EDAIC Basic Sciences 3 — Questions and Answers
Question 1: In the context of EDAIC pharmacology, the volume of distribution (Vd) of a drug is best described as:
- A theoretical volume relating dose to plasma concentration (Correct answer)
- The actual anatomical volume of plasma
- The volume of the central compartment only
- Renal clearance divided by half-life
Correct answer: A theoretical volume relating dose to plasma concentration
Vd = Dose / Cp, a theoretical construct reflecting how extensively a drug distributes into tissues relative to plasma.
Question 2: Which enzyme is responsible for the metabolism of remifentanil, giving it an ultra-short context-sensitive half-time?
- Non-specific blood and tissue esterases (Correct answer)
- Hepatic CYP3A4
- Plasma pseudocholinesterase
- Renal glucuronidation enzymes
Correct answer: Non-specific blood and tissue esterases
Remifentanil contains an ester linkage hydrolyzed by ubiquitous non-specific esterases in blood and tissues, making its elimination independent of organ function.
Question 3: The Frank-Starling mechanism describes the relationship between:
- Ventricular end-diastolic volume and stroke volume (Correct answer)
- Heart rate and cardiac output only
- Systolic pressure and afterload
- Coronary perfusion and contractility
Correct answer: Ventricular end-diastolic volume and stroke volume
The Frank-Starling law states that stroke volume increases as end-diastolic volume (preload) increases, up to a physiological limit.
Question 4: Which region of the nephron is the PRIMARY site of sodium reabsorption under aldosterone's influence?
- Distal tubule and collecting duct (Correct answer)
- Proximal convoluted tubule
- Loop of Henle descending limb
- Glomerulus
Correct answer: Distal tubule and collecting duct
Aldosterone acts on principal cells of the distal tubule and collecting duct to upregulate Na+/K+-ATPase and ENaC channels, increasing sodium reabsorption.
Question 5: Minimum alveolar concentration (MAC) of a volatile anesthetic is defined as the concentration that prevents movement in response to surgical incision in what percentage of patients?
- 50% (Correct answer)
- 95%
- 99%
- 100%
Correct answer: 50%
MAC is the alveolar concentration at 1 atm that prevents purposeful movement in 50% of patients in response to a standard noxious stimulus.
Question 6: Type II pneumocytes differ from Type I pneumocytes in that they:
- Produce surfactant and can regenerate Type I cells (Correct answer)
- Cover 95% of the alveolar surface area
- Are primarily responsible for gas exchange
- Lack the ability to proliferate
Correct answer: Produce surfactant and can regenerate Type I cells
Type II pneumocytes secrete pulmonary surfactant to reduce alveolar surface tension and serve as progenitor cells capable of regenerating Type I cells after injury.
Question 7: Which ion channel is responsible for the pacemaker current (If) in the sinoatrial node?
- HCN (hyperpolarization-activated cyclic nucleotide-gated) channel (Correct answer)
- L-type calcium channel
- Fast sodium channel
- Delayed rectifier potassium channel
Correct answer: HCN (hyperpolarization-activated cyclic nucleotide-gated) channel
The funny current (If) flows through HCN channels activated by hyperpolarization, carrying a mixed Na+/K+ inward current that drives spontaneous phase 4 depolarization.
EDAIC Basic Sciences 3
In the context of EDAIC pharmacology, the volume of distribution (Vd) of a drug is best described as: