for its success. It is not possible sometimes in partnership.
PARTNERSHIP DEEDS OR PARTNERSHIP AGREEMENT
It is document in which the term and condition of partnership agreement are written. Hence contract is said to be the essence of partnership business. It can be oral or written. The written document of partnership is known as partnership deeds. Partnership may be formed and condition of the contract put down in black and white. The partner is to be free from future confusions and misunderstandings. Good relation between partners may not continue for a long time.
In future there may be difference of opinion between the partners on some points. The differences may only be removed if the terms and conditions are in the document to avoid future disputes and misunderstanding between partners. A well drawn up partnership deed usually contains the following forms:
1. Name of the firm
2. The nature and object of the business
3. The duration of the business.
4. The names and address of the partners.
5. The amount of capital of the firm and the amount contributed by each partners.
6. The ratio of sharing of profits and losses of the firm
7. The management of the firm.
8. Salaries if any paid to partners.
9. Interest on partners.
10. The rights and duties of the partners.
11. The valuation and treatment of good will in case of dissolution of the firm.
12. Rules and regulation regarding the admission of new partners and expulsion and retirement of an existing partner.
13. Appointment of an arbitrator to settle disputes if any among the partners.
14. The names of banks where firm accounts will be opened.
15. The names of auditor or who will inspect the books of accounts.
16. The names of partners who will sign the important document.
17. The procedure of the dissolution of the firm and settlement of accounts.
18. Any other clause or clauses necessary for future safety for the conveniences of the partner.
The partnership deeds must be signed by all the partners.
RULES APPLICABLE IN THE ABSENCE OF AN AGREEMENT
In the absence of any agreement, the following rules are applicable. These rules are contained in Section 12 to 17 of the Indian Partnership Act as adopted in Pakistan.
1. Every partner has a right to take part in the conduct of the business.
2. In case of any difference arising out in ordinary matter connected with the business, the decision may be taken by a majority of the partners.
3. No change can be made in the nature of the business without the consent of all the partners.
4. Partners have right to see, inspect and copy any of the books of the firm. No remuneration is allowed to any partner.
5. All the partners will share equality in the profits and contribute equally to the losses.
6. Six percent interest is to be paid on the loan advanced by any partner.
7. The partnership firm must indemnify a partner in respect of payment made by the partner to the third party and also any liability incurred by any partner in the ordinary and proper conduct of the business.
8. A partner must indemnify the firm for any loss caused to the firm by his willful neglect in the conduct of the business of the firm.
9. All the property of the firm is to be held and used by the partners exclusively for the purposes of the business. In case a partner carries out any business competing with that of the firm, all profits made by him in that business should be paid to the firm.
REGISTRATION OF PARTNERSHIP FIRM
The partnership act of 1932 has not made registration of the firm compulsory in our country. It is quite optional. It depends upon the willingness of the partners whether the firm has to be registered or not. If they wish they can register their firm with the registrar pof the firms by filing with him a statement containing certain information and depositing requisite registration fees. It is essential that statement must be signed by all the partners and should contain following particulars;
1. the name of the firm,
2. The principal place of the business.
3. The names of the other places were firm may carry out its business.
4. The date on which each partner entered into the firm.
5. The names and permanent addresses of all the partners of the firm.
6. the duration of the firm
Now if the registrar is satisfied with the information provided and he thinks its necessary then he will register the firm. The name of the firm is then recorded in the register maintained for the purpose in the office of the registrar. The partnership act does not make the registration compulsory. However it imposes certain disabilities on the partners of an unregistered firm. If it is not registered, it will not be able to enforce its claim against third party against his follow partners.
DISSOLUTION OR LIQUIDATION
A partnership may be dissolved in any of the following manners.
1. DISSOLUTION BY AGREEMENT
A partnership may be dissolved when the partner is of one opinion to dissolve the firm, or it may be dissolved according to the contracts between the partners.
2. DISSOLUTION ON THE HAPPENING OF CERTAIN CONTINGENCIES
a) If a partnership has been formed for a fixed term, then it can be dissolved after the expirer of the term.
b) If the partnership has been formed for carrying on one or more venture, then it can be dissolved after completion of that venture or ventures.
c) On the death of partner it may be resolved.
d) By adjudication of a partner as an insolvent by the court of law.
e) A partnership may be dissolved on the insolvency of itself.
3. DISSOLUTION BY NOTICE OF PARTNERSHIP AT-WILL
A partnership at will may be dissolved at any time if any one of the partners gives notice in writing to all the partners of the firm of his intention to dissolve the firm.
4. COMPULSORY DISSOLUTION
a) By the adjudication of all the partners or of all but one partners as insolvent.
b) By the happening of an event which makes it illegal or unlawful for the business to be carried on.
5. DISSOLUTION BY THE COURT
If any partner brings a suit in the court, the court may dissolve the firm on any on any of the following grounds.
a) When a partner becomes of unsound mind.
b) When the partner becomes permanently incapable of performing his duties as a partner.
c) When the partner becomes guilty of his misconducts in carrying on business.
d) If partner willfully commits breach of agreements in the matter of managing the affairs of the firm or his misconducts is such that it is not possible on the part of other partners to carry on business of the firm with him.
e) If the partners transfers his entire share to other or his share in the firm have been changed by the court for his debts.
f) Where a partnership cannot be carried on except at a loss.
g) On any other grounds on which the court thinks just and equitable to wind up the business.

