Cardio L10 Tissue Fluid and Oedema Flashcards Preview

Cardio > Cardio L10 Tissue Fluid and Oedema > Flashcards

Flashcards in Cardio L10 Tissue Fluid and Oedema Deck (25):
1


Types of capillary:

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

2


Metabolite Exchange across the Capillary Wall:

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

3

Fluid exchange across the Capillary Wall:

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.

4

Tissue fluid:

1. Extracellular fluid (ECF).
2. Isotonic to intracellular fluid (ICF).

5

Tissue fluid produced by

a. Ultrafiltration across the capillary wall.

6

Tissue fluid drained into

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

7

Ultrafiltration: Definition

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

8

Ultrafiltration: Driven by

A pressure gradient

9

Ultrafiltration: Pore size permits

Selective passage of molecules according to their size

10

Ultrafiltration: Example of molecules

Glucose and ions

11

Ultrafiltration:Impermeable molecules

Albumin

12

Reflection Coefficient: definition

This is an index of the membranes molecular selectivity.

13

Reflection Coefficient =0

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

14

Reflection Coefficient =1

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

15

Hydraulic Conductance (Lp):

1. This describes the permeability of the membrane to fluid.
2. Increased during inflammation.

16

Starling Principle:

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

17

Filtration Pressure (I):

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.

18

Filtration Pressure (II):

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.

19

Landis Model →

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

20

Functions of the Lymphatic System:

1. Fluid balance
2. Nutrition
3. Defence

21

Oedema:

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

22

Raised Capillary Pressure:

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

23

Decreased Plasma COP: due to

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

24


Increased Capillary Permeability:
due to

1. Inflammation
2. Allergy

25

Lymphatic insufficiency: due to

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

Decks in Cardio Class (108):