long discription about human being
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Answer:
HUMAN HEART;
heart is the organ in the human body that acts as a double pump .
STRUCTURE OF HUMAN HEART
the human heart is divided into four chambers . the upper two chambers are called right and left atrium. and the lower two chambers are called the right and left ventricle.
◆ the left atrium receives the oxygenated blood from the lungs via the pulmonary vein.
◆ when the left atrium contracts, the oxygenated blood is pumped into the left ventricle.
◆ when the left ventricle contracts, the oxygenated blood is forced into the aorta, which transports the blood to all the parts of the body, except the lungs. when oxygenated blood passes through the capillaries of different organs, it gives oxygen to the body cells , along with oxygen , blood also gives the digested food and other dissolved materials to the body cells. at the same time , carbon dioxide which is produced as a waste material during respiration, enters into the blood .
◆ From the body tissues , the deoxygenated blood carrying Co2 is pumped back to the heart, into the right atrium , by the vena cava
◆ when the right atrium contracts, the deoxygenated blood is pumped into the right ventricle.
◆ the oxygenated blood is again sent to the left atrium of the heart by the pulmonary vein for being circulated in the body.
◆ the whole process is repeated again and again so as the blood keeps circulating in our body and keep circulating oxygen , digested food and other materials to all parts of the body. this blood also keeps on removing waste products in the form of deoxygenated blood formed in the cells of the body.
right side of the heart pumps blood into the lungs.
left side of the heart pumps blood to the entire body, except the lungs.
BLOOD VESSELS PRESENT IN HEART
In human beings , the organs of circulatory system are heart, arteries, veins, and capillaries.
ARTERIES
◆ they carry blood away from the heart to the various organs of the body , at a high pressure.
◆ they transport only oxygenated blood except for the pulmonary artery.
◆ they have a narrow lumen, do not have valves.
VEINS
◆ they transports blood towards the heart from various organs , at a low pressure.
◆ they transport only deoxygenated blood except for the pulmonary vein.
◆ they have a wide lumen, they have valves to prevent backward flow of the blood.
CAPILLARIES
◆ they carry blood from the arteries to the veins.
◆ they exchange O2, CO2 , H2O, and salts between the blood and the surrounding tissues.
◆ they have a very narrow lumen, do not have valves.
MEMBRANES PRESENT IN HEART
heart consists of two membranes: -
an inner serous membrane called the epicardium, and an outer fibrous membrane.
VALVES PRESENT IN HEART
heart needs the valves to regulate the flow of blood, it allows the blood to flow through the heart only in one direction.
heart consists of four valves:-
The mitral valve and the tricuspid valve.it controls flow of blood from the artria to the ventricles.
The aortic valve and the pulmonary valve.which control flow of blood out of the ventricles.