NEET-PG 2013 Practice Questions

Q: Which of the following is NOT a content of the occipital triangle?

Suprascapular nerve. Suprascapular nerve - The **suprascapular nerve** originates from the brachial plexus and supplies the supraspinatus and infraspinatus muscles; it travels through the suprascapular notch and is not found within the occipital triangle. - Its primary course and innervation are associated with the shoulder, entirely separate from the neck region defining the occipital triangle. *Great auricular nerve* - The **great auricular nerve** emerges from the cervical plexus and supplies sensory innervation to the skin over the parotid gland, mastoid process, and auricle, courses superficially across the sternocleidomastoid in the region of the occipital triangle. - It is a recognized content of the posterior triangle of the neck, which encompasses the occipital triangle. *Lesser occipital nerve* - The **lesser occipital nerve** arises from the cervical plexus at C2 and C3, providing sensory innervation to the skin of the neck and scalp posterior to the auricle. - It ascends along the posterior border of the sternocleidomastoid muscle, placing it within the boundaries of the occipital triangle. *Occipital artery* - The **occipital artery** is a branch of the external carotid artery that supplies blood to the posterior scalp. - It traverses the apex of the posterior triangle (including the occipital triangle) as it ascends to the back of the head.

Q: The main function of Vitamin C in the body is

Cofactor for hydroxylation reactions in collagen synthesis. ***Cofactor for hydroxylation reactions in collagen synthesis*** - Vitamin C (ascorbic acid) serves as an essential **cofactor** for **prolyl hydroxylase** and **lysyl hydroxylase** enzymes. - These enzymes catalyze the **hydroxylation of proline and lysine** residues in collagen, forming **hydroxyproline** and **hydroxylysine**. - This hydroxylation is crucial for the **stability and cross-linking** of collagen triple helix structure. - Deficiency leads to **scurvy**, characterized by defective collagen synthesis, bleeding gums, poor wound healing, and bone abnormalities. - This is the **primary and main function** of Vitamin C in the human body. *Involvement as antioxidant* - While Vitamin C does act as a **water-soluble antioxidant**, protecting cells from oxidative damage by free radicals, this is a **secondary function**. - It can donate electrons to neutralize reactive oxygen species and regenerate other antioxidants like Vitamin E. - This protective role is important but not the main function compared to its role in collagen synthesis. *Regulation of lipid synthesis* - Vitamin C is **not directly involved** in the primary pathways of lipid synthesis or metabolism. - It may play a minor role in **carnitine synthesis** (needed for fatty acid oxidation), but this is not a major function. - Other nutrients like B vitamins play more significant roles in lipid metabolism regulation. *Inhibition of cell growth* - Vitamin C does **not inhibit normal cell growth**; it is essential for cell health, differentiation, and tissue repair. - While high doses may have some anti-proliferative effects in certain cancer cell lines in vitro, this is not a physiological function in the healthy body.

Q: Concentration of which is inversely related to the risk of coronary heart disease?

HDL. ***HDL*** - **High-density lipoprotein (HDL)** is known as "good cholesterol" because it helps remove excess cholesterol from the arteries and transport it back to the liver for excretion. - Higher levels of HDL are generally associated with a **lower risk of coronary heart disease (CHD)**, hence the inverse relationship. *VLDL* - **Very low-density lipoprotein (VLDL)** carries triglycerides and cholesterol and is considered an independent risk factor for CHD when present in high concentrations. - High VLDL levels are associated with an **increased risk of CHD**, not an inverse relationship. *LDL* - **Low-density lipoprotein (LDL)** is often referred to as "bad cholesterol" because it contributes to plaque buildup in arteries (**atherosclerosis**). - High levels of LDL are strongly associated with an **increased risk of CHD**, indicating a direct, not inverse, relationship. *None of the options* - This option is incorrect because HDL clearly demonstrates an **inverse relationship** with the risk of coronary heart disease.

Q: Which of the following organs does not primarily utilize fatty acids for energy?

Brain. ***Brain*** - The **brain primarily uses glucose** as its main energy source because fatty acids cannot efficiently cross the **blood-brain barrier**. - During prolonged starvation, the brain can adapt to use **ketone bodies**, which are derived from fatty acid breakdown in the liver. *Muscle* - **Skeletal muscle** can utilize both **glucose and fatty acids** for energy, with fatty acids becoming a more prominent fuel source during prolonged exercise and at rest. - **Cardiac muscle** (heart) heavily relies on **fatty acid oxidation** as its primary energy substrate, especially during basal conditions. *Liver* - The **liver is highly metabolically flexible** and readily oxidizes fatty acids for its own energy needs, particularly during fasting states. - It also plays a key role in **fatty acid metabolism**, including synthesis, breakdown, and conversion into ketone bodies. *Kidney* - The **renal cortex** is rich in mitochondria and has a high metabolic rate, primarily utilizing **fatty acid oxidation** to meet its significant energy demands for filtration and reabsorption. - While the renal medulla can use glucose, the cortex's reliance on fatty acids makes it a significant consumer.

