Active Transport and the Sodium Pump Flashcards
Learning objectives
Explain the role that the sodium pump plays in regulating the intracellular ionic concentrations
Briefly explain the clinical significance of the interaction between the binding of the cardiac glycosides such as ouabain, and the extracellular potassium concentration
Explain the difference between primary active transport and secondary active transport
Explain sodium dependent calcium transport
Explain the mechanisms involved in the trans epithelial transport of glucose
Which direction of movement is passive diffusion and active transport for sodium and potassium
Passive diffusion is sodium going into the cell and potassium going out of the cell
Active transport is the sodium potassium pump moving sodium out of the cell and potassium moving into the cell
Describe the structure of the sodium pump
The sodium pump has four subunits. There are 2 alpha subunits and 2 beta subunits. The alpha subunit is an integral protein that has the potassium, sodium, cardiac glycoside and ATP binding sites. The 2 beta subunits are smaller integral proteins.
What is the sodium potassium equation?
[3Na+]i + [2K+]o —> [3Na+]o + [2K+]i
How does the pump get energy for this reaction?
ATP is hydrolyzed to ADP and the phosphate bond being broken is used as energy for the pump to occur.
What inhibits and stimulates the sodium pump?
Removing K+ inhibits the pump and increasing Na+ stimulates the pump
Why is the sodium potassium important?
This energy is used to remove acid from the body. The sodium-potassium pump also functions to maintain the electrical charge within the cell. This is particularly important to muscle and nerve cells.
What do cardiac glycosides do to the sodium pump?
Cardiac glycosides inhibit the active site and prevents potassium from binding to the active site. Therefore it decreases pump activity
What substance comes into the cell when you inhibit the sodium potassium pump?
Calcium comes into the cell
What do diuretics do?
Diuretics increase urine output and promote diuresis. It also increase the urinary excretion of potassium
What is the difference between primary and secondary active transport?
Sodium pump is primary
Primary: Active transport uses the hydrolysis of ATP for movement
Secondary: Active transport across a biological membrane in which a transporter protein couples the movement of NA+ down its electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient.
What is the therapeutic index?
The ratio between the dosage of a drug that causes a lethal effect and the dosage that causes a therapeutic effect.
Explain sodium dependent calcium transport
Sodium binds with calcium so when sodium goes down the electrochemical gradient, calcium goes up the concentration gradient
What types of glucose transporters are there?
Some that are non sodium dependent or ion dependent (glucose has no charge) and moves glucose down concentration gradient
Some glucose transporters that depend on sodium. Uses electrochemical gradient of sodium to move glucose into the cell
