Free practice final
Pathophysiology practice final (free, with answers)
A pathophysiology final usually asks you to explain disease from the cell up: cell injury and adaptation, inflammation and immunity, fluid, electrolyte, and acid-base balance, the major cardiovascular, respiratory, renal, and endocrine disorders, and cancer. These 15 questions focus on mechanisms and include an ABG interpretation and an anion gap calculation. Answer each one yourself before opening the explanation.
For exam practice only, not clinical advice. Drug and treatment decisions belong to licensed clinicians and current references.
Topics
- Cell Injury and Adaptation
- Inflammation and Healing
- Immunity and Hypersensitivity
- Fluids, Electrolytes, and Acid-Base
- Cardiovascular Disorders
- Respiratory Disorders
- Renal Disorders
- Endocrine Disorders
- Neoplasia
15 questions
Try each one before you open its answer.
1. After years of acid reflux, a biopsy of a patient's lower esophagus shows that the normal stratified squamous epithelium has been replaced by columnar epithelium with goblet cells. Which cellular adaptation is this?
- A Hyperplasia
- B Hypertrophy
- C Metaplasia
- D Atrophy
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Answer: C. Metaplasia
Metaplasia is the replacement of one mature cell type by another that better withstands the stress, here acid-resistant columnar cells in place of squamous cells (Barrett esophagus). It is not cancer, but it raises the risk of dysplasia and adenocarcinoma. Hyperplasia and hypertrophy are increases in cell number and cell size, and atrophy is a decrease in cell size.
2. In the early, reversible stage of hypoxic cell injury, cells swell. What is the main cause of the swelling?
- A Falling ATP slows the Na⁺/K⁺-ATPase, so Na⁺ and water accumulate inside the cell
- B Increased aerobic respiration produces excess water inside the cell
- C The plasma membrane ruptures and extracellular fluid rushes in
- D Lysosomal enzymes digest the cytoskeleton, so the cell loses its shape
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Answer: A. Falling ATP slows the Na⁺/K⁺-ATPase, so Na⁺ and water accumulate inside the cell
Without oxygen, oxidative phosphorylation stops and ATP falls, so the Na⁺/K⁺ pump cannot keep Na⁺ out; Na⁺ builds up inside and water follows by osmosis. The cell shifts to anaerobic glycolysis, producing lactic acid. If oxygen returns in time the swelling can reverse, whereas membrane rupture marks irreversible injury.
3. The tissue around an infected cut becomes red, warm, and swollen. What mainly causes the swelling?
- A Low plasma oncotic pressure from a reduced serum albumin
- B Increased permeability of small venules, letting protein-rich fluid leak into the tissue
- C Bacteria blocking the lymphatic vessels that drain the area
- D High venous pressure caused by heart failure
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Answer: B. Increased permeability of small venules, letting protein-rich fluid leak into the tissue
Mediators such as histamine and bradykinin make the endothelial cells of venules contract, opening gaps through which plasma proteins and fluid escape as an exudate. Edema from low albumin or high venous pressure, as in liver disease or heart failure, is instead a protein-poor transudate. The redness and warmth come from arteriolar dilation that increases blood flow.
4. A tuberculin skin test produces a firm, raised area of induration 48 to 72 hours after the injection. Which type of hypersensitivity reaction is this?
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Answer: Type IV (delayed-type, T cell–mediated) hypersensitivity
Memory T cells that recognize the tuberculin antigens release cytokines that recruit and activate macrophages, which takes 2 to 3 days to produce visible induration. No antibody is involved, unlike in types I, II, and III.
5. Minutes after eating peanuts, a sensitized person develops hives, wheezing, and low blood pressure. What is the immediate mechanism?
- A IgG antibodies bind to antigens on the person's own red blood cells
- B Antigen–antibody complexes deposit in blood vessel walls
- C Sensitized T cells release cytokines that recruit macrophages
- D The allergen cross-links IgE on mast cells, which release histamine and other mediators
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Answer: D. The allergen cross-links IgE on mast cells, which release histamine and other mediators
This is type I (immediate) hypersensitivity: an earlier exposure produced peanut-specific IgE, which sits on mast cells and basophils. On re-exposure, the allergen cross-links that IgE, and the released histamine and leukotrienes cause vasodilation, leaky vessels, and bronchoconstriction. The other choices describe types II, III, and IV.
6. A patient who took an opioid overdose is breathing slowly and shallowly. Arterial blood gas: pH 7.26, PaCO₂ 60 mmHg, HCO₃⁻ 26 mEq/L. (Normal: pH 7.35 to 7.45, PaCO₂ 35 to 45 mmHg, HCO₃⁻ 22 to 26 mEq/L.) What is the interpretation?
- A Metabolic acidosis with respiratory compensation
- B Respiratory alkalosis
- C Uncompensated respiratory acidosis
- D Fully compensated respiratory acidosis
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Answer: C. Uncompensated respiratory acidosis
The pH is low, so this is acidosis, and the high PaCO₂ shows the cause is respiratory: slow breathing is retaining CO₂. HCO₃⁻ is still within the normal range because the kidneys need days to compensate, so the picture is uncompensated; full compensation would bring the pH back into the normal range.
