General Pathology Practice Questions

Q: Sudden decrease in atmospheric pressure in deep sea divers resulting in "bends" and "chokes" are features of which condition?

Air embolism. **Explanation:** The clinical scenario describes **Decompression Sickness (DCS)**, also known as "Caisson disease." This condition occurs due to **Henry’s Law**, which states that the solubility of a gas in a liquid is proportional to its partial pressure. 1. **Why Air Embolism is correct:** When a diver is deep underwater, high atmospheric pressure causes large amounts of Nitrogen to dissolve into the blood and tissues. If the diver ascends too rapidly (sudden decrease in pressure), the Nitrogen comes out of solution and forms **gas bubbles** in the blood and tissues. These bubbles act as **air emboli**, obstructing blood flow. * **"The Bends":** Bubbles in the joints and muscles causing severe pain. * **"The Chokes":** Bubbles in the pulmonary capillaries causing shortness of breath, chest pain, and cough. 2. **Why other options are incorrect:** * **Fat embolism:** Typically occurs after long bone fractures (e.g., femur) where marrow fat enters the circulation; it is not related to atmospheric pressure changes. * **Aspiration pneumonia:** Caused by inhaling foreign material (vomit/food) into the lungs, leading to inflammation/infection. * **Gangrene:** This is tissue death due to lack of blood supply or infection. While severe DCS can lead to necrosis (e.g., dysbaric osteonecrosis), it is a late complication, not the immediate mechanism of "bends and chokes." **NEET-PG High-Yield Pearls:** * **Nitrogen Narcosis:** Occurs at depth (high pressure) due to the anesthetic effect of nitrogen; often called "Rapture of the Deep." * **Treatment:** The definitive treatment for Decompression Sickness is **Hyperbaric Oxygen Therapy (HBOT)** in a recompression chamber. * **Helium-Oxygen (Heliox):** Used by deep-sea divers to prevent nitrogen narcosis because helium is less soluble and diffuses faster.

Q: Both pale and hemorrhagic infarcts are found in which organ?

Brain. **Explanation:** The nature of an infarct (pale vs. hemorrhagic) is primarily determined by the tissue's vascular supply and density. **Why Brain is the Correct Answer:** The brain is unique because it can exhibit both types of infarcts depending on the mechanism of injury. 1. **Pale (Anemic) Infarcts:** These typically occur due to **thrombotic arterial occlusion** [1]. Since the brain tissue is relatively solid (until liquefactive necrosis sets in), the lack of blood flow results in a pale area of necrosis. 2. **Hemorrhagic (Red) Infarcts:** These occur in the brain following **embolic occlusion** [1]. When an embolus lodges and then fragments or undergoes lysis (reperfusion), blood flows into the previously ischemic, necrotic tissue [1]. Because the brain has a loose texture, blood easily extravasates, turning a pale infarct into a hemorrhagic one. **Analysis of Incorrect Options:** * **Liver:** The liver has a **dual blood supply** (Portal vein and Hepatic artery). While this makes it resistant to infarction, when they do occur, they are typically **hemorrhagic**. * **Heart:** The heart is a solid organ with end-arterial circulation. Myocardial infarctions are almost exclusively **pale**. * **Kidney:** Like the heart, the kidney is a solid organ with a single arterial supply. Renal infarcts are the classic example of **pale, wedge-shaped infarcts**. **High-Yield NEET-PG Pearls:** * **Pale Infarcts:** Occur in solid organs with single venous drainage (Heart, Spleen, Kidney). * **Hemorrhagic Infarcts:** Occur in tissues with dual circulation (Lung, Liver), loose tissues (Bowel, Testis), or following reperfusion [1]. * **Liquefactive Necrosis:** The brain is the only organ where ischemic injury leads to liquefactive necrosis rather than coagulative necrosis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1266-1269.

Q: Isoprostanes are formed from archidonic acid by which mechanism?

Non-enzymatic free radical peroxidation. **Explanation:** **Isoprostanes** are prostaglandin-like compounds that serve as highly sensitive and specific biomarkers of **oxidative stress**. **1. Why Option D is Correct:** Unlike prostaglandins, which are synthesized via enzymatic pathways, isoprostanes are formed by the **non-enzymatic, free radical-induced peroxidation** of arachidonic acid (and other polyunsaturated fatty acids) while they are still attached to membrane phospholipids. They are subsequently released by phospholipases and can be detected in plasma and urine. Because their formation is independent of enzymes and directly proportional to free radical activity, they are considered the "gold standard" for measuring lipid peroxidation in vivo. **2. Why Other Options are Incorrect:** * **Option A (Cyclooxygenase):** COX-1 and COX-2 enzymes are responsible for the enzymatic conversion of arachidonic acid into prostaglandins (PGE2, PGD2, etc.) and thromboxanes [1]. * **Option B (Lipooxygenase):** LOX enzymes (e.g., 5-LOX) convert arachidonic acid into leukotrienes and lipoxins [1]. * **Option C (Epoxide hydrolase):** This enzyme is involved in the metabolism of epoxides (like EETs) into diols; it is not involved in the primary peroxidation of arachidonic acid. **3. NEET-PG High-Yield Pearls:** * **Biomarker Status:** Isoprostanes (specifically **8-iso-PGF2α**) are the most reliable markers of oxidative stress in diseases like atherosclerosis, diabetes, and Alzheimer’s. * **Vasoactivity:** Unlike some prostaglandins, isoprostanes are potent **vasoconstrictors** (especially in renal and pulmonary vasculature). * **Membrane Damage:** Their formation is a hallmark of **irreversible cell injury** caused by reactive oxygen species (ROS). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 95.

