blood vessels

Question 1

What are three types of blood vessels?

Answer 1

• veins
• arteries
• capillaries

Question 2

What type of blood does arteries carry?

Answer 2

Carry oxygenated blood except the pulmonary artery.
- carries oxygenated blood away from heart.

Question 3

What does artery walls contain and how does it adapt to their function?

Answer 3

• Artery walls contain elastic fibres, smooth muscle and collagen.
• Elastic fibres enable them to withstand the force of blood pumped out of the heart and stretch to take lather blood volume.
• In between the contractions of the heart, the elastic fibres recoil and return to their original length. This helps to even out the surges of blood pumped from the heart to give a continuous flow.
• Endothelium lining the artery is smooth so blood flows easily over it.

Question 4

What links arteries to capillaries?

Answer 4

Arterioles.

Question 5

How are arterioles adapted to its functions?

Answer 5

• They have more smooth muscle and less elastin in their walls than arteries, but can constrict or dilate to controls the flow into individual organs.
• when smooth muscle in the arteriole contracts it constricts the vessel and prevents blood flowing into a capillary bed. This is vasoconstriction.
• when the smooth muscle in the wall becomes of an arteriole relaxes, blood flows through into the capillary bed. this is vasodilation.

Question 6

What do veins do?

Answer 6

• carries blood away from the cells of the body towards the heart.
• Carry deoxygenated blood.

Question 7

How are veins adapted to function?

Answer 7

• wide lumen.
• smooth endothelium reduces friction.
• one-way valves which prevents back flow of blood.
• blood is at low pressure.

Question 8

Where are capillaries found and what do they do?

Answer 8

• surround all cells and exchange substances (e.g Oxygen / glucose)

Question 9

How are capillaries adapted for their role?

Answer 9

• They provide a very large surface area for the diffusion of substances into and out the blood.
• The total cross-sectional area of the capillaries is always greater than the arteriole supplying them so the rate of blood flow falls. The relatively slow movement of blood through capillaries gives more time for the exchange of materials by diffusion between the blood and the cells.
• Thin walls are a one endothelial cell thick, giving a very thin layer for diffusion.

Question 10

Function of artery.

Answer 10

Carry blood away from the heart under high pressure.

Question 11

Structure of artery.

Answer 11

• Thicker elastic layer enables them to withstand pressure.
• Thicker elastic layer enables them to stretch recoil.
• Elastic layer evens out surges from the pumping of the heart.
• Collagen provides structure.
• Collagen maintains shape and volume.
• Smooth muscle contacts and relaxes to change the size of the lumen and control blood pressure.

Question 12

Function of veins.

Answer 12

• Carey blood back to the heart.

Question 13

Structure of veins.

Answer 13

• Thinner elastic layer.
• Have valves to prevent back flow of blood.
• Mode collagen then arteries to give structural support as they carry large volumes of blood.

Question 14

Function of capillaries.

Answer 14

Allow substances to be exchanged between blood and tissue fluid/ surrounding cells.

Question 15

Structure of capillaries.

Answer 15

• Walls are one cell thick.
• Short diffusion distance.

Question 16

Difference in lumen size between arteries and veins.

Answer 16

• In arteries small lumen maintains pressure.
• In veins low resistance needed because of low pressure.