Q: Human sperm remains fertile for how many hours in a female genital tract ?

Up to 5 days (120 hrs). ***Up to 5 days (120 hrs)*** - **Sperm viability** within the female reproductive tract can extend up to **5 days (120 hours)** under optimal conditions. - This extended viability is crucial for fertility, as it allows for fertilization even if ovulation occurs several days after intercourse. *6-8 hrs* - This timeframe is significantly **too short** for typical human sperm viability in the female genital tract. - While some sperm may lose motility or viability relatively quickly, a substantial portion remains viable for much longer. *12-24 hrs* - This represents the average **lifespan of an ovum** (egg) after ovulation, not the typical viability of sperm. - Sperm generally survive longer than an unfertilized egg. *24-48 hrs* - This duration underestimates the maximum potential survival time of human sperm in the female reproductive tract. - While many sperm may be viable within this period, it does not represent the full potential for fertilization.

Q: According to WHO/ISN classification, which class of lupus nephritis shows a membranous pattern in SLE?

Membranous pattern. ***Membranous pattern*** - This corresponds to **Class V lupus nephritis** in the WHO/ISN classification, characterized by widespread immune complex deposition along the **glomerular basement membrane (GBM)**. - The subepithelial immune deposits lead to GBM thickening, creating the characteristic membranous pattern on light microscopy. - This pattern resembles idiopathic membranous nephropathy but occurs in the context of SLE. *Mesangial pattern involvement* - This refers to **Class I (minimal mesangial LN)** or **Class II (mesangial proliferative LN)**, where immune deposits are primarily confined to the mesangium. - There is minimal or no involvement of the glomerular capillary walls, distinguishing it from the membranous pattern. *Diffuse proliferative pattern* - This is **Class IV lupus nephritis**, the most severe form characterized by widespread **endocapillary and/or extracapillary proliferation** involving ≥50% of glomeruli. - The primary feature is cellular proliferation (mesangial, endocapillary, epithelial crescents), not the subepithelial immune deposits typical of membranous pattern. *Focal proliferative pattern* - This corresponds to **Class III lupus nephritis**, involving **endocapillary or extracapillary proliferation** in <50% of glomeruli. - Distinguished by focal (not diffuse) involvement and active proliferation rather than the membranous pattern seen in Class V.

Q: Which of the following stimuli is primarily responsible for triggering the Bezold-Jarisch reflex?

Activation of cardiac C-fiber afferents. ***Activation of cardiac C-fiber afferents*** - The **Bezold-Jarisch reflex** is primarily triggered by stimulation of **cardiac mechanoreceptors and chemoreceptors** located in the ventricles, particularly the inferoposterior wall of the left ventricle. - These receptors have **unmyelinated vagal C-fiber afferents** that transmit signals to the medullary cardiovascular centers. - Activation of these afferents leads to the characteristic triad: **bradycardia, hypotension, and vasodilation** via increased parasympathetic activity and withdrawal of sympathetic tone. - Common triggers include vigorous ventricular contraction with decreased filling, certain drugs (veratridine), myocardial ischemia (especially inferior wall MI), and reperfusion. *Decreased venous return* - While **decreased venous return** creates the hemodynamic context (ventricular underfilling) that can lead to vigorous contraction of a relatively empty ventricle, it is not itself the *trigger* of the reflex. - The actual trigger is the activation of the ventricular receptors sensing this abnormal contraction pattern, which then signal via C-fiber afferents. - Decreased venous return alone, without receptor activation, would not produce the reflex. *Parasympathetic withdrawal* - **Parasympathetic withdrawal** would cause tachycardia and is opposite to the Bezold-Jarisch reflex, which involves **increased parasympathetic activity**. - This is a compensatory response seen in other reflexes like the baroreceptor reflex during hypotension. *Increased sympathetic stimulation* - **Increased sympathetic stimulation** produces tachycardia, increased contractility, and vasoconstriction—effects opposite to the Bezold-Jarisch reflex. - The reflex actually causes **sympathetic withdrawal** along with parasympathetic activation.

Q: Which of the following is classified as a pain receptor?

Free nerve endings. ***Free nerve endings*** - **Free nerve endings** are the most common type of sensory receptor in the skin and are responsible for detecting **pain**, temperature, and crude touch. - They lack specialized structures and are found throughout the epidermis and dermis. *Meissner's corpuscle* - **Meissner's corpuscles** are encapsulated nerve endings that detect **light touch** and **vibration**. - They are rapidly adapting and are abundant in sensitive, hairless skin areas like fingertips and lips. *Pacinian corpuscle* - **Pacinian corpuscles** are large, encapsulated receptors that detect **deep pressure** and **vibration**. - They are rapidly adapting and respond to high-frequency stimuli. *Merkel disc* - **Merkel discs** are specialized epithelial cells associated with nerve endings that detect **sustained pressure** and **texture**. - They are slowly adapting receptors crucial for tactile discrimination.

