NEET-PG 2017 - Physiology PYQs Practice Questions

Q: Which of the following cells in the brain are responsible for handling information regarding ability to read the slide below? (Recent NEET Pattern 2016-17)

Parvocellular cells. ***Parvocellular cells*** - **Parvocellular cells** (P-cells) are responsible for processing detailed visual information, including **color**, **form**, and fine **texture**. Reading the Ishihara test requires the ability to distinguish specific colors and fine patterns. - They have **small receptive fields** and transmit information about high spatial resolution and chromatic detail, crucial for tasks such as reading and recognizing fine visual cues. *Magnocellular cells* - **Magnocellular cells** (M-cells) are primarily involved in detecting **motion** and processing **low-spatial frequency information**, such as global shape and location. - They have **large receptive fields** and are not primarily responsible for detailed color or pattern discrimination needed for reading. *Purkinje cells* - **Purkinje cells** are a type of large, extensively branched neuron located in the **cerebellar cortex**. - Their primary function is motor coordination, balance, and motor learning, not visual processing or reading. *Pyramidal cells* - **Pyramidal cells** are excitatory neurons found in the cerebral cortex and hippocampus, characterized by their pyramidal-shaped cell bodies. - While they are involved in complex cognitive functions, including parts of visual perception, they are not the specific cells in the primary visual pathway responsible for initial processing of fine details and color as required for reading this type of visual test. [Practice more Physiology PYQs on OnCourse]

Q: What is correct about the composition of fluid in the area marked as X?

Na = 3 mEq/L, K = 150 mEq/L, Chloride = 125 mEq/L. ***Na = 3 mEq/L, K = 150 mEq/L, Chloride = 125 mEq/L*** - The area marked as X points to the **endolymph** within the scala media of the cochlea, which has a unique high **potassium concentration** (~150 mEq/L) and low **sodium concentration** (~3 mEq/L). - This composition is maintained by the **stria vascularis** and is essential for proper **hair cell function** and hearing transduction. - The high K⁺/low Na⁺ ratio creates the **endocochlear potential** (+80 mV) necessary for cochlear amplification. *Na = 150 mEq/L, K = 3 mEq/L, Chloride = 125 mEq/L* - This represents typical **extracellular fluid** or **perilymph** composition with high sodium and low potassium, which is the opposite of endolymph. - The **perilymph** is found in the scala vestibuli and scala tympani, not in the area marked as X (scala media). *Na = 152 mEq/L, K = 30 mEq/L, Chloride = 125 mEq/L* - The sodium level is too high and potassium too low to represent **endolymph**, which requires an extreme K⁺/Na⁺ gradient for proper cochlear function. - These intermediate values don't match any specific **cochlear fluid compartment** and would not support normal hearing. *Na = 50 mEq/L, K = 30 mEq/L, Chloride = 125 mEq/L* - Both sodium and potassium levels are insufficient to create the **electrochemical gradient** necessary for cochlear hair cell depolarization. - These values don't correspond to either **endolymph** or **perilymph** compositions found in the inner ear. [Practice more Physiology PYQs on OnCourse]

Q: The image given below shows stapedial reflex. What does ' $X$ ' denote?

Superior olivary complex. ***Superior olivary complex*** - The image depicts the neural pathway for the **stapedial reflex**, where sound input from the cochlea is processed, and the signal travels to the superior olivary complex. - From the superior olivary complex (labeled 'X'), signals project to the **facial nerve nucleus**, which then innervates the **stapedius muscle** to contract and dampen sound. *Medial geniculate body* - The medial geniculate body is part of the **thalamus** and is involved in processing auditory information before it reaches the auditory cortex. - It is a more rostral structure in the auditory pathway and is not directly involved in the brainstem reflex arc of the stapedius reflex at the labeled point 'X'. *Superior colliculus* - The superior colliculus is primarily involved in **visual reflexes** and directing gaze towards salient stimuli. - Although it has some multimodal sensory integration, it is not a key relay in the auditory pathway for the stapedial reflex. *Lateral lemniscus* - The lateral lemniscus is an **ascending auditory pathway** in the brainstem, carrying information from the cochlear nuclei and superior olivary complex to higher centers like the inferior colliculus. - While it carries auditory signals, "X" represents a more specific processing center (superior olivary complex) that integrates bilateral auditory input and projects to motor nuclei for acoustic reflexes. [Practice more Physiology PYQs on OnCourse]

Q: Name the product marked as X in the image shown below:

