NEET-PG 2019 Practice Questions

Q: Frey's syndrome occurs due to aberrant regeneration of parasympathetic nerve fibers following parotid surgery, leading to gustatory sweating. The nerve directly involved in this aberrant reinnervation is:

Auriculotemporal nerve. ***Auriculotemporal nerve*** - Frey's syndrome, or **gustatory sweating**, occurs due to damage to the **auriculotemporal nerve**, typically during parotidectomy. - Aberrant regeneration leads to misdirection of parasympathetic fibers meant for the parotid gland to the sweat glands in the preauricular and temporal regions. *Trigeminal nerve* - The trigeminal nerve (CN V) is primarily responsible for **sensory innervation of the face** and **motor innervation of the muscles of mastication**. - It does not directly provide secretomotor innervation to the parotid gland or sweat glands. *Facial nerve* - The facial nerve (CN VII) innervates the **muscles of facial expression** and provides taste sensation to the anterior two-thirds of the tongue, and secretomotor innervation to the submandibular and sublingual glands. - While it passes through the parotid gland, it does not provide secretomotor innervation to the parotid gland itself. *GlossoPharyngeal nerve* - The glossopharyngeal nerve (CN IX) provides presynaptic parasympathetic fibers to the **otic ganglion**, which then synapse with postsynaptic fibers carried by the auriculotemporal nerve to the parotid gland. - Although it is the origin of the parasympathetic innervation for the parotid, the direct aberrant reinnervation in Frey's syndrome involves the auriculotemporal nerve, not the glossopharyngeal nerve itself.

Q: Which IV anesthetic does not cause cardiac depression?

Etomidate. **Etomidate** - **Etomidate** is known for its **minimal cardiovascular effects**, making it a preferred choice in patients with **pre-existing cardiac disease** or hemodynamic instability. - Unlike other IV anesthetics, it causes very little change in **heart rate**, **blood pressure**, or **cardiac output**. *Propofol* - **Propofol** frequently causes **dose-dependent myocardial depression** and **vasodilation**, leading to significant decreases in blood pressure. - Its cardiovascular effects can be problematic in patients with compromised cardiac function. *Thiopentone* - **Thiopentone**, a barbiturate, typically causes **dose-dependent cardiovascular depression**, including reduced **myocardial contractility** and **vasodilation**. - This can result in a decrease in **blood pressure** and **cardiac output**. *Methohexital* - **Methohexital**, another barbiturate, also causes **cardiovascular depression** similar to thiopentone. - It can lead to decreased **blood pressure** due to both **myocardial depression** and **peripheral vasodilation**.

Q: True regarding mitochondrial DNA is:

Inherited from mother. ***Inherited from mother*** - **Mitochondrial DNA (mtDNA)** is exclusively inherited from the mother because the sperm's mitochondria are typically destroyed after fertilization or do not enter the oocyte. - This **maternal inheritance pattern** makes mtDNA useful for tracing lineage and studying human population movements. *Linear double stranded* - **Mitochondrial DNA** is typically **circular**, not linear, and double-stranded, similar to a plasmid in bacteria. - **Linear DNA** is characteristic of nuclear chromosomes in eukaryotes. *All respiratory proteins are synthesized within mitochondria itself* - While mitochondria contain their own ribosomes and synthesize some proteins, the majority of **respiratory chain proteins** are encoded by **nuclear DNA** and imported into the mitochondria. - The **mitochondrial genome** encodes only a small fraction of the proteins necessary for mitochondrial function, primarily components of the electron transport chain. *Low mutation rate* - **Mitochondrial DNA** has a **higher mutation rate** compared to nuclear DNA due to a less robust DNA repair system and exposure to reactive oxygen species generated during oxidative phosphorylation. - The high mutation rate can contribute to mitochondrial diseases and can also be used in evolutionary studies.

Q: MHC II is associated with:-

Antigen presenting cells. ***Antigen presenting cells*** - **MHC II (Major Histocompatibility Complex class II)** molecules are primarily expressed on the surface of professional **antigen-presenting cells (APCs)**. - APCs, such as **macrophages**, **dendritic cells**, and **B lymphocytes**, use MHC II to present **extracellularly derived antigens** to **CD4+ T helper cells**. *Red blood cells* - **Red blood cells (RBCs)** are anucleated and lack MHC molecules entirely. - Their primary function is **oxygen transport**, not immune cell communication. *Platelets* - **Platelets** are cell fragments involved in **hemostasis** (blood clotting). - They do not express MHC class II molecules as they are not involved in antigen presentation. *Epithelial cells* - Most **epithelial cells** primarily express **MHC class I** molecules to present **intracellular antigens** to **CD8+ cytotoxic T cells**. - They do not typically express MHC class II unless under specific inflammatory conditions, and even then, not as their primary function.

