Topic 3---B: More Exchange and Transport System- 3. The Circulatory System

Question 1

What is the circulatory system made up of?

Answer 1

• Heart
• Blood vessels

Question 2

Pulmonary artery

Answer 2

Transports deoxygenated blood from the heart to the lungs

Question 3

Pulmonary vein

Answer 3

Transports oxygenated blood from the lungs to the heart

Question 4

Aorta

Answer 4

Transports oxygenated blood from the heart to the respiring body tissues

Question 5

Vena cava

Answer 5

Transports deoxygenated blood from the respiring body tissues to the heart

Question 6

Renal artery

Answer 6

Transport oxygenated blood from body to kidneys

Question 7

Renal vein

Answer 7

Transport deoxygenated blood from kidneys to vena cava

Question 8

Waht blood vessel has the lowest pressure?

Answer 8

Vena cava

Question 9

What is the closed double circulatory system?

Answer 9

Blood passes through the heart twice to complete 1 full circuit of the body

Question 10

What are the 2 circuits?

Answer 10

1. On the right side, deoxygenated blood gets pumped from the heart-lungs and then oxygenated blood returns to the left side.
2. On the left side, oxygenated blood gets pumped from the heart to the rest of the body and then deoxygenated blood returns to the right side.

Question 11

Suggest the importance of a double circulatory system

Answer 11

• Prevents mixing of oxygenated/ deoxygenated blood
  (so blood pumped to body is fully saturated with oxygen for aerobic respiration)
• Blood can be pumped to body at a high pressure after being lower from the lungs so substances can be removed from body cells more quickly.

Question 12

Coronary arteries

Answer 12

They carry oxygenated blood to the heart muscle
They are located on the surface of the heart branching from aorta.

Question 13

Arteries (function)

Answer 13

They carry blood from the heart to the rest of the body.

Question 14

Arteries (characteristics)

Answer 14

• Thick muscular walls
• Elastic tissue to stretch and recoil as the heart beats
  (helps maintain high pressure)
• Folded endothelium allowing the artery to stretch
• Narrow lumen (maintains high pressure)

Question 15

Arterioles (function)

Answer 15

Division of arteries to smaller vessels which can direct blood to different capillaries/ tissues

Question 16

Arterioles (characteristics)

Answer 16

• Thicker smooth muscle layer than arteries
• Contracts (narrows lumen) (vasocconstriction) reduces blood flow to capillaries
• Relaxes (widens lumen) (vasodilation)- increases blood flow to capillaries
• Thinner elastic layer as pressur eis lower

Question 17

Veins (function)

Answer 17

Carry blood back to the heart at a lower pressure

Question 18

Veins (characteristics)

Answer 18

• Wider lumen
• Very little elastic and muscle tissue as blood pressure is lower
• Valves so prevents backflow of blood

Question 19

What kind of blood do arteries have?

Answer 19

Oxygenated apart from the pulmonary artery

Question 20

What kind of blood do veins have?

Answer 20

Deoxygenated apart from the pulmonary vein

Question 21

Capillaries (function)

Answer 21

Allow efficient gas exchange of substances between blood and tissue fluid

Question 22

Capillaries (characteristics)

Answer 22

• Wall is thin (one cell) layer of endothelial cells- reduces diffusion distance
• Large number of capillaries- increases surface area for exchange
• Narrow lumen- reduces blood flow rate

Question 23

What is tissue fluid?

Answer 23

The fluid that surrounds cells in tissues.

Question 24

What is tissue fluid made from?

Answer 24

It’s made from small molecules that leave the blood plasma e.g. oxygen, water and nutrients.

Question 25

Explain the formation of tissue fluid
(arterial end)

Answer 25

• At the arteriole end of the capillary, the hydrostatic pressure inside the capillary (due to contraction of ventricles) is greater than the hydrostatic pressure in the tissue fluid.
• This difference in hydrostatic pressure means an overall outwards pressure which forces water and dissolved substances out of capillaries and into the spaces around cells forming tissue fluid so hydrostatic pressure lowers at the venule end
• Large plasma proteins remain in the capillary

Question 26

At the venule end

Answer 26

• Hydrostatic pressure reduces as fluid leaves the capillary
• Due to the water loss and an increasing concentration of plasma proteins which don’t leave the capillaries it lowers the water potential at the venule end of the capillary compared to the water potential of the tissue fluid
• Water enters the capillaries from tissue fluid from osmosis down a water potential gradient
• Excess water taken up by lymph capillaries and returned to the circulatory system through veins.

Question 27

Suggest and explain causes of excess tissue fluid accumulation

Answer 27

High blood pressure leading to high hydrostattic pressure
So it increases the outwards pressure from arterial end and reduces inwards pressure at venule end
So more tissue fluid formed at arteriole end