7. A patient in diabetic ketoacidosis has these results: Na⁺ 136 mEq/L, Cl⁻ 98 mEq/L, HCO₃⁻ 10 mEq/L. Using anion gap = Na⁺ − (Cl⁻ + HCO₃⁻), what is the anion gap?
Show answer
Answer: 28 mEq/L
136 − (98 + 10) = 28 mEq/L, far above the usual reference range (often given as about 8 to 12 mEq/L). The extra unmeasured anions are the ketoacids β-hydroxybutyrate and acetoacetate, which used up bicarbonate as they were buffered.
8. A patient's left ventricle is failing and can no longer pump out the blood it receives. Which finding results most directly from this left-sided failure?
- A Crackles in the lungs and shortness of breath that worsens when lying flat
- B Distended jugular veins
- C Swelling of the ankles and lower legs
- D An enlarged, tender liver
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Answer: A. Crackles in the lungs and shortness of breath that worsens when lying flat
When the left ventricle fails, blood backs up into the pulmonary veins and capillaries, and the raised pressure pushes fluid into the lungs, causing crackles, dyspnea, and orthopnea. Jugular venous distension, dependent edema, and an enlarged liver come from blood backing up into the systemic veins in right-sided failure.
9. In early atherosclerosis, macrophages in the intima of an artery take up large amounts of oxidized LDL. What are these lipid-filled macrophages called?
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Answer: Foam cells
Foam cells collect beneath the endothelium to form the fatty streak, the earliest visible lesion of atherosclerosis. They release inflammatory signals that draw in smooth muscle cells, which build the fibrous cap of a mature plaque.
10. In emphysema, why does air become trapped in the lungs during exhalation?
- A Excess surfactant keeps the alveoli from emptying
- B Scar tissue makes the lungs too stiff to expand
- C Bronchial smooth muscle spasm that fully reverses with a bronchodilator
- D Destruction of alveolar walls reduces elastic recoil, so small airways collapse during exhalation
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Answer: D. Destruction of alveolar walls reduces elastic recoil, so small airways collapse during exhalation
Elastic fibers in the alveolar walls normally recoil to push air out and hold the small airways open; when they are destroyed, largely by protease activity triggered by smoking, the airways collapse on exhalation and air is trapped. The result is hyperinflation, a larger residual volume, and a reduced FEV₁/FVC ratio. Fully reversible bronchospasm is typical of asthma, and stiff, scarred lungs describe restrictive disease such as pulmonary fibrosis.
11. A patient with advanced chronic kidney disease has a normocytic, normochromic anemia. What is the main cause?
- A Red blood cells are lost into the urine through damaged glomeruli
- B The damaged kidneys produce too little erythropoietin
- C Urea directly destroys red cell precursors in the bone marrow
- D Kidney failure blocks the absorption of vitamin B12 from the gut
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Answer: B. The damaged kidneys produce too little erythropoietin
Interstitial cells around the renal tubules sense low oxygen delivery and secrete erythropoietin, which stimulates red cell production in the bone marrow. As functioning kidney tissue is lost, erythropoietin output falls and fewer red cells are made.
12. A patient with type 1 diabetes in diabetic ketoacidosis is breathing very deeply and rapidly (Kussmaul respirations). What does this breathing pattern accomplish?
- A It raises PaCO₂ to buffer the excess acid
- B It blows off CO₂, partially compensating for the metabolic acidosis
- C It corrects hypoxemia caused by ketones filling the alveoli
- D It removes excess glucose from the blood through the lungs
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Answer: B. It blows off CO₂, partially compensating for the metabolic acidosis
Ketoacids use up bicarbonate and cause a metabolic acidosis, and the low pH stimulates chemoreceptors that drive breathing. Exhaling more CO₂ lowers PaCO₂, which moves the pH back toward normal, although the compensation is not complete.
13. In uncontrolled diabetes mellitus, why does a very high blood glucose level cause polyuria?
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Answer: Filtered glucose exceeds what the renal tubules can reabsorb, and the glucose left in the tubular fluid holds water in it osmotically (osmotic diuresis).
Once blood glucose rises above the renal threshold, about 180 mg/dL, the glucose transporters of the proximal tubule are saturated and glucose spills into the urine. Water and electrolytes follow it, so the patient passes large volumes of urine, becomes dehydrated, and feels very thirsty (polydipsia).
14. Which feature most reliably identifies a tumor as malignant rather than benign?
- A It invades surrounding tissue and can metastasize
- B It is larger than 5 cm across
- C It is surrounded by a fibrous capsule
- D Its cells are well differentiated and closely resemble the tissue of origin
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Answer: A. It invades surrounding tissue and can metastasize
Invasion and, above all, metastasis define malignancy, whereas benign tumors stay localized, are often encapsulated, and are usually well differentiated. Size alone does not separate the two, since some benign tumors grow very large.
15. According to the two-hit hypothesis, how many alleles of a tumor suppressor gene such as RB must be inactivated before a cell loses that gene's control over growth?
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Answer: Both alleles (two hits)
One working copy of a tumor suppressor usually still restrains the cell cycle, so both copies must be lost, unlike a proto-oncogene, where one activating mutation is enough. In hereditary retinoblastoma, one defective RB allele is inherited, so a single further mutation in a retinal cell can cause a tumor, which is why these tumors appear earlier and often in both eyes.