blood vessels

Question 1

What is the function of an artery?

Answer 1

Transport blood under high pressure from the heart to tissue

Question 2

What is the structure of the artery?

Answer 2

1) muscle layer is thick so smaller arteries can be constricted and dilated in order to control volume of blood passing through.
2) elastic layer is thick, stretching and recoiling allows blood pressure must remain high.
3) wall is thick which resists vessel bursting under high pressure.
4) no valves, as blood flows at high pressure, blood tends not to flow backwards

Question 3

What is the function of the vein?

Answer 3

Transports blood under low pressure from capillaries in tissues to the heart

Question 4

What is the structure of the vein?

Answer 4

1) muscle layer is thin- no need to control blood flow to capillaries
2) elastic layer is thin- low pressure of blood means they will not burst.
3) thickness is thin, pressure is too low to create risk of bursting, it allows them to be flattened easily, aiding flow of blood within.
4) valves as the pressure is so low so ensures blood doesn’t flow backwards

Question 5

What is the function of capillaries?

Answer 5

Tiny vessels that link arterioles to veins and exchange metabolic materials such as oxygen, carbon dioxide and glucose

Question 6

What is the structure of capillaries?

Answer 6

1) wall consists of a lining layer, making them extremely thin, shorter diffusion pathway
2) numerous and highly branched, providing a large surface area.
3) narrow diameter so no cell is far away from a capillary and thus a short diffusion pathway.
4) lumen is narrow, red blood cells are squeezed flat against the side of the capillary which reduces diffusion distance.
5) spaces between the endothelial cells, allows white blood cells to escape to deal with infections within tissue

Question 7

What is the function of the arteriole?

Answer 7

Carry blood, under lower pressure than arteries, from arteries to capillaries

Question 8

What is the structure of arterioles?

Answer 8

1) muscle layer is thicker than arteries, the contraction of the muscle layer allows constriction of the lumen to control blood supply to the tissues
2) elastic layer is thinner than arteries as blood pressure is lower

Question 9

describe the general structure of arteries, veins and capillaries

Answer 9

lumen- space that blood flows through
endothelium- one cell thick and smooth.
elastic layer- stretches and recoils.
muscle layer- can contract to control blood flow.
tough fibrous outer layer- resists pressure changes

Question 10

describe the composition of tissue fluid

Answer 10

tissue fluid contains water, glucose, amino acids, fatty acids, ions and oxygen

Question 11

explain how tissue fluid is formed

Answer 11

at the arterial end of the capillary, there is a high hydrostatic pressure due to the pumping of the heart. water and other small molecules are forced out of the blood plasma to form tissue fluid (ultrafiltration). this lowers water potential of the blood as only cells and proteins are left. outward movement is opposed by hydrostatic pressure of tissue fluid and low water potential of the blood but overall movement is from blood to tissues. after exchange of materials, water and other small molecules return to the blood due to high hydrostatic pressure and water potential of the tissue fluid to the venous end of the capillary. excess water return to the blood via the lymphatic system