Fluid Compartments Flashcards
What is the most plentiful cation in the plasma?
Sodium
What is the most plentiful cation inside the cell?
Potassium (This is due to Na+/ K+ATPase pumps pumping 2 x K+into the cell for every 3 x Na+ which are pumped out the cel
Is Cl- found in a higher concentration inside the cell or out?
Found in much higher concentration outside the cel
What is the main intracellular anion?
Organic Phosphate
What does phosphorylation of proteins do?
Key for the activation and inactivation of certain proteins
What is the difference in the osmolarity between the blood and the intracellular compartment?
They are identical, so there is not much of an osmotic effect
What is the concentrations of Na+ inside the cell and outside the cell?
Outside = 150mmol/L
Inside = 10mmol/L
What is the concentrations of K+ inside the cell and outside the cell?
Inside = 150mmol/L
Outside = 5mmol/L
What is the concentration of Cl- inside and outside the cell?
Inside = 5mmol/L
Outside = 110mmol/L
What is the definition of diffusion?
Diffusion is the spontaneous movement of a solute down a concentration gradient until the solute molecules reach an equilibrium
Is the inside of the cell more acidic or more alkaline than the plasma?
Inside of the cell is more acidic- although the difference in pH is small, since the concentration of H+ ions determines pH and this follows a logarithmic scale, an small increase indicates a 2 fold increase in the concentration of H+ ions
What is meant by osmolarity?
A measure of the concentration of all the solute particles in a solution
What is an osmole?
The number of moles of solute which contribute to the osmotic pressure of a solution
What is the osmolarity of a solution which has a 150 mmol Conc of NaCl, 1 mmol/L conc of CaCl2 and 2mmol/L conc of glucose?
150 x 2 ions in NaCL = 300
1 x 3 ions in CaCl2 = 3
2 x 1 compound in glucose = 2
Total = 305
What is meant by tonicity?
The strength of a solution as it affects the final cell volumes - depends on both cell membrane permeability and solution composition
What happens to cells when they are placed in hypertonic solutions?
The cell shrinks
What is meant by a hypertonic solution?
A hypertonic solution is one where the solute osmolarity outside the cell is much greater than those of inside the cell. therefore, there is a low water concentration outside the cell, and hence water will move from outside the cell into the solution, resulting in a shrinkage of the cell
What happens when a cel is placed inside a hypotonic solution?
The cell swells
What is a hypotonic solution?
A solution in which the solute osmolarity is low in the solution. Therefore the concentration of water is higher outside the cell than inside, and so water moves from the outside solution into the cel, resulting in the swelling of the cell
What is an isotonic solution?
Where the osmolarity of the impermeant solutes outside the cel is the same as those inside the cell
WHat happens to the cell volume when placed in an isotonic solution?
Nothing - stays the same size
Why do cells of the body not burst?
The cells don’t burst because the Na+K+-ATPase maintains the concentration of Na+ ions (cyan squares) much lower inside the cell than outside.
The ATPase makes the membrane “effectively impermeable” to Na+ because any Na+ that diffuses in down the Na+ concentration gradient is actively pumped out again. Thus there is no net movement of Na+ across the membrane.
What substances can diffuse across the lipid bilayer?
Gases like oxygen and carbondioxide and other hydrophobic molecules like steroids
Why are transplanted organs cooled when transported to their recipient?
When any tissue loses its blood supply, ischaemic changes occur, but these can be significantly slowed by rapid cooling of the tissue/organ to +4°C.
How are the organs cooled to 4 degrees?
They are perfused with cold solutins via the arterial supply
What important pump stops working in transplanted organs below 15 degrees?
Na+ / K+ ATPase
What is the name of the solution which organs being transplanted are perfused with?
University of Wisconsin solution
What is UoW solution intended to do?
reduce hypothermic cell swelling and enhance preservation.
Three main factors serve to reduce cell swelling in UW-infused tissues:
Lack of Na+ or Cl- (therefore no influx possible).
Presence of extracellular impermeant solutes (lactobionate ions, raffinose).
Presence of a macromolecular colloid (starch)
How much plasma leaks out of blood vessels a day?
8L
What are ways in which molecules transverse the endothelial cell layer?
- Lipid soluble substances-pass thorugh epithelial cel
- Water soluble substances = pass thorugh tight H2O junctions
- Plasma proteins generally cannot get across the epithelial cell membrane
Where is there a higher concentration of plasma proteins?
Inside the plasma is much higher than that of outside the capillary
What is the colloid osmotic pressure?
The pulling force of the higher concentration of plasma proteins intside the vessel compared to outside
What is the hydrostatic pressure of the blood?
The pushing force which is generated through the flow of blood through the vessel, pushes molecules through the capillary pores
What is the balance between oncotic and hydrostatic pressure in a normal situation?
Net leakage due to the hydrostatic pressure being slightly greater than the colloid osmotic pressure
What is an oedema?
An accumulation of fluids within tissues
What causes an oedema?
An imbalance between the hydrostatic pressure being alot greater than the oncotic pressure due to increased pore size, so when blood forces molecules out the capillary pores, many more molecules can pass
What are the effects of a leaky capillary?
Proteins are lost into the interstitial space due to increased pore size, this reduces the oncotic colloid pressure which means fluids are more rapidly pushed out from the capillary
What is the system which combats the issue of capillaries leaking fluid?
Lymphatic system collects interstitial fluid that is destined to return to the blood
What features of lymphatic capillaries results in the net flow of fluids from tissues into the lymphatic capillaries?
Lymphatic capillaries are blind ended and have a low internal pressure which results into the net flow of fluids from tissues into the lymphatic capillaries.
What does oedema indicate?
Inflammation
Why do overweight individuals often have swelling?
Individual is likely to have high blood pressure which means increased hydrostatic pressure in vessels - this pushes fluid out of the vessels and can lead to an accumulation of interstitial fluid
Why might a breast cancer survivor have swelling of the upper limb on the side of her breast tumour?
Breast cancer patients are likely to ave their axillary nodes removed in order to limit the extent of spreading, which can removes the pathway of drainage from the upper limb on the affected side, resulting in the accumulation of fluid
What is the primary cause of elephantitis?
When parasitic worms block lymphatic vessels which prevents the drainage of lymph
When does oedema occur?
When the leakage of plasma into the interstitium exceeds the capacity of the lymphatics to collect and return it to the circulation - oedma will result as the fluid accumulates in the interstitial space
