General Physiology Practice Questions

Q: Mycophenolate mofetil is used in which of the following conditions?

Prevention of organ transplantation rejection. **Explanation:** **Mycophenolate Mofetil (MMF)** is a potent immunosuppressant widely used in clinical practice. Its mechanism of action involves the **reversible inhibition of Inosine Monophosphate Dehydrogenase (IMPDH)**. This enzyme is crucial for the *de novo* synthesis of guanosine nucleotides. Since T and B lymphocytes lack a salvage pathway for purine synthesis and rely solely on the *de novo* pathway, MMF selectively inhibits lymphocyte proliferation and functions, such as antibody formation and cellular adhesion. * **Option A (Correct):** Due to its selective action on lymphocytes, MMF is primarily used for the **prevention of acute and chronic organ transplant rejection** (kidney, heart, and liver). It is often used in combination with corticosteroids and calcineurin inhibitors (like Cyclosporine). * **Option B & C (Incorrect):** Tuberculosis and Leprosy are mycobacterial infections. These are treated with specific multidrug therapy (MDT) including Rifampicin, Isoniazid, and Dapsone. Immunosuppressants like MMF are contraindicated as they would worsen the infection. * **Option D (Incorrect):** Methanol poisoning is treated with Fomepizole (alcohol dehydrogenase inhibitor) or Ethanol, along with supportive care like hemodialysis. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits IMPDH (Inosine Monophosphate Dehydrogenase). * **Clinical Use:** Prophylaxis of transplant rejection and autoimmune diseases like Systemic Lupus Erythematosus (SLE) and Lupus Nephritis. * **Side Effects:** Primarily Gastrointestinal (diarrhea, vomiting) and Hematological (leukopenia, anemia). * **Teratogenicity:** It is associated with congenital malformations (Category D); hence, it must be avoided during pregnancy.

Q: What is the Nernst potential for Na+?

+61 mV. ### Explanation The **Nernst Potential** (Equilibrium Potential) is the membrane potential at which the electrical gradient exactly balances the chemical (concentration) gradient for a specific ion, resulting in no net movement of that ion across the membrane. **Why B is correct:** The Nernst potential is calculated using the Nernst equation: $E = \pm 61 \times \log(\text{Ion}_{\text{outside}} / \text{Ion}_{\text{inside}})$. For Sodium ($\text{Na}^+$), the extracellular concentration is high (~142 mEq/L) and the intracellular concentration is low (~14 mEq/L). Plugging these values into the formula: $E_{\text{Na}} = +61 \times \log(142 / 14) \approx +61 \text{ mV}$. The positive sign indicates that since $\text{Na}^+$ is more concentrated outside, the inside of the cell must be positive to electrically repel and prevent further $\text{Na}^+$ influx. **Analysis of Incorrect Options:** * **A (+94 mV):** This value does not correspond to a major physiological ion equilibrium potential in human neurons. * **C (-64 mV):** This is close to the typical **Resting Membrane Potential (RMP)** of a neuron (usually -70 mV to -90 mV), which is determined by multiple ions, primarily $\text{K}^+$ leakage. * **D (-94 mV):** This is the Nernst potential for **Potassium ($\text{K}^+$)**. Because $\text{K}^+$ is more concentrated inside, the cell interior must be negative to prevent $\text{K}^+$ efflux. **High-Yield Clinical Pearls for NEET-PG:** * **RMP vs. Nernst:** The RMP is closest to the Nernst potential of the ion to which the membrane is most permeable (Potassium). * **Goldman-Hodgkin-Katz Equation:** Unlike Nernst (single ion), this equation calculates RMP by considering the permeability and concentration of all major ions ($\text{Na}^+$, $\text{K}^+$, $\text{Cl}^-$). * **Action Potential:** During the depolarization phase, the membrane potential rapidly shifts toward the Nernst potential of $\text{Na}^+$ (+61 mV) but usually peaks at +35 to +45 mV.

Q: Residual bodies are related to which of the following cellular organelles?

