Active transport: Sodium Pump

Question 1

Briefly explain the clinical significance of the interaction between the binding of the cardiac glycosides such as ouabain, and the extracellular potassium concentration

Answer 1

When the extracellular potassium concentration decreases (sometimes due to diuretics, causing the excretion of potassium in the urine), the affinity for binding of the cardiac glycosides increases which causes the inhibition of the sodium potassium pump. This can cause an increase in heart contractions (especially important if diuretics are being prescribed to hypokalaemic patients)

Question 2

Explain the difference between primary active transport and secondary active transport

Answer 2

Primary active transport uses the energy directly
Secondary active transport uses the energy stored in the Na + gradient to drive molecular transport against the electrochemical gradient

Question 3

Explain sodium dependent calcium transport

Answer 3

Na + going against gradient into cell causes an electrochemical gradient, this fuels the driving of calcium out of the cells

Question 4

Explain the mechanisms involved in the transepithelial transport of glucose

Answer 4

For every two sodium that enter the cell one glucose comes in with it