Indolequinone. ***Indolequinone*** - The image depicts the **melanin biosynthesis pathway** starting from **tyrosine**. - Tyrosine is converted to **L-DOPA** by tyrosinase, which is then oxidized to **dopaquinone** (also called DOPA-quinone). - Dopaquinone undergoes intramolecular cyclization to form **leucodopachrome**, which is subsequently oxidized to **dopachrome**. - Dopachrome is then converted through a series of steps to **5,6-dihydroxyindole**, which is finally oxidized to **indole-5,6-quinone** (indolequinone). - **Indolequinone** is a key intermediate that polymerizes to form **melanin**, the pigment responsible for coloration in skin, hair, and eyes. - Based on the pathway shown, X represents indolequinone, an oxidized indole derivative in melanin synthesis. *Tetrabenazine* - **Tetrabenazine** is a pharmaceutical drug that inhibits **vesicular monoamine transporter 2 (VMAT2)**. - It is used therapeutically to treat hyperkinetic movement disorders such as **Huntington's disease** and tardive dyskinesia. - It is not a natural metabolic intermediate in the tyrosine-to-melanin biosynthetic pathway. *Homovanillic acid* - **Homovanillic acid (HVA)** is a major end metabolite of **dopamine** in the catecholamine degradation pathway. - It is formed by the sequential actions of **monoamine oxidase (MAO)** and **catechol-O-methyltransferase (COMT)** on dopamine. - This represents a completely different branch of tyrosine metabolism (catecholamine pathway), not the melanin synthesis pathway. *Kynurenine* - **Kynurenine** is an intermediate metabolite in the **kynurenine pathway**, which is the major route of **tryptophan** degradation. - The kynurenine pathway leads to the formation of NAD+ and various neuroactive metabolites. - This pathway is completely separate from tyrosine metabolism and is unrelated to the melanin synthesis pathway shown in the image. [Practice more Physiology PYQs on OnCourse]

Q: Which of the following will occur on efferent arteriolar constriction?

Increased GFR. ***Increased GFR*** - **Efferent arteriolar constriction** increases resistance to blood flow out of the glomerulus, causing blood to 'back up' and increase the **glomerular hydrostatic pressure (PGC)** - Higher **glomerular hydrostatic pressure** leads to increased net filtration pressure, which directly results in **increased glomerular filtration rate (GFR)** - This is the **primary and most clinically significant effect** of efferent arteriolar constriction - The increased PGC helps maintain GFR even when renal blood flow decreases slightly *Decreased GFR* - This is incorrect because **efferent arteriolar constriction** increases glomerular hydrostatic pressure, thereby **increasing GFR**, not decreasing it - Only severe efferent constriction that critically reduces renal plasma flow would eventually decrease GFR - The immediate and primary effect is always an increase in GFR *Increase flow in vasa recta* - This is incorrect; **efferent arteriolar constriction** actually **decreases** flow to the vasa recta - The constriction reduces blood flow exiting the glomerulus, which means less blood reaches the downstream peritubular capillaries and vasa recta - This decreased perfusion of the vasa recta can enhance urine concentration by reducing washout of the medullary concentration gradient *Decreased flow in vasa recta* - While this is physiologically true (efferent constriction does reduce peritubular and vasa recta blood flow), it is **not the primary or most significant effect** being tested - In the context of efferent arteriolar constriction, the **increased GFR** is the dominant and most clinically relevant consequence - The question asks "which will occur" expecting the primary hemodynamic effect on glomerular function - Decreased vasa recta flow is a secondary consequence, whereas increased GFR is the direct and immediate result [Practice more Physiology PYQs on OnCourse]

Question 1

Which of the following cells in the brain are responsible for handling information regarding ability to read the slide below? (Recent NEET Pattern 2016-17)

Accepted Answer

Parvocellular cells

Answer

Magnocellular cells

Answer

Purkinje cells

Answer

Pyramidal cells

Question 2

What is correct about the composition of fluid in the area marked as X?

Accepted Answer

Na = 3 mEq/L, K = 150 mEq/L, Chloride = 125 mEq/L

Answer

Na = 150 mEq/L, K = 3 mEq/L, Chloride = 125 mEq/L

Answer

Na = 152 mEq/L, K = 30 mEq/L, Chloride = 125 mEq/L

Answer

Na = 50 mEq/L, K = 30 mEq/L, Chloride = 125 mEq/L

Question 3

The image given below shows stapedial reflex. What does ' $X$ ' denote?

Accepted Answer

Superior olivary complex

Answer

Medial geniculate body

Answer

Superior colliculus

Answer

Lateral lemniscus

Question 4

Name the product marked as X in the image shown below:

Accepted Answer

Indolequinone

Answer

Tetrabenazine

Answer

Homovanillic acid

Answer

Kynurenine

Question 5

Which of the following will occur on efferent arteriolar constriction?

Accepted Answer

Increased GFR

Answer

Decreased GFR

Answer

Increase flow in vasa recta

Answer

Decreased flow in vasa recta

Question 6

The A wave in His bundle electrogram shows presence of:

Accepted Answer

Atrial depolarization

Answer

Atrial repolarization

Answer

AV node activation

Answer

Atrial depolarization to AV node activation

Question 7

Which of the following is correct about the pressure volume loop of left ventricle?

Accepted Answer

Aortic valve opens at 2

Answer

1 to 2 indicates isovolumetric relaxation

Answer

2 to 3 indicates ventricular diastole

Answer

Pulmonic valve opens at 3

Question 8

Which of the following is correct about the point marked $Z$ on the cardiac cycle?

Accepted Answer

Aortic valve opens

Answer

Mitral valve opens

Answer

Tricuspid valve opens

Answer

Mid systolic click

Question 9

The pressure-volume loop of left ventricle tracing of the patient indicates:

Accepted Answer

Diastolic dysfunction

Answer

Systolic dysfunction

Answer

Decreased atrial compliance

Answer

Increased atrial compliance

Question 10

Which of the following dissociation curve mentioned is for myoglobin?

Accepted Answer

Green

Answer

Purple

Answer

Red

Answer

None

NEET-PG 2017 — Physiology