Hello friends.. In today's topic we are going to discuss about the "ANATOMY & PHYSIOLOGY OF THE HEART".
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Channel link:https://www.youtube.com/channel/UCZrabu-CtMa5AEexu1j2GNw
English video:https://youtu.be/FoAgaIEYZXo
Tamil video:https://youtu.be/H0fgTUwZQlQ
STRUCTURE OF HEART:
The heart is a roughly conical shape.
It’s a hollow muscular organ.
It is about 10 cm long
The heart size is about the owner’s fist.
It weighs around 225 g in women and around 310 g in men .
ORGANS ASSOCIATED WITH HEART:
Inferiorly – the apex of the heart rests on the diaphragm
Superiorly – the aorta, superior vena cava, pulmonary artery ,pulmonary veins.
Posteriorly – the oesophagus, trachea, the left and the the right bronchus, descending aorta, the inferior vena cava and thoracic vertebrae
Laterally – the lungs
Anteriorly – the sternum, ribs , intercostal muscles.
LAYERS OF THE HEART:
The wall of heart consists of three layers of tissue
pericardium,
myocardium
endocardium.
Pericardium
The pericardium is the outermost layer and it consists of two sacs.
The outer sac OR the fibrous pericardium consists of fibrous tissue and the inner OR the serous pericardium consists of a continuous double layer of serous membrane.
INTERIOR OF THE HEART:
The heart is divided by a septum into right and left
Before birth, blood can cross the septum from one side to the other, after birth it cannot.
The right and the left side is divided by an atrioventricular valve. The upper part is known as the atrium and the lower one is the ventricle .
The atrioventricular valves are made up of double folds of endocardium which are strengthened by a little fibrous tissue.
The Right atrioventricular valve also known as The Tricuspid valve has three flaps or cusps and the Left atrioventricular valve or The Mitral valve has two cusps.
The valves are extend from the inferior surface of the cusps to little projections which are prevented from opening upwards into the atrium by tendinous cords called Chordae Tendinae.
RIGHT SIDE of the heart consists of Inferior and the superior vena cava, the pulmonary artery.
LEFT SIDE OF THE HEART consists of The 4 pulmonary veins and The aorta.
FLOW OF BLOOD IN THE HEART:
The blood flows inside the heart in one way.
The blood enters the heart through the atrium and passes to the ventricles below.
The valves between the atria and ventricles i.e. TRICUSPID & MITRAL VALVE open and close passively according to changes in pressure inside the chambers .
The valves open when the pressure in the atrium is greater than the ventricles.
During ventricular contraction or ventricular systole the pressure in the ventricles rises above the atria and the valves snap shut which prevents the backward flow of blood.
DEOXYGENATED BLOOD:
Taken into RIGHT ATRIUM- through The Superior and the Inferior vena cava .
Through TRICUSPID VALVE taken into RIGHT VENTRICLE.
From RIGHT VENTRICLE into Pulmonary artery.
From PULMONARY ARTERY Into lungs for purification [ The only artery which carries deoxygenated blood]
OXYENATED BLOOD:
From Lungs into LEFT ATRIUM through 4 Pulmonary veins.
Through MITRAL VALVE taken into LEFT VENTRICLE.
From left VENTRICLE- taken into Aorta.
Through Aorta taken into All the parts of the body.
The opening of the aorta is protected by the aortic valve which is formed by three semilunar cusps.
Both the atria contract at the same time which is followed by the simultaneous contraction of both the ventricles.
The muscle layer of the atria walls is thinner than the ventricles
The atria pump the blood only through the atrioventricular valves into the ventricles, the more powerful ventricles pump the blood to the lungs and the whole body.
The pulmonary trunk or The Pulmonary artery leaves the heart from the upper part of the right ventricle, and the aorta leaves from the upper part of the left ventricle.
BLOOD SUPPLY TO THE HEART / C0RONARY CIRCULATION:
Arterial supply
The Right and the Left coronary artery supply the heart with arterial blood , the coronary artery branch from the aorta .
The coronary arteries receives about 5% of the blood which is pumped from the heart, even though the heart is a small proportion of body weight.
In this 5% large blood supply proportion goes to the left ventricle.
VENOUS DRAINAGE:
Most of the venous blood is collected into cardiac veins that join and form the coronary sinus, which opens into the right atrium.
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