Lesson 7 - Blood vessels

Question 1

Components of blood vessels:

Answer 1

• Elastic fibres
• Smooth muscle
• Collagen

Question 2

Role of arteries

Answer 2

Carry blood away from heart to the tissues in the body

Question 3

What type of blood do arteries mostly carry

Answer 3

Oxygenated blood.

Accept the pulmonary artery. This carried deoxygenated blood to the lungs.
And during pregnancy: umbilical artery carries deoxygenated blood from foetus to the placenta.

Question 4

Structure of arteries?

Answer 4

• Lumen
• Endothelium
• Elastic layer (elastic fibres)
• Muscle layer
• Tough outer layer (collagen)

Question 5

Role of elastic fibres in arteries?

Answer 5

Enable arteries to withstand the force of the blood pumped out of the heart and stretch (within limits of collagen layer) to take larger blood volume.

Question 6

Elastic fibres actions with pumping of heart?

Answer 6

In between contractions of the heart, the elastic fibres recoil and return to original length. Helps to even out surges of the heart and maintain steady flow.

Can feel a pulse (surge of blood) when the heart contracts, which the elastic fibres cannot completely eliminate.

Question 7

Role of endothelium in Arteries

Answer 7

Lining of artery (endothelium) is smooth so blood flows easily over it.

Question 8

role of Arterioles

Answer 8

link arteries and the capillaries

Question 9

Structure of arterioles:

Answer 9

Have less elastin and more smooth muscle in walls than arteries.

Question 10

Role of smooth muscle in arterioles?

Answer 10

When smooth muscle contracts the arterioles constrict. Blood is prevented from flowing into capillary bed.

When smooth muscle relaxes the arterioles dilate.

Question 11

Vasoconstriction:

Answer 11

When smooth muscle contracts and the arterioles are constricted, reducing blood flow.

Question 12

Vasodilation:

Answer 12

When smooth muscle relaxes and the arterioles are dilated, increasing blood flow.

Question 13

What has the most collagen?
Artery
Aorta
Arteriole

Answer 13

Aorta

Question 14

What has the most elastic fibres?
Artery
Aorta
Arteriole

Answer 14

Aorta

Question 15

What has the most smooth muscle?
Artery
Aorta
Arteriole

Answer 15

Artery

Question 16

What has the least collagen?
Artery
Aorta
Arteriole

Answer 16

Artery

Question 17

What has the least smooth muscle?
Artery
Aorta
Arteriole

Answer 17

Aorta

Question 18

What has the least elastic fibres?
Artery
Aorta
Arteriole

Answer 18

Arteriole

Question 19

Aneurysms:

Answer 19

Bluge or weakness in the blood vessel

Most commonly occur in the brain and aorta. Most people don’t know they have an aneurysm until it bursts. Can be fatal.

Question 20

What increases the risk of an aneurysm?

Answer 20

• High blood pressure
• Changes in proportions of collagen to elastin in aorta wall can cause

Screening used to find people most at risk.

Question 21

Capillary structure?

Answer 21

• Lumen
• Capillary wall

Question 22

Role of capillaries

Answer 22

Microscopic blood vessels that link the arterioles to the venules. Form an extensive network through all the tissues in the body.

Question 23

Diffusion distance

Answer 23

Gaps between endothelium cells that make up the capillaries are large in most areas of the body. Not in the central nervous system. Very tight junctions between cells.

Question 24

How are capillaries adapted for role?

Answer 24

• Provide very large surface area for diffusion of substances into and out of blood.
• The cross-sectional area of capillaries is always greater than that of the arteriole supplying blood, so the rate of blood flow decreases. Slow movement of blood through capillaries gives more time for the exchange of materials by diffusion between the blood and cells.
• Walls are single endothelium cell thick, small diffusion distance

Question 25

What type of blood do veins carry?

Answer 25

Deoxygenated towards the heart.

Exceptions:
- Umbilical vein carries oxygenated blood from the placenta to the foetus
- Pulmonary vein carries oxygenated blood from lungs to heart

Question 26

What are in between veins and capillaries?

Answer 26

Venules

Question 27

Inferior vena cava?

Answer 27

From lower parts of body to heart

Question 28

Superior vena cava?

Answer 28

From head and upper parts of the body to the heart

Question 29

Why do veins not have a pulse?

Answer 29

Surges from the heart pumping are lost as the blood passes through the narrow capillaries. Do hold large reservoirs of blood

Question 30

Structure of veins structure?

Answer 30

• Wide lumen
• Thin layer of endothelium
• Relatively small elastic lining
• medium smooth muscle
• Lots of collagen (tough outer layer)

Question 31

How do veins prevent backflow?

Answer 31

• One-way valves at intervals
• Flaps / infoldings of the inner lining of the vein.
• When blood flows in the direction of the heart, the valves open to let blood flow.
• If the blood flows backwards, then the valves close.

Question 32

Why do bigger veins run in between the big, active muscles in the body?

Answer 32

When muscles contract they squeeze the veins, forcing blood towards the heart. Valves open so the blood can pass through. Valves prevent backflow when the muscles relax.

Question 33

How do the chest’s breathing movements prevent backflow?

Answer 33

• Breathing movements of the chest act as a pump.
• Pressure changes and the squeezing motions move blood in the veins of the chest and abdomen towards the heart.