module 3: blood vessels

Question 1

describe arteries

Answer 1

carry blood away from heart
thick muscular walls
elastic tissue to stretch and recoil- maintains high pressure
folded endothelium for expansion
carry oxygenated blood

Question 2

describe arterioles

Answer 2

smaller than arteries and branch off from them
layer of smooth muscle allows expanding and contracting
less elastic tissue

Question 3

describe capillaries

Answer 3

smallest vessel
branch from arterioles
glucose and oxygen exchanged between cells and capillaries
endothelium one cell thick for fast diffusion

Question 4

describe venules

Answer 4

thin walls
some smooth muscle
connect to capillaries
going together to form veins

Question 5

describe veins

Answer 5

take blood back to the heart under low pressure
wide lumen
little elastic tissue
contain valves to stop back flow
carry deoxygenated blood

Question 6

what is tissue fluid

Answer 6

surrounds cells in tissues
made from substances that leave blood plasma e.g. water and oxygen
doesn’t contain blood cells or big proteins as they are too large to be pushed out capillary walls

Question 7

what is pressure filtration

Answer 7

substances move out capillaries in capillary bed into tissue fluid

Question 8

describe pressure filtration

Answer 8

at start of capillary bed near arteries there is a high hydrostatic pressure in capillaries compared to tissue fluid so fluid is forced out capillaries Ito spaces around cells
this reduces hydrostatic pressure in capillaries near the end of capillary bed near venules
at venule end there is a high oncotic pressure generated by plasma proteins which lowers water potential so some water re enters from the tissue fluid by osmosis

Question 9

what happens to excess tissue fluid

Answer 9

it drains into the lymph vessels and into the lymphatic system to be returned to blood near the heart