Class XI, Principles of Commerce, "Commencement of New Business"

Q: What is the important consideration for the commencement of new business? OR What are the important points a business will consider first before the starting of new business? INTRODUCTION
There was a time when any body thought of setting up a shop to earn could launch upon the said enterprise with fair expectations of success. But those comfortable days have sunk into the yawning gulf of the time. In modern times of over crowded business, business has become a very risky game and those who are engage in it have to take utmost precautions and care at every step. This is more so at the time of commencement of a new business.
FUNDAMENTAL CONSIDERATION IN STARTING A BUSINESS
Before starting a business a plan and a systematic study should be made of various preliminary considerations upon which depends the success or failure of business. The various considerations which must be carefully thought over before starting a business are discussed below.
1. KIND OF BUSINESS
The first thing which man is extending to enter into a business has to consider is the kind of the business he should take up. There are so many classes and sub classes of business. And to pick up the best and most profitable line out them requires considerable knowledge, experience and for sight. The criteria determining the suitability or otherwise of a business are several. The are profit yielding capacity, the degree of risk involved. The extend of skill and knowledge and finally the personnel taste of a person.
2. FORMS OF BUSINESS ORGANIZATION
Once the actual business to be launched upon is decided the next logical question coming up for consideration is the form of business establishment is to take. In other words it has to be settled whether is to be one man’s business or partnership or joint stick company. Hence a business should be given a form which is most suited to it from all angle of vision.
3. ESTIMATION OF PROFITABILITY OF BUSINESS
Next stage is to estimate the profitability of the business which the product and service which are going to be sold will give.
4. SIZE OF BUSINESS
There are three types of business, via, manufacturing, non-manufacturing and services. All the three kinds may be large, medium or small. The size of business depends upon the recourses which a business man is going to invest. So the business man will consider what size of business he should start and how much he should invest so that he can earn profit according to his requirements.
5. FINANCE
Financial consideration is very important before staring a business. Unless sufficient funds are not arranges it would not be possible to operate the business. The funds or capital can be arranged by the owner himself or credit.
6. KNOWLEDGE OF THE MARKET
The knowledge of the market available for the particular product is necessary part for the business man to know. Before staring a business he should have information regarding the target customers, income patterns, buying habits and tastes, numbers of competitors etc.
7. LOCATION
Another worth considering factor is the location. If it is manufacturing business one must consider the availability of raw material, skilled labor, transportation etc. and if it is a retail business then factors like nearest to market, sale promotional devices come under consideration.
8. ORGANIZATION AND MANAGEMENT
The managerial and organizing capacities must be considered very carefully. Large business has huge complicated managerial problems. So skilled and qualified employer must be hired.
9. GOVERNMENT POLICIES
The government has formulated some rules and regulations for the particular type of business, to regulate the activities of the business. So the government policies should be considered. After establishment, income, tax, sales tax etc. must also be considered.
10. STAFF OF THE OFFICE
The business may require the service of some clerk; salesman etc. special care should be bestowed on engaging the staff. Efficiency should never be scarified for cheapness. The sound course is to make correct salaries in proper proportion.
11. OFFICE EQUIPMENT
Every business has to maintain an office. In these days of rapid development, stationery type writers, duplicating machines etc. must be provided, so that the business process are more quick and efficiently carried out.
12. BUSINESS ETHICS OR MORAL
Morally in business as anywhere else has distinct role to play in the shaping of successful business career. Business ethics is more important because it shapes sound. Economic policy, honest cost accounting sounds credit arrangement.

Class XI, Principles of Commerce, "Commerce and Its Scope"

Scope of Commerce Commerce means the process of distribution of goods which means removal of goods from a place where they are produce and found in abundant to a place where they are scare and hence in demand. It is a vast and complex organism and embraces all the functions involved in the buying and selling of goods. It is rightly said that commerce is the life blood of a nation. A nation economic prosperity is entirely dependent upon the development in the field of commerce. The most obvious effect of the development as said before has been the availability of such goods to a community which, out of necessity are produce elsewhere.
Some of the definitions of commerce is reproduced below;
“The term commerce embodies all the operations connected with the act of exchange goods and services”
“In the widest sense the term commerce is applied to all these activities or functions which are intended to bring about an exchange of goods and services against money or money’s worth. It covers trade as well as the aids to trade, such as banking, insurance and transport.”
“Commerce comprises a group of specialized activities which together from an essential part of the process of production. It links the suppliers and the consumers by means of trade and activities auxiliary to trade such as banking, insurance and transport and warehousing.”
It is now made clear that commerce is basically concerned with the production and distribution of goods. Under commerce we study those activities which help produce good and services and their distribution. In the chain of productivity the first in the line is the extractors or cultivators and the last link is the consumers. To elaborate this statement it can be said that extractive activities related to raising from the soil or obtain from beneath earth various form of wealth. Manufacturing consists of activities which are concerned with the working up of the raw material from the extractive industry into finished products. The commercial and distributive group includes all those people who are concerned with the transfer of raw material from the producer to consumers. It consists of this entire person who is engaged in the distribution of goods such as railways, banks, insurance companies, brokers, wholesalers, retailers, etc.
Thus it can be fairly said that commerce is the sum of total of all the activities beginning from the place of production and ending at the retailer’s shop from where the consumer purchases his goods.
Divisions of Commerce
Commerce is divided into trades and auxiliaries of trade. Trade simply means selling and buying of goods. A mediation of the exchange of goods between the producer and the consumer is called trade. Trade is of two kind Home trade and foreign trade. The trade which is done with in the country is called home trade. The trade which is done between two countries is called foreign trade. Auxiliaries to trade mean aids to trade. It includes the following services; banking, insurance, warehousing and agents.
BANKING
Banking business not only provides the facility of advancing the loans but also provides the facilities of transferring the money from one country to another. Foreign trade is impossible with out the services of the bank. Bank provide loan and thus advance means by which capital is transferred from those who can not profitable use it to those who can use it more productively for the benefits of society as a whole.
INSURANCE COMPANY
At the present stage of business development every capitalist does not invest capital in large amount without any security from loss. Insurance company come forward and takes the risk enabling the business man to run the business without any hesitation.
TRANSPORTS
Transportation services are considered as a backbone for the development of the trade. Highly developed transport system is very necessary for the commercial development of the county. Transport performs the entire work of assembling and distributing of goods. It adds place utility to producer things. It helps widen the market for the commodity. It services the purpose of. Commerce to large extends. i.e. in getting the greater satisfaction by using product of greater diversity of choice at reasonable prices.
WARE HOUSING
Business man needs some place to store his goods. If he cannot afford his own gawdon than he hires the go-down i.e. he obtains the service of ware house to store his good in bulk or small quantity.
MERCANTILE AGENTS
They are those middle men who create links between the producer and the wholesaler. They take the goods from producer on their behalf and sell the goods to the wholesalers.
Difference between Commerce and Trade, Commerce and Industry, Commerce and Business
Business is a wide term and it includes all the activities carried out for mutual gain or profit and where exchange of something valuable (goods or services) takes place. Business activities may be classified as:
1) Commerce
2) Industry
3) Service.
Industry involves the production of goods and materials. Commerce deals with their distribution. As far services doctors, teachers. Fisherman’s, weavers, they are all businessmen since they sell their services. Hence an agency through which business is regularly conducted may be an industrial enterprise, commercial unit or a service establishment.
COMMERCE
Commerce is the branch of business. It is the aggregate of all the activities which take place between the producer and the consumers. All these occupations which affect the exchange of goods and services between producers and consumers stand within the scope of commerce. It embraces all those functions which are essential for maintaining a free and uninterrupted flow of goods and services between those who produce and those who consume. It includes trade as well as auxiliary to trade.
TRADE
Trade stand within the scope of commerce. It is concerned with buying and selling of goods. It fulfills the aims of productions which is consumption. It is a mean to exchange things we do not need for things which we need. Trade can be of two types.
1) Foreign or international trade.
2) Home or internal trade.
Foreign trade means trade with foreign countries. Such a trade is carried out on a whole sale basis. It can be classified as follow.
a) import trade: buying goods from suppliers in other countries.
b) Export trade: selling of goods to purchasers in other countries.
The trade which is done with in the country is called home trade. It can be conducted on one of the following basis;
a) Whole sale trade
b) Retail trade
A whole sale merchant deals in large quantity but limited variety of goods. A retail merchant on the other hand deals in small quantity of large variety of goods.
INDUSTRY
The term industry refers to the productive aspects of business. It creates “Form Utility’ for the satisfaction of human wants and hence play and important role. Industry may be classified into following ways.
a) Extractive Industries: In which goods are extracted or raised from the soil, air, or water.
b) Genetic Industries: they involve reproducing or multiplying certain species of plant and animals as in the case of agriculture, cattle breeding etc.
c) Manufacturing Industries: which are considered with the transformation of the raw material or semi manufactured goods into finished products creating “form utility” as in case of spinning and weaving textiles from cotton.
d) Construction industries; which include construction of buildings, roads, bridge, dams, canals etc.

