KA5 Arteries, capillaries and veins

Question 1

Where does blood circulate from?

Answer 1

Blood circulates from the heart through the Arteries to the Capillaries then to the Veins and back to the heart.
There is a decrease in blood pressure as blood moves away from the heart.

Question 2

What is the function of the arteries?

Answer 2

They carry OXYGENATED blood around the body, away from the heart. They carry blood at a high pressure.

Question 3

What is the endothelium?

Answer 3

The endothelium lining the central lumen of blood vessels is surrounded by layers of tissue.

Question 4

What is the structure of the arteries?

Answer 4

They have an outer layer of connective tissue containing elastic fibres.
A middle THICK muscular layer and an inner layer of elastic fibres.
Endothelium lines the NARROW central lumen.

Question 5

What do the elastic walls of the arteries do?

Answer 5

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

Question 6

Why does smooth muscle surrounding the arteries contact or relax?

Answer 6

The control blood flow

Question 7

What is vasoCONstriction?

Answer 7

Muscles in the artery walls CONTRACT

This can allow a decrease in blood flow

Question 8

What is vasodilation?

Answer 8

Muscles in the artery walls RELAX

This allows an increase in blood flow

Question 9

What is the function of the coronary arteries?

Answer 9

Supply the cardiac muscle of the heart with blood containing glucose and oxygen

Question 10

What is the function of the capillaries?

Answer 10

Capillaries allow exchange of substances with tissues through their thin walls.

Question 11

What is the function of veins?

Answer 11

They carry DEOXYGENATED blood around the body and back to the heart
They carry blood at a low pressure
Veins have valves which prevent the back flow of blood

Question 12

What is the structure of veins?

Answer 12

The endothelium lines the WIDE central lumen, which is surrounded by layers of tissue.
They have an outer layer of connective tissue containing elastic fibres.
A middle layer with a THINNER muscular wall and an inner layer of elastic fibres.

Question 13

What are arterioles and venules?

Answer 13

Arterioles - small narrow arteries

Venules - small narrow veins

Question 14

What do capillaries exist in?

Answer 14

A dense network called a capillary bed.

It is in here that gases, nutrients and waste materials are exchanged with tissue cells.

Question 15

What is every body cell bathed in?

Answer 15

Every body cell is near a capillary and is constantly bathed in a liquid called tissue fluid.

Question 16

What happens when blood arrives at the arteriole end of a capillary bed?

Answer 16

Pressure filtration causes plasma to pass through the capillary walls at a HIGH pressure into the tissue fluid surrounding the cells. Most of the dissolved substances in the plasma are also forced through the capillary walls. Only large PROTIEN molecules and blood cells remain behind.

Question 17

What substances does the tissue fluid supply the cells with?

Answer 17

Tissue fluid supplies cells with glucose, oxygen and other substances.

Question 18

What diffuses out of the cells?

Answer 18

Carbon dioxide and other metabolic wastes diffuse out of the cells and into the tissue fluid to be excreted. Much of the tissue fluid returns to the blood.

Question 19

Not all tissue fluid returns to the bloodstream in the capillaries. What is the other transport system?

Answer 19

The lymphatic system. Excess tissue fluid enters lymphatic vessels where it becomes lymph. The lymph vessels collect the excess tissue fluid and return it as lymph to the circulatory system.