INI-CET 2025 - Physiology PYQs Practice Questions

Q: What is the cause of hyponatremia in diarrhea-induced hypovolemia?

Decreased aldosterone. ***Decreased aldosterone*** * In scenarios where salt loss (e.g., due to diarrhea) leads to hypovolemia, a relative or true deficiency of **aldosterone** prevents maximal sodium reabsorption in the distal tubules and collecting ducts. * This failure to maximally conserve sodium leads to **renal salt wasting**, which exacerbates the volume deficit and, when coupled with ADH-mediated water retention, results in hyponatremia. ***Decreased ADH*** * Hypovolemia (volume depletion) is the strongest non-osmotic trigger for the release of **Antidiuretic Hormone (ADH)** from the posterior pituitary, overriding low plasma osmolality [1]. * Therefore, in diarrhea-induced hypovolemia, **ADH levels are actually increased**, which drives powerful free water reabsorption in the kidney, resulting in dilutional hyponatremia [1]. ***Decreased sodium absorption from gastrointestinal tract*** * This is the primary mechanism by which diarrhea causes salt and water loss, leading to the state of **hypovolemia**. * However, the mechanism driving the *hyponatremia* (low plasma sodium concentration) involves the kidney's disproportionate reabsorption of water relative to sodium, mediated by **ADH**. ***Increased sodium absorption from kidney*** * System mechanisms like the Renin-Angiotensin-Aldosterone System (RAAS) are activated by hypovolemia to increase **sodium and water absorption** in an attempt to restore blood volume [2]. * Increased renal sodium absorption is a compensatory mechanism that works against hyponatremia; thus, it is not the cause of low plasma sodium. [Practice more Physiology PYQs on OnCourse]

Question 1

A single muscle twitch lasts 40 milliseconds. What is the minimum tetanization frequency required to produce a sustained (fused) contraction in this muscle?

Accepted Answer

25 Hz

Answer

10 Hz

Answer

20 Hz

Answer

40 Hz

Question 2

What is the cause of hyponatremia in diarrhea-induced hypovolemia?

Accepted Answer

Decreased aldosterone

Answer

Decreased ADH

Answer

Decreased sodium absorption from gastrointestinal tract

Answer

Increased sodium absorption from kidney

Question 3

Which type of pulse is based on the Frank-Starling law?

Accepted Answer

Pulsus alternans

Answer

Pulsus parvus

Answer

Pulsus bisferiens

Answer

Pulsus paradoxus

Question 4

Which of the following tissues will not be able to take up glucose in insulin resistance/insulin absence/diabetes mellitus?

Accepted Answer

Skeletal muscle

Answer

Kidney

Answer

Brain

Answer

Red blood cells

Question 5

Which of the following is not a mechanism of action of ADH?

Accepted Answer

Increases absorption of urea in descending limb of loop of Henle

Answer

Increases absorption of NaCl in thin ascending limb

Answer

Increases water permeability in collecting ducts

Answer

Increases absorption of urea in medullary collecting duct

Question 6

Patient presents to OPD with fever. Which area is most likely involved?

Accepted Answer

Pre-optic nucleus

Answer

Periventricular hypothalamus

Answer

Dorsomedial hypothalamus

Answer

Insular cortex

Question 7

Which of the following is an example of feed forward mechanism?

Accepted Answer

Temperature regulation

Answer

Vasoconstriction in response to cooling

Answer

Increase in cardiac output in response to anemia

Answer

HR increases from supine to standing

Question 8

In a normal awake person at rest with eyes closed, EEG waves that are reduced on opening the eyes:

Accepted Answer

Alpha waves

Answer

Theta waves

Answer

Beta waves

Answer

Delta waves

Question 9

Which of the following are features of Bezold Jarisch reflex?
1. Bradycardia
2. Hypertension
3. Coronary vasodilation
4. Tachycardia

Accepted Answer

1,3

Answer

1,2,3

Answer

1,3,4

Answer

All of the above

Question 10

Surface tension of the fluid lining the alveoli increases during:

Accepted Answer

Expiration

Answer

Inspiration

Answer

Standing

Answer

Supine

INI-CET 2025 — Physiology