Class XI, BIOLOGY, "Immune System"

Immune System

IMMUNITY
DEFINITION
“The ability of human body to resist almost all types of micro-organisms, their toxins if any, foreign cells & abnormal cells of the body is termed as “Immunity”
IMMUNOLOGY
DEFINITION
“The study of functioning & disorders of Immune system is termed as “Immunology”.
IMMUNE SYSTEM
Immunity is conferred to animals through the activities of the Immune System, which combats infectious agents.
DEFINITION
“Immune System is a collection of cells & proteins that work to protect the body from potentially harmful, infectious micro-organisms”
MAIN FUNCTIONS OF IMMUNE SYSTEM
Protection of body from all types of micro organisms & toxins that tend to damage the tissues and organs of body.
ADDITIONAL FUNCTIONS
Immune system also play important role in:

• Control of cancer
• Allergy
• Hypersensitivity
• Rejection problems when organs or tissues are transplanted.

DIVISIONS OF IMMUNE SYSTEM
Immune system can be divided into two functional divisions:
1. Innate Immunity System
2. Acquired Immunity System
INNATE IMMUNITY
DEFINITION
“The NON SPECIFIC type of immunity which result from general processes , rather than from processes directed at specific disease organism (Such as antigen –antibody reaction) is called. INNATE OR NATURAL IMMUNITY & the system which is responsible for this type of immunity is called Innate IMMUNITY System.
TYPES OF BARRIERS PROVIDED BY INNATE IMMUNITY SYSTEM
This system provides two types of barriers:
Physical Barrier
Chemical Barrier
PHYSICAL BARRIERS

• SKIN
• MUCOUS MEMBRANE & etc.

CHEMICAL BARRIERS

• Lysozyme
• Gastric juice (Acidic secretion of stomach) & etc.

FIRST LINE OF DEFENCE
Skin, Mucous membrane & their secretions act as “First line of Defence”
1. SKIN
The intact skin provides an impenetrable barrier to the vast majority of infectious agents.
2. MUCOUS MEMBRANES
Most of the micro-organisms can enter only through the mucous membranes that lines the digestive, respiratory & urogenital tracts. However these areas are protected by movements of mucous & secretions (e.g Lysozyme in tears) to destroy many microbs.
3. ACIDIC SECRETIONS
Most of he microorganisms present in food or trapped in swallowed mucus from the upper respiratory tracts are destroyed by highly acidic gastric juice of stomach.
SECOND LINE OF DEFENSE
If some how micro-organisms are able to penetrate the outer layer of the skin or mucous membrance, they encounter a second line of Defence offered by Innate Immunity system.
It is non specific & comprises of
1. PHAGOCYTES
2. ANTIMICROBIAL PROTEINS
3. INFLAMMATORY RESPONSE
1. PHAGOCYTES
Phagocytes are certain type of WBC’S which can injest internalize & destroy the particles including infectious agents.
EXAMPLES OF PHAGOCYTIC CELLS
NEUTROPHILS
MACROPHAGES
NEUTROPHILS
Neutrophils (Polymorphonuclear Neutrophiles are short lived phagocytic cells which can ingest the bacteria or any foreign matter very actively.
MACROPHAGES (BIG EATERS)
The other phagocytic cells, the MONOCYTE can develop into large LONG-LIVED MACRO PHAGES when they reside in various tissues of body. ALSO CALLED AS ANTIGEN PRESENTING CELLS.
Macrophages not only destroy individual micro organisms but also play a crucial rule in further immune response by “Presenting” parts of that microorganisms to other cells of immune system. For this reason, they are termed as “ANTIGEN PRESENTING CELLS.
NATURAL KILLER (NK ) CELLS
Natural killer cells (NK Cells ) are the large lymphocytes, which destroy the

