Pathophysiology Flashcards

Maturity-onset diabetes of the young (MODY) is characterized by which distinctive genetic feature?

Answer: Autosomal dominant single-gene mutations impairing beta-cell function

MODY is caused by autosomal dominant mutations in single genes (e.g., HNF-1alpha, glucokinase, HNF-4alpha) that impair beta-cell development or function, distinguishing it from polygenic type 2 diabetes.

In gestational diabetes mellitus (GDM), placental hormones contribute to insulin resistance primarily through which mechanism?

Answer: Placental lactogen and progesterone impairing post-receptor insulin signaling

Human placental lactogen, progesterone, and cortisol secreted by the placenta antagonize insulin signaling at the post-receptor level, creating physiologic insulin resistance that unmasks GDM in susceptible women.

Diabetic autonomic neuropathy affecting the cardiovascular system most characteristically presents as:

Answer: Resting tachycardia followed by fixed heart rate unresponsive to maneuvers

Cardiovascular autonomic neuropathy initially causes resting tachycardia from vagal denervation, then progresses to a fixed heart rate as both parasympathetic and sympathetic cardiac innervation is lost.

Which of the following correctly describes the pathophysiology of hypoglycemia unawareness in diabetes?

Answer: Recurrent hypoglycemia shifts the glycemic threshold for counterregulatory responses to lower glucose levels

Recurrent hypoglycemia causes both the threshold for counterregulatory hormone release and the threshold for symptom perception to shift to lower glucose values, reducing or eliminating warning symptoms.

Secondary diabetes mellitus caused by chronic pancreatitis differs from type 1 and type 2 in that it features:

Answer: Impaired glucagon secretion from alpha-cell damage making hypoglycemia more severe

In pancreatogenic (type 3c) diabetes, destruction of both alpha and beta cells means glucagon secretion is also impaired, resulting in labile glucose control and increased severe hypoglycemia risk without glucagon rescue.

The hexosamine biosynthesis pathway contributes to diabetic complications by:

Answer: O-GlcNAc modification of transcription factors altering gene expression and causing endothelial dysfunction

Excess glucose flux through the hexosamine pathway leads to O-GlcNAc modification of proteins including transcription factors, altering expression of genes involved in endothelial function, plasminogen activator inhibitor-1, and TGF-beta.

Diabetic cardiomyopathy can occur in the absence of coronary artery disease through which pathophysiologic mechanism?

Answer: Intramyocardial lipid accumulation and AGE-mediated myocardial fibrosis impairing diastolic function

Diabetic cardiomyopathy results from intramyocardial lipid deposition, AGE-mediated collagen cross-linking and fibrosis, and mitochondrial dysfunction, causing diastolic stiffness even without epicardial coronary disease.