COMAT COMAT Pathophysiology and Disease Processes 1 — Questions and Answers
Question 1: Which mechanism best explains the pain of angina pectoris in coronary artery disease?
- Direct myocardial necrosis with troponin release
- Ischemia-induced accumulation of metabolites stimulating cardiac nociceptors (Correct answer)
- Pericardial inflammation irritating the diaphragm
- Aortic dissection compressing coronary ostia
Correct answer: Ischemia-induced accumulation of metabolites stimulating cardiac nociceptors
Myocardial ischemia causes metabolite accumulation (adenosine, lactate, H+) that stimulates cardiac sympathetic afferents, producing the characteristic chest pain of angina.
Question 2: Type 2 diabetes mellitus is primarily characterized by which underlying pathophysiologic mechanism?
- Autoimmune destruction of beta cells
- Peripheral insulin resistance with relative insulin deficiency (Correct answer)
- Absolute insulin deficiency due to pancreatectomy
- Glucagon receptor mutation causing hyperglycemia
Correct answer: Peripheral insulin resistance with relative insulin deficiency
Type 2 DM involves peripheral tissue insulin resistance (especially muscle and liver) combined with progressive beta cell dysfunction leading to relative insulin deficiency.
Question 3: A patient with COPD has a PaCO2 of 55 mmHg chronically — which acid-base disorder is present?
- Acute respiratory acidosis
- Chronic respiratory acidosis with metabolic compensation (Correct answer)
- Metabolic alkalosis with respiratory compensation
- Mixed metabolic and respiratory acidosis
Correct answer: Chronic respiratory acidosis with metabolic compensation
Chronic CO2 retention in COPD leads to respiratory acidosis with compensatory renal bicarbonate retention, resulting in a near-normal pH (chronic respiratory acidosis).
Question 4: The pathophysiology of nephrotic syndrome involves loss of which glomerular barrier property?
- Size selectivity allowing water filtration
- Charge selectivity allowing albumin to cross the GBM (Correct answer)
- Tubular reabsorption capacity for glucose
- Juxtaglomerular apparatus renin secretion
Correct answer: Charge selectivity allowing albumin to cross the GBM
Nephrotic syndrome results from loss of the glomerular basement membrane's negative charge barrier, permitting albumin (normally repelled) to pass into the filtrate.
Question 5: Which cytokine is primarily responsible for the fever response during acute systemic infection?
- IL-4
- IL-10
- IL-1β (Correct answer)
- TGF-β
Correct answer: IL-1β
IL-1β (along with IL-6 and TNF-α) is an endogenous pyrogen that acts on the hypothalamus to raise the thermoregulatory set point, producing fever.
Question 6: In left heart failure, pulmonary edema occurs primarily due to which hemodynamic change?
- Decreased pulmonary vascular resistance
- Elevated pulmonary capillary wedge pressure exceeding oncotic pressure (Correct answer)
- Increased lymphatic drainage absorbing excess fluid
- Decreased right ventricular output reducing lung perfusion
Correct answer: Elevated pulmonary capillary wedge pressure exceeding oncotic pressure
Left ventricular failure raises left atrial and pulmonary venous pressure (PCWP), which when it exceeds plasma oncotic pressure (~25 mmHg), forces fluid into alveoli.
COMAT COMAT Pathophysiology and Disease Processes 1
Which mechanism best explains the pain of angina pectoris in coronary artery disease?