• Virally infected own cells of the body
• Foreign cells
• Abnormal cells (cancerous cells)

MECHANISM OF ACTION (CYTOTOXICITY)
NK cells do not phagocytize the target cells, instead, they bind to their target cells, release some PORE FORMING PROTEINS (PERFORINS), that literally punch large round holes in the membrane of attacked cells & eventually cause lysis of the target cells. This kind of destroying the target cells is called “CYTOTOXICITY”
2. ANTIMICROBIAL PROTEINS
EXAMPLES

• Important antimicrobial proteins are:
• Lysozyme
• Compliment proteins
• Interferon

LYSOZYMES
Lysozyme, is a mucolytic polysaccharide that causes the LYSIS OF BACTERIA it is present in TEARS, SALIVA, & MUCUS SECRETION.
COMPLEMENT PROTEINS
Complement is a collective terms that describes a system of about 20 PROTEINS, many of which are INACTIVE ENZYME PRECURSORS. The principal actors in this system are 11 Proteins. All these proteins are present among the Plasma Proteins.
ACTIVATION OF COMPLIMENT PROTEINS
These proteins can be activated by two ways.

• CLASSICAL PATH WAY-Act in Adaptive Immunity system.
• ALTERNATIVE PATH WAY- Act in Innate Immunity System.

FUNCTIONS
Main functions of compliment proteins are as follows:
1. DIRECT LYSIS OF BACTERIA
2. PROMOTE THE PHAGOCYTOSIS OF BACTERIA
3. NEUTRILIZATION OF VIRUSES
4. CHEMOATTRACTANTS FOR MACROPHAGES.
INTERFERONS (ANTIVIRAL AGENTS)
Interferon are secreted by virally infected cells or some lymphocytes to induce a state of ANTI VIRAL RESISTANCE in unaffected tissues of the body.
3. INFLAMMATION
Inflammation is the body’s reaction to an injury or by entry of micro organisms.
EFFECTS OF INFLAMMATION
A cascade of chemical reactions take place during inflammatory response.
1. When injured, BASOPHILS and MAST CELLS release a substance called HISTAMINE which causes.

• Increased permeability of adjacent capillaries.
• Local vasodilatation
• Increased leakage of capillaries.

2. Due to CHEMOTAXIS, Phagocytes & macrophages are attracted at the injured site. Thus Phagocytes literally eat up microorganisms, dirt, cell debris & etc forming pus.
SYMPTOMS
Redness, heat, swelling, pain in injured tissue.
FEVER -(ALSO CONTRIBUTES TO DEFENSE OF BODY)
In case of warm blooded animals, a no. of micro organisms who escape away from inflammatory response to infect some large part of the body, trigger FEVER. It is usually caused by WBC’S, that release the substance called as PYROGEN.
FUNCTIONS

• High fever is dangerous but moderate fever contributes to the defense of the body.
• It inhibits the growth of micro-organisms.
• May speed up the repair of damaged tissues.
• Facilitates the phagocytosis, increase the production of interferons.

ADAPTIVE IMMUNE SYSTEM
DEFINITION
“The specific type of Immunity which does not develop until after the body is first attacked by a bacterial disease or a toxin, is called “Adaptive or Acquired Immunity”. The system which provides this type of immunity is called “ADAPTIVE or ACQUIRED IMMUNE SYSTEM”

OR
“Acquired Immunity is provided by special Immune System that form Antibodies & activated lymphocytes that attack & destroy the specific organisms or toxins. This is the THIRD LINE OF DEFENCE.
DEVELOPMENT OF IMMUNE SYSTEM (LYMPHOCYTES ARE THE BASIS OF ADAPTIVE IMMUNE SYSTEM)
Acquired Immune system is actually the product of body’s Lymphocytic system. The responses of adaptive Immune system is provided by Lymphocytes.
TYPES OF LYMPHOCYTES
During fetal development, all lymphocytes come from Bone Marrow. But depending upon their migration & maturity, they can be divided into two populations.
1. “T” – Cells or “T” LYMPHOCYTES
2. “B” – Cells or “B” LYMPHOCYTES.
1. “T” LYMPHOCYTES
DEFINITION
“The lymphocytes that are destined to eventually form ACTIVATED “T” LYMPOCYTES first migrate to & then mature in THYMUS GLAND, that is why, they are called as “T” LYMPHOCYTES”
FUNCTIONS
These are responsible for “CELL-MEDIATED IMMUNITY
2. “B” LYMPHOCYTES
DEFINITION
“The lymphocytes that are destined to form ANTIBODIES are processed first in the LIVER (before birth) & then in BONE MARROW (after the birth). This population of cells was first discovered in birds where processing occurs in BURSA OF FABRICIUS (not found in mammals), hence they are called as “B” LYMPHOCYTES.”
FUNCTIONS
These are responsible for HUMORAL IMMUNITY
ADAPTIVE IMMUNE SYSTEM IS INITIATED BY ANTIGENS
In order to develop a specific immune response, the immune system must recognize the invading organisms and / or foreign proteins from its self tissues & proteins.
ANTIGEN
Any foreign substance, that elicit the immune response is called antigen. In general Antigens are proteins or large polysaccharides.
RESPONSE OF IMMUNE SYSTEM TO ANTIGEN
The immune system responds to an antigen by ACTIVATING LYMPHOCYTES & PRODUCING ANTIBODIES (Soluble Proteins). The antibody combines with antigen & helps to eliminate it from the body.
BASIC TYPES OF ADAPTIVE IMMUNITY
The adaptive immune system mounts two types of attacks on invading micro-organisms.
1. HUMORAL IMMUNITY
2. CELL MEDIATED IMMUNITY (CMI)
1. HUMORAL IMMUNITY
DEFINITION
“The immunity which is mediated by circulating antibodies produced by B-lymphocytes is called “ HUMORAL IMMUNITY”.

