Component 3.2 - Intercellular Fluid

Question 1

How is tissue fluid useful?

Answer 1

It is forced out of the capillary walls and it bathed the cells, supplying them with solutes they need to survive and removing any waste made by the cells.

Question 2

What happens at the arterial end of a capillary bed?

Answer 2

1) Hydrostatic pressure is greater than osmotic pressure, so water and small soluble substances are forced out through capillary walls forming tissue fluid
2) Plasma has a low solute potential, due to plasma proteins being too large to be forced out so they pull water back into the capillary by osmosis
3) Solutes such as glucose, oxygen and ions are used during metabolism - concentration is higher in blood than around cells so diffuses from blood into tissue fluid.

Question 3

What happens at the venous end of the capillary bed?

Answer 3

1) The blood hydrostatic pressure is lower than at the arterial end because much fluid has been lost and at venous end osmotic pressure of the blood is higher than hydrostatic pressure
2) Most Water from tissue fluid moves back into blood capillaries by osmosis down water potential gradient

Question 4

What happens to remainder of tissue fluid

Answer 4

Some is returned to blood via the lymph vessels