INI-CET 2017 - Physiology PYQs Practice Questions

Q: Phonocardiogram tracing is shown below with corresponding ECG. Identify the phase corresponding with $S_{2}$ in phonocardiogram.

Isovolumetric relaxation. ***Isovolumetric relaxation*** - **S₂ (second heart sound)** occurs due to closure of the **aortic and pulmonary semilunar valves** at the end of systole, marking the onset of isovolumetric relaxation. - On the **ECG**, S₂ corresponds to the **end of the T wave**, when ventricular pressure drops below aortic pressure causing valve closure. *Isovolumetric contraction* - This phase corresponds to **S₁ (first heart sound)** caused by closure of the **mitral and tricuspid valves** at the beginning of systole. - Occurs on the ECG around the **QRS complex**, not at the timing of S₂. *Rapid ejection* - This phase occurs **between S₁ and S₂** when blood is actively ejected from the ventricles into the aorta and pulmonary artery. - The **semilunar valves are open** during this phase, so no heart sounds are produced. *Rapid ventricular filling* - This phase occurs **after S₂** during early diastole when the **AV valves open** and blood rapidly fills the ventricles. - May be associated with **S₃ gallop** in pathological conditions, but not with S₂. [Practice more Physiology PYQs on OnCourse]

Q: The blood levels of hormones are elevated during exercise and sleep as shown. Which hormone would exhibit this diurnal pattern?

Growth hormone. ***Growth hormone*** - **Growth hormone (GH)** secretion is known to increase significantly during both **strenuous exercise** and **sleep**, particularly during deep sleep stages. - The elevated levels during exercise promote **lipolysis** and **glucose production**, while during sleep, it facilitates **tissue repair** and **growth**. *Insulin* - **Insulin** levels typically **decrease during exercise** to promote the utilization of fat as fuel and increase during sleep in response to reduced metabolic demand and preparation for morning. - Its primary role is to regulate blood glucose, and its secretion is mainly stimulated by **high blood glucose** rather than exercise or sleep directly in this pattern. *Cortisol* - **Cortisol** secretion follows a **circadian rhythm**, peaking in the early morning and gradually decreasing throughout the day, reaching its lowest point at night. - While exercise can acutely increase cortisol, its **sleep-related pattern** is the opposite of what is shown, typically decreasing during early sleep. *Thyroid* - **Thyroid hormones (T3 and T4)** maintain a relatively **stable level** throughout the day and night, with minor diurnal fluctuations. - Their primary function is to regulate **metabolism** and they do not exhibit sharp, distinct peaks in response to exercise or sleep in the manner depicted. [Practice more Physiology PYQs on OnCourse]

Q: Calculate the tetanizing frequency based on the contraction dynamics of gastrocnemius muscle of frog shown in the image?

20-25 Hz. **20-25 Hz** - Tetanizing frequency (or fusion frequency) is the stimulation rate at which individual muscle twitches fuse to produce a **smooth, sustained contraction** (tetanus). - For the **frog gastrocnemius muscle**, a common model in physiology, this frequency typically falls within the **20-25 Hz range**. *10-15 Hz* - At this lower frequency, the muscle would likely exhibit **incomplete tetanus** or summation, where individual twitches are still discernible, but tension is increasing. - This range is generally insufficient to achieve a **smooth, fused tetanic contraction** in the frog gastrocnemius. *15-20 Hz* - This range might produce **treppe** or early stages of incomplete tetanus, where successive contractions are slightly stronger, but the relaxation phase is still partially visible between stimuli. - While closer to the tetanizing frequency, it's generally not high enough to achieve **complete fusion** for the frog gastrocnemius. *30-35 Hz* - While this frequency would certainly result in a **fused tetanic contraction**, it's higher than the minimum required for the frog gastrocnemius, which means the muscle is already in complete tetanus at a lower frequency. - Using excessively high frequencies beyond the fusion frequency does not significantly increase tension and can lead to **faster fatigue**. [Practice more Physiology PYQs on OnCourse]

Q: There are two blood vessels shown below. Assuming that pressure along both the vessels is same and both of them follow linear flow pattern, what will be the amount of blood flow in A compared to B?

32 times. ***32 times*** - According to **Poiseuille's law**: Q = (ΔP × π × r⁴) / (8 × η × L), where flow is proportional to the **fourth power of radius** and inversely proportional to vessel length. - Vessel A has **double the diameter** (radius = 2r) and **half the length** (L/2) compared to vessel B: Q_A ∝ (2r)⁴/(L/2) = 32r⁴/L vs Q_B ∝ r⁴/L, giving ratio of **32**. *4 times* - This would occur with a much smaller radius difference between the vessels than what is shown. - Does not account for the **fourth power relationship** of radius with flow in Poiseuille's equation. *8 times* - This would result if vessel A had **double the diameter** but also **double the length** of vessel B. - Calculation: (2r)⁴/(2L) ÷ (r⁴/L) = 16r⁴/2L ÷ r⁴/L = **8 times**. *16 times* - This would occur if vessel A had **double the radius** but **equal length** to vessel B. - Calculation: (2r)⁴/L ÷ (r⁴/L) = 16r⁴/L ÷ r⁴/L = **16 times**. [Practice more Physiology PYQs on OnCourse]

Question 1

Phonocardiogram tracing is shown below with corresponding ECG. Identify the phase corresponding with $S_{2}$ in phonocardiogram.

Accepted Answer

Isovolumetric relaxation

Answer

Isovolumetric contraction

Answer

Rapid ejection

Answer

Rapid ventricular filling

Question 2

Hysteresis is observed between the deflation and inflation curves in an isolated lung compliance diagram. What is the best description for the same?

Accepted Answer

Variation in surface tension forces at air- liquid interface

Answer

Stretching of elastic elements of lung parenchyma

Answer

Decrease in surface tension in air-water interface at higher lung volumes

Answer

Hering Breuer reflex is operational at higher lung volumes

Question 3

The blood levels of hormones are elevated during exercise and sleep as shown. Which hormone would exhibit this diurnal pattern?

Accepted Answer

Growth hormone

Answer

Insulin

Answer

Cortisol

Answer

Thyroid hormones

Question 4

Calculate the tetanizing frequency based on the contraction dynamics of gastrocnemius muscle of frog shown in the image?

Accepted Answer

20-25 Hz

Answer

10-15 Hz

Answer

15-20 Hz

Answer

30-35 Hz

Question 5

There are two blood vessels shown below. Assuming that pressure along both the vessels is same and both of them follow linear flow pattern, what will be the amount of blood flow in A compared to B?

Accepted Answer

32 times

Answer

4 times

Answer

8 times

Answer

16 times

Question 6

A patient has a blood glucose level of $200 \mathrm{mg} \%$ and GFR of 90. The transport maximum of the patient is as shown in the picture given below. What is the amount of glucose excreted?

Accepted Answer

30 mg/min

Answer

50 mg/min

Answer

90 mg/min

Answer

180 mg/min

Question 7

Calculate the FEV1/FVC ratio from the spirometry reading shown below.

Accepted Answer

80-89 %

Answer

60-69 %

Answer

70-79 %

Answer

90-99 %

INI-CET 2017 — Physiology