The Structure And Function Of Arteries, Capillaries And Veins

Question 1

In what order does blood circulate?

Answer 1

From the heart through the arteries to the capillaries then to the veins and back to the heart

Question 2

What happens as blood moves away from the heart?

Answer 2

The blood pressure decreases

Question 3

What is the centre of a vessel called?

Answer 3

Central lumen

Question 4

What lines the central lumen?

Answer 4

The endothelium, surrounded by layers of tissue.

Question 5

Describe the structure of an artery

Answer 5

Arteries have an outer layer of connective tissue containing elastic fibres and a smooth muscle layer outside the endothelium with more elastic fibres.

Question 6

What is the purpose of elastic fibres?

Answer 6

Elastic fibres stretch and recoil to accommodate the surge of blood after each contraction

Question 7

What is vasodilation?

Answer 7

Vasodilation is the process by which the smooth muscle surrounding arteries relax to increase the amount of blood flow through an artery

Question 8

What is vasoconstriction?

Answer 8

Vasoconstriction is the process by which smooth muscle surrounding the arteries contract to limit blood flow, increasing blood pressure.

Question 9

What is the function of the capillaries?

Answer 9

To allow for exchange of substances with tissues through their thin walls

Question 10

What makes capillaries good at exchanging substances?

Answer 10

Capillaries have thin walls ( one cell thick ) and have a large surface area along with an extensive blood supply

Question 11

What do veins contain that arteries don’t?

Answer 11

Valves to prevent the back flow of blood

Question 12

Describe the structure of a vein

Answer 12

Veins have thinner muscular walls than arteries, a wider central lumen, an endothelium lining and an outer layer of connective tissue containing elastic fibres.

Question 13

How are materials exchanged between capillaries and tissue fluid?

Answer 13

Pressure filtration which causes plasma to pass through capillary walls into the tissue fluid surrounding the cells

Question 14

What is plasma?

Answer 14

The liquid component of blood that transports the red blood cells, white blood cells and platelets

Question 15

What does the tissue fluid do?

Answer 15

The tissue fluid supplies cells with glucose, oxygen and other substances

Question 16

What do the cells give tissue fluid?

Answer 16

Carbon dioxide and other metabolic wastes which diffuse out of the cells into the tissue fluid to be excreted. Eg carbon dioxide breathed out

Question 17

What happens to most of the tissue fluid?

Answer 17

Most of the tissue fluid returns to the blood

Question 18

What happens to excess tissue fluid?

Answer 18

Excess tissue fluid is absorbed by lymphatic vessels and returned as lymph to the circulatory system.

Question 19

What is the differences between plasma and tissue fluid?

Answer 19

Tissue fluid and plasma are similar in composition, however tissue fluid doesn’t contain plasma proteins, which are too large to be pressure filtered through the capillary walls.