MAJOR FUCTIONS OF HUMORAL IMMUNITY
Humoral Immunity provides major defence against “BACTERIAL INFECTIONS
MECHANISM OF ACTION OF B CELLS
“B” CELL RECEPTORS
Each B-cell has specific type of antibodies on its cell surface. This antibody serves as ANTIGENIC RECEPTOR.
ACTIVATION OF SPECIFIC “B” CELLS
On entry of foreign antigen, those B cells specific for that antigen enlarge immediately, becomes activated & form two types of cells:
1. PLASMA CELLS
2. MEMORY CELLS
1. PLASMA CELLS
The activated B-cells proliferate rapidly & transform into enlarged effectors cells called plasma cells.
FUNCTION
Plasma cells secrete ANTIBODIES into the circulation that help to eliminate that particular antigen.
ACTIONS OF ANTIBODIES.
After the formation of antigen-antibody complex antibody can inactivate the invading agent in one of the several ways.

• By activation of complement system that cause the Lysis.
• Direct Phagocytosis.
• Neutralization of the toxins released by bacteria.
• Agglutination of microorganism.

2. MEMORY CELLS
DEFINITION
Some of the activated B-cells don’t go on to form the plasma cells but instead, form moderate number of new B-cells, which don’t secrete antibodies such cells are called as Memory cells.

FUNCTIONS
The memory cells play important role in future immunity to this specific organism in case of re-infection.
2. CELL MEDIATED IMMUNITY (CMI)
DEFINITION
The second type of acquired immunity is achieved through the formation of large number of Activated LYMPHOCYTES. This is called cell mediated or T-cell immunity.
FUNCTIONS OF CMI

• CMI is responsible for delayed allergic reactions & rejection of transplantation of foreign tissue.
• It provides major defence against infections due to VIRUSES, FUNGI, TUBERCLE BACILLI & some parasites.
• It also provides defence against TUMOUR CELLS.

MECHANISM OF ACTION OF “T”-CELLS.
T-CELL RECEPTORS (TCRS)
Antigens bind with specific RECEPTOR MOLECULES on the surface of T-Cells, in the same way that they bind the antibodies.
ACTIVATION OF SPECIFIC “T” CELLS.
On exposure to proper antigen, the “T” cells of specific type proliferate & release large no. of activated T-Cells.
SEVERAL TYPES OF “T” CELLS
Different types of T cells are classified into four major groups.
1. HELPER “T” CELLS
2. CYTOTOXIC “T” CELLS
3. SUPRESSER “T” CELLS
4. MEMORY “T” CELLS
1. HELPER “T” CELLS
Helper T cells are the MAJOR REGULATOR of all the immune functions.
RECEPTORS
Helper T cell receptors actually recognize a combination of antigen fragment & one of the body’s own self marker called. “MAJOR HISTO-COMPATIBILITY” (MHC) CLASS II molecules on the surface of macrophages or B cells.
FUNCTIONS
Helper T-cells secrete the LYMPHOKINES which stimulate the production of both CYTOTOXIC & SUPRESSER TOXINS.
2. CYTOTOXIC “T” CELLS (KILLER CELLS)
RECEPTORS
Receptors on the surface of cytotoxic ‘T” cells recognize a combination of antigen fragment & self surface marker molecules called MHC CLASS I , found on every nucleated cells of its own body.
FUNCTIONS
They are especially lethal to virally infected cells. They also destroy the cancer cells, heart transplant cells & other foreign cells.
3. SUPRESSOR “T” CELLS
Along with helper cells, In supressor, T-cells are classified as Regulatory T-Cells
FUNCTIONS
After the conquerence of infection, they seems to shut off the immune response in both B-cells & cytotoxic T-cells.
4. MEMORY “T” CELLS
During CMI response, some T-cells turn into MEMORY CELLS
FUNCTION
Memory cells protect the body in case of reaction in future.
TYPES OF IMMUNE RESPONSE
The immune system has also the ability to memorize the antigen it has encountered. Thus upon subsequent exposure to the same pathogen responds in two different ways.
1. Primary Immune Response
2. Secondary Immune Response
1. PRIMARY IMMUNE RESPONSE
DEFINITION
The first exposure to an antigen to the immune system elicits formation of clones of effectors cells to develop specific immunity with in 5 to 10 days. This response of immune system is termed as Primary Immune response.
CHARACTERISTICS

• DELAYED APPEARANCE
• WEAK POTENCY
• SHORT LIFE

2. SECONDARY IMMUNE RESPONSE
DEFINITION
Subsequent exposure of same antigen causes a much more rapid & much more potent antibody response. This is called Secondary Immune response. It develops to it max. with in 3-5 days.
CHARACTERISTICS

• Rapid & quicker appearance
• Far more potent
• Longer duration (form antibodies for many months rather than for only a few weeks.)

BASIS OF SECONDARY RESPONSE (IMMUNOLOGICAL MEMORY)
The quicker secondary response is made possible due to ability called “Immunological Memory” of the immune system. It is based upon the long lasting memory cells produced with short lived effectors cells of pri immune response. The development of memory cells may provide life long protection against some diseases like chicken pox.
ACTIVE & PASSIVE IMMUNITY
ACTIVE IMMUNITY
DEFINITION
The immunity which is acquired by own immune response is called active immunity
FUNCTION OF ACTIVE IMMUNITY
Active immunity due to development of immunological memory provide LONG TERM PROTECTION, even in some diseases (e.g in chicken Pox ) life long protection is provided.
TYPES OF ACTIVE IMMUNITY
There are two types.
1. Natural active immunity
2. Artificial active Immunity
1. NATURAL ACTIVE IMMUNITY
DEFINITION
When the active immunity is acquired as a consequence of natural infection then it is called Natural active immunity”
2. ARTIFICIAL ACTIVE IMMUNITY
DEFINITION
Active immunity can be acquired artificially by vaccination. In this case it is said to be “ARTIFICIAL ACTIVE IMMUNITY”
PASSIVE IMMUNITY
DEFINITION
Temporary immunity which is achieved in a person without injecting an antigen, by transferring the antibodies, activated T-cells or both obtain from another person or even an animal, is called passive immunity.
FUNCTIONS OF PASSIVE IMMUNITY
Although, acquired passive immunity is short lived (last for 2-3 weeks), it boosts the immune response of the victim several folds.
TYPES OF PASSIVE IMMUNITY
There are 2 Types:
1. Natural passive Immunity
2. Artificial passive Immunity
1. NATURAL PASSIVE IMMUNITY
DEFINITION
When antibodies are transferred from one person to another of the same species during natural processes, then such immunity is called Natural passive immunity.

