INI-CET 2021 - Physiology PYQs Practice Questions

Q: The relaxation of the intestinal segment distal to the segment with the bolus of food during peristalsis is because of?

Nitric oxide (NO). ***Nitric oxide (NO)*** - **Nitric oxide (NO)** is a key **inhibitory neurotransmitter** that causes relaxation of the smooth muscle distal to the bolus during peristalsis, allowing the food to move forward. - Along with **Vasoactive Intestinal Peptide (VIP)**, NO mediates the **descending relaxation reflex** in the gut, which is essential for effective propulsion. *Substance P* - **Substance P** is an **excitatory neurotransmitter** that primarily mediates contraction of the smooth muscle proximal to the bolus during peristalsis. - It works synergistically with **acetylcholine** to initiate the muscular squeeze that propels food. *Norepinephrine from adrenergic fibers* - **Norepinephrine** is the primary neurotransmitter released by **sympathetic adrenergic fibers** in the gastrointestinal tract. - While sympathetic stimulation generally **inhibits gastrointestinal motility**, this is a systemic effect that reduces overall gut activity rather than causing the specific segmental relaxation distal to a bolus during peristalsis. - The descending relaxation during peristalsis is mediated by **intrinsic enteric neurons** (releasing NO and VIP), not by extrinsic sympathetic innervation. *VIP* - **Vasoactive Intestinal Peptide (VIP)** is an **inhibitory neurotransmitter** that causes relaxation of smooth muscle in the gut. - While VIP does contribute to descending relaxation, **nitric oxide (NO)** is considered a more significant and primary mediator of this specific relaxation during peristalsis. [Practice more Physiology PYQs on OnCourse]

Q: Milk production in pregnancy is inhibited by :

High estrogen. ***High estrogen*** - High levels of **estrogen** and progesterone during pregnancy inhibit milk production by blocking the action of **prolactin** on the mammary glands. - After delivery, the sudden drop in these hormones removes the inhibition, allowing prolactin to stimulate **lactogenesis**. *Low luteinizing hormone* - **Luteinizing hormone (LH)** is primarily involved in ovulation and corpus luteum formation, not directly in the inhibition of milk production. - Low LH levels would impact fertility but not have a direct inhibitory effect on lactation. *Low thyroid-stimulating hormone* - **Thyroid-stimulating hormone (TSH)** regulates thyroid function, which can indirectly affect metabolism and overall well-being. - While **hypothyroidism** can impact milk supply, low TSH itself is not a direct inhibitor of milk production. *Human somatomammotropin* - **Human placental lactogen (HPL)**, also known as human chorion somatomammotropin, is produced by the placenta. - It promotes mammary gland development and has weak lactogenic properties but does not inhibit milk production. [Practice more Physiology PYQs on OnCourse]

Q: All of the following increases gastric acid secretion except?

Serotonin. ***Serotonin*** - **Serotonin** (5-HT) is primarily known for its roles in gastrointestinal motility and CNS function, but it does not directly stimulate **gastric acid secretion**. - While it can influence gastric function indirectly, it is not a direct secretagogue for **parietal cells**. *Acetylcholine* - **Acetylcholine** (ACh), released from parasympathetic nerve endings, directly stimulates **parietal cells** to secrete hydrochloric acid. - It also enhances the release of **histamine** and **gastrin**, both of which promote acid secretion. *Histamine* - **Histamine**, released from enterochromaffin-like (ECL) cells in the gastric mucosa, is a potent stimulator of **gastric acid secretion**. - It acts on **H2 receptors** on parietal cells, leading to increased acid production. *Gastrin* - **Gastrin**, a hormone produced by G cells in the pyloric antrum, is a powerful stimulator of **gastric acid secretion**. - It acts directly on **parietal cells** and also promotes **histamine release** from ECL cells. [Practice more Physiology PYQs on OnCourse]

Q: Pacinian corpuscle is stimulated by which of the following?