Q: Characteristic feature of hypertrophic obstructive cardiomyopathy is:

Asymmetric septal hypertrophy. ***Asymmetric septal hypertrophy*** - This is the hallmark feature of **hypertrophic obstructive cardiomyopathy (HOCM)**, where the **interventricular septum** thickens disproportionately more than the free wall of the left ventricle [1], [2]. - This septal thickening can lead to **left ventricular outflow tract obstruction**, particularly during systole, obstructing blood flow out of the heart [1]. *Increased size of ventricle* - While the left ventricle may appear enlarged in some dimensions due to hypertrophy, the primary characteristic is specifically **asymmetric thickening of the septum**, not a generalized increase in ventricular size [2]. - In other forms of cardiomyopathy, such as dilated cardiomyopathy, a global increase in ventricular size is observed, which is distinct from HOCM. *Normal myofiber arrangement* - A characteristic microscopic feature of HOCM is **myocardial disarray**, where cardiac muscle fibers are abnormally arranged instead of their usual parallel alignment [1]. - This disorganized arrangement contributes to the impaired function and electrical instability seen in HOCM. *Increased size of atria* - While **left atrial enlargement** can be a secondary finding in HOCM due to increased left ventricular end-diastolic pressure and impaired diastolic filling, it is not the primary or characteristic feature defining the condition [1]. - The fundamental pathology of HOCM lies in the specific hypertrophy of the ventricular myocardium, particularly the septum. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 577-578. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 303-304.

Q: Which chamber of the heart is enlarged first in a patient with McCallum patch?

Left atrium. ***Left atrium*** - A **McCallum patch** is a thickened, often irregular endocardial lesion found in the **left atrium**. - It results from the jet lesion of **mitral regurgitation**, indicating the left atrium has been subjected to increased volume and pressure leading to enlargement [1]. *Left ventricle* - While **mitral regurgitation** can eventually lead to **left ventricular enlargement** (due to volume overload), the primary chamber affected by the regurgitant jet causing the McCallum patch is the left atrium. - Left ventricular enlargement is a later consequence, not the first chamber to show this specific lesion. *Right atrium* - The **right atrium** is affected by conditions like **tricuspid regurgitation** or **pulmonary hypertension**, which are unrelated to mitral valve disease or McCallum patches. - It handles systemic venous return, separate from the left-sided circulation involved in mitral pathology. *Right ventricle* - The **right ventricle** is primarily impacted by conditions affecting the **pulmonary circulation** or **tricuspid valve**. - It fills from the right atrium and pumps blood to the lungs, making it unlikely to be the first chamber enlarged in the context of a McCallum patch from mitral regurgitation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 533-534.

Q: Cholesterol gallstones are made up of:-

Crystalline cholesterol monohydrate. ***Crystalline cholesterol monohydrate*** - **Cholesterol gallstones** primarily consist of **crystalline cholesterol monohydrate**, which forms when the bile becomes supersaturated with cholesterol [1]. - The **crystallization** of cholesterol leads to the formation of visible stones within the gallbladder. *Amorphous cholesterol dihydrate* - This form of cholesterol is not typically found as the primary component of **gallstones**. - **Amorphous** structures lack a defined crystalline lattice and are less stable for forming solid stones. *Amorphous cholesterol monohydrate* - While **cholesterol monohydrate** is the core component, it is in a **crystalline** rather than amorphous state in gallstones [1]. - **Amorphous** forms are generally transient intermediates and do not constitute the bulk of the stones. *Crystalline cholesterol dihydrate* - **Dihydrate** forms of cholesterol are not the main constituent of gallstones; the **monohydrate** form is the predominant type [1]. - The specific hydration state of **cholesterol monohydrate** makes it the primary compound found in the solid, crystalline structure of gallstones [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, p. 882.

Q: Which among the following is NOT part of the classic clinical triad of necrotizing enterocolitis?

Metabolic acidosis. ***Metabolic acidosis*** - Metabolic acidosis is **not** part of the classic clinical triad of necrotizing enterocolitis, though it is a common laboratory finding in severe cases. - The **classic triad of NEC** consists of: **abdominal distension**, **bloody stools**, and **pneumatosis intestinalis** on radiography. - Metabolic acidosis occurs as a consequence of intestinal ischemia and sepsis but is not included in the defining triad. *Abdominal distension* - **Abdominal distension** is a cardinal clinical feature and part of the classic triad. - Results from intestinal inflammation, ileus, and gas accumulation. *Bloody stools* - **Bloody stools** (grossly bloody or occult blood positive) are part of the classic triad. - Reflect mucosal injury and intestinal necrosis. *Pneumatosis intestinalis* - **Pneumatosis intestinalis** (intramural gas on abdominal X-ray) is the pathognomonic radiological finding in the classic triad. - Indicates gas-forming bacterial invasion of the damaged intestinal wall.

