NEET-PG 2019 - Physiology PYQs Practice Questions

Q: Functional residual capacity (FRC) is defined as the volume of air remaining in the lungs at which specific moment in the respiratory cycle?

After normal expiration. ***After normal expiration*** - **Functional residual capacity (FRC)** is the volume of air remaining in the lungs at the end of a **normal, passive expiration**. - It represents the sum of the **expiratory reserve volume (ERV)** and the **residual volume (RV)**. *During active expiration* - **Active expiration** involves the use of accessory muscles to force more air out of the lungs than during normal expiration. - This process would result in a lung volume less than FRC, closer to the **residual volume**. *At peak inspiration* - **Peak inspiration** represents the total lung capacity (TLC), which is the maximum volume of air the lungs can hold after a maximal inspiratory effort. - This is the largest lung volume, significantly greater than FRC. *During active inspiration* - **Active inspiration** is the process of inhaling air, which increases lung volume. - FRC is a static volume measured at the end of expiration, not during the dynamic process of inhaling. [Practice more Physiology PYQs on OnCourse]

Q: Vasopressin acts through which aquaporin channels in the collecting duct?

Aquaporin 2. ***Aquaporin 2*** - Vasopressin (ADH) stimulates the insertion of **Aquaporin 2 (AQP2)** channels into the apical membrane of collecting duct cells, increasing water reabsorption. - This process is crucial for the kidney's ability to concentrate urine and maintain **water balance**. *Aquaporin 1* - **Aquaporin 1 (AQP1)** is predominantly found in the proximal tubules and descending limb of the loop of Henle, where **constitutive water reabsorption** occurs, independent of vasopressin. - It plays a role in bulk water reabsorption rather than regulated fine-tuning. *Aquaporin 3* - **Aquaporin 3 (AQP3)** is located on the **basolateral membrane** of collecting duct cells, facilitating the exit of water from the cell into the interstitial fluid. - While essential for water movement, its insertion into the membrane is **not directly regulated by vasopressin** in the same way as AQP2. *Aquaporin 4* - **Aquaporin 4 (AQP4)** is also found on the **basolateral membrane** of collecting duct cells and in other tissues like the brain. - Similar to AQP3, it allows water to leave the cell but is not the primary target for vasopressin-mediated regulation of water permeability. [Practice more Physiology PYQs on OnCourse]

Q: Which of the following is the MOST CHARACTERISTIC metabolic feature of type 1 diabetes mellitus?

Increased lipolysis. ***Increased lipolysis*** - Due to **absolute insulin deficiency** in type 1 diabetes, the body cannot properly utilize glucose, leading to a shift toward **fat metabolism** for energy. - This results in increased breakdown of **triglycerides** into **fatty acids** and **glycerol**, which are then converted to **ketone bodies** in the liver. - **Ketoacidosis** resulting from increased lipolysis is the most **characteristic and distinguishing** metabolic feature of type 1 diabetes, differentiating it from type 2 diabetes. *Decreased glucose uptake* - Decreased glucose uptake by insulin-sensitive tissues (muscle and adipose tissue) is the **primary metabolic defect** in type 1 diabetes due to the absolute lack of insulin. - While this is fundamental to the pathophysiology, it occurs in **both type 1 and type 2 diabetes**, making it less characteristic of type 1 specifically. *Increased hepatic glucose output* - Increased hepatic glucose output (via gluconeogenesis and glycogenolysis) is a prominent feature due to loss of insulin's suppressive effects on the liver. - However, this also occurs in **type 2 diabetes** and is not as distinctive as the dramatic shift to lipolysis and ketone production seen in type 1. *Increased protein catabolism* - While protein catabolism is increased in type 1 diabetes, contributing to **muscle wasting** and providing substrates for gluconeogenesis, it is a less immediate and less specific feature. - The metabolic shift to **lipolysis and ketogenesis** is more rapid, more clinically significant, and more characteristic of the type 1 diabetic state. [Practice more Physiology PYQs on OnCourse]

Q: With increase in age, which of the following statements about lung function is true?

