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.