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प्रश्न
Give reason:
Valves are present in the veins.
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उत्तर
- The main function of the valves in veins is to prevent backflow of blood.
- They are thin walled with semilunar valves to prevent backward flow of blood.
- Blood in the arteries, after being pumped by the heart, are under much higher pressure than blood in veins so there is no need for valves in arteries to prevent back flow.
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संबंधित प्रश्न
Choose the correct answer:
Which chamber of the heart has the thickest wall?
The figure below represents the internal structure of a mammalian heart and the associated blood vessels.
(i) (a) Name each of the structures labeled 1, 2, 3, 4, 5, 6, 7 and 8.
(b) State the function of each of the structures 5, 6, 7, and 8.
(ii) (a) State the function of the heart as an entire organ.
(b) Why are the walls of the left ventricle more muscular than the right?
Column 2 is a list of items related to ideas in Column 1. Match the term in Column 2 with the suitable idea given in Column 1.
| Column 1 | Column 2 |
| (i) Superior vena cava | (a) Collect deoxygenated blood from the wall of the heart. |
| (ii) Inferior vena cava | (b) Carry oxygenated blood to heart muscle. |
| (iii) Pulmonary vein | (c) Collects deoxygenated blood from upper part. |
| (iv) Coronary veins | (d) Collects deoxygenated blood from lower parts. |
| (v) Coronary artery | (e) Brings oxygenated blood from lungs. |
| (vi) Aorta | (f) Large artery |
| (vii) Heart attack | (g) Large vein |
| (viii) Blood Pressure | (h) Oxygenated blood |
| (ix) Tricuspid valve | (i) Sphygmomanometer |
| (x) Bicuspid valve | (j) Allows blood flow from right auricle to right ventricle. |
| (xi) Contraction and relaxation of heart | (k) Blocking of coronary arteries. |
| (l) Cardiac muscle. | |
| (m) Allows blood flow from left auricle to left ventricle. | |
| (n) Allows blood flow from right ventricle of pulmonary aorta. |
Give scientific reason.
Left ventricle is thick than all other chambers of heart.
Describe the structure and working of the human heart.
For which of the following reason the left ventricle of human heart has its wall thicker than the right ventricle?
____________ guards the left atrioventricular aperture in human heart.
The walls of the heart is made up of cardiac muscle.
Explain the term Fossa ovalis.
A man's heart rate is 68 and cardiac output is 5440. Find the stroke volume.
