8.2 Blood Vessels

Question 1

What are the five types of blood vessels called

Answer 1

Arteries
Arterioles
Capillaries
Venules
Veins

Question 2

What does the tough collagen layer in blood vessels provide

Answer 2

It provides structural support to maintain the shape of the vessel so it can resist pressure

Question 3

What does the smooth muscle layer in blood vessels do

Answer 3

It can contract and relax to control the flow of blood by changing the size of the lumen

Question 4

What does the elastic layer in blood vessels do

Answer 4

It can stretch and recoil to maintain blood pressure (stretch under high pressure and contract&recoil under low pressure) and contains elastic it also can help smooth out blood flow during pressure surges created by the beating heart

Question 5

What does the endothelium in blood vessels do

Answer 5

It is a very thin inner lining of cells, it’s a smooth layer which prevents friction and provides a short diffusion pathway eg; in capillaries

Question 6

What is the lumen (found in blood vessels)

Answer 6

It’s a cavity which blood flows through

Question 7

What’s the function of the arteries

Answer 7

To transport blood rapidly at high pressure away from the heart into the arterioles(to tissues) it’s used in transport and most carry oxygenated blood except from the pulmonary artery

Question 8

What’s the structure of the arteries likes

Answer 8

Thick muscle layer
Thick elastic layer
Smooth endothelium
Overall very thick walls
No valves
Contains collagen

Question 9

Why do some blood vessels contain valves

Answer 9

To prevent the back flow of blood when it’s carried at low pressure

Question 10

What’s the structure of arterioles like

Answer 10

Similar to arteries, but more smooth muscles (relative to size) to allow vasoconstriction to reduce blood flow before entering capillaries
Thinner elastic layer (relative to size) as blood pressure is lower in arterioles
They have no valves and are smaller in diameter

Question 11

What’s the function of arterioles

Answer 11

They are used in transport to transport the blood from arteries to capillaries

Question 12

What is vasoconstriction

Answer 12

When smooth muscle In the arterioles contracts, it constricts the vessels and prevents blood flowing into a capillary bed

Question 13

What is vasodilation

Answer 13

When smooth muscle in the arteriole wall relaxes, blood flows through into the capillary bed

Question 14

What’s the function of the capillaries and what helps them carry out their function

Answer 14

They are used in substance exchange, to exchange metabolic substances between blood and body tissues to help with their function they have very slow blood flow and single file red blood cells

Question 15

What is the structure of capillaries like

Answer 15

Overall very thin walls
Numerous and branched (larger surface area)
Narrow diameter
Spaces between endothelial cells (fenestrations)
Total cross section area of capillaries is greater than the arteriole suppling them (decreases rate of blood = more time to exchange substances)

Question 16

What are fenestrations and where are they found

Answer 16

They are spaces in the endothelial cells found in capillaries, they allow WBCs to leave blood and enter tissue fluids they also allow the exchange of some substances

Question 17

Why do capillaries have a narrow diameter

Answer 17

They can permeate tissues so no cell is far away from a capillary so short diffusion pathway.
Them being narrow forces RBC to move slowly in single file to allow time for diffusion to take place this also allows for a greater SA of RBC to be in contact with the capillary wall for more efficient diffusion

Question 18

What’s the function of venules

Answer 18

To transport blood slowly at low pressure from capillaries to veins

Question 19

What’s the structure of venules like

Answer 19

Very thin muscle layer (as they don’t control the flow of blood via constricting and dialating)
Very thin elastic layer (as low blood pressure)
Valves (to prevent back flow of blood)
Smooth endothelium (reduces friction for smooth blood flow)
Collagen (maintain vessels shape as veins carry large volumes of blood)

Question 20

What’s the function of veins

Answer 20

To transport blood at low pressure fork the venules back to the heart, most carry deoxygenated blood except for the pulmonary vein

Question 21

What’s the structure of veins like

Answer 21

Thin muscle layer (don’t control blood flow by c&d)
Thin elastic layer (due to low blood pressure)
Overall thin wall (don’t need to withstand high pressure so no risk of bursting and allows compression which aids blood flow)
Don’t have a pulse (surges of blood are lost as blood passes through narrow veins)
Valves (prevent back flow of blood)
Smooth endothelium (reduce friction)
Collagen (maintain shape as they carry large volumes of blood)