Blood Vessels

Question 1

When does blood pressure decrease?

Answer 1

When the blood moves away from the heart.

Question 2

What is the lumen?

Answer 2

The central space or cavity of a blood vessel.

Question 3

Where is the endothelium located?

Answer 3

Around the central lumen.

Question 4

What is the endothelium surrounded by?

Answer 4

Layers of tissue.

Question 5

Which blood vessel has the thickest endothelium layer and the most elastic fibres?

Answer 5

Arteries as they have to withstand high pressure from the blood.

Question 6

In which direction do arteries carry blood?

Answer 6

Away from the heart.

Question 7

What is the structure of an artery?

Answer 7

They have an outer layer of connective tissue containing elastic fibres and a thick middle layer containing smooth muscle with more elastic fibres.

Question 8

What do the arteries do to accommodate the surge of blood after each contraction of the heart?

Answer 8

The thick elastic walls contract and relax.

Question 9

What is vasoconstriction?

Answer 9

The contraction of the smooth muscle in the walls of the arterioles.

Question 10

What is vasodilation?

Answer 10

The relaxing of the smooth muscle in the walls of the arterioles.

Question 11

How is blood flow increased during exercise?

Answer 11

The vasodilation of the arterioles supplying the muscles.

Question 12

What happens to the abdominal organs during exercise?

Answer 12

The arterioles supplying these organs vasoconstrict reducing blood flow.

Question 13

What are venules?

Answer 13

Capillaries that have merged into one another.

Question 14

How thick are the walls of capillaries?

Answer 14

One cell thick.

Question 15

What is the function of capillaries?

Answer 15

They allow the exchange of substances with other tissues.

Question 16

What is the structure of a vein?

Answer 16

They have an outer layer of connective tissue containing elastic fibres but a much thinner muscular wall than arteries with a wide lumen.

Question 17

Why are valves present in veins?

Answer 17

To prevent the backflow of blood as blood is flowing back to the heart at low pressure and generally against the force of gravity.

Question 18

What causes pressure filtration?

Answer 18

Higher blood pressure at the arteriole end of the capillary bed.

Question 19

What does pressure filtration result in?

Answer 19

The plasma, with small soluble molecules, being forced out of the capillaries into the tissues.

Question 20

What is the difference between tissue fluid and blood plasma?

Answer 20

Tissue fluid does not contain plasma proteins.

Question 21

What does tissue fluid contain?

Answer 21

Glucose, oxygen, and dissolved substances.

Question 22

What diffuses out of the cells into the tissue fluid to be excreted?

Answer 22

Carbon dioxide and waste substances.

Question 23

Where does tissue fluid re-enter the capillaries?

Answer 23

At the venule end of the capillary bed by osmosis.

Question 24

What happens to excess tissue fluid?

Answer 24

It enters the lymph vessels and passes into the lymphatic system.

Question 25

What is the structure of lymph vessels?

Answer 25

They have thin walls and valves.

Question 26

Where does the lymphatic system return the lymph fluid to?

Answer 26

The circulatory system.