INI-CET High Yield Questions for Physiology

Mastering the INI-CET demands a strategic approach to preparation, with an emphasis on high-yield topics proving to be a successful tactic. This blog zeroes in on exactly that – a curated list of high-yield questions in Physiology that are highly likely to appear on the INI-CET. By acquainting yourself with these questions and their detailed explanations, you'll deepen your understanding of Physiology concepts, enhancing your confidence and readiness for exam day.

Q.1. The rate of movement of molecules across the membranes changes by concentrations of molecules in both intracellular and extracellular fluids. The following graphs are plotted using the results of a study. Which among the following best relates to the kinetics of Trace B?

1. Transport of Ca⁺⁺ into the sarcoplasmic reticulum of a smooth muscle cell
2. Transport of K⁺ into a muscle cell
3. Transport of Na⁺ out of a nerve cell
4. Transport of O₂ across an artificial lipid bilayer

Correct Option D - Transport of O₂ across an artificial lipid bilayer:

• Transport of O2 across an artificial lipid bilayer best relates to the kinetics of Trace B. This trace represents a process that is not limited by an intrinsic maximum velocity (Vmax), indicating simple diffusion. The rate of movement increases with increasing oxygen concentration, and there is no plateau observed, which is characteristic of simple passive diffusion across a lipid bilayer. This process does not require energy and does not involve carrier molecules, aligning with the movement of oxygen across an artificial lipid bilayer.

Incorrect Options:

• Options A, B, and C involve processes that are either mediated by carrier proteins (facilitated diffusion) or require energy (active transport), which are not consistent with the kinetics observed in Trace B.

2. The image below illustrates the contraction of the cardiac muscle. Which protein should fill in the question mark?

1. RyR1
2. RyR2
3. RyR3
4. None of the above

Correct Option B - RyR2:

• In cardiac muscle, ryanodine receptor type 2 (RyR2) is the primary isoform involved in releasing calcium ions from the sarcoplasmic reticulum during excitation-contraction coupling.
• This release of calcium triggers the contraction of cardiac muscle fibers.

Incorrect Options:

Option A – RyR1: The RyR1 receptor is primarily found in skeletal muscle, not cardiac muscle. It is the ryanodine receptor subtype that responds to the voltage change sensed by the DHPR in the skeletal muscle to release calcium from the sarcoplasmic reticulum

Option C – RyR3: RyR3 receptors are expressed in a variety of tissues but are not the primary ryanodine receptors mediating calcium release for cardiac muscle contraction. Their role is more supplemental and not as well-defined as RyR1 in skeletal muscle and RyR2 in cardiac muscle.

Option D – None of the above: Ryanodine receptor type 2 (RyR2) is the primary isoform involved in releasing calcium ions from the sarcoplasmic reticulum during excitation-contraction coupling

3. What is the positive wave in an ECG that appears after the wave representing atrial depolarization?

1. Q wave
2. R wave
3. T wave
4. S wave

Correct Option B - R wave:

• The R wave is the first positive deflection within the ECG after the P wave(atrial depolarization). It represents the depolarization of the ventricles.

Incorrect Options:

Option A - Q wave: The Q wave is the first negative deflection after the P wave. It indicates septal depolarization.

Option C - T wave: The T wave represents the repolarization of both the right and left ventricles.

Option D - S wave: The S wave represents depolarization of the base of ventricles.

4. A 60-year-old man is admitted to the intensive care unit observation after undergoing a coronary artery bypass grafting. His heart rate is 70 bpm. Respiratory rate is 20/ min, and blood pressure is 140/ 65 mm Hg. His arterial oxygen content is 200ml/ litre of blood, and the venous oxygen content is 150ml/ litre of blood. The cardiac output of this ventricle is closest to whichone of the following?

1. 4.55 L/min
2. 5.25 L/min
3. 8.00 L/min
4. 9.85 L/min

Correct option B: 5.25L/min

• Stroke volume = EDV-ESV

                          = 140-65

                          = 75 mL

• Cardiac output = SV x HR

                        = 75 mL × 70 beats /min

                        = 5250 mL/min

                        = 5.25 L/min.

Incorrect options

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

5. The following graph shows a relationship between lung volume and intrapleural pressure changes during inspiration & expiration. What is the most likely cause of different behaviour of inspiratory and expiratory curve?

