NEET-PG 2013 Practice Questions

Q: Which nucleus is primarily involved in the Papez circuit?

Anterior nucleus of the thalamus. ***Anterior nucleus of the thalamus*** - The **anterior nucleus of the thalamus** is a key relay station in the Papez circuit [1], receiving input from the mamillary bodies and projecting to the cingulate gyrus. - This circuit is crucial for **memory formation** [2] and emotional processing. *Pulvinar nucleus* - The pulvinar nucleus is primarily involved in **visual processing**, attention, and eye movements. - It does not form a direct part of the classic Papez circuit for emotion and memory. *Intralaminar nucleus* - The intralaminar nuclei are involved in **arousal**, attention, and pain perception, with widespread projections to the cerebral cortex [1]. - They are not considered a primary component of the Papez circuit. *Ventral posterolateral (VPL) nucleus* - The VPL nucleus is a major **somatosensory relay** in the thalamus, transmitting touch, proprioception, and vibration information from the body to the cortex. - It has no direct role in the Papez circuit or limbic functions.

Q: Which muscle is the deepest in the anterior neck region?

Longus colli. ***Longus colli*** - The **longus colli** muscle is the **deepest muscle** located in the anterior neck region, running along the front of the cervical vertebral column from C1 to T3. - It lies in the **prevertebral layer**, deep to all other anterior neck structures including the carotid sheath, visceral compartment, and superficial muscles. - Its position directly anterior to the vertebral bodies makes it the deepest anterior neck muscle. *Platysma* - The platysma is the **most superficial muscle** of the neck, located just beneath the skin in the superficial fascia. - It is not a deep muscle and lies superficial to all other neck muscles. *Sternocleidomastoid* - The sternocleidomastoid is enclosed within the **investing layer of deep cervical fascia**, making it relatively superficial. - While prominent in the anterior and lateral neck, it is not the deepest anterior neck muscle. *Trapezius* - The trapezius is a large, **superficial muscle of the back and posterior neck**. - It is not located in the anterior neck and is a superficial, not deep, muscle.

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 trace elements has vitamin E-like action?

Selenium. ***Selenium*** - Selenium is an essential component of **glutathione peroxidase**, an enzyme that works alongside vitamin E to protect cells from **oxidative damage**. - Its antioxidant properties are similar to **vitamin E**, as both scavenge free radicals and prevent lipid peroxidation. *Iron* - Iron is vital for **oxygen transport** in hemoglobin and myoglobin, and for cellular respiration as a component of cytochromes. - While essential, iron does not have direct **antioxidant properties** akin to vitamin E; in excess, it can even promote oxidative stress. *Copper* - Copper is a cofactor for several enzymes, including **superoxide dismutase (SOD)**, an antioxidant enzyme, but its primary role is not directly analogous to vitamin E's lipid-soluble antioxidant function. - It also plays a role in **energy production**, iron metabolism, and neurotransmission. *Zinc* - Zinc is crucial for **immune function**, wound healing, and DNA synthesis, acting as a cofactor for over 300 enzymes. - Although it has indirect antioxidant effects by stabilizing cell membranes and reducing oxidative damage, its mechanism and direct action are not considered "vitamin E-like."

Q: Which of the following cell types is classified as a labile cell?

Surface epithelium. ***Surface epithelium*** - Surface epithelium is classified as **labile tissue**, meaning it undergoes constant regeneration due to its high turnover rate [1]. - Cells in this tissue are typically found in areas that experience frequent damage or abrasion, such as the skin and lining of the intestines. *Cardiac cell* - Cardiac cells are considered **permanent cells**, as they do not undergo significant regeneration after injury or damage. - Damage to cardiac cells typically leads to **fibrosis** rather than repair of the original tissue. *Liver parenchymal cell* - Liver parenchymal cells are categorized as **stable cells**, which can regenerate but do so under specific circumstances, such as injury. - They have a slower turnover rate compared to labile cells and do not constantly renew under normal conditions. *Vascular endothelial cells* - Vascular endothelial cells are considered **stable cells** as well, typically maintaining a stable population but capable of regeneration following injury. - They do not have the same rapid turnover and regeneration capability as labile cells do, especially under normal physiological conditions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 113-115.

