The human heart is one of the most important organs present in the body.
Heart – is a small hollow muscular organ , shaped somewhat like an upside-down pear , about the size of a fist, that is responsible for pumping blood throughout the blood vessels to various parts of the body, called the cardiovascular system.
The weight of the human heart can be anything in between 250 -400 grams. Heart is found superior to diaphragm, posterior to sternum, slightly left or center of the chest and between the lungs and is specifically located in the mediastinum of thoracic cavity. The average human heart beats at 72 bpm and pumps approximately 4.7-5.7 litres of blood per minute and more if you are running.
FOUR CHAMBERS OF THE HEART AND THEIR FUNCTIONS:
* two atria ( upper chambers) and
* two ventricles(lower chambers)
- The right atrium receives deoxygenated blood from the veins and pumps it to the right ventricle.
- The right ventricle receives deoxygenated blood from the right atrium and pumps it to the lungs, where it is oxygenation takes place..
- The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
- The left ventricle (the strongest chamber) receives oxygenated blood from the left atrium and pumps oxygen-rich blood to the rest of the body via aorta.
LAYERS OF THE HEART AND THEIR FUNCTIONS:
- Pericardium
The pericardium is the double walled , fluid filled sac that contains the heart and the proximal ends of the aorta, vena cava, and the pulmonary artery.
FUNCTIONS:
Holds the heart in the chest cavity.
Prevents the heart from becoming too large when blood volume increases.
Limits heart movements. - Myocardium
The myocardium is the thickest and middle layer of the heart. It is made of cardiac muscles, responsible for the heart’s pumping of blood to the entire body. The coronary arteries supply blood and oxygen to myocardium. - Endocardium
The endocardium is the thin inner layer of the heart. Its main function is to allow the smooth flow of blood through the heart.
FOUR VALVES OF THE HEART AND THEIR FUNCTIONS:
Function of the valves:
Controls the direction of blood flow,thus preventing the backward flow of blood.
Blood passes through a valve before leaving the four chamber of the heart that collect and pump blood. Valves are made of flaps, or leaflets that act as one-way inlets for blood coming into a ventricle and one-way outlets for blood leaving a ventricle. The four heart valves include the following:
- Tricuspid valve -( atrioventricular valve) located between the right atrium and the right ventricle( right side of the heart). The tricuspid valve is the first valve where blood flows through in the heart. It is made of three flaps, or leaflets, that work together to stop and start the flow of blood.
- Pulmonary valve – is the second valve of the heart referred as semilunar valve, because of its shape. It is located between the right ventricle and the pulmonary artery, which carries blood to the lungs. When the right ventricle contracts, the tricuspid valve opens, allowing blood to flow to the lungs.
- Mitral valve or bicuspid valve (atrioventricular valve) is the third valve of the heart. located between the left atrium and the left ventricle. The mitral valve is composed of two flaps, or leaflets, that prevent blood from flowing into the ventricle prematurely. When the atrium contracts, the mitral valve opens, allowing blood to move into the ventricle.
- Aortic valve -The aortic valve is the fourth heart valve, located between the left ventricle and the aorta . The valve is composed of three flaps or leaflets, working together to prevent blood from entering the aorta prematurely. The aortic valve opens when the ventricle contracts, allowing blood to move from the heart to the rest of the body.
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