Regulation of fluid compartments and the lymphatic system Flashcards
What is extracellular fluid made up of?
Plasma and interstitial fluid.
What is colloid osmotic pressure?
The pressure exerted by the higher levels of protein in the plasma compared with the interstitial fluid - it draws water back into the plasma by osmosis.
What is hydrostatic pressure?
Pressure created due to fluid and the force of gravity.
What is the volume of interstitial fluid?
12 litres.
What is the volume of plasma?
3 litres.
What is the volume of intracellular fluid?
28 litres.
What can failure of regulation of the bodies fluid result in?
Oedema.
What is osmosis?
The net diffusion of water across a selectively permeable membrane from a region of high water concentration to one that has a lower water concentration (low particle concentration to high particle concentration).
What is one osmole?
1 mole of solute particles in 1 litre.
Is osmolarity dependent on molecular weight?
No.
What are the properties of cellular membranes?
They are permeable to water, impermeable to solutes such as Na+, Cl-, K+.
What is osmotic pressure?
The pressure required to prevent osmosis. It is proportional to the osmotically active particles in a solution.
What is an isotonic solution?
Inside has the same osmotic pressure as outside.
What is an hypotonic solution?
Inside has a higher osmotic pressure than outside. (cell swells)
What is a hypertonic solution?
Outside has a higher osmotic pressure than inside (cell shrinks)
What does the semi-permeable membrane allow diffusion of?
Ions, water, oxygen, nutrients, waste but NOT PROTEINS.
What does hydrostatic pressure drive?
Blood from plasma into interstitial space.
What is the overall movement across capillary membranes determined by?
Capillary net filtration pressure (NFP).
At the arterial end of the capillaries, what pressure dominates?
Hydrostatic pressure - there is net outward filtration.
At the venous end of the capillaries, what pressure dominates?
Colloid osmotic pressure - there is net inward filtration.
What did William Hunter describe the lymphatic system as?
Present in almost every tissue apart from the brain and that they are essential for the absorption of interstitial fluid.
What are the two main functions of the lymph system?
Draining fluid from the tissues and returning to the cardiovascular system, the maintenance of the immune response.
What happens to the fluid that passes into the interstitial area and collects in veins?
It passes into lymph capillaries through lymph nodes before passing back to the blood stream at the neck.
How does fluid move along the lymph system?
Vessels contain valves and fluid is forced along by the action of muscles and breathing.
What cells does lymph fluid contain?
White blood cells such as lymphocytes, macrophages and dendritic cells.
How is immunity activated in the lymph system?
The lymph system collects antigens that are recognised by b-lymphocytes in the lymph nodes.
What happens to b lymphocytes when they recognise antigens?
The proliferate to produce antibodies.
How is oedema caused?
Increased capillary pressure (both ends) and decrease in colloid osmotic pressure
What can cause an increase in capillary pressure at both ends?
Heart failure, excessive kidney retention of water, increased arteriolar resistance and a high venous pressure.
What can cause a decrease in colloid osmotic pressure?
A reduction in plasma proteins, a loss of proteins in the urine and a loss of protein in the denuded skin areas, malnutrition.
What is intracellular oedema?
The depression of metabolic systems of the tissues and lack of adequate nutrition to the cells.