Lysosomes. **Explanation:** The correct answer is **Lysosomes**. **Why Lysosomes?** Lysosomes are the "digestive system" of the cell, containing hydrolytic enzymes that break down macromolecules, damaged organelles (autophagy), and foreign substances (heterophagy). After the enzymatic digestion of these materials within a secondary lysosome (phagolysosome), some indigestible substances remain. The vesicle containing these undigested residues is termed a **Residual Body** (or tertiary lysosome). In many cells, these are eliminated via exocytosis, but in long-lived cells like neurons and cardiac muscles, they persist as **lipofuscin granules** (the "wear-and-tear" pigment). **Why other options are incorrect:** * **Mitochondria:** These are the "powerhouses" of the cell, primarily involved in ATP production via oxidative phosphorylation and apoptosis regulation. They do not form residual bodies. * **Nucleus:** This is the genetic control center containing DNA. While it undergoes changes during cell death (pyknosis, karyorrhexis), it is not involved in the lysosomal digestive pathway. * **Golgi Apparatus:** This organelle is responsible for packaging, modifying, and sorting proteins. While it is involved in the formation of *primary* lysosomes, it does not contain the undigested waste that characterizes residual bodies. **High-Yield NEET-PG Pearls:** * **Lipofuscin:** A brown-yellow pigment found in residual bodies; it is a hallmark of aging and free radical damage. * **Primary Lysosome:** A newly formed vesicle from the Golgi containing inactive enzymes. * **Secondary Lysosome:** Formed by the fusion of a primary lysosome with a phagosome/endosome; this is where active digestion occurs. * **Autophagy:** The process by which lysosomes digest the cell's own components, a key survival mechanism during starvation.

Q: The feed-forward mechanism is employed in the regulation of which of the following?

Temperature. ### Explanation **Correct Option: A (Temperature)** The **feed-forward mechanism** (also known as anticipatory control) is a regulatory process where the body initiates a response **before** a change in the internal environment actually occurs. It anticipates a disturbance based on sensory input from the external environment. In **temperature regulation**, peripheral thermoreceptors in the skin detect a drop in external temperature and signal the hypothalamus to initiate heat-conserving mechanisms (like shivering or vasoconstriction) *before* the core body temperature actually drops. This prevents a deviation from the set point rather than just reacting to it. **Why Incorrect Options are Wrong:** * **B, C, and D (pH, Blood Pressure, Blood Volume):** These parameters are primarily regulated by **negative feedback mechanisms**. In these systems, the body detects a deviation from the set point (e.g., a drop in BP detected by baroreceptors) and initiates a compensatory response to return the parameter to normal. These are reactive processes, not anticipatory. **High-Yield Clinical Pearls for NEET-PG:** * **Feed-forward Examples:** 1. **Cephalic phase of digestion:** Seeing or smelling food triggers insulin and gastric acid secretion before food reaches the stomach. 2. **Exercise:** Increased heart rate and ventilation occur at the onset of exercise (or even just before) due to cortical input, anticipating the metabolic demand. * **Negative Feedback:** The most common homeostatic mechanism (e.g., Thyroid hormone regulation, Glucose control). * **Positive Feedback:** Rare and leads to instability/climax (e.g., LH surge, Oxytocin in labor, Blood clotting cascade, Nerve action potential).

Q: Decreased basal metabolic rate is seen in which of the following conditions?

Obesity. **Explanation:** **Basal Metabolic Rate (BMR)** is the minimum energy expenditure required to maintain vital functions at rest. The correct answer is **Obesity** because BMR is primarily determined by **Lean Body Mass (LBM)**. In obese individuals, the ratio of adipose tissue to lean muscle is high. Since fat is metabolically less active than muscle, the overall BMR per unit of body weight is decreased compared to lean individuals. **Analysis of Options:** * **Hyperthyroidism (Incorrect):** Thyroid hormones ($T_3$ and $T_4$) are the primary regulators of BMR. In hyperthyroidism, increased $Na^+-K^+$ ATPase activity and cellular metabolism significantly **increase** BMR. * **Starvation (Incorrect):** While BMR does decrease during prolonged starvation as an adaptive mechanism to conserve energy, the question asks for a condition characterized by a lower baseline rate relative to body composition. (Note: In some contexts, starvation is a correct answer for decreased BMR, but in clinical physiology, the metabolic inefficiency of adipose tissue in obesity is a classic teaching point). * **Exercise (Incorrect):** Physical activity increases energy expenditure and oxygen consumption, leading to a significant **increase** in the metabolic rate above basal levels. **High-Yield Clinical Pearls for NEET-PG:** * **Surface Area Rule:** BMR is directly proportional to the surface area of the body. * **Age & Gender:** BMR is higher in children (due to growth) and males (due to higher testosterone and muscle mass). It declines with age. * **Specific Dynamic Action (SDA):** Protein has the highest SDA (30%), meaning it increases metabolic rate the most during digestion. * **Hormonal Influence:** Epinephrine and Testosterone increase BMR, while Hypothyroidism is the most common pathological cause of decreased BMR.

Q: With reference to human body's requirement for proteins, they are essential because they are: 1. an important alternative source for energy during specific metabolic states. 2. the primary molecules responsible for maintenance of osmotic pressure within the extracellular compartment. 3. critical for upkeep of cell mediated immune response. 4. vital for the synthesis of certain hormones. Which of the statements given above are correct?

