intercellular or tissue fluid

Question 1

what is meant by the term solute potential

Answer 1

the potential for substances to move into a solute
the higher the solute potential- the lower the concentration of solutes in a solution
the lower the solute potential- the higher the concentration of solutes, therefore smaller gradient to diffuse.

Question 2

explain the movement of substances at the arteriole end of the capillary

Answer 2

1) blood is under high pressure from the pumping of the heart and the muscle contraction of the artery and arteriole walls
2) this increases hydrostatic pressure pushing liquids outwards from the capillary into the spaces between surrounding cells
3) plasma is a solution with a low solute potential so pulls water back into the capillary via osmosis
4) the hydrostatic pressure is greater than the solute potential so water and solutes are forced out the capillary
5) diffusion is aided by the fact that blood is high in solutes compared to tissues which are low so it moves down the gradient via diffusion

Question 3

outline how the low solute potential in the capillary causes water to want to be pulled into the capillary

Answer 3

the low solute potential is formed through the presence of plasma proteins, therefore creating a low water potential
the water potential is more dilute at the arteriole end therefore wants to move down the water potential gradient via osmosis

Question 4

explain the movement of substances at the venous end of the capillary

Answer 4

1) blood hydrostatic pressure has dropped because so much water has been lost
2) the plasma proteins are more concentrated so the solute potential is more negative (even lower solute potential)
3) the osmotic force pulling water inwards is greater than the hydrostatic force pushing water outwards so water passes into the capillary by osmosis
4) tissue fluid surrounding cells pick up CO2 and other waste which diffuses down the conc gradient into the capillaries

Question 5

not all the fluid is returned to the capillaries- where does it go

Answer 5

10% drains into the lymph capillaries of the lymphatic system as lymph fluid wich eventually returns to the venous system where it empties into the subclavian veins above the heart