mass transport exam questions

Question 1

during a myocardial infarcation areas of heart muscle begin to die.
explain why (3)

Answer 1

-reduced blood flow in coronary arteries
-less oxygen
-lower respiration rate.

Question 2

use info in figure 2 to explain how pressure in the dog’s ventricle is related to blood flow into the aaorta. (2)

Answer 2

-first ventricle pressure increases followed by increased blood flow into the aoorta
-as when pressure in ventricles is greater than in aaorta, the semi lunar valves open

Question 3

use info in figure 2 to explain how pressure in the dog’s ventricle is related to thickness of the ventricle wall

Answer 3

-thickness of wall increases as ventricle wall contracts
-contraction causes pressure increase

Question 4

describe how hearbeat is initiated and coordinated. (5)

Answer 4

SAN releases wave of electrical impulses, causing atria to contract
non conducting tissue prevents impule passing to ventricles
AVN delays impulse while blood enters the ventricles
AVN releases wave of electrical activity down bundle of his
causes ventricles to contract from base of heart upwards

Question 5

suggest why the left ventricle requires the help of the artifical heart but the right ventricle does not. (2)

Answer 5

–left ventricle pumps blood to the rest of the body
-produces a greater pressure

Question 6

the maximum pressure in the ventricles is much higher than in the atrium. Explain why. (2)

Answer 6

-thicker wall
-so contractions are stronger

Question 7

when a wave of electrical activity reaches the AVN, there is a short delay before the new wave leaves the AVN.
explain the importance of this short delay (2)

Answer 7

-allows ventricles to fill
-before they contract.