KMU Past Paper Practice

Question:

A researcher stimulates vascular endothelial cells and activated platelets separately. The endothelial product prevents platelet activation, whereas the platelet product promotes formation of a hemostatic plug. Which pair of mediators best accounts for these opposing effects?

Options:

Correct Answer: PGI₂ and TXA₂

Explanation: Endothelial PGI₂ inhibits platelet activation, while platelet-derived TXA₂ promotes aggregation; their opposing actions help regulate hemostasis.

Question:

A tissue is stimulated during inflammation and rapidly generates lipid mediators rather than releasing them from preformed storage granules. Which sequence best describes their synthesis?

Options:

Correct Answer: Membrane phospholipids → arachidonic acid → cyclooxygenase pathway → prostanoids

Explanation: Cellular stimulation releases arachidonic acid from membrane phospholipids, after which cyclooxygenase generates intermediates used to form individual prostanoids.

Question:

A 25-year-old woman receives a prostaglandin preparation before planned induction of labor. Examination later shows a softer, more favorable cervix with increased uterine activity. Which preparation most closely produces this combination?

Options:

Correct Answer: Dinoprostone

Explanation: Dinoprostone is a PGE₂ preparation whose cervical-ripening and uterine effects make it suitable for induction of labor.

Question:

Two smooth-muscle tissues are exposed to the same prostaglandin concentration. One contracts while the other relaxes. The drug concentration and chemical structure remain unchanged. Which factor best explains the different responses?

Options:

Correct Answer: Different receptor subtype and intracellular signaling

Explanation: Prostanoid receptor subtypes couple to different second-messenger pathways, allowing the same mediator to produce different tissue responses.

Question:

A patient with inflammatory pain receives a drug that decreases synthesis of PGE₂. The patient reports less tenderness even though the underlying tissue lesion is still present. Which change best explains the analgesic effect?

Options:

Correct Answer: Reduced nociceptor sensitization

Explanation: PGE₂ enhances pain by sensitizing peripheral nociceptors; reducing its formation therefore decreases hyperalgesia without removing the underlying lesion.

Question:

A 66-year-old patient with compromised renal perfusion loses the protective action of locally generated PGE₂ and PGI₂. Which physiological change would most directly threaten renal blood flow?

Options:

Correct Answer: Loss of local vasodilator support

Explanation: Renal PGE₂ and PGI₂ provide local vasodilation, which becomes particularly important when vasoconstrictor influences threaten renal perfusion.

Question:

A newborn with a duct-dependent congenital cardiac lesion deteriorates as the ductus arteriosus begins to constrict. A prostaglandin preparation is started to restore the required communication. Which drug is most appropriate?

Options:

Correct Answer: Alprostadil

Explanation: Alprostadil is PGE₁ and can maintain ductus arteriosus patency when continued ductal flow is required in selected congenital cardiac lesions.

Question:

During an allergic airway response, mast cells release a prostanoid that contributes to bronchial narrowing. Which receptor family is most directly associated with the principal prostanoid released from these cells?

Options:

Correct Answer: DP receptors

Explanation: Mast cells characteristically produce PGD₂, which acts through DP receptors and contributes to allergic inflammatory and bronchial responses.

Question:

A 54-year-old patient with glaucoma receives a drug related to PGF₂α. Follow-up shows a significant fall in intraocular pressure without suppression of aqueous formation being the main mechanism. Which drug was most likely prescribed?

Options:

Correct Answer: Latanoprost

Explanation: Latanoprost is a PGF₂α analogue that lowers intraocular pressure mainly by increasing uveoscleral aqueous humor outflow.

Question:

A patient with inflammatory fever receives a cyclooxygenase-inhibiting drug. His temperature begins to fall despite persistence of the inflammatory trigger. Reduction of which prostaglandin action most directly explains this response?

