EDAIC Basic Sciences 2 — Questions and Answers
Question 1: Which receptor mediates the bronchodilatory effect of beta-2 agonists in airway smooth muscle?
- Gs-coupled receptor increasing cAMP (Correct answer)
- Gi-coupled receptor decreasing cAMP
- Gq-coupled receptor increasing IP3
- Ligand-gated ion channel increasing Ca2+
Correct 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.
Question 2: The oxygen-hemoglobin dissociation curve shifts LEFT in response to which condition?
- Alkalosis (Correct answer)
- Hyperthermia
- Hypercarbia
- 2,3-DPG increase
Correct answer: Alkalosis
Alkalosis increases hemoglobin's affinity for oxygen (Bohr effect), shifting the curve left and decreasing oxygen delivery to tissues.
Question 3: Which phase of the action potential in cardiac ventricular myocytes is primarily carried by the rapid sodium current (INa)?
- Phase 0 (rapid depolarization) (Correct answer)
- Phase 1 (early repolarization)
- Phase 2 (plateau)
- Phase 4 (resting potential)
Correct 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.
Question 4: Fick's law of diffusion states that gas transfer across a membrane is directly proportional to which factor?
- Surface area and partial pressure gradient (Correct answer)
- Membrane thickness only
- Molecular weight of the gas
- Blood viscosity
Correct 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.
Question 5: What is the primary mechanism by which volatile anesthetics cause hypotension?
- Peripheral vasodilation and myocardial depression (Correct answer)
- Increased vagal tone alone
- Beta-1 receptor blockade
- Histamine release causing vasodilation
Correct answer: Peripheral vasodilation and myocardial depression
Volatile anesthetics cause dose-dependent hypotension primarily through direct myocardial depression and peripheral vasodilation via calcium channel interference.
Question 6: The Henderson-Hasselbalch equation relates pH to which variables?
- pKa and ratio of base to acid concentration (Correct answer)
- PaCO2 and bicarbonate only
- Temperature and ionic strength
- Osmolality and albumin
Correct 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.
Question 7: Which neuromuscular blocking agent has the shortest duration of action due to rapid hydrolysis by plasma cholinesterase?
- Succinylcholine (Correct answer)
- Mivacurium
- Cisatracurium
- Rocuronium
Correct answer: Succinylcholine
Succinylcholine is hydrolyzed within 5–10 minutes by plasma pseudocholinesterase, giving it the shortest duration among neuromuscular blockers.
EDAIC Basic Sciences 2
Which receptor mediates the bronchodilatory effect of beta-2 agonists in airway smooth muscle?