FMGE 2026 - Physiology PYQs Practice Questions

Q: A patient is admitted with head injury in the ER. On examination he is having bradycardia with hypertension and posturing. You notice the following breathing pattern. Diagnosis is?

Biot breathing. ### ***Biot breathing*** - This breathing pattern is characterized by groups of **quick, shallow inspirations** followed by regular or irregular periods of **apnea**, often indicating damage to the **pons** or **medulla**. - Given the clinical context of a **head injury** presenting with **Cushing triad** features (bradycardia, hypertension, and posturing/altered consciousness), this indicates significant **increased intracranial pressure (ICP)** affecting the brainstem. ### *Cheyne stokes breathing* - This pattern involves a gradual increase and then decrease in depth of breathing followed by a period of apnea, classically associated with **bilateral hemispheric disease** or **heart failure**. - It typically occurs in **metabolic encephalopathy** or deep **cerebral lesions**, rather than profound brainstem compression seen with Biot breathing. ### *Kussmaul breathing* - This is a form of deep, rapid, labored breathing (hyperpnea) seen primarily in patients with **metabolic acidosis**, such as **diabetic ketoacidosis**. - It functions as a **respiratory compensation** for metabolic acidosis by blowing off CO2, and is not a sign of brainstem structural injury. ### *apneustic breathing* - This involves **prolonged inspiratory gasps** with short expirations; it signifies damage to the **upper pons**. - While it relates to brainstem injury, it is distinct from Biot breathing because of the characteristic **pause at full inspiration** rather than the irregular pattern of bursts and apnea. [Practice more Physiology PYQs on OnCourse]

Q: The ductus venosus in fetal circulation primarily functions to:

Umbilical vein → IVC. ***Umbilical vein → IVC*** - The **ductus venosus** serves as a specialized vascular shunt that allows approximately 30-50% of the oxygenated, nutrient-rich blood from the **umbilical vein** to bypass the hepatic microcirculation. - By shunting blood directly into the **inferior vena cava (IVC)**, it ensures that highly oxygenated blood is preferentially directed toward the **fetal heart** and brain. *Umbilical vein → liver* - While the **umbilical vein** does provide some blood to the liver (via the left portal vein), the primary function of the **ductus venosus** specifically is to *bypass* the liver rather than supply it. - If all flow went to the liver, the resistance would be too high and fetal hepatic blood flow would be dangerously restricted. *Pulmonary artery → aorta* - This describes the **ductus arteriosus**, which shunts blood away from the high-resistance **fetal lungs** to the systemic circulation via the descending aorta. - The **ductus arteriosus** connects the pulmonary trunk to the aorta, not the IVC. *Right atrium → left atrium* - This describes the **foramen ovale**, an anatomical opening in the atrial septum that allows right-to-left shunting of blood. - It acts as a bypass to keep oxygenated blood from the IVC moving toward the **left atrium**, avoiding the pulmonary circulation. [Practice more Physiology PYQs on OnCourse]

Q: Identify the breathing pattern shown in the image below:

Cheyne -Stokes breathing. ***Cheyne-Stokes breathing*** - Characterized by a **gradual waxing and waning** of tidal volume (amplitude) with periods of **apnea** between cycles. - Commonly associated with **congestive heart failure**, **stroke**, or severe **metabolic encephalopathy** due to impaired feedback loop sensitivity in the brainstem. *Biot's breathing* - Features **irregular** episodes of rapid, shallow breaths followed by unpredictable, variable periods of **apnea**. - Most typically associated with **increased intracranial pressure** or damage to the **medulla oblongata**. *Kussmaul breathing* - Presents as a deep, rapid, and **labored breathing** pattern characterized by a **sighing** quality. - Typically triggered by severe **metabolic acidosis**, most classically seen in **diabetic ketoacidosis (DKA)**. *Apneustic breathing* - Characterized by prolonged, **gasping inspirations** followed by extremely short, insufficient expirations. - Results from damage to the **pons**, often due to severe ischemic or hemorrhagic stroke. [Practice more Physiology PYQs on OnCourse]

Q: In the following Pressure-Volume curve of the bladder, what is the physiological basis for the segment labeled 1b?