1, 3 and 4. ***1, 3 and 4*** - Proteins act as an **alternative energy source** through **gluconeogenesis** during specific metabolic states like starvation, providing 4 kcal/g when glycogen and fat stores are insufficient. - They are essential for **cell-mediated immunity** as they constitute antibodies, cytokines, and MHC molecules; additionally, many hormones like **insulin** and **growth hormone** are peptide-based. *2, 3 and 4* - This option incorrectly includes statement 2; **Sodium (Na+)** and chloride are the primary determinants of osmotic pressure in the **extracellular fluid (ECF)**, not proteins. - Plasma proteins specifically maintain **oncotic pressure** within the vascular space, but they do not serve as the primary molecules for general ECF osmotic balance. *1, 2 and 3* - This combination incorrectly validates statement 2, which confuses **colloid osmotic pressure** (oncotic pressure) with the overall osmotic pressure regulated by electrolytes. - While it recognizes **gluconeogenesis** and **immune function**, it misses the critical role of proteins in the synthesis of **peptide hormones**. *1, 2 and 4* - Including statement 2 is incorrect because the high concentration of electrolytes in the interstitium makes them the dominant osmotic agents, whereas protein concentration there is relatively low. - This option fails to acknowledge that **T-cell function** and immune signaling proteins are strictly dependent on protein intake, making statement 3 vital.

Q: Which of the following options shows the correct sequence?

***This question cannot be answered without the accompanying image.*** The question asks to identify the correct sequence, with options showing different arrangements of items labeled 1, 2, 3, and 4. However, the image that should display these items is missing from the question data. **To complete this question, the following is required:** - The source image showing the physiological structures, processes, or events labeled as 1, 2, 3, and 4 - Once the image is available, the correct sequence can be determined - The explanation should then detail why the correct sequence is accurate based on physiological principles **Common NEET-PG sequence questions in General Physiology include:** - Steps in action potential generation - Stages of muscle contraction - Sequence of events in synaptic transmission - Steps in cellular transport mechanisms - Phases of cardiac cycle *This question requires image data to be valid and answerable.*

Question 1

Mycophenolate mofetil is used in which of the following conditions?

Accepted Answer

Prevention of organ transplantation rejection

Answer

Tuberculosis

Answer

Leprosy

Answer

Methanol poisoning

Question 2

What is the Nernst potential for Na+?

Accepted Answer

+61 mV

Answer

+94 mV

Answer

-64 mV

Answer

-94 mV

Question 3

Which of the following conditions is NOT characterized by caseous necrosis within a granuloma?

Accepted Answer

Tuberculosis

Answer

Leprosy

Answer

Cytomegalovirus (CMV) infection

Answer

Wegener's granulomatosis

Question 4

Residual bodies are related to which of the following cellular organelles?

Accepted Answer

Lysosomes

Answer

Mitochondria

Answer

Nucleus

Answer

Golgi apparatus

Question 5

The feed-forward mechanism is employed in the regulation of which of the following?

Accepted Answer

Temperature

Answer

pH

Answer

Blood pressure

Answer

Blood volume

Question 6

Decreased basal metabolic rate is seen in which of the following conditions?

Accepted Answer

Obesity

Answer

Hyperthyroidism

Answer

Starvation

Answer

Exercise

Question 7

Which of the following is an example of feed forward mechanism?

Accepted Answer

Temperature regulation

Answer

Vasoconstriction in response to cooling

Answer

Increase in cardiac output in response to anemia

Answer

HR increases from supine to standing

Question 8

With reference to human body's requirement for proteins, they are essential because they are:

1. an important alternative source for energy during specific metabolic states.
2. the primary molecules responsible for maintenance of osmotic pressure within the extracellular compartment.
3. critical for upkeep of cell mediated immune response.
4. vital for the synthesis of certain hormones.

Which of the statements given above are correct?

Accepted Answer

1, 3 and 4

Answer

2, 3 and 4

Answer

1, 2 and 3

Answer

1, 2 and 4

Question 9

Which of the following options shows the correct sequence?

Answer

$1 \rightarrow 2 \rightarrow 3 \rightarrow 4$

Answer

$2 \rightarrow 1 \rightarrow 3 \rightarrow 4$

Answer

$1 \rightarrow 3 \rightarrow 2 \rightarrow 4$

Answer

$3 \rightarrow 1 \rightarrow 2 \rightarrow 4$

Question 10

The countercurrent mechanism is present in which of the following parts of the body?
A. Eye
B. Testes
C. Kidney
D. Gut
E. Lungs

Accepted Answer

B and C are correct

Answer

A, B, C, D, E are correct

Answer

B, C, D, E are correct

Answer

A, B, C are correct

General Physiology — MCQs

General Physiology — MCQs

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