A.Difference in active and passive work during respiration

B. Difference in surfactant during inspiration and expiration

C. Difference in airway resistance during inspiration and expiration

D. Difference in intrapleural pressure

Correct Option B - Difference in surfactant during inspiration and expiration

• During inspiration, alveoli are small, and surfactant concentration is high, leading to decreased surface tension and increased lung compliance. This results in a steep increase in volume with a small change in pressure.
• Conversely, during expiration, alveoli are large, the surfactant is scattered, and surface tension is comparatively higher, leading to decreased lung compliance. This results in a less significant change in volume despite a greater change in pressure, reflected by a straighter graph.

Incorrect Options:

Option A - Difference in active and passive work during respiration:

• Inspiration occurs due to the diaphragm mainly. However, expiration is a passive process. It does not affect the relationship between the change in volume and intrapleural pressure during inspiration and expiration.

Option C - Difference in airway resistance during inspiration and expiration:

• The difference in change in the volume of lungs between inspiration and expiration is due to the surfactant, not airway resistance.

Option D - Difference in intrapleural pressure:

• Intrapleural pressure is negative all the time. During inspiration, it becomes more negative and causes expansion of the lungs. However, the graph following a different curve during inspiration and expiration is due to a change in surfactant.

Also Read: INI-CET Previous Year Question Papers

6. A 28-year-old patient presents to the clinic with complaints of dull, aching pain in the flanks. Ultrasound KUB was performed, and a diagnosis of a kidney stone was made. The patient gave a history of familial hypomagnesemia. Which of the following is responsible for the patient’s condition?

1. Mutation at the level of NKCC
2. Mutation at Claudin 16 gene
3. Mutation at the level of ROMK channel
4. Mutation at the level of Chloridechannel Kb (ClC-kb) channel

Correct Option B – Mutation at Claudin 16 gene:

• Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is often caused by mutations in the Claudin 16 gene, which encodes the paracellin 1 protein. Paracellin 1 is essential for the reabsorption of magnesium in the thick ascending limb of the loop of Henle. Mutations in this gene result in dysfunctional tight junctions, leading to impaired magnesium and calcium reabsorption. This dysfunction increases the risk of kidney stone formation (nephrocalcinosis).

Incorrect Options:

Option A - Mutation at the level of NKCC: Mutations in the Na+-K+-2Cl- cotransporter (NKCC) primarily affect sodium, potassium, and chloride handling and are not directly linked to familial hypomagnesemia.

Option C - Mutation at the level of ROMK channel: Mutations in the ROMK channel result in disorders of potassium handling, such as Bartter syndrome, rather than isolated hypomagnesemia.

Option D - Mutation at the level of ClC-kb channel: Mutations in the ClC-kb chloride channel are associated with Bartter syndrome type 3, characterized by salt wasting and hypokalemic alkalosis, not directly with familial hypomagnesemia.

7. What is the term for the property of a synapse where the simultaneous stimulation of neurons A and B results in a net effect greater than the sum of their excitations?

1. Subliminal fringe
2. Temporal summation
3. Post-tetanic potentiation
4. Convergence-facilitation

Correct Option A - Subliminal fringe:

• Subliminal fringe refers to the property of a synapse where the simultaneous stimulation of neurons A and B results in a net effect greater than the sum of their excitations. It occurs when the subthreshold excitations from individual neurons summate to reach the threshold for generating an action potential.

Incorrect Options:

Option B - Temporal summation:

• Temporal summation occurs when a high frequency of action potentials in the presynaptic neuron causes postsynaptic potentials that summate with each other.

Option C - Post-tetanic potentiation:

• Post-tetanic potentiation (PTP) is an increase in the release of neurotransmitters following a short, high-frequency series of action potentials.

Option D - Convergence-facilitation:

• Convergence refers to merging signals from multiple presynaptic inputs to excite a single postsynaptic neuron.

8. Which of the following hormones is correctly represented by the graph below?

1. Insulin
2. Cortisol
3. Growth hormone
4. Thyroid

Correct Option C - Growth hormone:

• GH secretion occurs in a pulsatile pattern, characterized by fluctuations in secretion levels.