Pulmonary compliance increases. ***Pulmonary compliance increases*** - With **increasing age**, there is a loss of **elastic recoil** in the lungs due to changes in elastin and collagen fibers, leading to an increase in **pulmonary compliance**. - This increased compliance means the lungs become less stiff and easier to inflate, but also less able to recoil and expel air effectively. - The **net effect** of aging is increased compliance, as the loss of elastic fibers is the predominant change in normal aging. *Residual volume decreases* - **Residual volume (RV)** actually **increases** with age. This is because the loss of elastic recoil makes it harder to fully exhale, causing more air to remain in the lungs after a maximal exhalation. - An increased residual volume contributes to an overall rise in **functional residual capacity** and total lung capacity in older adults. *Mucociliary clearance increases* - **Mucociliary clearance** generally **decreases** with age. This is due to a reduction in the number and function of cilia, as well as changes in mucus quality. - Impaired mucociliary clearance makes older individuals more susceptible to respiratory infections and difficulties in clearing secretions. *Fibrosis of the interstitium decreases* - The **fibrosis of the interstitium** can **increase** with age in some individuals. However, in normal aging (without pathological conditions), the predominant change is loss of elastic recoil rather than significant fibrotic changes. - When present, increased interstitial fibrosis would make the lungs stiffer, but this is not the primary age-related change in healthy individuals. [Practice more Physiology PYQs on OnCourse]

Q: In forceful expiration, which of the following neurons gets fired?

VRG. ***VRG*** - The **ventral respiratory group (VRG)** contains both inspiratory and expiratory neurons, and it is primarily involved in controlling the muscles necessary for **forceful breathing**. - During forceful expiration, the expiratory neurons in the VRG become active, stimulating accessory muscles of expiration like the **internal intercostals** and **abdominal muscles**. *DRG* - The **dorsal respiratory group (DRG)** primarily contains inspiratory neurons and is fundamental for **normal, quiet breathing**. - Its activity leads to contraction of the diaphragm and external intercostals, and it is largely inactive during quiet expiration, which is a passive process. *Pneumotaxic centre* - The **pneumotaxic center** (or pontine respiratory group) helps to fine-tune breathing patterns by **inhibiting inspiration**, thereby limiting the duration of inhalation. - It influences the rate and depth of breathing but does not directly activate muscles for forceful expiration. *Chemoreceptors* - **Chemoreceptors** (central and peripheral) monitor blood levels of **carbon dioxide (PCO2)**, **oxygen (PO2)**, and **pH**, and they send signals to the respiratory centers to adjust breathing accordingly. - While they regulate the overall respiratory drive, they do not directly fire to initiate forceful expiration; rather, they modulate the activity of the respiratory groups in the brainstem. [Practice more Physiology PYQs on OnCourse]

Question 1

Functional residual capacity (FRC) is defined as the volume of air remaining in the lungs at which specific moment in the respiratory cycle?

Accepted Answer

After normal expiration

Answer

During active expiration

Answer

At peak inspiration

Answer

During active inspiration

Question 2

Vasopressin acts through which aquaporin channels in the collecting duct?

Accepted Answer

Aquaporin 2

Answer

Aquaporin 1

Answer

Aquaporin 4

Answer

Aquaporin 3

Question 3

Which of the following is the MOST CHARACTERISTIC metabolic feature of type 1 diabetes mellitus?

Accepted Answer

Increased lipolysis

Answer

Increased protein catabolism

Answer

Increased hepatic glucose output

Answer

Decreased glucose uptake

Question 4

With increase in age, which of the following statements about lung function is true?

Accepted Answer

Pulmonary compliance increases

Answer

Fibrosis of the interstitium decreases

Answer

Residual volume decreases

Answer

Mucociliary clearance increases

Question 5

In forceful expiration, which of the following neurons gets fired?

Accepted Answer

VRG

Answer

DRG

Answer

Pneumotaxic centre

Answer

Chemoreceptors

Question 6

Tubuloglomerular feedback control is useful for which one of the following?

Accepted Answer

GFR

Answer

Plasma sodium

Answer

Plasma volume

Answer

Determining tubular secretion

Question 7

What is the effect of the Bainbridge reflex?

Accepted Answer

Increased heart rate

Answer

Bradycardia

Answer

Increased cardiac output

Answer

Decreased venous return

Question 8

Type of sensation lost on same side of Brown Sequard syndrome?

Accepted Answer

Loss of proprioception

Answer

Loss of pain sensation

Answer

Loss of touch sensation

Answer

Loss of temperature sensation

Question 9

Day 20 of menstrual cycle falls under which phase?

Accepted Answer

Luteal phase

Answer

Menstrual phase

Answer

Follicular phase

Answer

Ovulation phase

Question 10

Hormone predominantly secreted after 14 days that acts on the endometrium is?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

LH

Answer

FSH

NEET-PG 2019 — Physiology