Q: What is the effect of moderate exercise on cerebral blood flow?

Increases. ***Increases*** - Moderate exercise leads to an **increase in systemic arterial pressure** and an increase in **cardiac output**, which often results in a moderate increase in cerebral blood flow. - This increase is also attributed to **vasodilation of cerebral arteries** in response to metabolic demands and changes in blood gas levels during exercise. *Decreases* - A decrease in cerebral blood flow is generally associated with conditions leading to **hypoperfusion** or **severe vasoconstriction**, which are not typical effects of moderate exercise. - While extreme exercise could potentially cause some transient vasoconstriction, moderate exercise typically has the opposite effect due to compensatory mechanisms. *Initially decreases then increases* - There is generally no physiological mechanism by which moderate exercise would cause an initial decrease in cerebral blood flow followed by an increase. - Cerebral autoregulation usually maintains a stable blood flow, and the overall trend with moderate exercise is an increase. *Does not change* - While **cerebral autoregulation** aims to keep cerebral blood flow stable over a range of blood pressures, moderate exercise often pushes parameters (like CO2 levels and systemic pressure) enough to cause a measurable, albeit modest, **increase in blood flow**. - The brain's metabolic demand also increases during exercise, necessitating an increased blood supply.

Q: How many transmembrane spanning domains does the Na+-K+-Cl- cotransporter contain?

12 transmembrane spanning domain. ***12 transmembrane spanning domain*** - The **Na+-K+-Cl- cotransporter (NKCC)**, specifically NKCC1 and NKCC2 isoforms, is a multipass transmembrane protein. - It is known to contain **12 transmembrane spanning domains**, which are α-helical regions that cross the cell membrane. *5 transmembrane spanning domain* - This number is **too low** for the complex structure of the NKCC cotransporter. - Proteins with 5 transmembrane domains typically have different functional roles and structural characteristics. *7 transmembrane spanning domain* - This number is characteristic of **G protein-coupled receptors (GPCRs)**, a distinct family of membrane proteins. - The NKCC cotransporter functions as an ion transporter and does not share the structural motif of GPCRs. *9 transmembrane spanning domain* - This number is also **insufficient** to describe the known topology of the NKCC cotransporter. - Ion transporters like NKCC generally require a higher number of transmembrane domains to form the necessary pore and binding sites.

Q: All should be features of a substance to measure GFR, except?

Freely reabsorbed. ***Freely reabsorbed*** - A substance used to measure GFR should **not be reabsorbed** by the kidney tubules. If it were reabsorbed, the amount excreted in the urine would be less than the amount filtered, leading to an **underestimation of GFR**. - The ideal GFR marker is **neither reabsorbed nor secreted**, ensuring that its excretion rate directly reflects the filtration rate. *Freely filtered across the glomerulus membrane* - For a substance to accurately measure GFR, it must be **freely filtered** from the blood into the Bowman's capsule, without any restriction due to its size or charge. - This ensures that its concentration in the glomerular filtrate is the same as in the plasma, allowing for a direct calculation of the filtration rate. *Not secreted by kidney* - An ideal GFR marker should **not be secreted** by the renal tubules, as active secretion would add to the amount excreted in the urine, leading to an **overestimation of GFR**. - This property, along with not being reabsorbed, ensures that the amount of the substance appearing in the urine solely reflects the amount filtered. *None of the options* - This option is incorrect because there is a definitive feature listed among the choices that is *not* a characteristic of an ideal GFR marker. The ability to be "freely reabsorbed" is a disqualifying trait.

Q: Mechanism of action of cholecystokinin?

