Topic 1

Question 1

What are the three types of circulatory system?

Answer 1

Open
Closed, single
Closed, double

Question 2

Describe open circulatory systems

Answer 2

They partly depend on diffusion, as the heart pumps blood into cavities surrounding organs, leaving substances to diffuse in and out. Only occurs in small animals, like insects, because diffusion is inefficient

Question 3

Describe closed circulatory systems

Answer 3

More efficient than open because blood travels quicker through tube, as it’s under higher pressure. It is found most animals

Question 4

Describe single circulatory systems

Answer 4

Blood goes through the heart once in one circulation. It mainly happens in fish. The heart pumps deoxygenated blood to gills, where gaseous exchange occurs. The newly oxygenated blood then travels to the rest of the body

Question 5

Describe double circulatory systems

Answer 5

Blood goes through the heart twice in one circulation. The right ventricle pumps dexygenated blood to the lungs, where gaseous exchange takes place. The newly oxygenated blood returns to the heart, where it receives an extra boost to reduce the time taken to got round the body

Question 6

What are three main types of blood vessels in mammals?

Answer 6

Arteries
Veins
Capillaries

Question 7

What is the function of arteries?

Answer 7

To take blood away from the heart to the rest of the body. Apart from the pulmonary artery, all arteries carry oxygenated blood

Question 8

How are arteries adapted to their function?

Answer 8

Thick walls- lots of muscle and elastic tissue to cope with the high pressure
Endothelium is folded- allows lumen to expand to cope with the high pressure
No valves- high pressure keeps blood going in the right direction

Question 9

What is the function of veins?

Answer 9

To take blood back to the heart from the body. Apart from the pulmonary vein, all veins carry deoxygenated blood

Question 10

How are veins adapted to their function?

Answer 10

Wide lumens- very little muscle or elastic tissue because the blood is under low pressure
Valves- to stop blood flowing backwards

Question 11

What is the function of capillaries?

Answer 11

The location of metabolic exchange

Question 12

How are capillaries adapted to their function?

Answer 12

Walls are only one cell thick- speeds up diffusion in and out of capillaries
Network of capillaries- increase the surface area for exchange

Question 13

Which ventricle has more muscular walls and why?

Answer 13

Left ventricle, in order to pump blood around the body

Question 14

What is the function of atrioventricular valves?

Answer 14

To stop blood flowing back into atria from ventricles when ventricles contract. Cords attach AV valves to ventricles, which stops them being forced into atria when ventricles contract

Question 15

Function of sumilunar valves?

Answer 15

To stop blood flowing back into the heart when the ventricles relax

Question 16

What are the three stages in the cardiac cycle?

Answer 16

Atrial systole/ventricular diastole
Ventricular systole/atrial diastole
Cardiac diastole

Question 17

What happens during atrial systole/ventricular diastole ?

Answer 17

The ventricles are relaxed. The atria contract, meaning the volume inside decreases and the pressure increases. This pushes blood into the ventricles, through the open AV valves

Question 18

Describe what happens during ventricular systole/atrial diastole

Answer 18

Ventricles contract, causing the volume to decrease and the pressure to increase. AV valves are forced shut because the pressure is higher in ventricles than atria. Semi-lunar valves are forced open, blood is forced out of the heart through aorta/pulmonary artery

Question 19

Describe what happens in cardiac diastole

Answer 19

Whole heart is relaxed. Semi-lunar valves forced shut due to pressure in pulmonary artery/aorta. Blood returns to the heart and the atria begin to fill. The pressure in the atria is higher than in ventricles, so AV valves open, blood passively into ventricles

Question 20

How can the endothelium be damaged?

Answer 20

High blood pressure, toxins in tobacco

Question 21

Define endothelial damage

Answer 21

When damage to the endothelium means it can’t function properly

Question 22

Describe the process of atherosclerosis

Answer 22

• damage to the endothelium causes an inflammatory response
• white blood cells, as well as lipids, move to the area and clump together under endothelium
• more WBC, lipids, and connective tissue build up over time to form atheromas, fibrous plaques
• this hardens artery walls

Question 23

Why does the build up of atheromas result in a dangerous negative feedback system?

Answer 23

The plaques make the arteries narrower, restricting blood flow. This increases blood pressure, which makes it more likely for another plaque to form

Question 24

Suggest another reason why the formation of atheromas is bad.

Answer 24

The amount of blood arteries can carry reduces, so they can’t supply enough oxygen or nutrients to tissues

Question 25

Why does atherosclerosis only happen in arteries?

Answer 25

The blood in arteries is under much higher pressure than in veins.