Tissue fluid

Question 1

Tissue fluid

Answer 1

Fluid that contains water, amino acids, ions and glucose which bathes the tissue and supplys cells with what it contains

Question 2

How is tissue fluid formed and reabsorbed? (UNDERSTANDING)

Answer 2

Capillaries have smalls gaps in the wall so liquid so at the arteriole end of a capillary the hydrostatic pressure is greater than the osmotic pressure so plasma is forced out DOWN the hydrostatic pressure gradient of the capillary leaving large proteins behind as they are too large to pass through the gaps. This forms tissue fluid which bathes the tissues and supplies them with essential substance e.g amino acids. Near the venous end, since the proteins are left behind in the capillaries the osmotic pressure is greater than the hydrostatic pressure (hydrostatic pressure in capillaries decreased due to loss of plasma volume) So tissue fluid is reabsorbed back into the capillaries down the water potential gradient by osmosis. Or absorbed into the lymphatic system

Question 3

Osmotic pressure

Answer 3

Pressure exerted by plasma proteins in a blood vessel

Question 4

Hydrostatic pressure

Answer 4

Pressure exerted by blood in the capillaries

Question 5

Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system. (4 marks)

TIP : 4th mark is lymph— figure out the rest

Answer 5

1. (Plasma) proteins remain;
   Accept albumin/globulins/fibrinogen for (plasma)
   protein
2. (Creates) water potential gradient
   OR
   Reduces water potential (of blood);
3. Water moves (to blood) by osmosis;
4. Returns (to blood) by lymphatic system;

Question 6

Explain how tissue fluid is formed and how it may be returned to the circulatory system.
(6 marks)

Answer 6

High hydrostatic pressure at the arteriole end of the capillary forces water and small molecules out of the blood plasma.

Large plasma proteins remain in the capillary, contributing to a lower water potential inside the capillary.

Tissue fluid is formed as water and dissolved substances pass into the surrounding tissues.

At the venule end, the hydrostatic pressure is lower, but the water potential remains lower inside the capillary due to the retained plasma proteins.

Water re-enters the capillary from the tissue fluid by osmosis.

Excess tissue fluid is collected by the lymphatic system and returned to the circulatory system.

Question 7

Why is all the tissue fluid not reabsorbed back into the capillary?

Answer 7

Eventually the water potential gradients will reach equilibrium so there is no water potential gradient for tissue fluid to move back into capillaries by osmosis so some is reabsorbed by the lymphatic system and drains back into the bloodstream by the heart