Draw nd explain the structure of human heart
Answers
The heart is a complex muscle that pumps blood through the three divisions of the circulatory system: the coronary (vessels that serve the heart), pulmonary (heart and lungs), and systemic (systems of the body). Coronary circulation intrinsic to the heart takes blood directly from the main artery (aorta) coming from the heart. For pulmonary and systemic circulation, the heart has to pump blood to the lungs or the rest of the body, respectively .
Circulatory SystemThe mammalian circulatory system is divided into three circuits: the systemic circuit, the pulmonary circuit, and the coronary circuit. Blood is pumped from veins of the systemic circuit into the right atrium of the heart, then into the right ventricle. Blood then enters the pulmonary circuit and is oxygenated by the lungs. From the pulmonary circuit, blood re-enters the heart through the left atrium. From the left ventricle, blood re-enters the systemic circuit through the aorta and is distributed to the rest of the body. The coronary circuit, which provides blood to the heart, is not shown.
The heart muscle is asymmetrical as a result of the distance blood must travel in the pulmonary and systemic circuits. Since the right side of the heart sends blood to the pulmonary circuit, it is smaller than the left side, which must send blood out to the whole body in the systemic circuit.
In humans, the heart is about the size of a clenched fist. It is divided into four chambers: two atria and two ventricles. There are one atrium and one ventricle on the right side and one atrium and one ventricle on the left side. The atria are the chambers that receive blood while the ventricles are the chambers that pump blood. The right atrium receives deoxygenated blood from the superior vena cava, which drains blood from the veins of the upper organs and arms. The right atrium also receives blood from the inferior vena cava, which drains blood from the veins of the lower organs and legs. In addition, the right atrium receives blood from the coronary sinus, which drains deoxygenated blood from the heart itself. This deoxygenated blood then passes to the right ventricle through the right atrioventricular valve (tricuspid valve), a flap of connective tissue that opens in only one direction to prevent the backflow of blood. After it is filled, the right ventricle pumps the blood through the pulmonary arteries to the lungs for re-oxygenation. After blood passes through the pulmonary arteries, the right semilunar valves close, preventing the blood from flowing backwards into the right ventricle. The left atrium then receives the oxygen-rich blood from the lungs via the pulmonary veins. The valve separating the chambers on the left side of the heart is called the biscuspid or mitral valve (left atrioventricular valve).The blood passes through the bicuspid valve to the left ventricle where it is pumped out through the aorta, the major artery of the body, taking oxygenated blood to the organs and muscles of the body. Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes, preventing blood from flowing backward into the left ventricle. This pattern of pumping is referred to as double circulation and is found in all mammals.
Human Heart(a) The heart is primarily made of a thick muscle layer, called the myocardium, surrounded by membranes. One-way valves separate the four chambers. (b) Blood vessels of the coronary system, including the coronary arteries and veins, keep the heart muscles oxygenated.
Structure of heart —
Pericardium —
Heart is enclosed in a sac pericardium. It is formed of two pericardial membranes. The space between these two membranes is occupied by the pericardial fluid. It Prevent friction between these membranes. Pericardium protects heart from injury.
Heart Chambers—
Human heart has four chambers—
Upper two chambers— right and left auricle.
Lower to Chambers— right and left ventricle.
Auricles—
Auricles are receiving Chambers of heart. They have comparatively thin walls. The right auricle receives deoxygenated blood from the whole body by to large vessel the superior and inferior Vena cava the left auricle receives oxygenated blood from lungs by four pulmonary veins.
Ventricles—
Ventricles are distributing Chambers of the heart. They pump blood into blood vessels. Their walls are thicker than those of auricles. The right ventricle receives deoxygenated blood from the right auricle and pump it into the lungs for oxygenation. The left ventricle is the largest heart chamber and has the thickest walls. It receives oxygenated blood from the right auricle and pumps it into the whole body.
Septum—
A muscular wall between left and right auricle is called interauricular septum and between the left and right ventricle is called interventricular septum, separates the left side of the heart from its right side so the blood cannot go from one auricle to the other auricle and from one ventricle to the other ventricle.
Significance of separation of right and left sides of heart—
Complete separation of right and left sides of heart prevents the mixing of oxygenated blood from deoxygenated blood. It has resulted in two independent circulations, pulmonary circulation and systemic circulation.
Cardiac valves—
There are four valves in the heart which control the direction of blood flow in the heart and into the blood vessels. They open and close about 100000 times a day.
Tricuspid valve—
It guards the opening of right auricle to the right ventricle.
Bicuspid valve—
It guards the opening of left auricle to the left ventricle.
Semilunar valve—
Semilunar valves are three half-moon shaped valves present in the base of pulmonary aorta and aorta. They control the flow of blood from right ventricle into pulmonary aorta and from left ventricle into aorta. when artria contract the cuspid valves open the ventricles contract the pulmonary and aortic semilunar valves open and the Cuspid valves are slam shut.
Function of valves—
Valves prevent the backflow of blood.
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