EXAMPLE
A pregnant woman passes some of the antibodies to her fetus through placenta. The first breast feeding, the colostrum, of mother pass certain antibodies to her newly born infant.
2. ARTIFICIAL PASSIVE IMMUNITY
DEFINITION
PASSIVE IMMUNITY can also be transferred artificially by introducing antibodies derived from animals or human being who are already actively immunized to that disease. This is called artificial passive immunity.

EXAMPLE
RABIES is treated in man by injecting antibodies derided from persons who have been already vaccinated against rabies. This confers the rapid immunity to combat the rapidly progressing rabies in new victim.
IMMUNIZATION
The process of inducing immunity as a preventive measure against certain infectious diseases is called immunization.
ADVANTAGES OF IMMUNIZATION
The incidence of number of diseases (e.g Diptheria, Measles) has declined dramatically since the introduction of effective immunization programmes. Some dread full diseases (e.g. Tuberclosis) is now under control.

Class XI, BIOLOGY, "Lymphatic System"

Lymphatic System

MAIN FUNCTION OF LYMPHATIC SYSTEM
All body tissues are bathed in a watery fluid derived from the blood stream. This intercellular or tissue fluid is formed when blood passes trough the capillaries. The capillary walls are permeable to all components of blood except the R.B.C’s & blood proteins. The fluid passes from the capillary into the intercellular spaces as the inter-cellular or tissue fluid. About 85% of the tissue fluid returns into the blood at the venous end of capillary. The rest 15 % of tissue fluid drains into lymphatic capillaries as lymph along with W.B.C’s, cell debris & micro organism like Bacteria , are transported back to the heart through lymphatic system.
COMPONENTS OF LYMPHATIC SYSTEM
Lymphatic System Consists of
1. Lymph
2. Lymphatic tissues
3. Lymphatic vessels or Lymphatics
4. Lymph nodes (type of lymphatic tissue)
DETAILS OF COMPONENTS
1. LYMPH
DEFINITION
“Lymph is the name given to the tissue fluid once it has entered a lymphatic vessel. OR It can be defined as “Colour less body fluid that contains lymphocytes (agranular WBC’S), small proteins & fats”.
EXPLANATION
Lymph is a medium of exchange between blood & body cells. It takes the fluid substances from cell of tissues & intercellular spaces, which cannot penetrate the blood capillaries.
2.LYMPHATIC TISSUES
DEFINITION
“Lymphatic tissues are a type of connective tissues that contain large no. of lymphocytes”
ORGANS THAT CONTAIN LYMPHATIC TISSUES
Lymphatic tissue is organized into following structures (organs).

• Lymph nodes
• Thymus
• Spleen
• Tonsils
• Some of the patches of tissues in vermiform appendix & in small intestine.

FUNCTION
Lymphatic tissue is essential for immunologic defenses of the body against viruses & bacteria.
3. LYMPHATICS
DEFINITION
Lymphatic vessels or lymphatics are blind tubes that assist the cardiovascular system in removal of tissue fluid from tissues spaces of the body, the vessels then return the fluid to the blood.
AREAS WHERE LYMPHATIC ARE NOT PRESENT
Lymphatics are present in all tissues & organs of the body except.

• Central Nervous System
• The eye ball
• Internal Ear
• Epidermis of Skin
• Cartilage & bone

TYPES
Two Types of Lymphatics are there:-
SMALL - LYMPH CAPILLARIES
LARGE - LYMPH VESSELS.
1. LYMPH CAPILLARIES
DEFINITION
“Lymph capillaries are a network of thin walled, anastomosing, microscopic vessels which are closed towards the tissue sinuses & drain the Lymph from tissues.”
2. LYMPH VESSELS
DEFINATION
The capillaries are in turn drained by lymph tubes having larger diameters & beaded appearance, called the Lymph vessels.
These vessels contain smooth muscles in them as well as Internal valves to prevent the back flow of Lymph. The Lymph circulates through the Lymph vessels by the contraction of surrounding skeletal muscles in one direction (towards the heart). These vessels converge into collecting ducts i.e right
Lymphatic duct & thoracic duct that drain into large veins at the root of neck.
4. LYMPH NODES
DEFINITION
“Lymph nodes are lymphoid tissue which are present through out the course of Lymphatics, through which the lymph must passes”
INTERNAL STRUCTURE
Each node consists of a thin, fibrous, outer capsule & an inner mass of lymphoid tissue.
AFFERENT VESSELS
Several small Lymphatics which carry the lymph into the lymph node are referred to as “Afferent vessels.”
EFFERENT VESSEL
A single large vessel which carry the lymph away from the node is called “Efferent vessel”
FUNCTION
Lymph nodes act as filters that trap the microorganisms & other foreign bodies in the lymph. The Lymphocytes & macro-phages present here, neutralize & engulf the microorganisms, respectively.
MAJOR FUNCTIONS OF LYMPHATIC SYSTEM.
From Text Book Pg. 379.
EDEMA
DEFINITION
“Whenever the tissue fluid accumulates rather than being drained into the blood by the lymphatic system, tissue & body cavities become swollen. This condition is known as “Edema”.

TYPES OF EDEMA
There are two types of Edema.
1. INTRACELLULAR
2. EXTRACELLULAR
1. INTRACELLULAR EDEMA
“Accumulation of excess of fluid within the cells causing cellular swelling is called “Intra cellular Edema. It usually occurs after severe extracellular Edema.
2. EXTRACELLULAR EDEMA
“Excess fluid accumulation in extra cellular spaces is called Extracellular Edema. ”
It is the most commonly occurring form of Edema.
FACTORS CAUSING EDEMA
Any factor that increases the tissue fluid high enough than normal value can cause excess tissue fluid volume causing edema. Some of these factor are as follows.

• High blood pressure
• Kidney failure
• Hart failure & etc.

