Explain the working of human heart , with the help of a labelled diagram
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sorry I can't post you two images otherwise I would have given the diagram also.
Hope you will understand......
Hope you will understand......
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Human Heart
●Appearance and Position
-The heart is a hollow, muscular organ, roughly of the size of the one's fist (12×9 cm.)
-Its average weight is about 300 gm in males and about 250 gm. in females. It attains the adult weight at the age of 17 to 20 years.
-The heart is reddish-brown in colour and somewhat conical in form.
-It is located almost in the middle of the thoracic cavity close to its front wall and b/w lungs.
●Protective Covering
-The heart is enclosed in a tough, two-layered sac, the pericardium, comprising inner visceral pericardium attached to the heart and outer parietal pericardium.
-The two layers are continuous at the roots of the great vessels (Blood vessels that enter or leave the heart)
●Internal Structure
1-Auricles. The auricles act as collecting chambers for the blood returning to the heart. They have thin walls because they have to force the blood into the ventricles, that lie just below them.
2-Ventricles. The ventricles act as disturbing chambers for the blood reaching from the atria. They have thicker walls than the auricles have, and the wall of the left ventricle is about three times as thick as that of the right ventricle.
●Working (Cardiac Cycle)
The heart pumps the blood to all the parts of the body. It pumps out over 7,000 litres of blood daily.
A regular sequence of three events: (i)auricular systole,(ii) ventricular systole, and (iii) joint diastole, or complete cardiac diastole (relaxation of both auricles and ventricles) during the completion of one heart beat is known as cardiac cycle.
✧Joint Diastole.
-During this phase, blood from the great veins and coronary sinus flows into the auricles.
-This flow of blood caused not by contraction of any part of the heart but simply by the fact that the pressure in the heart is less than that in the great veins and the A-V valves are open.
✧Auricular Systole
-Contraction of the auricles drives most of their blood into the respective ventricles which are still relaxed.
-During auricular systole, blood does not return to the great veins as the contraction of the auricles begins at their upper ends and passes toward the ventricles, forcing the blood into the latter.
- Also the blood filling viens offer resistance to the blood that may return from the auricles. At the end of auricular systole, there start relaxation of the auricles and contraction of the ventricles simultaneously.
✧Ventricular Systole
-As the contraction of the ventricles begins, the pressure of blood in them almost immediately rises above that in the auricles.
-The semilunar valves of the great arteries remain closed for a moment, so that the blood is blocked on all sides and its pressure rises with further contraction of the ventricles.
-When the pressure in the ventricles exceeds that in the great arteries, the semilunar valves are pressed, the apertures they guard open, and the blood spurts into the great arteries. This is the end of ventricular systole.
-As the ventricular diastole progresses, the pressure in the ventricles falls below that in the great arteries, the flow of blood from the ventricles stops and the the semilunar valves close to check the back flow of the blood from the great arteries to the ventricles.
-The semilunar valves close as they get filled with blood trying to return and meet together, closing the outlets of the great arteries.
_______________________________________
●Systematic circulation by heart and lungs
The heart receives blood in auricles and pumps out blood from the ventricles. From the right ventricle arises a great artery named pulmonary aorta. It divides into two pulmonary arteries which enters the lungs and break up into capillaries around the lung alveoli. Here, the blood takes up oxygen and becomes oxygenated blood from alveolar capillaries to the left auricle. This course of the blood from right ventricle to the left auricle of the heart is called pulmonary circulation
The left ventricle pumps the oxygenated blood into the great artery known as systemic aorta. It gives off arteries to all organs of the body except the lungs. In capillaries, the blood becomes deoxygenated by disturbing oxygen to the tissue cells. The deoxygenated blood from the viceral capillaries is brought to the right auricle by two great veins known as superior and inferior venae cavae. This course of the blood from the left ventricle to the right auricle of the heart via body tissues is called systemic circulation
______________________________________
Important!