Options:

Correct Answer: PGE₂-mediated elevation of the hypothalamic set point

Explanation: PGE₂ raises the hypothalamic thermoregulatory set point during inflammation; reduced PGE₂ formation allows the set point and body temperature to fall.

Question:

A gastric mucosal biopsy is obtained after prolonged suppression of protective prostaglandin synthesis. Which functional change would make the mucosa more vulnerable to acid-related injury?

Options:

Correct Answer: Reduced mucus and bicarbonate protection

Explanation: PGE₂ and related prostaglandins support mucus, bicarbonate and mucosal blood flow; their loss weakens the gastric defensive barrier.

Question:

A patient receives a PGE₁ analogue because both gastric mucosal protection and an effect on uterine activity are therapeutically useful. Which drug has this combination of actions?

Options:

Correct Answer: Misoprostol

Explanation: Misoprostol is a PGE₁ analogue that enhances gastric mucosal defense while also promoting cervical and uterine responses.

Question:

An experimental prostanoid activates a receptor on vascular smooth muscle and platelets, producing vessel constriction and increased aggregation. Which receptor is most likely being stimulated?

Options:

Correct Answer: TP receptor

Explanation: TXA₂ activates TP receptors, producing vasoconstriction and promoting platelet aggregation at sites of vascular injury.

Question:

A 34-year-old woman develops marked uterine bleeding because of inadequate uterine contraction after delivery. The clinician selects a PGF₂α analogue because a powerful uterotonic response is required. Which preparation best fits this rationale?

Options:

Correct Answer: Carboprost

Explanation: Carboprost is a PGF₂α analogue with a strong uterotonic action, making it suitable when marked uterine contraction is required.

Question:

A prostanoid released from vascular endothelium binds to its receptor on platelets and increases intracellular cyclic AMP. Which receptor–mediator pairing best matches this response?

Options:

Correct Answer: IP receptor — PGI₂

Explanation: Endothelial PGI₂ activates IP receptors and raises platelet cyclic AMP, thereby reducing platelet activation and aggregation.

Question:

A 46-year-old patient has pulmonary arterial hypertension and is treated with a prostacyclin-related agent. Which cellular and organ-level effects best explain the therapeutic benefit?

Options:

Correct Answer: Vascular relaxation with reduced platelet activation

Explanation: Prostacyclin-related drugs produce pulmonary vasodilation and inhibit platelet activation, providing the physiological basis for their use in pulmonary arterial hypertension.

Question:

A tissue sample from an inflamed area shows increased blood flow responsible for redness and warmth. Local prostanoid synthesis is increased. Which combination most directly contributes to this vascular response?

Options:

Correct Answer: PGE₂ and PGI₂

Explanation: PGE₂ and PGI₂ can dilate local vessels, increasing tissue blood flow and contributing to the redness and warmth of inflammation.

Question:

A pharmacologist blocks the receptor primarily activated by PGF₂α. Which therapeutic response would be most directly reduced as a consequence?

Options:

Correct Answer: Strong contraction of uterine smooth muscle

Explanation: PGF₂α acts through FP receptors and has a prominent uterotonic action; blocking this receptor would reduce PGF₂α-mediated uterine contraction.

Question:

A student constructs a pathway linking an inflammatory stimulus to the resulting biological response. Which sequence best represents prostaglandin signaling after the prostanoid has been synthesized?

Options:

Correct Answer: GPCR binding → second-messenger change → organ response

Explanation: Prostanoids mainly bind cell-surface GPCRs, alter second messengers such as cyclic AMP or intracellular calcium, and thereby produce tissue-specific effects.

Question:

A drug reproduces an endogenous prostanoid effect that simultaneously relaxes vascular smooth muscle and reduces platelet reactivity. Which source–mediator–effect combination is most consistent with this observation?

Options:

Correct Answer: Endothelium — PGI₂ — vasodilation and platelet inhibition

Explanation: Vascular endothelium produces PGI₂, which promotes vasodilation and inhibits platelet aggregation, physiologically opposing platelet-derived TXA₂.