Tissue Fluid

Question 1

What does plasma do?

Answer 1

Solvent and transport medium for
cells, nutrients, waste products,
mineral salts, hormones, plasma
proteins, respiratory gases, e.g.
oxygen, carbon dioxide

Question 2

What do rbc do?

Answer 2

Haemoglobin (carries oxygen), no
cell organelles (more room for HB,
changes shape to flatten against
capillary endothelium ), bi-concave
shape (large SA:V ratio)

Question 3

What do wbc do?

Answer 3

Phagocytes (phagocytosis of
pathogens, dead cells)
Lymphocytes (antibody production
for specific immune response)

Question 4

What do platelets do?

Answer 4

Role in blood clotting

Question 5

What is tissue fluid mostly made up of?

Answer 5

Water

Question 6

What are the 2 main forces of tissue fluid?

Answer 6

• Higher hydrostatic pressure at arterial side forces liquid out
• Lower water potential in capillaries (caused by plasma proteins)
draws liquid back in – osmotic water potential gradient (osmotic
pressure)

Question 7

Model answer – tissue fluid formation

Answer 7

• Higher hydrostatic pressure of blood at arterial
end of capillary;
• Water and soluble molecules pass out, but proteins /
large molecules remain;
• This lowers the water potential
• Water moves back into venous end of capillary by
osmosis;
• The lymph system collects any excess tissue fluid
which returns to the circulatory system

Question 8

What is lymph movement caused by?

Answer 8

• Hydrostatic pressure of tissue fluid leaving capillaries
• Contraction of body muscles surrounding the lymph vessels