NEET PG High Yield Questions for Physiology

To do well in the NEET PG exam, you need a smart study plan focusing on important topics. This blog provides a list of key questions in Physiology that are likely to be on the exam. By studying these questions and their explanations, you'll improve your understanding of Physiology concepts and feel more prepared and confident for the exam.

1. Examine the graph representing voltage over time, where each point on the graph has the capacity to generate an action potential. Based on the graph, what is the chronaxie of the neuron?

A. 8 ms

B. 3 ms

C. 4 ms

D. 2 ms

Correct Option B – 3 ms:

• In the case of this particular nerve, the rheobase is 6 mV, and the chronaxie can be determined by finding the time at which the stimulus is double the rheobase or 12 mV. This time is approximately 3 ms.

Incorrect Options:

Option A – 8 ms: This option suggests a longer duration for the chronaxie, this duration represents the utilization time of the nerve. Chronaxie is the duration of the minimal stimulus required to evoke an action potential at twice the rheobase which is 3 ms.

Option C – 4 ms: This option suggests a slightly longer duration than the assumed correct answer.

Option D – 2ms: This option suggests a shorter duration than the assumed correct answer.

2. A 40-year-old man with hypertension and type 2 diabetes mellitus is admitted to the hospital for evaluation of breathlessness and fatigue. On checking his vitals HR = 92/min, BP = 110/70 mm Hg. The further evaluation shows sinus tachycardia on ECG. The echocardiography of this patient shows that the end-systolic volume is 40 ml. What would the physiological HR_max of this person be?

A. 160 bpm

B. 180 bpm

C. 200 bpm

D. 220 bpm

Correct Option B - 180 bpm:

• The patient presented in this case is hypertensive and diabetic and has breathlessness and tachycardia, whose ESV is 40ml, and HRmax has to be measured.
• HR_max = (220 – age in years)
  •  = (220 – 40 years)
  •  = 180 bpm

Incorrect Options:

• Options A, C, and D: Refers to the option B explanation.

3. What will be the free water clearance of a patient whose urine output is 3000 ml per day, urine osmolality is 400 mOsm/L, and plasma concentration is 300 mOsm/L?

A. Positive

B. Negative

C. Zero

D. None of the above

Correct Option B – Negative:

• To measure the free water clearance, the formula used is:

• Substituting the values in the above-given formula:

• The free water clearance will be – 0.99. Hence, the value is negative, suggesting the urine to be hypertonic.
• Another method to measure the free water clearance is the Ratio of U/P.
• Substituting the values from the question:
• U/P = 400/300 = 1.33, which is more than 1, suggesting the free water clearance to be negative.

Incorrect Options:

Options A, C, and D are incorrect. Refer to option B for the explanation.

4. A 17-year-old boy presents with an itchy rash on his hands for 1 week due to excessive hand washing. He is upset about the ongoing pandemic and feels like everything is dirty. Which chemical substance does not belong to the same group of neurotransmitters responsible for this boy's underlying pathology?

A. Glutamate

B. GABA

C. Dopamine

D. Orexins

Correct Option D - Orexins:

• The boy presents with obsessive-compulsive disorder (OCD). This condition is associated with abnormalities in serotonin neurotransmission. Serotonin is a low molecular weight, rapidly acting neurotransmitter implicated in mood regulation and compulsive behaviors, making it the underlying pathology.
• Orexins are neuropeptides, large and slow-acting neurotransmitters, distinct from serotonin, glutamate, GABA, and dopamine, which are small molecule neurotransmitters. Therefore, orexins do not belong to the same group as the neurotransmitters responsible for the boy's pathology.

Incorrect Options

Option A: Glutamate, Option B: GABA, and Option C: Dopamine are all low molecular weight neurotransmitters like serotonin, involved in various brain functions.

5. Suppose the crystalline lens is a dynamic focusing element that accounts for approximately one-third of the dioptric power of the relaxed eye. What would be the contribution of a crystalline lens to the total dioptric power of the eye?

A. 41 D

B. 18 D

C. 59 D

D. 72 D

Correct Option B - 18 D:

• The primary function of the lens in the eye is to transmit the light and focus it on the retina.
• The power of a lens is inversely proportional to the focal length. So, the power of the lens is 1 divided by the focal length in meters.
• The diopter is the unit to measure the refractive index of the lens.
• The cornea accounts for most refraction in the eye.
• The dioptric power of the crystalline lens is +18 D.
• The total refractive power of the entire eye is +59 D; ⅓ of 59D amounts to approximately +18D.
• Most of the refraction occurs at the anterior surface of the cornea (41 D).

Incorrect Options:

• Options A, C and D: Refer to the explanation option B.

Also Read: NEET PG Previous Year Question Papers of Last 6 Years

6. A 16-year-old male presents to the clinic with a fever, headache, and sore throat. The physician diagnoses him with pharyngitis. During an infection, the set point of the hypothalamic temperature controller is set above normal. The diagram shows the effects of changing the set point of the hypothalamic temperature controller. Which of the following changes occurs at point W compared to point V?