Q: Plasma volume is measured by ?

Evans blue. ***Evans blue*** - **Evans blue** is a dye that binds to plasma proteins and **does not readily cross capillary membranes**, making it an effective tracer for measuring plasma volume. - After intravenous injection, its concentration can be measured to calculate the dilution space, which corresponds to the **plasma volume**. *Inulin* - **Inulin** is a polysaccharide primarily used to measure the **glomerular filtration rate (GFR)** because it is freely filtered by the glomeruli and neither reabsorbed nor secreted by the renal tubules. - It distributes into the **extracellular fluid compartment** and is not confined to the plasma, making it unsuitable for plasma volume measurement. *Mannitol* - **Mannitol** is an osmotic diuretic that distributes in the **extracellular fluid (ECF)**, it is generally used for its osmotic effects to reduce edema or intracranial pressure. - Due to its distribution beyond the plasma compartment, it is not used directly to measure **plasma volume**. *D20* - **D2O (deuterium oxide)**, or heavy water, is used to measure **total body water (TBW)** as it distributes throughout all fluid compartments of the body. - It does not selectively remain within the plasma compartment, making it unsuitable for measuring **plasma volume** alone.

Q: Most common type of calcium channels of skeletal muscles is?

L-type. ***L type*** - **L-type calcium channels**, also known as **dihydropyridine receptors (DHPRs)**, are the predominant type of calcium channel found in skeletal muscle. - In skeletal muscle, they serve as voltage sensors that **mechanically link** to ryanodine receptors (RyRs) on the sarcoplasmic reticulum to trigger calcium release without significant calcium influx from the extracellular space. *N-type* - **N-type calcium channels** are primarily found in **neurons** and play a crucial role in neurotransmitter release at synapses. - They are not the primary calcium channels involved in skeletal muscle excitation-contraction coupling. *T-type* - **T-type calcium channels** are low-voltage activated channels found in various excitable cells, including cardiac muscle and neurons, where they contribute to **pacemaker activity** and repetitive firing. - They are not the main calcium channels responsible for excitation-contraction coupling in skeletal muscle. *R-type* - **R-type calcium channels** are found in various neural cells and are involved in diverse functions, including **synaptic transmission**, but their precise physiological role is less clearly defined compared to other types. - These channels are not the primary calcium entry pathways in skeletal muscle and do not play a significant role in its contraction.

Question 1

Which of the following is NOT a content of the occipital triangle?

Accepted Answer

Suprascapular nerve

Answer

Lesser occipital nerve

Answer

Occipital artery

Answer

Great auricular nerve

Question 2

The main function of Vitamin C in the body is

Accepted Answer

Cofactor for hydroxylation reactions in collagen synthesis

Answer

Regulation of lipid synthesis

Answer

Involvement as antioxidant

Answer

Inhibition of cell growth

Question 3

Concentration of which is inversely related to the risk of coronary heart disease?

Accepted Answer

HDL

Answer

VLDL

Answer

LDL

Answer

None of the options

Question 4

Which of the following organs does not primarily utilize fatty acids for energy?

Accepted Answer

Brain

Answer

Muscle

Answer

Liver

Answer

Kidney

Question 5

Human sperm remains fertile for how many hours in a female genital tract ?

Accepted Answer

Up to 5 days (120 hrs)

Answer

6-8 hrs

Answer

12-24 hrs

Answer

24-48 hrs

Question 6

According to WHO/ISN classification, which class of lupus nephritis shows a membranous pattern in SLE?

Accepted Answer

Membranous pattern

Answer

Diffuse proliferative pattern

Answer

Mesangial pattern involvement

Answer

Focal proliferative pattern

Question 7

Which of the following stimuli is primarily responsible for triggering the Bezold-Jarisch reflex?

Accepted Answer

Activation of cardiac C-fiber afferents

Answer

Parasympathetic withdrawal

Answer

Decreased venous return

Answer

Increased sympathetic stimulation

Question 8

Which of the following is classified as a pain receptor?

Accepted Answer

Free nerve endings

Answer

Meissner's corpuscle

Answer

Pacinian corpuscle

Answer

Merkel disc

Question 9

Plasma volume is measured by ?

Accepted Answer

Evans blue

Answer

Inulin

Answer

D2O

Answer

Mannitol

Question 10

Most common type of calcium channels of skeletal muscles is?

Accepted Answer

L-type

Answer

N-type

Answer

T-type

Answer

R-type

NEET-PG 2013

Anatomy

Biochemistry

Obstetrics and Gynecology

Pathology

Physiology