Unit 2 (K5) - Structure & Function of Arteries, Capillaries & Veins

Question 1

What do arteries do?

Answer 1

Carry blood away from the heart under high pressure.

Question 2

What do capillaries do?

Answer 2

Allow the exchange of materials with tissues.

Question 3

What do veins do?

Answer 3

Carry blood back to the heart under low pressure.

Question 4

What is the central cavity of a blood vessel called?

Answer 4

The lumen.

Question 5

What is the endothelium of a blood vessel?

Answer 5

The cells of the inner wall or lining.

Question 6

Describe the structure of an artery.

Answer 6

1. Outer layer of connective tissue with elastic fibres.
2. Middle layer of smooth muscle and elastic fibres.
3. Inner layers is the endothelium which is not elastic.

Question 7

Describe the structure of a capillary.

Answer 7

1. One layer of endothelium cells surrounded by a thin layer of connective tissue.

Question 8

Describe the structure of a vein.

Answer 8

1. Outer layer of connective tissue with elastic fibres.
2. Middle layer of elastic fibres and smooth muscle.
3. Inner layer is the endothelium.

Question 9

How are arteries different to veins?

Answer 9

1. Arteries carry blood away from the heart under high pressure.
2. Veins carry blood back to the heart under low pressure.
3. Arteries have thicker outer and middle layers than veins and are much more muscular.
4. Veins have larger lumen than arteries.
5. Veins have valves to prevent backflow of blood.

Question 10

What is the role of elastic fibres in the wall of an artery?

Answer 10

Allows arteries to stretch and recoil to accommodate the surge of blood after each contraction of the heart.

Question 11

What is a structural feature of a vein and its purpose?

Answer 11

Veins have valves to prevent the backflow of blood.

Question 12

What is vasoconstriction?
When does it happen?

Answer 12

1. Middle layer of smooth muscle in the artery can contract causing vasoconstriction of the arterioles and arteries (narrowing of the lumen). Reducing blood flow to parts of the body.
2. This happens when we are cold, frightened or angry.

Question 13

What is Vasodilation?

Answer 13

1. This is where smooth muscle in in the arteriole relaxes and results in a wider lumen allowing increased blood flow to skeletal muscles.

Question 14

What can be found in the blood?

Answer 14

1. Proteins
2. Glucose
3. Amino Acids
4. Oxygen
5. Carbon Dioxide

Question 15

What do lymphatic vessels do?

Answer 15

Absorb excess tissue fluid and return it as lymph to the circulatory system.

Question 16

Explain the difference between tissue fluid, blood plasma and lymph.

Answer 16

1. Tissue fluid does not have large plasma proteins as they are filtered out by the capillary walls.
2. Lymph is tissue fluid with large concentrations of white blood cells in it.