CAUSES OF EDEMA
Following are three main causes of Edema.
1. HYPOPROTEINEMIA (SEVERE DIETARY PROTEIN DEFICIENCY)
When body is starving for Amino acids, it consumes its own blood proteins. This reduces the osmotic potential of the blood causing tissue fluid to accumulate in body tissues rather than being drawn back into capillaries, resulting in Edema.
2. LYMPHATIC OBSTRUCITON (COMMONEST CAUSE –FILARIASIS )
Another cause of edema is lymphatic obstruction, which results in more & more protein collection in the local tissue fluid hence, the increased volume. Commonest cause of lymphatic obstruction is FILARIASIS (infection by NEMOTODES) such condition is also called as “Elephantiasis” (because of swollen legs).
3. INCREASED PERMEABILITY OF CAPILLARIES (CAUSES-BURNS & ALLERGIC REACTIONS)
Sometimes the permeability of capillaries increase due to burns or allergic reactions, so blood proteins & plasma come out of capillaries & enter the tissue fluid thus causing Edema.

Class XI, BIOLOGY, "Circulation of Blood"

Circulation of Blood

CARDIAC CYCLE
Sequence of events which take pace during completion of one heart beat is called “Cardiac Cycle”
PHASES
(I) DIASTOLE
It is resting period of heart chambers.
II) SYSTOLE
During which heart’s chambers contract. In cardiac cycle, blood is circulated in whole body.
TYPES OF CIRCULATION
PULMONARY CIRCULATION
In pulmonary circulation following events take place.
RT. ATRIAL SYSTOL
First the blood from whole systems of body, except lungs enter in right Atrium through superior and Inferior vena cavae into the right atrium by atiral systole, blood comes into right ventricle from right atrium via Tricuspid valve.
RT. VENTRICLE SYSTOLE
After coming of blood into the Rt. Ventricle, it goes to the lungs via pulmonary trunk by ventricular systole, for oxygenation of blood by passing through pulmonary valve.
SYSTEMIC CIRCULATION
In systemic circulation, following events take place.
LEFT ATRIAL SYSTOLE
When oxygenated blood comes into left atrium, then left atrial sytole causes blood to enter left ventricle through bicuspid valve
LEFT VENTRICULAR SYSTOLE
When blood reaches here it sends into aorta through aortic valve to provide blood to body systems.
CARDIAC OUTPUT
The blood volume pump per minute by left ventricle into the systemic circulation
HEART BEAT
The contraction of heart chambers are known heart beat which are regular, rhythmic.
Ventricular systole is LUB
Ventricular diastole is DUB
TIME FOR HEART BEAT
0.8 sec is time for one heart beat.
CONDUCTING SYSTEM OF HEART
It consists of
1.AV-NODE
2.SA-NODE
3)AV-BUNDLE
4) PURKINJI FIBERS.
1. SA-NODE
SA NODE found near upper end of superior vena cava in RT. atrium
PARTS
1. Specialized cardiac Muscles.
2. Autonomic Nerve endings.
FUNCTIONS
It Initiates the contraction of heart chambers through impulses & also transmit to AV node.
2. AV- NODE
It is found in lower end of RT. Atrium. Structurally it is smilar to SA-NODE
FUNCTION
It transmit nerve impulses to ventricles for contraction rhythmically.
3. AV-BUNDLE
AV BUNDLE are the fibers originate from AV node. The bundle divided into Right AV bundle, Left AV bundle
FUNCTION
It transmit nerve impulses to ventricles.
4. PURKINJI FIBERS
AV bundles red divided into small fibres which penetrate the ventricle wall also known as purkinji fibers / Bundle of His small thin fibers.
LEUKEMIA
DEFINATION
“The malignant disorder of increase number of abnormal leucocytes in blood.”
CAUSE
The cause of leukemia is unknown.
FACTORS
Factors associated with leukemia are

• Ionizing Radiation
• Cytotoxic drugs.
• Retroviruses.
• Genetic

EFFECTS OF DISEASE

• In result of leukemia, normal leucocytes counts become less.
• This is progressive, and fatal condition which leads to heamorrhage or infection

THALASSEMIA
DEFINITION
“Genetically impaired globin chains formation leads to impaired or defected formation of hemoglobin.”
GENETIC DISEASE
Thalassemia is a genetic disorder, it may be
1. Hetrozygous /Mild thalassemia:
2. Homozygous.
TYPE
BETA – Thalassemia
α – Thalassemia
BETA-THALASSEMIA
When globin chain is impaired or defected. It is most common one.
ALPHA-THALASSEMIA
when α-thalassemia globin chain of (HB) hemoglobin is defected.
KINDS OF THALASSEMIA
THALASSEMIA MINOR
When thalassemia is of heterozygous type with mild anemia.
THALASSEMIA MAJOR
When thalassemia is of homozygous type with profound hypochromic anemia. It is more common in children & results with enlargement of kidney.
REMEDY
The only remedy is transfusion of blood at regular intervals.
CVD CARDIOVASCULAR DISEASE
Diseases of heart, blood vessels and blood circulation are generally term as CVD.
ATHEROSCLEROSIS
The disease of arterial wall with lose of elasticity, thickness of inner wall causing narrowing of lumen, results in impairing of blood flow.
ATHEROMATOUS PLAQUES
The narrowing is due to formation of fatty lesions called atheromatous plaque in inner lining of arteries.
COMPONENTS OF PLAQUE
These plaques consist of

