7.6 blood vessels and their functions (DO EVERYDAY)

Question 1

explain the structure of arterioles and how it is related to their function.

Answer 1

• thicker muscular layer, constriction narrows blood flow and lumen
• thinner elastic layer than that of arteries as the pressure is lower

Question 2

explain the structure of veins and how it is related to their function.

Answer 2

• thin muscle layer as constriction and dilation cannot control flow to tissues as blood flowing in opposite direction
• elastic layer is thin because of low pressure of blood to create recoil action
• thin wall because of low pressure so won’t burst
• valves to ensure no backflow as pressure is so low

Question 3

explain the structure of capillaries and how it is related to their function.

Answer 3

• narrow diameter => short diffusion pathway
• narrow lumen so red blood cells are flat against side of capillary => short diffusion pathway
• endothelial cells => allow white blood cells to escape
• numerous highly branched => a large surface area
• walls are made up of mostly of lining cells => short diffusion pathway

Question 4

explain the structure of arteries and how it is related to their function.

Answer 4

• thick muscle layer => can dilate and constrict to reduce blood flow
• thick elastic layer => when the pressure in the arteries is increased, wall stretch and recoils back
• this helps maintain smooth pressure
• thick wall => prevent vessel bursting
• no valves => blood is under high pressure

Question 5

explain how tissue fluid is formed

Answer 5

• blood plasma is more positive at the venule end that the arteriole end
• as water losses the capillary
• proteins are too large to leave

Question 6

explain how tissue fluid is returned to the circulatory system

Answer 6

• low water potential in capillary
• due to plasma proteins
• water enters capillaries
• by osmosis
• remaining by lymph

Question 7

function of arteries

Answer 7

carry blood from heart -> arterioles

Question 8

function of arterioles

Answer 8

carry blood from arteries-> capillaries

Question 9

function of capillaries

Answer 9

carry blood from arterioles-> veins

Question 10

function of veins

Answer 10

carry blood from capillaries-> heart