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| Heart |
Heart is conical and hollow organ.
Location of heart
The heart lies in the thorax between the lungs behind the sternum.
Two third of the heart is on the left side.
Two third of the heart is on the left side.
Long - 12 Cm
wide - 9 cm
thick - 6Cm
in adult female, heart weight – 250gm
in adult male, heart weight – 300gm
Pericardium
The pericardium membrane is surrounds and protect the heart.
The pericardium consist of two main parts:
Fibrous pericardium
The superficial fibrous pericardium is composed of tough inelastic dense connective tissue.
Serous pericardium
The deeper serous pericardium is thinner or more delicate membrane that forms double layer around the heart.
The outer parietal layer of the serous pericardium is fused to the fibrous pericardium.
The inner visceral layer of the pericardium also called epicardium.
Between the parietal and visceral layer of the serous pericardium is a thinner film of lubricating serous fluid.
Layer of heart wall
The wall of the heart consist of three layer
- Epicardium (External layer)
- Myocaridum (middle layer)
- Endocardium (inner layer)
Chamber of the heart
The heart has four chambers.
The two superior receiving chambers are the arteria and interior pumping chambers are ventricles.
The two superior receiving chambers are the arteria and interior pumping chambers are ventricles.
Right atrium
The right artrium receive blood three veins:
- The superior vana cava
- Inferior vana cava
- Coronary sinus
Veins always carry blood toward the heart.
Arteries always take blood away from the heart.
Blood passes from the right artrium into the right ventricle through a valve that is called the tricuspid valve. Right atrium thickness around 2-3mm. it is also known as right atrioventricular valve.
Right ventricle
It thickness is 4-5mm. the right ventricle is seprated from the left ventricle by a thinner wall, called the interventricular septum. Blood passes from the right ventricle through the pulmonary valve in to a large artery called the pulmonary artery and carries blood into the lungs.
Left atrium
Its thickness 2-3mm. it receives blood from the lungs through pulmonary vein.
Blood passed from the left atrium into the left ventricle through the bicuspid valve (mitral valve or semilunar valve).
Blood passed from the left atrium into the left ventricle through the bicuspid valve (mitral valve or semilunar valve).
Left ventricle
Its thickness is 10-15mm. blood passes from the left ventricle through the aortic valve in to the ascending aorta. Some of blood in to the aorta flows into the coronary artery which carry blood to the heart wall. Blood passes into the arch of the aorta.
Valve of heart:
Tricuspid valve
That valve present in between right artrium and right ventricle.
Pulmonary valve
That valve present between right ventricle and pulmonary artery.
Bicuspid valve
That valve is present between left atrium and left ventricle.
Aortic valve or aortic semilunar valve
That valve is present in between the left ventricle and aorta.
Blood circulation
It is classified into four parts:
- Systemic circulation
- Pulmonary Circulation
- Coronary circulation
- Portal circulation
Systemic circulation
It is the circulation involving blood supply to all parts of the body except lungs. This circulation starts from aorta (which carries oxygenated blood from left ventricle).
Pulmonary Circulation
It is the part of the circulation involving the purification of blood in lungs. The pulmonary artery carries deoxygenated blood from right ventricles to lungs, where oxygen molecules are bind with hemoglobin and blood became oxygenated.
Coronary circulation
The circulation involve to the heart cells and tissues.
Portal circulation
Portal vein carries blood (that has circulated blood in stomach, intestine and pancreas).
Function of heart
The heart is act as a pump. It maintains a constant circulation of blood throughout the body.
Mechanism of heart
Deoxygenated blood comes from cells and tissues in right atrium through superior vena cava, inferior vena cava and coronary sinus.
De-oxygenated blood fill in right atrium and tricuspid valve is open. Blood transfer into right atrium.
Deoxygenated blood goes lungs through pulmonary artery, where deoxygenated blood is change into oxygenated blood (oxygen bind to haemoglobin molecules of blood). Oxygenated blood is transfer from lungs to left atrium through pulmonary vein. Bicuspid valve is open and blood transfer to left ventricle.
Deoxygenated blood goes lungs through pulmonary artery, where deoxygenated blood is change into oxygenated blood (oxygen bind to haemoglobin molecules of blood). Oxygenated blood is transfer from lungs to left atrium through pulmonary vein. Bicuspid valve is open and blood transfer to left ventricle.
Oxygenated blood is send to all body cells and tissues by arch of arota. Coronary artery supply oxygenated blood to heart tissues.
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