8.2 Blood Vessels

Question 1

What are the 3 key components within blood vessels?

Answer 1

Elastic fibres, smooth muscle and collagen

Question 2

What are elastic fibres?

Answer 2

Fibres made of elastin that can stretch and recoil, providing the vessel walls with flexibility

Question 3

What is the function of smooth muscle in a blood vessel?

Answer 3

Contracts or relaxes, changing the size of the lumen

Question 4

What is the function of collagen in a blood vessel?

Answer 4

Provides structural support to maintain the shape and volume of the vessel.

Question 5

Do arteries carry blood to or away from the heart?

Answer 5

Away, to bring it to the tissues of the body.

Question 6

Do arteries carry oxygenated or deoxygenated blood?

Answer 6

Oxygenated (except in the pulmonary artery)

Question 7

Is blood in the arteries under higher or lower pressure than blood in the veins?

Answer 7

Higher

Question 8

What do elastic fibres allow arteries to do?

Answer 8

Withstand the force of the blood pumping, and to stretch to withstand the volume

Question 9

Describe the endothelium of an artery

Answer 9

It is so smooth that the blood flows easily over it.

Question 10

What happens to the elastic fibres of the arteries in-between contractions of the heart? Why?

Answer 10

The elastic fibres recoil and return to their original length, to help even out the surges of blood pumping, and to give a continuous flow.

Question 11

What are arterioles?

Answer 11

Small blood vessels that link the arteries and capillaries

Question 12

What is the name of the blood vessels that link the arteries and capillaries?

Answer 12

Arterioles

Question 13

Describe the structure of arterioles.

Answer 13

Have more smooth muscle and less elastin in their walls than arteries, but can still constrict or dilate to control the flow of blood into individual organs.

Question 14

What type of blood vessel can perform vasoconstriction and vasodilation?

Answer 14

Arterioles (and arteries)

Question 15

What happens during vasoconstriction?

Answer 15

Smooth muscle in the arteriole contracts. This constricts the vessel, and prevents blood flowing into a capillary bed

Question 16

What happens during vasodilation?

Answer 16

Smooth muscle in the arteriole relaxes, allowing blood to flow into the capillary bed.

Question 17

What is a lumen?

Answer 17

The channel within the blood vessel

Question 18

What are capillaries?

Answer 18

Microscopic blood vessels that link the arterioles and the venules.

Question 19

What is the name of the blood vessel that links the arterioles and the venules?

Answer 19

Capillaries

Question 20

How small are capillaries?

Answer 20

One cell thick

Question 21

How do red blood cells travel through capillaries?

Answer 21

In a single file line

Question 22

How do substances pass out of the capillaries?

Answer 22

Through the relatively large gaps between the endothelial cells that make up the capillary walls in most areas of the body,

Question 23

Where do substances that pass out of the capillaries go?

Answer 23

Into the fluid surrounding the cells

Question 24

Is the blood entering the capillaries oxygenated or deoxygenated?

Answer 24

Oxygenated, though by the time it exits it is deoxygenated

Question 25

How are capillaries adapted for their function?

Answer 25

-Provide a large surface area for the diffusion of substances into and out of the blood -The walls are a single epithelial cell thick, giving it a thin layer for diffusion -Total cross-sectional area of the capillaries is greater than the arteriole supplying them, so blood flow falls.

Question 26

Why is it good that blood flow falls while the blood passes through the capillaries?

Answer 26

Relatively slow movement of blood through capillaries gives more time for the exchange of materials by diffusion between the blood and the cells.

Question 27

Do veins carry blood to or away from the heart?

Answer 27

To the heart, and away from the body.

Question 28

Do veins carry oxygenated or deoxygenated blood?

Answer 28

Deoxygenated

Question 29

What is the name for small veins?

Answer 29

Venules.

Question 30

What are the two main vessels carrying deoxygenated blood back to the heart?

Answer 30

Inferior vena cava and superior vena cava

Question 31

Where does the inferior vena cava take deoxygenated blood from?

Answer 31

The lower parts of the body

Question 32

Do veins have a pulse? Why / why not?

Answer 32

No, because the surges from the heart pumping are lost as the blood passes through the narrow capillaries

Question 33

Is blood pressure in the veins higher or lower than in the arteries?

Answer 33

Lower

Question 34

What feature do medium-sized veins contain?

Answer 34

Valves, to prevent the backflow of blood

Question 35

What do the walls of veins contain?

Answer 35

Epithelium, lots of collagen, and relatively little elastic fibre.

Question 36

What is the lumen of a vein like?

Answer 36

Wide.

Question 37

What is the epithelium of a vein like?

Answer 37

Smooth and thin, so the blood flows easily.

Question 38

What are the 3 main adaptations of veins that allow them to overcome their low blood pressure, and moving against the force of gravity?

Answer 38

-Majority of veins have one-way valves at intervals -Many of the bigger veins run between the big, active muscles in the body -Breathing movements of the chest act as a pump

Question 39

How does having valves help veins?

Answer 39

The valves open so that blood can pass through. If the blood starts to flow backwards the valves close to prevent this from happening.

Question 40

How does having larger veins run between the big, active muscles in the body assist the flow of blood?

Answer 40

When the muscles contract, they squeeze the veins, forcing the blood towards the heart.