E&T: Circulatory System

Question 1

What do arteries transport?

Answer 1

Oxygenated blood from the heart to the rest of the body.

Apart from pulmonary artery which takes deoxygenated blood to lungs.

Question 2

What are 3 characteristics of arteries?

Answer 2

• Thick, muscuar walls
• Elastic tissue to stretch + recoil as the heart beats
• Folded endothelium = allows stretch

Question 3

Why is it useful that the walls of arteries can stretch and recoil?

Answer 3

To help them maintain the high blood pressure.

Question 4

What do arteries divide into?

Answer 4

Arterioles

Question 5

What is the role of arterioles?

Answer 5

Direct blood to different areas of deman in the body by muscles inside arterioles.

Question 6

What do veins transport?

Answer 6

Deoxygenated blood back to the heart under low pressure.

Apart from the pulmonary veins which carry oxygenated blood from the heart to the lungs.

Question 7

What are 2 characteristics of veins?

Answer 7

• Wider lumen
• Very little elastic/muscle tissue

Question 8

Blood flow through the veins is helped by what?

Answer 8

Contraction of surrounding body muscles.

Question 9

What do arterioles branch into?

Answer 9

Capillaries

Question 10

How are capillaries adapted for efficient diffusion?

Answer 10

• Found very near cells in exchange tissues = short diffusion pathway
• Only one cell thick = short diffusion pathway
• Large number = increased surface area

Question 11

What is tissue fluid made from?

Answer 11

Small molecules that leave the blood plasma, eg. oxygen, water and nutrients.

Question 12

Why doesn’t tissue fluid contain red blood cells or big proteins?

Answer 12

Too large to push out of capillary walls.

Question 13

What do cells take from tissue fluid?

What do they release into it?

Answer 13

Take = oxygen + nutrients

Release = metabolic waste

Question 14

How do substances move out of capillaries by pressure filtration?

Answer 14

1. Arteriol end = hydrostatic pressure inside capillaries is greater than tissue fluid.
2. Overall outward pressure forces fluid out of capillaries, forming tissue fluid.
3. Fluid leaving reduces hydrostatic pressure in capillaries at venule end.
4. Fluid loss + increases conc. of plasma proteins lowers water potential at venule end of capillary.
5. Water re-enters from the tissue fluid at venule end by osmosis.

Question 15

What happens to excess tissue fluid?

Answer 15

Drained into lymphatic system, which transports excess from tissues and puts back into circulatory system.