Cardio L10 Tissue Fluid and Oedema

Question 1

Types of capillary:

Answer 1

1. Continuous
2. Fenestrated
3. Discontinuous (sinusoidal)

Question 2

Metabolite Exchange across the Capillary Wall:

Answer 2

1. Passive diffusion down concentration gradients (Fick’s First Law of diffusion)
2. Convective transport in trans capillary fluid “solvent drug” (minor importance).

Question 3

Fluid exchange across the Capillary Wall:

Answer 3

1. Fluid flows across the capillary wall due to a pressure gradient.
2. Water also diffuses across the capillary wall but this is bi-directional and no net transfer occurs.

Question 4

Tissue fluid:

Answer 4

1. Extracellular fluid (ECF).

2. Isotonic to intracellular fluid (ICF).

Question 5

Tissue fluid produced by

Answer 5

a. Ultrafiltration across the capillary wall.

Question 6

Tissue fluid drained into

Answer 6

a. The lymphatic system and eventually returned to the vascular system.

Question 7

Ultrafiltration: Definition

Answer 7

Flow through pores in the membrane (e.g. capillary endothelium)

Question 8

Ultrafiltration: Driven by

Answer 8

A pressure gradient

Question 9

Ultrafiltration: Pore size permits

Answer 9

Selective passage of molecules according to their size

Question 10

Ultrafiltration: Example of molecules

Answer 10

Glucose and ions

Question 11

Ultrafiltration:Impermeable molecules

Answer 11

Albumin

Question 12

Reflection Coefficient: definition

Answer 12

This is an index of the membranes molecular selectivity.

Question 13

Reflection Coefficient =0

Answer 13

If the solute passes freely through the membrane and it exerts no osmotic pressure across the membrane.

Question 14

Reflection Coefficient =1

Answer 14

If the solute is totally reflected by the membrane and it exerts its full osmotic effect across the membrane.

Question 15

Hydraulic Conductance (Lp):

Answer 15

1. This describes the permeability of the membrane to fluid.

2. Increased during inflammation.

Question 16

Starling Principle:

Answer 16

rate of production of tissue fluid = filtration pressure x surface area.

Question 17

Filtration Pressure (I):

Answer 17

1. There is a hydraulic pressure gradient across the capillary wall.
2. Pressure gradient= capillary hydrostatic pressure (Pc) – interstitial pressure (Pi).
3. Net effect is to “drive” ultrafiltration.

Question 18

Filtration Pressure (II):

Answer 18

1. There is an osmotic pressure gradient
2. Pressure gradient = colloid osmotic pressure of plasma – colloid osmotic pressure of interstitial fluid.
3. Net effect is to retain within the vascular system.

Question 19

Landis Model →

Answer 19

→ Transient capillary reabsorption probably only occurs under conditions such as haemorrhage.

Question 20

Functions of the Lymphatic System:

Answer 20

1. Fluid balance
2. Nutrition
3. Defence

Question 21

Oedema:

Answer 21

1. An excess of tissue fluid.
2. May be localised or generalised.
3. Occurs when production of tissue fluid exceeds its drainage.

Question 22

Raised Capillary Pressure:

Answer 22

1. Heart failure
2. Fluid overload
3. Venous thrombosis
4. Venous valve incompetence

Question 23

Decreased Plasma COP: due to

Answer 23

1. Malnutrition
2. Malabsorption
3. Protein losing enteropathy
4. Nephrotic syndrome
5. Hepatic failure

Question 24

Increased Capillary Permeability:

due to

Answer 24

1. Inflammation

2. Allergy

Question 25

Lymphatic insufficiency: due to

Answer 25

1. Congenital absence of lymphatic vessels.
2. Blockage by parasites or cancer cells
3. Iatrogenic