Thursday pathopysio

Question 1

What is the mechanism of action (and location of action) of spironolactone?

Answer 1

Competes with aldosterone for binding sites in the collecting tubule epithelial cells (mineralocorticoid receptor antagonist). Decreases reabsorption of sodium and secretion of potassium. Na remaining in tubules draws water by osmosis. Potassium sparing.

Question 2

What is the role of type A intercalated cells?

Answer 2

Important in acid/base regulation- secrete H ions by a hydrogen-ATPase transporter. The hydrogen is generated by the action of carbonic anhydrase on water and carbon dioxide to form carbonic acid which then dissociates to form bicarbonate and water.
 The hydrogen ions are then secreted in to the tubular lumen and for each H secreted a HCO3 becomes available for reabsorption.
 Type A are important in eliminating H and reabsorbing HCO3
o Type B do the opposite- secrete bicarbonate into the lumen while reabsorbing H
 Have H and HCO3 transporters on opposite sides of the membrane

Question 3

What are the differences in phagocytosis between neutrophils and macrophages?

Answer 3

Neutrophils can only phagocytose bacteria and can phagocytose between 2-30 before they die. Macrophages can phagocytose up to 100 bacteria before they die and can also phagocytose much larger structures such as RBCs

Question 4

What are the differential diagnoses for monoclonal gammopathy?

Answer 4

leukemia (usually chronic lymphocytic), myeloma, lymphoma, leishmania, ehrlichia, plasmacytoma, amyloidosis,