Give reason why
a) veins have valves at regular intervals where as arteries do not have valves
b) the heart beat increases after a physical exercise
C) the arteries are thick walled
Answers
Answer:
a. Veins have valves so that the the deoxygenated blood flows in only one direction and doesn't come back when it is carried to heart. Arteries don't have valves because they have to transport oxygenated blood from heart to body parts.
b. Heart beat increases after a physical exercise to supply more oxygen to the body.
c. Arteries are thick walled because they have to carry high pressure blood to body.
Answer:
VEINS HAVE VALVES SO AS TO PREVENT BACKFLOW OF BLOOD .while artries dont because force from heart is so strong that blood(oxygenated) flows in one direction.
AFTER EXERCISE THERE IS MORE NEED FOR OXYGEN (BCZ DURING PHYSICAL ACTIVITIES WE CONSUME MORE OXYGEN) SO AS TO MEET OXYGEN NEED HEART BEAT FASTER.
ARTRIES ARE THICK WALLED BECAUSE THEY NEED MUCH PRESSURE TO PUMP BLOOD.
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