Circulation of BloodCARDIAC CYCLE
Sequence of events which take pace during completion of one heart beat is called “Cardiac Cycle”
It is resting period of heart chambers.
During which heart’s chambers contract. In cardiac cycle, blood is circulated in whole body.
TYPES OF 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.
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.
The blood volume pump per minute by left ventricle into the systemic circulation
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
4) PURKINJI FIBERS.
SA NODE found near upper end of superior vena cava in RT. atrium
1. Specialized cardiac Muscles.
2. Autonomic Nerve endings.
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
It transmit nerve impulses to ventricles for contraction rhythmically.
AV BUNDLE are the fibers originate from AV node. The bundle divided into Right AV bundle, Left AV bundle
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.
“The malignant disorder of increase number of abnormal leucocytes in blood.”
The cause of leukemia is unknown.
Factors associated with leukemia are
- Ionizing Radiation
- Cytotoxic drugs.
- In result of leukemia, normal leucocytes counts become less.
- This is progressive, and fatal condition which leads to heamorrhage or infection
“Genetically impaired globin chains formation leads to impaired or defected formation of hemoglobin.”
Thalassemia is a genetic disorder, it may be
1. Hetrozygous /Mild thalassemia:
BETA – Thalassemia
α – Thalassemia
When globin chain is impaired or defected. It is most common one.
when α-thalassemia globin chain of (HB) hemoglobin is defected.
KINDS OF THALASSEMIA
When thalassemia is of heterozygous type with mild anemia.
When thalassemia is of homozygous type with profound hypochromic anemia. It is more common in children & results with enlargement of kidney.
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.
The disease of arterial wall with lose of elasticity, thickness of inner wall causing narrowing of lumen, results in impairing of blood flow.
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
- CLUMP OF BLOOD
Smoking, Hypertension, Obesity, Diabetes (Severe), family history of arterial disease
Atherosclerosis produces no symptoms until the damage to artery is so severe that it restricts blood flow.
If blood flow to heart muscles is restricted causes (cell damage) necrosis called angina pectoris. Pain in chest, arm, or jaws usually during exercise.
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.
Type of thrombosis when narrowing of lumen occurs in coronary blood vessels due to formation of clot.
Occulsion of coronary atery causes myocardial infarction and heart attack.
The escaping of blood from intact blood vessels.
Most dangerous type of heamorrhage is that of brain which results in paralysis or strokes.
The accumalation of blood in interstitial spaces known as haematoma.
This will lead to edema.
The damage to the part of brain caused by, restriction in blood supply or leakage of blood outside the vessels.
Impairment of sensation, movement & function controlled by damage part of brain.
Damage to any, one cerebral hemisphere can cause weakness or paralyses of one side of body called hemiplegia
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.
“The closed vessels or tubes through which transporting medium or blood circulate with in body called “blood vessels”.
TYPES OF BLOOD VESSELS
Thick walled blood vessels which carry blood from heart to the organs of body.
It consists of three layers.
1. Tunica Externa/ Adventitia
2. Tunica Media
3. Tunica Intima
It is thin but tough layer, having abundant amount of collagen fibers. It is outer most layer.
The middle layer has smooth muscle fibers & elastin fibers. It is the thickest layer.
It consists of squamous endothelium.
Thick walled vessels & having smaller lumen than that of veins except arteries of brain & related to cranium having large lumen.
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.
They are for regulating the diastolic pressure.
- 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.
The thin walled blood vessels that drian blood from body parts/organs into heart called veins.
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.
It has large lumen and thin wall.
They are present in veins to prevent back flow of blood in the influence of gravity.
Veninules -> small veins -> large veins -> vena cava.
In veins blood pressure is low and are non pulsatile.
The blood flows slowly and smoothly in veins. Veins are superficial and collapse when empty.
The intimate microscopic closed channels of both arterial & veinous interconnected network is called capillaries.
Capillaries are extremely narrow in diameter of about 7-10 μ.
Capillaries are thin walled vessels & contains single layer of endothelium which offers small resistance in transport of material across the capillary wall.
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.
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.
It is the most common cause of cyanosis or blue baby in which aorta originates from right ventricles rather than left & receives deoxygenated blood.