Q: Congenital hypercoagulability states include all of the following EXCEPT:

Antiphospholipid antibody syndrome. The core concept tested here is the distinction between **inherited (congenital)** and **acquired** hypercoagulable states (thrombophilias) [1]. **Why Antiphospholipid Antibody Syndrome (APS) is the correct answer:** APS is an **acquired** autoimmune hypercoagulable state characterized by the presence of antibodies (Lupus anticoagulant, Anti-cardiolipin, or Anti-β2 glycoprotein I) against phospholipid-binding proteins [1]. It is not a genetic condition present from birth; rather, it develops later in life, often secondary to other autoimmune diseases like SLE [3]. **Analysis of Incorrect Options (Congenital Causes):** * **Protein C & S Deficiency:** These are autosomal dominant inherited conditions [1]. Protein C and S are natural anticoagants that inactivate Factors Va and VIIIa. Their deficiency leads to an unchecked coagulation cascade. * **MTHFR Gene Mutation:** This is a genetic mutation (Methylenetetrahydrofolate reductase) that leads to hyperhomocysteinemia. Elevated homocysteine levels are a known genetic risk factor for both arterial and venous thrombosis. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Inherited Cause:** Factor V Leiden mutation (resistance to Activated Protein C) [1]. * **Most Common Acquired Cause:** Antiphospholipid Antibody Syndrome [2]. * **Paradoxical Lab Finding:** In APS, the **aPTT is prolonged** *in vitro*, but the patient is at high risk for thrombosis *in vivo*. * **Clinical Triad of APS:** Venous/arterial thrombosis, recurrent fetal loss, and thrombocytopenia [3]. * **Warfarin-Induced Skin Necrosis:** Classically associated with Protein C deficiency due to the rapid depletion of Protein C (short half-life) before the depletion of procoagulant factors.

Question 1

Amyloid (AA) originates from which cell type?

Accepted Answer

Reticulo-endothelial cell

Answer

RBC

Answer

Plasma cell

Answer

Lymphocytes

Question 2

Sudden decrease in atmospheric pressure in deep sea divers resulting in "bends" and "chokes" are features of which condition?

Accepted Answer

Air embolism

Answer

Fat embolism

Answer

Aspiration pneumonia

Answer

Gangrene

Question 3

Both pale and hemorrhagic infarcts are found in which organ?

Accepted Answer

Brain

Answer

Liver

Answer

Heart

Answer

Kidney

Question 4

Caisson's disease is a type of:

Accepted Answer

Gas embolism

Answer

Fat embolism

Answer

Amniotic fluid embolism

Answer

Tumor embolism

Question 5

What is the first cellular change observed in hypoxia?

Accepted Answer

Decreased oxidative phosphorylation in mitochondria

Answer

Cellular swelling

Answer

Alteration in cellular membrane permeability

Answer

Clumping of nuclear chromatin

Question 6

Isoprostanes are formed from archidonic acid by which mechanism?

Accepted Answer

Non-enzymatic free radical peroxidation

Answer

Cyclooxygenase

Answer

Lipooxygenase

Answer

Epoxide hydrolase

Question 7

Mitochondrial abnormality is seen in which of the following conditions?

Accepted Answer

Oncocytoma

Answer

Krabbe's disease

Answer

Fabry disease

Answer

Fanconi syndrome

Question 8

A wedge-shaped area in the adrenal gland is affected. On histopathology, the nucleus is not seen but cellular outlines are intact. Which type of necrosis is being described?

Accepted Answer

Coagulative

Answer

Liquefactive

Answer

Fibrinoid

Answer

Caseous

Question 9

Fat necrosis is not associated with which of the following procedures or conditions?

Accepted Answer

Carcinoma of the breast

Answer

Liposuction

Answer

Mammoplasty

Answer

Trauma

Question 10

Congenital hypercoagulability states include all of the following EXCEPT:

Accepted Answer

Antiphospholipid antibody syndrome

Answer

Protein C deficiency

Answer

Protein S deficiency

Answer

MTHFR gene mutation

General Pathology — MCQs

General Pathology — MCQs

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