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Edexcel A Level Biology > Topic 1 > Flashcards

Flashcards in Topic 1 Deck (25)
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1
Q

What are the three types of circulatory system?

A

Open
Closed, single
Closed, double

2
Q

Describe open circulatory systems

A

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

3
Q

Describe closed circulatory systems

A

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

4
Q

Describe single circulatory systems

A

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

5
Q

Describe double circulatory systems

A

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

6
Q

What are three main types of blood vessels in mammals?

A

Arteries
Veins
Capillaries

7
Q

What is the function of arteries?

A

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

8
Q

How are arteries adapted to their function?

A

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

9
Q

What is the function of veins?

A

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

10
Q

How are veins adapted to their function?

A

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

11
Q

What is the function of capillaries?

A

The location of metabolic exchange

12
Q

How are capillaries adapted to their function?

A

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

13
Q

Which ventricle has more muscular walls and why?

A

Left ventricle, in order to pump blood around the body

14
Q

What is the function of atrioventricular valves?

A

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

15
Q

Function of sumilunar valves?

A

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

16
Q

What are the three stages in the cardiac cycle?

A

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

17
Q

What happens during atrial systole/ventricular diastole ?

A

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

18
Q

Describe what happens during ventricular systole/atrial diastole

A

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

19
Q

Describe what happens in cardiac diastole

A

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

20
Q

How can the endothelium be damaged?

A

High blood pressure, toxins in tobacco

21
Q

Define endothelial damage

A

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

22
Q

Describe the process of atherosclerosis

A
  • 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
23
Q

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

A

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

24
Q

Suggest another reason why the formation of atheromas is bad.

A

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

25
Q

Why does atherosclerosis only happen in arteries?

A

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