TRANSPORT IN MAMMALS

Question 1

pulmonary circulation (2)

Answer 1

• right side of the heart pumps deoxygenated blood to lungs

- left side of the heart pumps oxygenated blood to heart

Question 2

systemic circulation (2)

Answer 2

• left side of the heart pumps oxygenated blood to tissues

- right side of the heart pumps deoxygenated back to heart

Question 3

how many times does blood pass through the heart in a double circulatory system?

Answer 3

• twice, once through the right and once through the left

Question 4

three types of blood vessels (3)

Answer 4

• arteries, away from heart
• veins, to heart
• capillaries - between veins and arteries

Question 5

layers of blood vessel (3)

Answer 5

• endothelium - innermost layer
• tunica media
• tunica externa - outermost layer

Question 6

endothelium (4)

Answer 6

• inner layer
• one-cell thick
• smooth lining to reduce friction
• minimum resistance to blood flow

Question 7

tunica media (4)

Answer 7

• middle layer
• elastic fibres and smooth muscle
• allow stretching for changes in pressure
• after stretching to certain degree fibres recoil pushing blood through (felt as pulse) maintains blood pressure

Question 8

tunica externa (2)

Answer 8

• outer layer

- contains collagen fibres to resist overstretching

Question 9

Arteries (3)

Answer 9

• carry blood from heart
• thick muscular wall to withstand high pressure blood
• branch into arterioles, then capilaries

Question 10

Capilaries (2)

Answer 10

• penetrate all tissues and organs of the body

- blood from capillaries collect into venules which take blood to veins and return them to the heart

Question 11

Veins

Answer 11

• large lumen and thinner walls

- lower pressure

Question 12

How does blood in veins above the heart return to the heart?

Answer 12

• via gravity

Question 13

How does blood in veins below the heart return to the heart? (2)

Answer 13

• peristalsis, alternating pressure from surrounding muscles

- valves prevent backflow

Question 14

What problems can faulty valves cause? (2)

Answer 14

• varicose veins

- heart failure

Question 15

describe capillary walls

Answer 15

• 1-cell thick walls (only endothelium on a basement membrane)
• permeable to water and solutes (for exchange between tissues and blood)
• small diameter, slows rate of blood flow (so plenty of time to exchange tissues)