Stimulate Growth Hormone Secretion	Inhibit Growth Hormone Secretion
Decreased blood glucose level Decreased blood free fatty acid levels Increased blood amino acid levels (arginine) Starvation or fasting, protein deficiency Trauma, stress, excitement Exercise Testosterone, estrogen Deep sleep (stages 2 and 4 ) Growth hormone-releasing hormone Ghrelin	Increased blood glucose level Increased blood free fatty acid levels Aging Obesity Growth hormone inhibitory hormone (somatostatin) Growth hormone (exogenous) Insulin-like growth factors (somatomedins)

Incorrect Options:

Option A - Insulin:

• Insulin secretion peaks after meals, followed by a rapid decline in plasma levels. It circulates mainly in an unbound form with a short plasma half-life of about 6 minutes, cleared within 10 to 15 minutes.

Option B - Cortisol:

• Cortisol secretion is stimulated by ACTH. Levels of corticotrophin-releasing hormone, ACTH, and cortisol are high in the early morning and low in the late evening. Plasma cortisol levels peak around 20 μg/dl before arising in the morning and decrease to about 5 μg/dl around midnight due to cyclical signals from the hypothalamus.

Option D - Thyroid:

• TSH and TRH regulate thyroid hormone secretion. TSH levels are low during the day and increase at night, controlling the release of thyroid hormones. Thyroid hormone secretion doesn't follow a pulsatile pattern and doesn't acutely change in response to heavy exercise.

9. A 55-year-old male smoker presents to the emergency department with acute shortness of breath. On examination, prolonged expiration and bilateral wheezing are observed, suggesting an acute emphysema exacerbation. Which change in pulmonary function is unlikely to be seen in this patient?

A.Increased total lung capacity

B.Increased residual volume

C,Increased FEV₁

D,Increased Δ V/Δ P

Correct Option C - Increased FEV₁:

• FEV₁ is decreased in emphysema. It is a form of COPD.
• In emphysema, the air sacs (alveoli) in the lungs become damaged and lose elasticity. This loss of elasticity leads to air trapping in the lungs, making it difficult to fully exhale. As a result, the forced expiratory volume in one second (FEV1) is reduced because the lungs cannot expel air as efficiently, leading to decreased lung function and impaired airflow

Incorrect Options:

Option A - Increased Total Lung Capacity

• Incorrect. Emphysema leads to loss of elastic recoil, causing hyperinflation of the lungs and increased TLC.

Option B - Increased residual volume

• Incorrect. Damage to elastic proteins in emphysema reduces elastic recoil, trapping air during expiration and raising RV.

Option D - Increased Δ V/Δ P

• Incorrect. Emphysema's loss of lung elasticity raises compliance, making lungs more distensible and contributing to hyperinflation. However, this doesn't directly increase the ratio of change in volume to change in pressure (Δ V/Δ P).

10. A 50-year-old patient presents with complaints of severe headache, dyspnea, hemoptysis, and shortness of breath for the last two months. His reports are suggestive of right to left heart shunt. Oxygen content on the arterial and venous sides are 18 and 14 ml/100 ml, respectively. Oxygen content in the pulmonary capillary is 20 ml/100 ml. What would be the percentage shunting of cardiac output in this patient?

A.23%

B. 33%

C. 43%

D.53%

Correct option B: 33%

• The complaints of severe headache, dyspnea, hemoptysis, shortness of breath, and a history of hypertension point toward a right to left shunt. This can be due to pulmonary hypertension.
• The formula is given below:

• In the given condition, O₂ content:
  • Arterial → 18 ml.
  • Venous → 14 ml.
• Shunting refers to the abnormal movement of blood from one part of the circulatory system to another, bypassing the usual pathways of blood flow. With respect to intrapulmonary shunting, blood passes through areas of the lung that are poorly ventilated or not ventilated at all, leading to insufficient oxygenation. This can happen in conditions like pneumonia, atelectasis, or pulmonary edema
  • Normal O₂ content.
    • Arterial → 20ml.
    • Venous → 14 ml.
    • The arteriovenous difference is  6 ml
• Arteriovenous difference → 4 ml:
  • 1/3 of the normal is reduced in the given shunting.
  • So, 33% (option-2) will be reduced or 2 ml.

Incorrect options

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

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