Unit 2-The Structure And Function of Arteries, Capillaries And Veins

Question 1

What is the pathway of blood circulation in the body in terms of vessels?

Answer 1

Leaves heart in arteries flows through capillaries before returning to the heart in veins.

Question 2

When blood leaves the heart is it under high or low pressure?

Answer 2

High pressure.

Question 3

What happens to blood pressure when it flows away from the heart and through the circulatory system?

Answer 3

Decrease in blood pressure.

Question 4

Where do arteries carry blood to?

Answer 4

Away from the heart, to the rest of the body.

Question 5

Describe the structure of arteries

Answer 5

Endothelium lines the central lumen and is surrounded by layers of tissue.

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

Question 6

What do the elastic fibres in arteries mean for the artery and why are they needed?

Answer 6

The elastic fibres mean that arteries have elastic walls which can stretch and recoil to accommodate the surge of blood after each contraction of the heart.

Question 7

What can the smooth muscle in arteries do and what does this cause?

Answer 7

The smooth muscle can contract to cause vasoconstriction or relax causing vasodilation to control blood flow.

Question 8

Why do arteries need more elastic fibres than veins?

Answer 8

Arteries constrict and dilate more than veins, to accumulate surges of high blood pressure.

Question 9

How does the central lumen of arteries compare to that of veins and why?

Answer 9

Arteries have a narrower central lumen than veins due to the thicker layer of muscle in arteries.

Question 10

What do arteries divide into?

Answer 10

Arteries divide into arterioles.

Question 11

Do arteries contain valves?

Answer 11

No.

Question 12

What do capillaries allow to happen?

Answer 12

Capillaries allow exchange of substances with diffusion through their very thin walls.

Question 13

What do veins do?

Answer 13

Veins carry blood back to the heart.

Question 14

What is the structure of a vein?

Answer 14

Veins have an outer layer of tissue containing elastic fibres and a much thinner muscular wall than arteries.

Wider central lumen than in arteries.

Contain valves that prevent the backflow of blood.

Question 15

What are the smaller vessels that come together to form veins called?

Answer 15

Venules.

Question 16

Where is the lumen in an artery and vein?

Answer 16

The very centre of the artery and vein.

Question 17

Where is the endothelium in an artery and vein?

Answer 17

Layer that surrounds the central lumen.

Question 18

Where is the muscle tissue in an artery and vein?

Answer 18

The muscle tissue is the middle layer of the artery and vein that surrounds the endothelium and is in between the connective tissue and endothelium.

Question 19

Where is the connective tissue in an artery and vein?

Answer 19

Outer layer.

Question 20

What do valves in veins do?

Answer 20

Prevent the back flow of blood.

Question 21

Why do arteries not need valves but veins do?

Answer 21

High pressure prevents backflow in arteries

Question 22

Describe vasoconstriction?

Answer 22

The artery wall contracts to make the size of the lumen smaller so less blood can flow through so blood pressure increases.

Question 23

Describe vasodilation?

Answer 23

The artery muscle increases in size so that the size of the lumen increases and more blood can flow through.

Question 24

Compare blood pressure arriving at the arteriole end of a capillary bed compared to the blood in the capillaries.

Answer 24

Higher arriving at than in capillaries

Question 25

Describe pressure filtration.

Answer 25

The blood is forced into the narrow capillaries and much of the plasma (the liquid part of the blood) is squeezed out through the thin walls into the tissue fluid which surrounds the cell.

Question 26

What is the difference between plasma and tissue fluid?

Answer 26

Plasma contains plasma proteins.

Question 27

Why does plasma contain plasma proteins but tissue fluid doesn’t?

Answer 27

The protein is too large to be filtered through the capillary walls.

Question 28

What role does tissue fluid have?

Answer 28

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

Carbon dioxide and other metabolic waste diffuse out of the cells and into the tissue fluid to be excreted.

Question 29

What happens to most of the tissue fluid?

Answer 29

It returns to the blood.

Question 30

What happens to tissue fluid which does not return to the blood?

Answer 30

The fluid that does not return to the blood (excess tissue fluid) is absorbed by small lymphatic vessels and the fluid is now referred to as lymph.

Question 31

What do the lymphatic vessels do with lymph?

Answer 31

The lymphatic vessels return the lymph to the circulatory system.