Tissue Flui d

Question 1

What is tissue fluid?

Answer 1

• Fluid containing water, glucose, amino acids, fatty acids, ions and oxygen which surrounds the tissues (to provide the tissues with the materials needed.)

Neumonic: Wanna give a fat imp oxygen

() - extra info for clarification.

Question 2

How is tissue fluid formed?

Answer 2

• Capilaries have small gaps in their walls so that liquids/ small molecules can be forced out, large molecules will remain in blood within capilary.
• Blood enters capilaries from arterioles, smaller diameter of capilaries leads to higher hydrostatic pressure so water, glucose, amino acids, fatty acids ions and O2 are forced out.

Question 3

What it is called when high hydrostatic pressure in capilaries causes glucose, water, fatty acids, amino acids, ions and O2 to be pushed out of the capilary to form tissue fluid?

Answer 3

• Ultrafiltration.

Question 4

What substances are forced out of blood in capilary through the small gaps in the walls of capilary at end closest to the arterioles?

Answer 4

• Water molecules
• Glucose
• Small proteins/ amino acids.
• Fatty acids
• Oxygen
• Ions.

Question 5

What substances remain in the capilary during ultrafiltration?

Answer 5

• Red blood cells
• Platlets
• Large proteins.

Question 6

How is tissue fluid re-absorbed?

Answer 6

• Large proteins remain in capilary during ultrafiltration, lowering water potential in capilary at venule end (side closest to veins. )
• towards venule end, hydrostatic pressure is lowered due to loss of liquid.
• Water re-enters the capilaries by osmosis.

() - extra info for clarification.

Question 7

Why is it important that tissue fluid is returned to the circulatory system?

Answer 7

• Water contains dissolved waste substances (CO2/ urea) that needs to be re-absorbed by capilaries so can be transported/ removed.

Question 8

Not all tissue fluid is re-absorbed by capilaries, what happens to rest of tissue fluid? Why isn’t all the tissue fluid re-absorbed?

Answer 8

• WHY: Not all liquid of tissue fluid will be re-absorbed by osmosis, as equilibrium will be eventually reached.
• Rest of tissue fluid absorbed into lymphatic system and eventually drains back into bloodstream, near the heart.

Question 9

What is the excess tissue fluid that isn’t re-absorbed by capilaries called?

Answer 9

• Lymph

Question 10

Explain the role of the heart in formation of tissue fluid (2 marks)

May 2017 Paper 1.

Answer 10

• Contraction of ventricle produces a high blood/hydrostatic pressure.
• This forces water out of the capilaries.

Question 11

Exam Q

Why can build up of excess tissue fluid lead to swells?

Answer 11

• Lymphatic system can’t drain away all the excess tissue fluid.