Great veins
=Superior Vena Cava and inferior vena cava.
●Appearance and Position
-The heart is a hollow, muscular organ, roughly of the size of the one's fist (12×9 cm.)
-Its average weight is about 300 gm in males and about 250 gm. in females. It attains the adult weight at the age of 17 to 20 years.
-The heart is reddish-brown in colour and somewhat conical in form.
-It is located almost in the middle of the thoracic cavity close to its front wall and b/w lungs.
●Protective Covering
-The heart is enclosed in a tough, two-layered sac, the pericardium, comprising inner visceral pericardium attached to the heart and outer parietal pericardium.
-The two layers are continuous at the roots of the great vessels (Blood vessels that enter or leave the heart)
●Internal Structure
1-Auricles. The auricles act as collecting chambers for the blood returning to the heart. They have thin walls because they have to force the blood into the ventricles, that lie just below them.
2-Ventricles. The ventricles act as disturbing chambers for the blood reaching from the atria. They have thicker walls than the auricles have, and the wall of the left ventricle is about three times as thick as that of the right ventricle.
●Working (Cardiac Cycle)
The heart pumps the blood to all the parts of the body. It pumps out over 7,000 litres of blood daily.
A regular sequence of three events: (i)auricular systole,(ii) ventricular systole, and (iii) joint diastole, or complete cardiac diastole (relaxation of both auricles and ventricles) during the completion of one heart beat is known as cardiac cycle.
✧Joint Diastole.
-During this phase, blood from the great veins and coronary sinus flows into the auricles.
-This flow of blood caused not by contraction of any part of the heart but simply by the fact that the pressure in the heart is less than that in the great veins and the A-V valves are open.
✧Auricular Systole
-Contraction of the auricles drives most of their blood into the respective ventricles which are still relaxed.
-During auricular systole, blood does not return to the great veins as the contraction of the auricles begins at their upper ends and passes toward the ventricles, forcing the blood into the latter.
- Also the blood filling viens offer resistance to the blood that may return from the auricles. At the end of auricular systole, there start relaxation of the auricles and contraction of the ventricles simultaneously.
✧Ventricular Systole
-As the contraction of the ventricles begins, the pressure of blood in them almost immediately rises above that in the auricles.
-The semilunar valves of the great arteries remain closed for a moment, so that the blood is blocked on all sides and its pressure rises with further contraction of the ventricles.
-When the pressure in the ventricles exceeds that in the great arteries, the semilunar valves are pressed, the apertures they guard open, and the blood spurts into the great arteries. This is the end of ventricular systole.
-As the ventricular diastole progresses, the pressure in the ventricles falls below that in the great arteries, the flow of blood from the ventricles stops and the the semilunar valves close to check the back flow of the blood from the great arteries to the ventricles.
-The semilunar valves close as they get filled with blood trying to return and meet together, closing the outlets of the great arteries.
_______________________________________
●Systematic circulation by heart and lungs
The heart receives blood in auricles and pumps out blood from the ventricles. From the right ventricle arises a great artery named pulmonary aorta. It divides into two pulmonary arteries which enters the lungs and break up into capillaries around the lung alveoli. Here, the blood takes up oxygen and becomes oxygenated blood from alveolar capillaries to the left auricle. This course of the blood from right ventricle to the left auricle of the heart is called pulmonary circulation
The left ventricle pumps the oxygenated blood into the great artery known as systemic aorta. It gives off arteries to all organs of the body except the lungs. In capillaries, the blood becomes deoxygenated by disturbing oxygen to the tissue cells. The deoxygenated blood from the viceral capillaries is brought to the right auricle by two great veins known as superior and inferior venae cavae. This course of the blood from the left ventricle to the right auricle of the heart via body tissues is called systemic circulation
______________________________________
Important!
Great veins
=Superior Vena Cava and inferior vena cava.
Attachments:
ventricles- disturbing chamber??
superb!! great job!
gr8 bro
Thanks (:
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