Through IP3- DAG system. ***Through IP3- DAG system*** - Cholecystokinin (CCK) primarily acts via **Gq protein-coupled receptors**, leading to the activation of **phospholipase C**. - This activation results in the hydrolysis of **PIP2 into IP3 and DAG**, which then mediate intracellular signaling cascades, causing actions like gallbladder contraction and pancreatic enzyme secretion. *Activation of adenylyl cyclase* - This mechanism is typically associated with **Gs protein-coupled receptors**, leading to increased levels of **cyclic AMP (cAMP)**. - Hormones like **glucagon** and **epinephrine** often utilize this pathway, which is distinct from CCK's primary signaling. *Opening of ion channels* - While ion channels are crucial for many cellular processes, CCK's direct mechanism of action typically involves **intracellular second messengers** rather than direct gating of ion channels. - Neurotransmitters like **acetylcholine** can directly open ion channels, but this is not the main signaling pathway for CCK. *Transcription factors* - Transcription factors regulate **gene expression** by binding to DNA, which is a slower, more long-term cellular response. - While CCK can eventually influence gene expression, its direct and immediate effects (e.g., gallbladder contraction) are mediated by **rapid second messenger systems**, not primary transcription factor modulation.

Q: What is the air remaining in the lung after normal expiration?

Functional Residual Capacity (FRC). ***Functional Residual Capacity (FRC)*** - **FRC** represents the volume of air remaining in the lungs after a **normal expiration**. - It is the sum of the **expiratory reserve volume (ERV)** and the **residual volume (RV)**. *Tidal Volume (TV)* - **TV** is the volume of air inspired or expired with a **normal breath**. - It does not represent the total air remaining in the lungs after expiration. *Residual Volume (RV)* - **RV** is the volume of air remaining in the lungs after a **maximal expiration**. - It is a component of FRC but does not fully describe the air remaining after a *normal* expiration. *Vital Capacity (VC)* - **VC** is the maximum volume of air that can be exhaled after a **maximal inspiration**. - It represents the maximum amount of air that can be exchanged with a single breath, not the air remaining after normal expiration.

Question 1

Which nucleus is primarily involved in the Papez circuit?

Accepted Answer

Anterior nucleus of the thalamus

Answer

Pulvinar nucleus

Answer

Intralaminar nucleus

Answer

Ventral posterolateral (VPL) nucleus

Question 2

Which muscle is the deepest in the anterior neck region?

Accepted Answer

Longus colli

Answer

Sternocleidomastoid

Answer

Platysma

Answer

Trapezius

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 trace elements has vitamin E-like action?

Accepted Answer

Selenium

Answer

Iron

Answer

Copper

Answer

Zinc

Question 5

Which of the following cell types is classified as a labile cell?

Accepted Answer

Surface epithelium

Answer

Liver parenchymal cells

Answer

Vascular smooth muscle cells

Answer

Neurons

Question 6

What is the effect of moderate exercise on cerebral blood flow?

Accepted Answer

Increases

Answer

Decreases

Answer

Initially decreases then increases

Answer

Does not change

Question 7

How many transmembrane spanning domains does the Na+-K+-Cl- cotransporter contain?

Accepted Answer

12 transmembrane spanning domain

Answer

5 transmembrane spanning domain

Answer

7 transmembrane spanning domain

Answer

9 transmembrane spanning domain

Question 8

All should be features of a substance to measure GFR, except?

Accepted Answer

Freely reabsorbed

Answer

Not secreted by kidney

Answer

Freely filtered across the glomerulus membrane

Answer

None of the options

Question 9

Mechanism of action of cholecystokinin?

Accepted Answer

Through IP3- DAG system

Answer

Activation of adenylyl cyclase

Answer

Opening of ion channels

Answer

Transcription factors

Question 10

What is the air remaining in the lung after normal expiration?

Accepted Answer

Functional Residual Capacity (FRC)

Answer

Tidal Volume (TV)

Answer

Residual Volume (RV)

Answer

Vital Capacity (VC)

NEET-PG 2013

Anatomy

Biochemistry

Pathology

Physiology