Pressure. ***Pressure*** - **Pacinian corpuscles** are rapidly adapting mechanoreceptors that detect **deep pressure** and **vibrations**. - Their layered, onion-like structure allows them to be very sensitive to rapid changes in pressure. *Pain* - **Pain** is primarily detected by **nociceptors**, which are free nerve endings, not Pacinian corpuscles. - Nociceptors respond to various noxious stimuli, including mechanical, thermal, and chemical. *Temperature* - **Temperature** changes are detected by **thermoreceptors**, such as Krause end bulbs for cold and Ruffini endings for warmth, not Pacinian corpuscles. - These receptors have specific temperature ranges over which they are active. *Touch* - **Touch** sensation is broadly detected by several mechanoreceptors, including **Meissner's corpuscles** (light touch), **Merkel discs** (sustained touch), and hair follicle receptors. - While Pacinian corpuscles contribute to sensing touch through deep pressure, they are not the primary receptors for general light or sustained touch. [Practice more Physiology PYQs on OnCourse]

Q: An individual is in an environment of a temperature of 47°C. What is the mechanism of heat loss?

Sweating. ***Sweating*** - In an environment where the ambient temperature (47°C) is **higher than body temperature**, heat can only be lost through the evaporation of sweat. - **Evaporation** is the primary mechanism for cooling the body in hot environments when other forms of heat loss become ineffective or even cause heat gain. *Conduction* - **Conduction** involves the transfer of heat through direct contact between surfaces. - In an environment hotter than the body, conduction would cause **heat gain** by the body, not heat loss. *Radiation* - **Radiation** involves the transfer of heat in the form of electromagnetic waves. - When the ambient temperature is higher than body temperature, the body will **absorb radiant heat** from the environment, leading to heat gain, not loss. *Convection* - **Convection** is the transfer of heat through the movement of fluids (air or water). - In an environment with a temperature of 47°C, convection would cause **heat gain** as the surrounding hot air transfers heat to the body. [Practice more Physiology PYQs on OnCourse]

Question 1

The relaxation of the intestinal segment distal to the segment with the bolus of food during peristalsis is because of?

Accepted Answer

Nitric oxide (NO)

Answer

Substance P

Answer

Norepinephrine from adrenergic fibers

Answer

VIP

Question 2

Milk production in pregnancy is inhibited by :

Accepted Answer

High estrogen

Answer

Low luteinizing hormone

Answer

Low thyroid-stimulating hormone

Answer

Human somatomammotropin

Question 3

All of the following increases gastric acid secretion except?

Accepted Answer

Serotonin

Answer

Acetylcholine

Answer

Histamine

Answer

Gastrin

Question 4

Pacinian corpuscle is stimulated by which of the following?

Accepted Answer

Pressure

Answer

Pain

Answer

Temperature

Answer

Touch

Question 5

An individual is in an environment of a temperature of 47°C. What is the mechanism of heat loss?

Accepted Answer

Sweating

Answer

Conduction

Answer

Radiation

Answer

Convection

Question 6

Which among the following has the highest airway resistance?

Accepted Answer

Bronchi

Answer

Alveolar duct

Answer

Respiratory bronchioles

Answer

Small bronchioles

Question 7

If the contractility of the heart is decreased, which of the following is seen ?

Accepted Answer

Decreased stroke volume

Answer

Increased ejection fraction

Answer

Increased stroke work

Answer

Increased cardiac output

Question 8

All of the following substances have decreased concentration on the luminal side of the proximal convoluted tubule except:

Accepted Answer

Chloride

Answer

Glucose

Answer

Amino acids

Answer

Bicarbonate

Question 9

A woman with right-sided loss of sensations of both the upper and lower limb complains of shooting pain from her fingers to the right shoulder and a burning sensation when touching cold water. Motor functions are normal. Which of the following structures is likely to be involved?

Accepted Answer

Lateral spinothalamic tract

Answer

Anterior spinothalamic tract

Answer

Spinocerebellar tract

Answer

Posterior column

Question 10

Identify the pathology from the given flow-volume loop:

Accepted Answer

Fixed central airway obstruction

Answer

Variable extra thoracic obstruction

Answer

Variable intrathoracic obstruction

Answer

Fixed distal airway obstruction

INI-CET 2021 — Physiology