Sodium pump (Na/K-ATPase Flashcards
Describe the function of the sodium pumps
It is involved in the extrusion of sodium ions against a electrochemical gradient. It does this my using enegery from the phosphorylation of an ATP molecule to cause a confromational change that transports 3 Na ions out of the cell and 2 K ions into the cell. This also generates a membrane potential as there is a net flow of 1 pos ion leaving the cell.
Describe the structure of the sodium pump
It is composed of two alpha subunits and two beta subunits. Each alpha subunit contains an ATP binding site and a cardiac glycoside binding site. The sodium ions bind internally and potassium externally
What causes the inhibition of the sodium pump and what is it used for
Cardiac Glycosides are used for inhibition, specific example is digoxin. This causes the heart to contract more vigorously. However also increases the extracellular levels of potassium
What will increase the affinity between the sodium pump and cardiac glycosides?
A decrease in potassium ion concentration
What is the therapeutic index?
Dose producing a toxin effect/minimum effective dose (for 50% of the population)
What are diuretics and what are they used for?
They are drugs that increase urine output by the kidney. They are used to treat high blood pressure however increase urinary excretion of potassium
Describe the effect of digoxin on potassium levels?
It results in increased digoxin binding to the cardiac glycoside binding site meaning there will be an increased potassium levels out of the cell
What are diuretics and what are they used for?
They are drugs that increase urine output by the kidney. They are used to treat high blood pressure however increase urinary excretion of potassium
Describe the effect of digoxin on potassium levels?
It results in increased digoxin binding to the cardiac glycoside binding site meaning there will be an increased potassium levels out of the cell
Describe the difference between primary and secondary active transport?
Primary - Directly use their energy from the hydrolysis of ATM
Secondary - Use energy stroed in the sodium gradients to drive molecular transport against the electrochemical gradient.
Describe the sodium calcium exchanger
It is a transmembrane antiporter protein that removes calcium from inside the cell. It uses energy stored in the sodium electrochemical gradient. It does this by allowing sodium to transport along its concentration gradient in exchange for a calcium ion.
Explain the mechanisms involved in the transepithelial transport of glucose
Na/K-ATPases create a downhill sodium concentration from outside the cell to inside the cell. Symport SGLT proteins use the energy from this concentration gradient to transport a glucose molecule across the apical membrane against a concentration gradient.
The glucose is then transported across the basal membrane into blood vessels.
