The heart

Question 1

List the order of blood flow through the heart.

Answer 1

Right atrium, right ventricle, pulmonary artery, pulmonary vein , left atrium, left ventricle, aorta,
vena cava (cycle begins again)

Question 2

Why does the left ventricle contain more muscle than the right ventricle?

Answer 2

It has to pump blood to the body, not just the lungs like the right side. When it contracts, it produces greater pressure because of this in order to pump.

Question 3

Explain the roles of atrioventricular valves.

Answer 3

Atrioventricular valves= These open when the atria contracts and the pressure is greater than the ventricles, so blood flows to the ventricles. AV valves close when the ventricles contract, preventing backflow as blood flows to the least pressure.

Question 4

What is the role of semi-lunar valves and tendinous cords?

Answer 4

Tendinous cords= These prevent the AV valves from turning inside out, as the ventricular pressure increases above that in the atria.
Semilunar valves= Open to allow blood flow into the pulmonary artery and aorta as the ventricles contract.
They close when the ventricle relaxes, preventing backflow into ventricles.

Question 5

Fill in the gaps of the cardiac cycle.

Answer 5

• 0-0.1 seconds= left —um contracts, blood to v—-
• 0.1 seconds= left ventricle contracts, volume -creases and pressure inside -creases, closing AV
• 0.15 seconds= pressure in ventricle –creases above that in the aorta, opening the ——r valve.
• 0.4 seconds= ventricle relaxes, aortic valve closes as pressure in the aorta —– above the ventricle
• 0.45 seconds= the pressure in the ventricle falls below the a—-. The a— contracts. producing pressure above the ventricle. AV opens.
• 0.8 seconds= One cardiac cycle, the graph repeats

Question 6

What is the equation of Cardiac output?

Answer 6

stroke volume (cm^3) X heart rate (min-1)

Question 7

What is stroke volume and heart rate? Why would athletes have a low resting heart rate?

Answer 7

Stroke volume= volume of blood expelled from left ventricle per beat
Heart rate= number of beats per minute
Regular exercise would increase the strength of the heart, the ventricles would be larger in size and volume, leading to an increased stroke volume and a reduction in resting heart rate.