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: 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: Scaphoid fracture which area has maximum chances of AVN/Non-union/Malunion:-

Proximal 1/3. ***Proximal 1/3*** - The **proximal pole of the scaphoid** has a precarious blood supply, primarily from retrograde extraosseous vessels entering distally. A fracture in this region can compromise this supply, leading to **avascular necrosis (AVN)**. - Due to the limited blood flow to the proximal fragment, healing is often impaired, increasing the risk of **non-union** and **malunion**. *Distal 1/3* - Fractures in the **distal 1/3 (distal pole)** of the scaphoid typically have a better prognosis. - This area has a more robust blood supply, reducing the risk of AVN and promoting faster healing. *Scaphoid Tubercle fracture* - Fractures of the **scaphoid tubercle** are usually considered stable and intra-articular, with a good blood supply. - These fractures generally heal well with conservative treatment and have a very low incidence of AVN or non-union. *Middle 1/3* - Fractures in the **middle 1/3 (waist)** of the scaphoid are the most common but still pose a significant risk of non-union. - While the risk of AVN is lower than for proximal pole fractures, it is still higher than for distal fractures, due to the critical vascular supply to both fragments.

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: Mechanism of action of teduglutide in short bowel syndrome:

GLP-2 analog that inhibits apoptosis. ***GLP-2 analog that inhibits apoptosis*** - **Teduglutide** is a synthetic analog of **glucagon-like peptide-2 (GLP-2)**, which is a naturally occurring human hormone [1]. - Its primary mechanism in **short bowel syndrome** involves promoting mucosal growth and inhibiting epithelial cell apoptosis, thereby enhancing nutrient absorption and gut adaptation. *GLP-1 analogs that inhibits apoptosis* - **GLP-1 analogs** like exenatide or liraglutide are primarily used for **type 2 diabetes mellitus** to stimulate insulin secretion and suppress glucagon [2]. - While they can have some effects on gut motility, their main role is not in promoting mucosal growth or inhibiting apoptosis in the context of short bowel syndrome. *HT1A inhibitor* - **HT1A inhibitors** (5-HT1A receptor antagonists) are typically involved in modulating serotonin pathways, often with applications in conditions like **anxiety** or **depression**. - There is no known direct link between HT1A inhibition and the treatment of short bowel syndrome. *C-peptide analogs* - **C-peptide** is a byproduct of insulin production and has been studied for potential roles in preventing diabetes complications, particularly in relation to **microvascular complications** [3], [4]. - It does not play a direct role as a therapeutic agent for promoting intestinal adaptation or inhibiting apoptosis in short bowel syndrome.

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: Degloving injury involves separation of:-

Skin + Fascia + Subcutaneous tissue. ***Skin + Fascia + Subcutaneous tissue*** - A **degloving injury** involves the traumatic separation of skin, subcutaneous tissue, and **superficial fascia** from the underlying deep fascia and muscle structures. - The separation typically occurs at the plane between the **superficial fascia** and **deep fascia**, creating the characteristic "degloved" appearance with loss of multiple tissue layers. *Skin + Subcutaneous tissue* - This option is incomplete as it fails to explicitly mention the **superficial fascia** component that is also involved in degloving injuries. - While anatomically the subcutaneous tissue includes fascial elements, the complete description should specifically include **fascia** as a separate component. *Skin* - This option is severely incomplete as degloving injuries involve much more than just the **epidermal and dermal layers**. - A true degloving injury must include separation of the **subcutaneous tissue** and **superficial fascia** to create the characteristic tissue defect. *Everything above from bone* - This description is too extensive and would represent a **complex avulsion** or **near-amputation** rather than a typical degloving injury. - Degloving specifically refers to separation at the **superficial-deep fascial plane**, not removal of all overlying tissues including muscle and deep fascia.

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

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 3

MHC II is associated with:-

Accepted Answer

Antigen presenting cells

Answer

Red blood cells

Answer

Platelets

Answer

Epithelial cells

Question 4

Scaphoid fracture which area has maximum chances of AVN/Non-union/Malunion:-

Accepted Answer

Proximal 1/3

Answer

Distal 1/3

Answer

Scaphoid Tubercle fracture

Answer

Middle 1/3

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

Mechanism of action of teduglutide in short bowel syndrome:

Accepted Answer

GLP-2 analog that inhibits apoptosis

Answer

HT1A inhibitor

Answer

C-peptide analog

Answer

GLP-1 analog that inhibits apoptosis

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

Degloving injury involves separation of:-

Accepted Answer

Skin + Fascia + Subcutaneous tissue

Answer

Skin

Answer

Everything above from bone

Answer

Skin + Subcutaneous tissue

NEET-PG 2019

Anatomy

Biochemistry

Microbiology

Orthopaedics

Pathology

Pharmacology

Surgery