Fluid Compartments and Solutes Flashcards
Which ion is most plentiful in the plasma?
Na+
Which ion is most plentiful inside the cells?
K+
How are the internally high concentrations neutralised?
By a variety of anions like proteins, nucleic acids and phosphorylated proteins
What is the main intracellular anion and why?
Organic phosphate which is a key metabolite in ATP production and cell signalling
Explain how proteins are anions?
Usually have a net negative charge and although they are found in low concentrations, they have a high net negative charge.
What is the osmolarity between the blood and the intracellular compartment?
Identical except the regions of the kidney
Definition of diffusion
The spontaneous movement of solute down a concentration gradient until the solute molecules reach an equilibrium.
What is an osmole?
The number of moles that contribute to the osmotic pressure of a solution
What is more reliable to determine the cells survival and state?
Tonicity not osmolarity
Why do cells not burst?
Because the Na+K+-ATPase maintains concentration of Na+ ions much lower inside the cell than outside
Explain the function of the ATP-ase
Makes membrane “effectively permeable” to Na+ because any Na+ diffusing down the concentration gradient is pumped out again => there is no net movement
Explain what can diffuse through the bilayer
Gases and hydrophobic molecules
How can you slow down ischaemic changes to organs?
Rapid cooling to 4 degrees C via perfusing tissues with cold solutions via arterial supply => reducing deterioration and allowing transport
Characteristics of Na+K+ATP-ase function
Stops functioning below 15 degrees C, compounded with the fact that there is little O2 without circulation => little ATP to fuel the pump
Therefore, unless precautions are taken, Na+ will enter the cell (along with Cl-) and water will also enter as K+ exits => cell will burst and this leads to cell death
What solution is used to prevent the damage to transplant organs?
University of Wisconsin solution (UW solution)
3 main factors that serve to reduce swelling in UW-infused tissues.
- Lack of Na+ or Cl- (therefore no influx is possible)
- Presence of extracellular impermeant solutes (lactobionate ions, raffinose)
- Presence of a macromolecular colloid (starch)
What antioxidants are used to protect organs from reactive oxygen species?
alluprinol and glutathione
What is the volume of blood plasma and how much leaks out every day?
Total volume = 3L
8L leak out every day
How often must the blood plasma recirculate and where through?
Every 9 hours the entire plasma volume must pass through the interstitial space and back into blood circulation
What is the difference between the blood brain barrier and the normal endothelium of capillaries?
The BBB is tightly sealed so there is no uncontrolled movement of small water soluble substances which squeeze through the fenestrations
What is it called when higher concentration of plasma proteins generates an osmotic and hydrostatic pressure?
Colloid osmotic pressure (COP)
What is the movement of solute and fluid across a vessel wall determined by?
Balance between opposing pressures
Relationship between COP and hydrostatic pressure
Although COP draws solute fluid in, high hydrostatic pressure pushes it back out therefore there is a net leakage
What is the term used to describe accumulation of fluids in tissues?
Oedema
