3. Circulatory System - Tissue Fluid

Question 1

What is tissue fluid?

Answer 1

The fluid which surrounds cells in tissue.

Question 2

What is tissue fluid made from?

Answer 2

Small molecules that leave the blood plasma.

eg oxygen, water, nutrients.

Question 3

What does tissue fluid NOT contain?

Answer 3

Red blood cells or big proteins unlike blood.

Question 4

What do the cells take in from the tissue fluid?

Answer 4

Oxygen and nutrients.

They then release metabolic waste into it.

Question 5

What is a capillary bed?

Answer 5

A network of capillaries.

Question 6

What happens in the capillary bed?

Answer 6

Substance move out of the capillaries into the tissue fluid by pressure filtration.

Question 7

What is pressure filtration?

Answer 7

The net driving force which pushes fluid into tissue spaces and out of vascular sites - filtration under pressure.

Question 8

At the start of the capillary bed, where is it nearest?

Answer 8

The arteries.

Question 9

At the start of the capillary bed, nearest the arteries, what is the hydrostatic pressure like?

Answer 9

Hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid.

Question 10

What happens because there is a higher hydrostatic pressure in the capillaries than in the tissue fluid?

Answer 10

The difference in hydrostatic pressure means an overall outwards pressure forces fluid out of the capillaries and into spaces around the cells, forming tissue fluid.

Question 11

What happens as the fluid leaves the capillaries?

Answer 11

The hydrostatic pressure reduces in the capillaries - so the hydrostatic pressure is lower at the venule end of the capillary bed.

Question 12

What is hydrostatic pressure?

Answer 12

The pressure exerted by a liquid.

Question 13

Due to the fluid loss and increase in concentration of plasma proteins - which don’t leave capillaries, what does this cause?

Answer 13

The water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid.
Meaning water has re-entered the capillaries from the tissue fluid at the venule end by osmosis.

Question 14

Where does excess fluid get drained into?

Answer 14

The lymphatic system.

Which transports excess fluid from the tissue and passes it back into the circulatory system.

Question 15

What is a lymphatic system?

Answer 15

A network of tubes which transports excess tissue fluid back into circulatory system.

Question 16

What is blood plasma?

Answer 16

The liquid which carries everything in the blood.

Question 17

In tissue fluid what is pressure filtration talking about?

Answer 17

Small molecules being filtered out of the capillaries under hydrostatic pressure, forming tissue fluid.

Question 18

Where is the pressure highest?

Answer 18

At the start of the capillary bed nearest the arterioles.

Question 19

Why is the pressure highest at the start of the capillary bed nearest the arterioles?

Answer 19

Because the left ventricle contracts and sends blood out of the heart, through the arteries and arterioles at high pressure.

Question 20

What does high blood pressure mean?

Answer 20

High hydrostatic pressure in the capillaries which can lead to an accumulation of tissue fluid in the tissues.

Question 21

Where is there a net gain of fluid?

Answer 21

At the venous.

Question 22

Where is there a net loss of fluid?

Answer 22

At the arterial.

Question 23

Where is the main location where tissue fluid is formed?

Answer 23

Capillaries.

Question 24

What allows the diffusion between blood and cells?

Answer 24

The liquid which surrounds the cells.

Question 25

What things only move out of the tiny gaps in the capillary wall and what Doesn’t move?

Answer 25

Dissolved gases/nutrients move through.

Larger plasma proteins and cell do not.

Question 26

The net loss of water from the capillaries gives the capillaries what?

Answer 26

More negative water potential.