blood vessels

Question 1

name the 4 different types of blood vessel

Answer 1

artery
arterioles
veins
capillaries

Question 2

what is the function of arteries

Answer 2

carry blood away from the heart and into arterioles

Question 3

describe and explain the structure of arteries

Answer 3

muscle layer is thick compared to arterioles

they can be constricted/dilated to control the flow of blood through them

elastic layer is thick

the elastic is stretched and relaxed at the beat of the heart. This allows the heart to maintain high and smooth pressure surges

Question 4

what is the function of arterioles

Answer 4

carry blood under lower pressure than arteries from arteries to capillaries

Question 5

describe and explain the structure of arterioles

Answer 5

muscle layer thicker than in arteries

contraction of muscle layer allows constriction of lumen of arteriole. This restricts flow of blood and controls movement into capillaries that supply tissue with blood

elastic layer is thinner than in arteries
blood pressure is lower

Question 6

what is the function of veins

Answer 6

transport blood from capillaries in tissues to the heart

Question 7

describe and explain the structure of veins

Answer 7

muscle layer is thin compared to arteries

veins carry blood away from tissues therefore their constriction/dilation so cannot control flow of blood to tissues

elastic layer is thin compared to arteries

low pressure of veins will not cause them to burst and pressure is too low to create a recoil action

Question 8

why do veins have valves

Answer 8

to prevent backflow when body muscles constrict veins compressed directing towards the heart

Question 9

what is the function of capillaries

Answer 9

exchange metabolic materials between blood and cells of the body

Question 10

describe the structure of capillaries

Answer 10

• walls constrict of the lining layer extremely thin so distance diffusion is extremely short allowing rapid diffusion
• numerous and highly branched
  so large surface area for exchange
• narrow diameter
  = short diffusion pathway
• narrow lumen
  red blood cells are squeezed flat against side of capillary so they are closer to the cells that they supply oxygen
  = reduced diffusion distance
• spaces between lining endothelial cells allows white blood cells to escape to deal with infection in tissues