A. Shivering and vasoconstriction

B. Shivering and vasodilation

C. Sweating and vasodilation

D. Sweating and vasoconstriction

Correct Option A - Shivering and vasoconstriction:

• When the set point of the hypothalamic temperature control center is raised above normal during an infection, it triggers shivering and vasoconstriction.
• Shivering generates heat by increasing muscle activity, while vasoconstriction reduces blood flow to the skin, minimizing heat loss to the environment.
• These responses help raise the body's temperature back to the elevated set point.

Incorrect Options:

Option B - Shivering and vasodilation:

• Vasodilation, which involves widening of blood vessels to increase blood flow to the skin and dissipate heat, is not characteristic of a response to an elevated set point during infection.

Option C - Sweating and vasodilation:

• Sweating and vasodilation, which are mechanisms to dissipate heat, are not typically activated when the hypothalamic set point is increased during infection.

Option D - Sweating and vasoconstriction:

• While vasoconstriction may occur to conserve heat, sweating, which helps dissipate heat, is not typically part of the response to an elevated set point during infection.

7. In repeated muscle stimulations, the second contraction is larger than the first stimulus, as shown in the image, also known as the "beneficial effect." What primarily causes this effect?

A. Increased calcium

B. Reduced oxygen

C. Increased ATP

D. Increased neurotransmitter release

Correct Option A - Increased calcium:

• The "beneficial effect" observed in repeated muscle stimulations, where the second contraction is larger than the first, is primarily caused by increased calcium concentration in the cell cytoplasm of skeletal muscle. This occurs because some calcium is already released from the sarcoplasmic reticulum after the first stimulus, and mopping up this calcium back into the sarcoplasmic reticulum takes some time.
• Therefore, when a second stimulus is given, further calcium is released into the cytoplasm by this time, resulting in a larger contraction.

Incorrect Options:

Option B - Reduced oxygen: Reduced oxygen levels may affect muscle function and performance, but the "beneficial effect" is not primarily caused by changes in oxygen levels.

Option C - Increased ATP: While ATP is essential for muscle contraction, and increased ATP availability can enhance muscle function, the "beneficial effect" is more directly related to calcium dynamics.

Option D - Increased neurotransmitter release: Increased neurotransmitter release can affect muscle excitability and responsiveness, but it is not the primary cause of the "beneficial effect," which is primarily attributed to calcium handling.

8. A patient is diagnosed with an autosomal-dominant disease affecting a channel in the collecting duct characterized by increased reabsorption of sodium and water, resulting in hypertension, metabolic alkalosis, and hypokalemia. Which of the following drugs will be helpful for this patient?

A. Furosemide

B. Thiazide

C. Amiloride

D. None of the above

Correct Option C – Amiloride:

• Liddle Syndrome, characterized by increased reabsorption of sodium and water in the collecting duct, is treated with amiloride, a potassium-sparing diuretic that directly blocks ENaC in the collecting duct.

Incorrect Options:

Option A, B & D are incorrect.

• Other options such as furosemide and thiazide are not suitable for treating Liddle Syndrome as they act on different parts of the nephron and may exacerbate hypokalemia.

9. A 50-year-old male with a history of ischemic heart disease presents to the emergency with left-sided chest pain, low blood pressure, and dyspnea for the last 1 hour. His O2 concentrations of mixed venous and arterial blood are 16 and 20 ml/min, respectively. The O2 consumption is 300 ml/min. According to Fick’s principle, what is cardiac output in liters/min?

A. 5

B. 8

C. 9

D. 7.5

Correct Option D - 7.5:

• The formula for cardiac output is :

CO = cardiac output 

VO₂ = oxygen consumption in ml of pure gaseous oxygen per minute 

C_a = oxygen content of arterial blood

C_v = oxygen content of mixed venous blood

• Given values are:
  • Oxygen consumption → 300 ml/min.
  • Arterial O2 → 20 ml.
  • Venous O2 → 16 ml.
• Cardiac output, in this case, after putting the values in the formula, is 7.5 liters/min.
• The patient is a known case of ischemic heart disease. Based on the symptoms of left-sided chest pain, low blood pressure, and dyspnea, he is most likely suffering from myocardial infarction.

Incorrect Options:

• Options A, B, and C: Refers to option D explanation.

10. A patient undergoing general anesthesia suddenly develops a rapid and dangerously high body temperature, along with muscle rigidity and metabolic acidosis. In this clinical context, which mutation is most likely responsible for the manifestation of this condition?

A. CaV1.1

B. RyR1

C. CaV1.2

D. RyR2

Correct Option B – RyR1:

• In the context of a patient developing rapid hyperthermia, muscle rigidity, and metabolic acidosis during general anesthesia, the most likely responsible mutation is in the RyR1 gene, leading to malignant hyperthermia.
• This condition is characterized by dysregulated calcium release from the sarcoplasmic reticulum, resulting in excessive muscle contraction and metabolic activity. Treatment involves the immediate administration of dantrolene sodium to reduce calcium release.

Incorrect Options:

Option A, C, and D: Mutations in CaV1.1, CaV1.2, and RyR2 are not typically associated with malignant hyperthermia. These proteins are primarily linked to other conditions, such as periodic paralysis (CaV1.1) and cardiac disorders (CaV1.2 and RyR2).

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