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प्रश्न
Why can you feel a pulse when you keep a finger on the wrist or neck but not when you keep them on a vein?
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उत्तर
- Pulse is the series of pressure waves that travel through arteries due to ventricular systole.
- When the heart contracts, it produces pressure that pulls blood out of the heart. This pressure operates as a wave, which corresponds to the pulse you feel. However, this pressure is not consistent.
- When the heart pumps blood out of itself during systole, the arteries are at their maximum pressure. This pressure decreases significantly when it reaches capillaries; therefore, the veins farthest from the heart are under less pressure. Due to the low pressure, veins include valves to prevent blood backflow.
- The pressure in the arteries can be felt whenever the heart beats, particularly in arteries that come to the surface of the body, such as those in the wrist and neck, but not in veins.
- Vein pressure is usually lower than arterial pressure, resulting in a weaker pulse that cannot be detected by touch alone.
- As a result, we may feel a pulse when we place our fingers on the arteries of the wrist or neck but not when we place them on a vein.
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संबंधित प्रश्न
Write one structural difference between the composition of arteries and veins.
Answer very briefly, Why is it necessary to know The blood groups of the donor as well as the recipient ?
Name the main artery which carries blood to different parts of the body.
The figures given below are cross-sections of blood vessels.
(i) Identify the blood vessels A, B, and C.
(ii) Name the parts labeled 1-4.
(iii) Mention two structural differences between A and B.
(iv) Name the type of blood A that flows (a) through A, (b) through B.
(v) In which of the above vessels referred to in (iv) above does exchange of gases actually take place?
The diagram below represents a certain category of blood vessels showing the role of a special structure in their walls :
(i) Name the kind of blood vessels shown.
(ii) What is the structure shown inside the blood vessels?
(iii) What is the role of these structures?
(iv) Are these structures present in any other kind of blood vessel? If so, name it.
(v) Towards which side of the figure (Top or Bottom) is the heart located?
Multiple Choice Questions
Arteries are:
How a portal vein differs from normal vein?
Select the incorrect statements with respect to blood vessels.
- Capillaries are thin-walled having a single layer of ciliated epithelium.
- Arteries are pulsatile and devoid of valves.
- Portal vein starts as capillaries from one organ and ends as capillaries in another organ.
- All arteries carry oxygenated blood whereas all veins carry deoxygenated blood.
- Capillary walls bear fenestrae through which WBCs can move out by diapedesis.
Choose the correct answer from the options given below:
Give reason Arterial walls are thicker than those of veins.
______ carry blood to an organ and break up into ______ ending in capillaries.
