Pathophysiology Flashcards

Which pathophysiological mechanism primarily underlies the development of type 2 diabetes mellitus?

Answer: Insulin resistance combined with progressive beta-cell dysfunction

Type 2 DM is characterized by peripheral insulin resistance and gradual decline in pancreatic beta-cell secretory capacity, unlike the autoimmune destruction seen in type 1 DM.

In heart failure with reduced ejection fraction (HFrEF), which compensatory mechanism initially helps maintain cardiac output but ultimately worsens cardiac remodeling?

Answer: Activation of the renin-angiotensin-aldosterone system (RAAS)

RAAS activation causes fluid retention and vasoconstriction that initially compensates for low output, but chronic activation promotes maladaptive cardiac hypertrophy and fibrosis.

A patient with chronic kidney disease develops anemia. What is the primary pathophysiological reason?

Answer: Decreased erythropoietin production by the diseased kidneys

The peritubular interstitial cells of the kidney are the primary source of erythropoietin; CKD destroys these cells, reducing EPO production and thereby red cell production.

Which of the following best describes the pathophysiology of asthma?

Answer: Reversible airway inflammation and bronchospasm driven by Th2-mediated hypersensitivity

Asthma involves a Th2 lymphocyte-driven inflammatory response with eosinophil recruitment, mast cell degranulation, and reversible bronchoconstriction, distinguishing it from COPD.

In atherosclerosis, which event is considered the earliest pathological change in the arterial wall?

Answer: Accumulation of oxidized LDL and foam cell formation in the intima

The fatty streak, formed by oxidized LDL being engulfed by macrophages to form foam cells in the subintimal space, is the earliest lesion in atherosclerosis.

A patient presents with polyuria, polydipsia, and hyponatremia. MRI shows a pituitary tumor. Which pathophysiological defect best explains the polyuria?

Answer: Deficient ADH secretion leading to inability to concentrate urine

A pituitary lesion can disrupt ADH (vasopressin) synthesis or secretion, causing central diabetes insipidus with hypotonic polyuria and compensatory polydipsia.

Which mechanism explains the hypercalcemia seen in primary hyperparathyroidism?

Answer: Excess PTH stimulating osteoclast activity, renal calcium reabsorption, and calcitriol synthesis

Excess PTH acts on bone to release calcium via osteoclasts, on the kidney to reabsorb calcium, and induces 1-alpha hydroxylase to increase calcitriol, collectively raising serum calcium.

In rheumatoid arthritis, the chronic joint destruction is primarily mediated by:

Answer: Pannus formation driven by synovial fibroblasts and macrophages secreting destructive cytokines

RA pannus is a hyperplastic synovial tissue containing activated fibroblasts and macrophages that secrete TNF-α, IL-1, IL-6, and metalloproteinases that erode cartilage and bone.

A patient with acute pancreatitis develops hypocalcemia. Which mechanism is most responsible?

Answer: Saponification of peripancreatic fat by lipases binding calcium

Released pancreatic lipases cleave peripancreatic fat into fatty acids, which bind calcium ions to form calcium soaps (saponification), sequestering calcium and lowering serum levels.

Which pathophysiological event triggers the cascade of cellular injury in ischemia-reperfusion injury?

Answer: Rapid restoration of oxygen leading to reactive oxygen species generation and cellular damage

Paradoxically, reoxygenation after ischemia produces a burst of ROS from xanthine oxidase and mitochondria, activating proteases and causing endothelial and parenchymal cell damage.

In nephrotic syndrome, the edema forms primarily because:

Answer: Massive proteinuria lowers plasma oncotic pressure, allowing fluid to shift into interstitial spaces

Heavy urinary protein loss (>3.5 g/day) depletes albumin, reducing intravascular oncotic pressure and allowing Starling forces to drive fluid out of capillaries into the interstitium.

Pernicious anemia is caused by:

Answer: Autoimmune destruction of gastric parietal cells impairing intrinsic factor production

Pernicious anemia is an autoimmune condition with antibodies against parietal cells and/or intrinsic factor, leading to loss of IF and inability to absorb dietary vitamin B12 in the terminal ileum.

Which pathophysiological mechanism explains the Somogyi effect in diabetes management?

Answer: Nocturnal hypoglycemia triggering counter-regulatory hormone release causing rebound morning hyperglycemia

The Somogyi effect involves nocturnal hypoglycemia that triggers glucagon, epinephrine, cortisol, and growth hormone release, causing liver glycogenolysis and rebound morning hyperglycemia.

In systemic lupus erythematosus (SLE), glomerulonephritis is primarily caused by:

Answer: Deposition of anti-dsDNA immune complexes in the glomerular basement membrane activating complement

SLE nephritis results from type III hypersensitivity: circulating anti-dsDNA immune complexes deposit in the glomerulus and activate complement (C3, MAC), causing inflammation and structural damage.