INI-CET 2022 - Physiology PYQs Practice Questions

Q: Which physiological adaptation does not happen at high altitudes?

Respiratory acidosis. ***Respiratory acidosis*** - At high altitudes, the primary physiological response to **hypoxia** is to increase ventilation, leading to a decrease in **arterial PCO2**. - This reduction in **PCO2** causes **respiratory alkalosis**, not acidosis, as the body tries to compensate for the lower oxygen levels. *Pulmonary vasoconstriction* - This is a significant physiological response to **hypoxia** at high altitudes, leading to an increase in **pulmonary artery pressure**. - Its purpose is to divert blood flow to better-ventilated areas of the lung, but it can also contribute to **pulmonary hypertension**. *Hypoxia* - Reduced **atmospheric pressure** at high altitudes directly results in a lower partial pressure of oxygen (**PO2**), leading to **hypoxia**. - This low **PO2** is the primary trigger for most other physiological adaptations seen at high altitudes. *Polycythemia* - Prolonged exposure to **hypoxia** stimulates the kidneys to release **erythropoietin (EPO)**, which in turn increases **red blood cell production**. - This adaptive increase in **red blood cell count** and **hemoglobin concentration** aims to enhance the oxygen-carrying capacity of the blood. [Practice more Physiology PYQs on OnCourse]

Q: What does zero pressure indicate in the pressure-volume curve?

Functional residual capacity. ***Functional residual capacity*** - This is the lung volume at which the **elastic recoil of the lungs** exactly balances the **elastic recoil of the chest wall**, resulting in zero net pressure across the respiratory system. - At **functional residual capacity (FRC)**, there is no airflow, and the **alveolar pressure equals atmospheric pressure (zero)**, indicating the equilibrium point. - Note: The **transpulmonary pressure remains positive** at FRC (approximately +5 cm H₂O), which keeps the lungs inflated against their elastic recoil. *Inspiratory reserve volume* - This is the **extra volume of air** that can be forcibly inhaled after a normal inspiration. - It involves active inspiration and therefore is associated with a **negative intrathoracic pressure**, not zero pressure. *Tidal volume* - This is the **volume of air inhaled and exhaled** during a normal quiet breathing cycle. - While breathing, pressures fluctuate, and the respiratory system is not at an equilibrium point of **zero pressure** throughout the tidal breath. *Residual volume* - This is the **volume of air remaining in the lungs** after a maximal exhalation. - The chest wall's outward recoil is greater than the lung's inward recoil at this point, resulting in a **negative intrapleural pressure** to keep the lungs from collapsing. [Practice more Physiology PYQs on OnCourse]

Q: The graph below shows oxygen dissociation curves. What does the curve marked as 'A' indicate?

Myoglobin. ***Myoglobin*** - Curve A shows a **hyperbolic oxygen dissociation curve** which is characteristic of myoglobin, indicating high oxygen affinity even at low partial pressures. - Myoglobin has only one heme group, allowing it to bind a single oxygen molecule with high affinity to **store oxygen in muscles**. *Methemoglobin* - Methemoglobin has a **ferric (Fe3+) iron** in its heme group, which cannot bind oxygen, thus reducing the overall oxygen-carrying capacity. - It would typically cause a **left shift** of the remaining functional hemoglobin's dissociation curve due to increased oxygen affinity, but this isn't directly represented as curve A's primary characteristic. *Carboxyhemoglobinemia* - **Carbon monoxide (CO)** binds to hemoglobin with a much higher affinity than oxygen, forming carboxyhemoglobin. - This binding leads to a **left shift** in the oxygen dissociation curve of the remaining functional hemoglobin and a decreased oxygen-carrying capacity, but curve A represents a species with inherently higher oxygen affinity. *Fetal hemoglobin* - Fetal hemoglobin (HbF) has a **higher affinity for oxygen** than adult hemoglobin (HbA), which is represented by a **left-shifted sigmoidal curve** compared to adult hemoglobin. - While it has higher affinity, its curve is still **sigmoidal**, unlike the hyperbolic curve of myoglobin (A). [Practice more Physiology PYQs on OnCourse]

Q: What is the ratio of T cells to B cells in a healthy adult?

3:1. ***3:1*** - In healthy adults, a typical peripheral blood sample shows a **predominance of T cells** over B cells. - This ratio reflects the differing roles and distributions of these lymphocytes; **T cells are more numerous** in circulation. *1:3* - This ratio would indicate **more B cells than T cells**, which is not typical for peripheral blood in a healthy individual. - An inversion of the usual T:B cell ratio could suggest certain disease states, such as specific **lymphoid malignancies**. *1:1* - While possible in some specific lymphoid tissues, a **1:1 ratio is not the standard** for circulating T and B cells in healthy adults. - This ratio would represent a **significantly higher proportion of B cells** than usually found in peripheral blood. *1:2* - This ratio implies **twice as many B cells as T cells**, which is significantly skewed compared to normal physiological levels in peripheral blood. - Such a high proportion of B cells is typically observed in states of **B-cell proliferation** or specific immune dysregulation. [Practice more Physiology PYQs on OnCourse]

Question 1

Which physiological adaptation does not happen at high altitudes?

Accepted Answer

Respiratory acidosis

Answer

Pulmonary vasoconstriction

Answer

Hypoxia

Answer

Polycythemia

Question 2

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

Question 3

What does zero pressure indicate in the pressure-volume curve?

Accepted Answer

Functional residual capacity

Answer

Inspiratory reserve volume

Answer

Tidal volume

Answer

Residual volume

Question 4

The graph below shows oxygen dissociation curves. What does the curve marked as 'A' indicate?

Accepted Answer

Myoglobin

Answer

Methemoglobin

Answer

Carboxyhemoglobinemia

Answer

Fetal hemoglobin

Question 5

What is the ratio of T cells to B cells in a healthy adult?

Accepted Answer

3:1

Answer

1:3

Answer

1:1

Answer

1:2

Question 6

During polysomnography, which stage of sleep is represented by the marked areas when observing the following wave patterns?

EOG (Electrooculography)
EEG (Electroencephalography)
EMG (Electromyography)

Accepted Answer

NREM I sleep

Answer

REM sleep

Answer

NREM II sleep

Answer

NREM III sleep

Question 7

Which among the following organs has the least arteriovenous oxygen difference?

Accepted Answer

Kidney

Answer

Liver

Answer

Skin

Answer

Brain

Question 8

Which of the following is the primary tissue dependent on insulin for glucose uptake?

Accepted Answer

Muscle

Answer

Adipose tissue

Answer

Brain

Answer

Pancreas

Question 9

What is the normal insensible water loss?

Accepted Answer

50 mL/hour

Answer

150 mL/hour

Answer

200 mL/hour

Answer

100 mL/hour

Question 10

A woman must vomit whenever she eats spicy food. Arrange the sequence of events during vomiting.

1. LES is open and UES is closed
2. Strong contractions in the stomach
3. Inspiration against a closed glottis
4. Relaxation of the pyloric sphincter
5. LES opens and UES opens
6. Reverse peristalsis in the small intestine

LES: Lower esophageal sphincter
UES: Upper esophageal sphincter

Accepted Answer

6,4,2,3,1,5

Answer

4,6,2,1,3,5

Answer

4,6,2,5,3,1

Answer

6,4,2,5,1,3

INI-CET 2022 — Physiology