Q: Mannitol is used in the management of:-

Acute angle-closure glaucoma. ***Acute angle-closure glaucoma*** - **Mannitol** is an osmotic diuretic [1] used to rapidly reduce **intraocular pressure** in conditions like acute angle-closure glaucoma [2]. - It works by creating an **osmotic gradient** that draws fluid from the vitreous humor into the bloodstream [2]. - This is a well-established **emergency indication** for mannitol [2]. *Acute renal failure* - While mannitol may be used in **prevention** of acute kidney injury (e.g., in rhabdomyolysis, cardiovascular surgery) [2], its use in established acute renal failure is generally **contraindicated** if the patient is **anuric**, as it can exacerbate fluid overload [2]. - It is **not a primary management** for acute renal failure among the given options. *Pulmonary edema* - **Mannitol** is generally **contraindicated** in pulmonary edema because its initial effect is to increase **intravascular volume** [2], which can worsen fluid accumulation in the lungs. - Loop diuretics like **furosemide** are preferred for their rapid onset and profound diuretic effect in pulmonary edema. *Congestive cardiac failure* - **Mannitol** is typically **contraindicated** in congestive cardiac failure as it can cause a **transient increase in plasma volume**, potentially worsening cardiac workload and leading to decompensation [2]. - Diuretics commonly used in heart failure, such as **loop diuretics** (e.g., furosemide) or **thiazide diuretics**, are preferred to reduce fluid overload.

Q: All of the following statements are true about Frey's Syndrome except

Sympathetic nerve involvement is the primary cause. ***Sympathetic nerve involvement is the primary cause*** - **This is FALSE (Correct answer for EXCEPT question)** - Frey's syndrome is **NOT** caused by sympathetic nerve involvement - The primary cause is **aberrant regeneration of severed PARASYMPATHETIC fibers** of the auriculotemporal nerve - These parasympathetic fibers mistakenly re-innervate sweat glands (which are sympathetically innervated) instead of the parotid gland - This misdirection causes gustatory sweating during meals *Less chances with enucleation than parotidectomy* - **TRUE** - Enucleation is a less extensive procedure compared to complete parotidectomy - Less tissue removal means less nerve disruption and lower risk of auriculotemporal nerve damage - The risk of Frey's syndrome is directly proportional to the extent of parotid tissue removal *Gustatory sweating* - **TRUE** - This is the hallmark symptom of Frey's syndrome - Characterized by sweating on the skin over the parotid region in response to salivary stimuli (smelling, seeing, or eating food) - Results from misdirected parasympathetic fibers stimulating sweat glands instead of salivary tissue *Aberrant misdirection of parasympathetic fibers of auriculotemporal nerve* - **TRUE** - This is the correct pathophysiological mechanism underlying Frey's syndrome - Following injury to the auriculotemporal nerve during parotid surgery, regenerating parasympathetic secretomotor fibers become misdirected - These fibers intended for the parotid gland instead innervate sweat glands in the overlying skin

Question 1

Frey's syndrome occurs due to aberrant regeneration of parasympathetic nerve fibers following parotid surgery, leading to gustatory sweating. The nerve directly involved in this aberrant reinnervation is:

Accepted Answer

Auriculotemporal nerve

Answer

Trigeminal nerve

Answer

Facial nerve

Answer

GlossoPharyngeal nerve

Question 2

Which IV anesthetic does not cause cardiac depression?

Accepted Answer

Etomidate

Answer

Propofol

Answer

Thiopentone

Answer

Methohexital

Question 3

True regarding mitochondrial DNA is:

Accepted Answer

Inherited from mother

Answer

Linear double stranded

Answer

All respiratory proteins are synthesized within mitochondria itself

Answer

Low mutation rate

Question 4

MHC II is associated with:-

Accepted Answer

Antigen presenting cells

Answer

Red blood cells

Answer

Platelets

Answer

Epithelial cells

Question 5

Characteristic feature of hypertrophic obstructive cardiomyopathy is:

Accepted Answer

Asymmetric septal hypertrophy

Answer

Increased size of ventricle

Answer

Normal myofiber arrangement

Answer

Increased size of atria

Question 6

Which chamber of the heart is enlarged first in a patient with McCallum patch?

Accepted Answer

Left atrium

Answer

Left ventricle

Answer

Right atrium

Answer

Right ventricle

Question 7

Cholesterol gallstones are made up of:-

Accepted Answer

Crystalline cholesterol monohydrate

Answer

Amorphous cholesterol dihydrate

Answer

Amorphous cholesterol monohydrate

Answer

Crystalline cholesterol dihydrate

Question 8

Which among the following is NOT part of the classic clinical triad of necrotizing enterocolitis?

Accepted Answer

Metabolic acidosis

Answer

Bloody stools

Answer

Pneumatosis intestinalis

Answer

Abdominal distension

Question 9

Mannitol is used in the management of:-

Accepted Answer

Acute angle-closure glaucoma

Answer

Acute renal failure

Answer

Pulmonary edema

Answer

Congestive cardiac failure

Question 10

All of the following statements are true about Frey's Syndrome except

Accepted Answer

Sympathetic nerve involvement is the primary cause

Answer

Less chances with enucleation than parotidectomy

Answer

Gustatory sweating

Answer

Aberrant misdirection of parasympathetic fibers of auriculotemporal nerve

NEET-PG 2019

Anatomy

Anesthesiology

Biochemistry

Microbiology

Pathology

Pediatrics

Pharmacology

Surgery