3: EXCHANGE SYSTEMS AND MASS TRANSPORT - THE HEART + THE CIRCULATORY SYSTEM

Question 1

What side of the heart pumps deoxygenated blood to the lungs?

Answer 1

the right side

Question 2

What side of the heart pumps oxygenated blood to the rest of the body?

Answer 2

the left side

Question 3

Name the vessel that carries blood from the aorta to the heart muscle

Answer 3

coronary arteries

Question 4

Name the vessel that carries blood from the lungs to the left atrium

Answer 4

pulmonary vein

Question 5

Name the vessel that carries blood from the left ventricle to the body

Answer 5

aorta

Question 6

Name the vessel that carries blood from the body to the right atrium

Answer 6

vena cava

Question 7

Name the vessel that carries blood from the right ventricle to the lungs

Answer 7

pulmonary artery

Question 8

Name the vessel that carries blood from the body (aorta) to the kidneys

Answer 8

renal artery

Question 9

Name the vessel that carries blood from the kidneys to the vena cava

Answer 9

renal vein

Question 10

Do the ventricle/the atria have thicker walls and why?

Answer 10

• ventricles have thicker walls
• have to pump blood out of the heart whereas atria only have to pump blood a short distance to the ventricles

Question 11

Which ventricle has thicker, more muscular walls and why?

Answer 11

• the left ventricle
• has to pump blood to the rest of the body whereas the right ventricle only has to pump blood to the lungs

Question 12

What is the name of the valves between the atria and ventricles?

Answer 12

the atrioventricular (AV) valves

Question 13

What is the function of the atrioventricular (AV) valves?

Answer 13

stop blood flowing back into the atria when the ventricles contract

Question 14

What is the name of the valves between the ventricles and the pulmonary artery/aorta?

Answer 14

the semi-lunar (SL) valves

Question 15

What is the function of the semi-lunar (SL) valves?

Answer 15

stop blood flowing back into the heart after the ventricles contract

Question 16

When do valves open?

Answer 16

when there’s a higher pressure behind the valve

Question 17

What are the 3 stages of the cardiac cycle?

Answer 17

• atrial systole
• ventricular systole
• diastole

Question 18

What happens in atrial systole?

Answer 18

• the ventricles relax, and the atria contract
• the volume of the atria decreases
• the atrial pressure increases
• the AV valves open and SL valves remain closed
• blood flows into the ventricles
• slight increase in ventricular pressure and volume as they receive the ejected blood from the atria

Question 19

What happens in ventricular systole?

Answer 19

• the ventricles contract, and the atria relax
• the volume of the ventricles decreases
• the ventricular pressure increases
• the SL valves open, and the AV valves close
• blood flows into the arteries

Question 20

What happens in diastole?

Answer 20

• the ventricles and atria relax
• volume of both atria and ventricles increases
• pressure of both atria and ventricles decreases
• the SL valves close and AV valves open
• blood flows passively into the atria

Question 21

What is cardiac output?

Answer 21

the volume of blood pumped by the heart per min

Question 22

What is the equation for cardiac output?

Answer 22

cardiac output (cm^3 min^-1) = stroke volume (cm^3) x heart rate (bpm)

Question 23

What is the function of arteries?

Answer 23

carry blood away from the heart

Question 24

What is the function of veins?

Answer 24

carry blood back to the heart

Question 25

What are the adaptations of arteries?

Answer 25

- narrow lumen (maintains high pressure) - thicker layer of elastic tissue (stretch and recoil to maintain high pressure) - thicker layer of smooth muscle (constrict and dilate to maintain high pressure) - thicker layer of collagen (withstand high pressure) - folded endothelium (stretch to maintain high pressure) - single layer of flattened endothelium cells (reduce friction to allow blood to flow freely)

Question 26

What are the adaptations of veins?

Answer 26

- wide lumen (reduces resistance so blood flows more easily) - thinner layer of elastic tissue and smooth muscle (don't need to maintain high pressure) - thinner layer of collagen (withstands pressure (doesn't need to be thick due to low pressure)) - valves (prevent backflow) - single layer of smooth flattened endothelium cells (reduce friction to allow blood to flow freely) - surrounded by muscles (maintain blood flowing through veins in 1 direction)

Question 27

What is the function of capillaries?

Answer 27

deliver nutrients and O2 to cells throughout the body as well as removing CO2 and other waste from cells

Question 28

What are the adaptations of capillaries?

Answer 28

- narrow lumen (RBCs squeeze through lumen to decrease rate of flow, provides short diffusion pathway) - single layer of flattened endothelial cells (short diffusion pathway) - pores in endothelium (increase permeability) - capillary bed (increases SA) - close to cells (short diffusion pathway)

Question 29

What is the function of venules?

Answer 29

carry blood from capillaries to veins

Question 30

What is the function of arterioles?

Answer 30

carry blood from arteries to capillaries

Question 31

What is hydrostatic pressure?

Answer 31

pressure caused by fluid pushing on the walls of the vessel which is carrying it

Question 32

Which end of the capillary bed has a higher hydrostatic pressure?

Answer 32

the arteriole end

Question 33

Which end of the capillary bed has a lower hydrostatic pressure?

Answer 33

the venule end

Question 34

Explain how tissue fluid is formed and how it may be returned to the circulatory system (5 marks)

Answer 34

- hydrostatic pressure of blood high at arterial end - fluid / water / soluble molecules pass out (reject plasma) - proteins / large molecules remain - this lowers the water potential / water potential becomes more negative - water moves back into venous end of capillary (reject tissue fluid) by osmosis / diffusion - lymph system collects any excess tissue fluid which returns to blood / circulatory system / link with vena cava / returns tissue fluid to vein