Basic Sciences Flashcards

Which receptor mediates the bronchodilatory effect of beta-2 agonists in airway smooth muscle?

Answer: Gs-coupled receptor increasing cAMP

Beta-2 receptors couple to Gs protein, activating adenylyl cyclase to increase cAMP, which activates PKA and causes smooth muscle relaxation.

The oxygen-hemoglobin dissociation curve shifts LEFT in response to which condition?

Answer: Alkalosis

Alkalosis increases hemoglobin's affinity for oxygen (Bohr effect), shifting the curve left and decreasing oxygen delivery to tissues.

Which phase of the action potential in cardiac ventricular myocytes is primarily carried by the rapid sodium current (INa)?

Answer: Phase 0 (rapid depolarization)

Phase 0 represents rapid depolarization driven by fast voltage-gated Na+ channel opening, producing the upstroke of the cardiac action potential.

Fick's law of diffusion states that gas transfer across a membrane is directly proportional to which factor?

Answer: Surface area and partial pressure gradient

Fick's law: diffusion rate = (D × A × ΔP) / T, where D is diffusion constant, A is area, ΔP is pressure gradient, and T is thickness.

What is the primary mechanism by which volatile anesthetics cause hypotension?

Answer: Peripheral vasodilation and myocardial depression

Volatile anesthetics cause dose-dependent hypotension primarily through direct myocardial depression and peripheral vasodilation via calcium channel interference.

The Henderson-Hasselbalch equation relates pH to which variables?

Answer: pKa and ratio of base to acid concentration

pH = pKa + log([A-]/[HA]), relating pH to the dissociation constant and the ratio of conjugate base to weak acid.

Which neuromuscular blocking agent has the shortest duration of action due to rapid hydrolysis by plasma cholinesterase?

Answer: Succinylcholine

Succinylcholine is hydrolyzed within 5–10 minutes by plasma pseudocholinesterase, giving it the shortest duration among neuromuscular blockers.