Law of Laplace. ***Law of Laplace*** - Segment 1b on a bladder pressure-volume curve represents the **filling phase** of the bladder (cystometrogram), where the bladder wall exhibits **high compliance**. - This allows the bladder to accommodate increasing **volumes of urine** with minimal change in **intravesical pressure**, a property directly related to the **Law of Laplace** (P = 2T/r), which explains how the bladder wall tension adjusts to maintain low pressure even as the radius increases. *Sympathetic control* - Sympathetic stimulation occurs primarily during the **storage (filling) phase** via the **hypogastric nerve**, which promotes relaxation of the **detrusor muscle** (beta-3 receptors) and contraction of the **internal urethral sphincter** (alpha-1 receptors). - While the sympathetic system facilitates storage, segment 1b specifically describes the **passive mechanical property** of the bladder wall rather than the neural input itself. *Parasympathetic control* - Parasympathetic activation is the primary driver of the **voiding (micturition) phase**, mediated by the **pelvic splanchnic nerves** releasing acetylcholine onto **M3 receptors**. - This control leads to active **detrusor contraction** and a sharp rise in **intravesical pressure**, which corresponds to a different phase of the curve than the compliant filling phase. *Urethral valve* - The **urethra** and its associated sphincters act as the outlet mechanism, but they do not dictate the passive pressure-volume relationship of the **bladder wall** itself during filling. - The function of the urethral sphincter is to maintain **continence** to prevent leakage, rather than determining the **compliance** of the bladder reservoir. [Practice more Physiology PYQs on OnCourse]

Q: Based on the provided image of a nerve action potential, at which marked point is the combined transport of Na+ and K+ ions at its minimum?

Point E. ***Point E*** - This represents the **after-hyperpolarization phase** where voltage-gated **Na+ channels are inactivated** and **delayed rectifier K+ channels are closing**, resulting in minimal ion movement. - The membrane potential approaches the **K+ equilibrium potential**, and only the **Na+/K+-ATPase pump** operates at baseline levels to maintain ionic gradients. *Point A* - This is the **resting membrane potential** with continuous activity of **leak channels** allowing steady Na+ influx and K+ efflux. - Despite appearing stable, there is significant **background ion transport** through leak channels that maintains the resting potential. *Point B* - This marks the **threshold/depolarization phase** with massive opening of **voltage-gated Na+ channels** causing rapid Na+ influx. - This represents the **highest combined ion transport** phase, directly opposite to the minimum transport asked in the question. *Point C* - This corresponds to the **repolarization phase** with opening of **voltage-gated K+ channels** causing significant K+ efflux. - High **K+ conductance** results in substantial outward potassium transport to restore the membrane potential. [Practice more Physiology PYQs on OnCourse]

Question 1

A patient is admitted with head injury in the ER. On examination he is having bradycardia with hypertension and posturing. You notice the following breathing pattern. Diagnosis is?

Accepted Answer

Biot breathing

Answer

Cheyne stokes breathing

Answer

Kussmaul breathing

Answer

apneustic breathing

Question 2

The ductus venosus in fetal circulation primarily functions to:

Accepted Answer

Umbilical vein → IVC

Answer

Umbilical vein → liver

Answer

Pulmonary artery → aorta

Answer

Right atrium → left atrium

Question 3

Identify the breathing pattern shown in the image below:

Accepted Answer

Cheyne -Stokes breathing

Answer

Biot's breathing

Answer

Kussmaul breathing

Answer

Apneustic breathing

Question 4

In the following Pressure-Volume curve of the bladder, what is the physiological basis for the segment labeled 1b?

Accepted Answer

Law of Laplace

Answer

Sympathetic control

Answer

Parasympathetic control

Answer

Urethral valve

Question 5

Based on the provided image of a nerve action potential, at which marked point is the combined transport of Na+ and K+ ions at its minimum?

Accepted Answer

Point E

Answer

Point A

Answer

Point B

Answer

Point C

Question 6

Why is no new impulse generated during the depolarization phase of an action potential?

Accepted Answer

Voltage-gated sodium channels are inactivated

Answer

Potassium channels are closed

Answer

Sodium channels are closed

Answer

The neuron is hyperpolarized

Question 7

At which point on the Pressure -Volume loop does the aortic valve open?

Accepted Answer

Point C

Answer

Point A

Answer

Point B

Answer

Point D

Question 8

A patient undergoes a surgery where one lung is removed due to malignancy. Which of the following parameters should be measured to accurately assess the remaining lung's elasticity, independent of the change in lung volume?

Accepted Answer

Specific lung compliance

Answer

Chest wall compliance

Answer

Total lung compliance

Answer

Static compliance

Question 9

A patient with a history of head trauma presents with signs of increased Intracranial Pressure. Which of the following sets of vital signs characterizes the Cushing Reflex?

Accepted Answer

Bradycardia and Hypertension

Answer

Tachycardia and Hypertension

Answer

Bradycardia and Hypotension

Answer

Tachycardia and Hypotension

Question 10

A Strength-Duration curve is plotted for a skeletal muscle. Identify the parameters labeled in the correct order to successfully determine the tissue excitability.

Accepted Answer

A: Chronaxie; B: Rheobase; D: Utilization Time

Answer

A: Utilization Time; B: Rheobase; D: Chronaxie

Answer

A: Rheobase; B: Chronaxie; D: Utilization Time

Answer

A: Chronaxie; B: Utilization Time; D: Rheobase

FMGE 2026 — Physiology