Compartments & Solutes Flashcards
Which cation is most abundant in plasma?
Sodium
Which cation is most abundant intracellularly?
Potassium
Is calcium a more abundant intracellularly of extracellularly?
Higher concentrations extracellularly
How is the internally high concentration of potassium neutralized?
Anions
What are the anions present intracellularly?
Phosphate ins
Proteins (net negative charge)
What is an isotonic concentration?
No osmotic effect
Between blood and intracellular compartment
What is diffusion?
The spontaneous movement of a solute down a concentration gradient until solute molecules reach an equilibrium
What is osmosis?
Movements of water through a water potential gradient across a partially permeable membrane (High water potential to low)
What is water potential?
Water potential is the tendency of water to move out of a system
What is osmolarity?
Solute concentration*Number of particles
What is the final state of osmosis?
Intracellular osmolarity = Outside osmolarity
Equal concentrations, no net volume change or diffusion
What is tonicity?
Measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a semi-permeable cell membrane
Which two factors influence tonicity?
Cell membrane permeability
Solution composition
What are hypertonic solutions?
The osmolarity of the extracellular impermeant solutes greater than those inside the cells
Water moves to the region of lower water potential by osmosis, thereby the cell undergoes crenation
What are hypotonic solutions?
The osmolarity of the extracellular impermeant solutes are less than those inside the cell. The direction of osmosis and the net movement of water will be from the solution o to the cell
Cell swells and lysis
What is an isotonic solution?
The osmolarity of the extracellular impermeant solutes identical to those inside the cell
Cell volume, therefore, remains the cells
How do cells regulate cell volume?
Impermeant solute concentration greater intracellularly
Cells do not burst due to ATPase potassium-Sodium pump
Results in membrane permeability to Na, sodium actively pumped out
No net movement of sodium ions across the membrane
The intracellular osmolarity of the impermeant solutes negates the extracellular osmolarity of the impermeant solutes
The high concentration of protein within the cell
Which molecules can pass through the phospholipid bilayer into the cell?
Oxygen, nitrogen and carbon dioxide Hydrophobic molecules (steroids) undergo passive diffusion
How do hydrophilic molecules enter into the cell?
Active transport via carrier proteins and ion channels
How is ATP supplied to active transport?
ATP hydrolysis, ATP is supplied by creatine kinase via creatine phosphate
What conditions are used to preserve transplanted organs?
4 degrees celsius, perfused with cold solutions with the arteriole supply
What peripheral condition is associated with hypothermic conditions?
Ischaemia
What happens to ATPase Na-K during ischemia?
The function is inhibited, low oxygen availability , ATP supplied is limited
Sodium and chloride will subsequently enter the cell and sodium permeability increases, along their respective electrochemical and concnetration gradients, water will enter the cell as potassium exists, Cell swell, bleb and necrosis
What is the University of Wisconsin solution (UW) and why is it useful?
Organ is perfused with the solution, reduces hypothermic cell swelling and enhances cell preservation
Lack of Na+ and Cl-; prevents influx of extracellular impermeant solutes
Colloid (starch)
Allopurinol and glutathione antioxidants
Raffinose(EC impermeant solute)
What is in the UW solution?
Raffinose, lactobionate
HES
Potassium (high)
Low sodium
How do solutes exchange occur across endothelial membranes?
Pores and clefts
At the arteriole end, why is hydrostatic pressure greater?
The pressure generated due to ventricular systole
At the venule end describe the pattern of pressure?
The colloid oncotic pressure is greater attributed to plasma protein osmolarity.
What is edema?
Accumulation of fluids within tissues, results due to imbalance of normal cycle of fluid exchange in tissues causing accumulation of fluid in interstitial spaces
What causes oedema?
Increased permeability of capillary walls, proteins are lost through an increase in pore size, reducing the overall COP, osmolarity in interstitial space subsequently increased, water moves out.
What is the role performed by lymphatic capillaries?
Collect interstitial fluid to be returned to circulation, combats net loss of plasma fluid
Why do lymph nodes have low internal pressure?
Establishes pressure gradient, the net flow of fluids from tissue into capillaries.
What is inflammatory oedema?
Diapedesis occurs during inflammation, increases the permeability of the capillary, resulting in efflux and accumulation of interstitial fluid
How does hydrostatic pressure occur?
High salt diet results in high blood pressure, increasing hydrostatic pressure in vessels, increases outwards fluid movement lead to interstitial fluid accumulation
What are the potential causes of oedema?
Breast cancer survivor (axillary lymph node is removed), removes pathway of drainage
Elephantiasis: Parasitic worms blocks lymphatic vessels, right groin region
How to calculate osmolarity?
Number of particles * x concentration = osmolarity
e.g conc of NaCl = 2
osmolarity = 4 (NaCl is made up of 2 ions)
What is the distribution of CK isoforms like?
Ck-MM mainly in skeletal muscle
Ck-MB mainly in cardiac muscle
Ck-BB mainly in brain tissue