• LDL-LOW DENSITY LIPO PROTEINS
• DECAYING MUSCLES CELLS
• FIBROUS TISSUE
• PLATELETES
• CLUMP OF BLOOD

CAUSES
Smoking, Hypertension, Obesity, Diabetes (Severe), family history of arterial disease
EFFECTS
Atherosclerosis produces no symptoms until the damage to artery is so severe that it restricts blood flow.
ANGINA PECTORIS
If blood flow to heart muscles is restricted causes (cell damage) necrosis called angina pectoris. Pain in chest, arm, or jaws usually during exercise.
THROMBUS FORMATION
The formation of blood clot with in the intact blood vessel initiated by atheromatous plaque.
REASON FOR THROMBUS FORMATION
Due to formation athromatous plaque loss of elasticity, intact blood vessel get destroyed, blood from vessel wall comes out & later change to blood clot and blocks the lumen of small arteries.
RESULT OF THROMBUS FORMATION
Initially thrombus block the lumen partially result in decrease blood flow to organs & leading to impairment of physiology of organs. Later on, thrombus blocks the lumen completely so due to complete loss of blood supply, cells damage occur.
CORONARY THROMBOSIS
Type of thrombosis when narrowing of lumen occurs in coronary blood vessels due to formation of clot.
EFFECT
Occulsion of coronary atery causes myocardial infarction and heart attack.
HEAMORRHAGE
The escaping of blood from intact blood vessels.
STROKE
Most dangerous type of heamorrhage is that of brain which results in paralysis or strokes.
HAEMATOMA
The accumalation of blood in interstitial spaces known as haematoma.
This will lead to edema.
STROKE
DEFINITION
The damage to the part of brain caused by, restriction in blood supply or leakage of blood outside the vessels.
CHARACTERISTICS
Impairment of sensation, movement & function controlled by damage part of brain.
CAUSES

• Hypertension
• Atherosclerosis

HEMIPLEGIA
Damage to any, one cerebral hemisphere can cause weakness or paralyses of one side of body called hemiplegia
PRECAUTIONARY MEASURES
Blood pressure should be with in normal range through proper diet. Salt should be used in less quantities exercise should be the regular habit. Smoking must be avoided. Person life should be free of worries.
BLOOD VESSELS
DEFINITION
“The closed vessels or tubes through which transporting medium or blood circulate with in body called “blood vessels”.
TYPES OF BLOOD VESSELS
1. Arteries.
2. Capillaries.
3. Veins.
ARTERIES
DEFINITION
Thick walled blood vessels which carry blood from heart to the organs of body.
LAYERS
It consists of three layers.
1. Tunica Externa/ Adventitia
2. Tunica Media
3. Tunica Intima
1-TUNICA EXTERNA
It is thin but tough layer, having abundant amount of collagen fibers. It is outer most layer.
2-TUNICA MEDIA
The middle layer has smooth muscle fibers & elastin fibers. It is the thickest layer.
3-TUNICA INTIMA
It consists of squamous endothelium.
LUMEN
Thick walled vessels & having smaller lumen than that of veins except arteries of brain & related to cranium having large lumen.
SEMILUNAR VALVES
They are not present in arteries.
BRANCHES – DIVISIONS
Aorta divides into large arteries, large arteries into smaller arteries, smaller arteries into arterioles, then they give rise to capillary.
At arteriole level, small sphincters are present which are known as PRE-CAPILLARY SPHINCTER.
SPHINCTER
FUNCTION
They are for regulating the diastolic pressure.
CHARACTERSTICS

• Arteries are elastic so during systolic pressure, they do not rupture and dilate.
• During ceasement/ stopage of systolic pressure of heart, arteries contract & supply even flow of blood.
• The arteries carry oxygenated blood except pulmonary arteries.

VEINS
DEFINITION
The thin walled blood vessels that drian blood from body parts/organs into heart called veins.
LAYERS
Tunica Externa
Tunica Media
Tunica Intima
1. TUNICA EXTERNA
Thickest layer in veins. It contains collagen, elastin and smooth muscles cells.
2. TUNICA MEDIA
Not thicker as that of arteries. Elastic tissues and small smooth muscle.
3. TUNICA INTIMA
Contains endothelial cells layer.
LUMEN
It has large lumen and thin wall.
SEMILUNAR VALVES
They are present in veins to prevent back flow of blood in the influence of gravity.
TRIBUTARIES
Veninules -> small veins -> large veins -> vena cava.
BLOOD PRESSURE
In veins blood pressure is low and are non pulsatile.
CHARACTERISTICS
The blood flows slowly and smoothly in veins. Veins are superficial and collapse when empty.
CAPILARIES
The intimate microscopic closed channels of both arterial & veinous interconnected network is called capillaries.
DIAMETER
Capillaries are extremely narrow in diameter of about 7-10 μ.
LAYERS
Capillaries are thin walled vessels & contains single layer of endothelium which offers small resistance in transport of material across the capillary wall.
FUNCTION
Through diffusion and active transport of oxygen is transported to tissues & CO2 to capillaries. Nitrogenous waste is filtered through the capillaries into excretory tubules.
BLUE BABIES (CYANOSIS)
Blue baby is a layman terminology. In medical science it is known as cyanosis.
DEFINITION
The term cyanosis” means the blueish discolouration of the skin & mucous membrane due to excessive cone of reduced (deoxygenated haemoglobin) in the blood & it appears when reduced Hb conc in capillaries is more than 5 gm/dl of blood. The reduced Hb has an intense dark blue purple colour that is transmitted through the skin.
MOST COMMON CAUSE OF CYANOSIS
Although there are various other causes of cyanosis but the most common cause is CONGENITAL CYANOTIC HEART DISEASE.
BASIC CAUSE OF CYANOSIS
In congenital heart diseases, there is an abnormal connection b/w right and left side of heart, which permits the large amount of unoxygenated venous blood to bypass the pulmonary capillaries & dilute the oxygenated blood in systemic arteries i.e RIGHT TO LEFT SHUNT, which results in cyanosis.
SOME EXAMPLES OF CONGENITAL HEART DISEASES

• Some congenital heart diseases which are responsible for the abnormal connection between right and left sides of heart are as follows.
• ATRIAL SEPTUM DEFECT (ASD)
• VENTRICULAR SETPUM DEFECT (VSD)
• PERSISTANT DUCTUS ARTEROSUS
• In all these conditions, blood begins to flow from the aorta (left side) into pulmonary arteries (right side) & the people donot show cyanosis until late in life when heart fails or lungs become congested.

TETRALOGY OF FALLOT (RIGHT –TO-LEFT SHUNT)
It is the most common cause of cyanosis or blue baby in which aorta originates from right ventricles rather than left & receives deoxygenated blood.