FMGE 2023 - Physiology PYQs Practice Questions

Q: The first heart sound coincides with which cardiac cycle phase?

Isovolumetric contraction. ***Isovolumetric contraction*** - The **first heart sound (S1)** is produced by the simultaneous closure of the **mitral** and **tricuspid** (atrioventricular) valves. - This closure occurs the moment ventricular pressure exceeds atrial pressure, marking the beginning of **ventricular systole** and the phase of isovolumetric contraction. *Rapid atrial filling* - Rapid atrial filling (or **rapid ventricular filling**) occurs during **early diastole** when the mitral and tricuspid valves open. - This phase is associated with the potential generation of a **third heart sound (S3)**, not S1. *Aortic ejection* - Aortic ejection occurs *after* S1, commencing when the **aortic valve** opens because left ventricular pressure exceeds aortic pressure. - This phase ends with the closure of the semilunar valves, which produces the second heart sound (**S2**). *Isovolumetric relaxation* - Isovolumetric relaxation begins immediately after the **second heart sound (S2)**, which is caused by the closure of the aortic and pulmonic valves. - This phase is fully contained within **early diastole**, preceding ventricular filling. [Practice more Physiology PYQs on OnCourse]

Q: Which among the following is true regarding creatinine clearance?

It is more than inulin clearance. ***It is more than inulin clearance*** - Creatinine clearance **overestimates GFR** by approximately 10-20% compared to inulin clearance - This is because creatinine undergoes both **glomerular filtration AND tubular secretion** - The additional secretion increases the amount of creatinine excreted, making the calculated clearance higher - **Inulin clearance** remains the gold standard as inulin is only filtered (not secreted or reabsorbed) *Equal to inulin clearance* - Incorrect: Creatinine undergoes tubular secretion in addition to filtration, so clearances are not equal *It is less than inulin clearance* - Incorrect: This would only be true if creatinine were reabsorbed, but it is actually secreted, making its clearance higher *Equal to renal plasma flow* - Incorrect: Renal plasma flow is measured by PAH (para-aminohippuric acid) clearance (~650 mL/min), which is much higher than creatinine clearance (~120-130 mL/min) or GFR (~120 mL/min) [Practice more Physiology PYQs on OnCourse]

Q: Which of the following statements is true about GFR? GFR-Glomerular filtration rate RPF-Renal Plasma Flow

An increase in RPF increases GFR. ***An increase in RPF increases GFR***- **GFR** is directly proportional to the amount of **plasma delivered** to the glomerular capillaries for filtration, meaning higher **Renal Plasma Flow (RPF)** generally increases GFR.- Increased RPF contributes to a higher **glomerular hydrostatic pressure** and delivers more solute/fluid load to the capillary surface area for filtration.*An increase in sympathetic function increases GFR*- Strong sympathetic activation causes generalized **vasoconstriction** of the renal blood vessels (via alpha-1 receptors), significantly reducing **RPF** and thus GFR.- This response is critical during conditions like hemorrhage or shock to conserve fluid volume by prioritizing systemic circulation over **renal filtration**.*Afferent arteriolar constriction increases GFR*- Constriction of the **afferent arteriole** restricts blood flow into the glomerulus, immediately dropping the **glomerular capillary hydrostatic pressure (PGC)**.- Since PGC is the chief driving force for filtration, afferent constriction invariably leads to a *decrease* in GFR; this mechanism is essential for **GFR autoregulation**.*A decrease in RPF increases GFR*- A decrease in **Renal Plasma Flow (RPF)** means less plasma is physically available to be filtered across the glomerular membrane per unit time.- A primary reduction in RPF, assuming stable filtration dynamics, generally results in a proportional *decrease* in the absolute **GFR**. [Practice more Physiology PYQs on OnCourse]

Q: A new resident to a high-altitude area develops hypoxia. What is the causative factor?

Low partial pressure of O2. ***Low partial pressure of O2***- At high altitudes, the **barometric pressure** is significantly lower, and while the fraction of oxygen remains 21%, the resulting **partial pressure of inspired O2 (PiO2)** is reduced.- This reduction in PiO2 lowers the **alveolar PO2**, thereby decreasing the driving pressure for oxygen diffusion into the blood and causing **hypoxic hypoxia**.*Low hemoglobin levels*- The immediate cause of high-altitude illness is **hypoxic hypoxia**, where the problem is low inspired oxygen, not an issue with the carrying capacity of the blood.- Over time, the body adapts by increasing red blood cell mass and thus **hemoglobin levels** (polycythemia).*Low blood lactate levels*- Hypoxia often triggers **anaerobic metabolism**, especially under exertion, leading to an *increase* in blood lactate (lactic acidosis), not a decrease.- Lactate levels are a metabolic consequence of tissue hypoxia, not the primary cause of developing low oxygen levels at altitude.*High partial pressure of CO2*- The hypoxia stimulates peripheral chemoreceptors, leading to an **increase in ventilation** (hyperventilation).- Hyperventilation causes the body to "blow off" CO2, resulting in **decreased arterial PCO2 (hypocapnia)** and respiratory alkalosis, not high PCO2. [Practice more Physiology PYQs on OnCourse]

Q: Which of the following is an orexigenic hormone?

Ghrelin. ***Ghrelin (Correct Answer)*** - Ghrelin is often termed the "hunger hormone" as it acts primarily as a powerful **orexigenic signal**, stimulating appetite and food intake. - It is primarily produced by specialized cells in the **stomach**, and its levels typically rise before meals. *Melanocyte-stimulating hormone (Incorrect)* - MSH, specifically **alpha-MSH**, is released from **proopiomelanocortin (POMC) neurons** in the hypothalamus. - It acts to suppress appetite and is classified as an **anorexigenic hormone**. *Cholecystokinin (Incorrect)* - CCK is a **satiety hormone** released in response to fat and protein entering the duodenum and jejunum. - It acts on the brainstem and peripheral nerves to inhibit gastric emptying and induce short-term feelings of **satiety** (anorexigenic effect). *Leptin (Incorrect)* - Leptin is produced mainly by **adipocytes (fat cells)** and signals the brain about long-term energy stores. - High circulating levels of leptin act on the hypothalamus to **inhibit appetite** and increase energy expenditure, making it an **anorexigenic hormone (satiety signal)**. [Practice more Physiology PYQs on OnCourse]

Question 1

The first heart sound coincides with which cardiac cycle phase?

Accepted Answer

Isovolumetric contraction

Answer

Rapid atrial filling

Answer

Aortic ejection

Answer

Isovolumetric relaxation

Question 2

Which among the following is true regarding creatinine clearance?

Accepted Answer

It is more than inulin clearance

Answer

Equal to inulin clearance

Answer

It is less than inulin clearance

Answer

Equal to renal plasma flow

Question 3

Which of the following statements is true about GFR? GFR-Glomerular filtration rate RPF-Renal Plasma Flow

Accepted Answer

An increase in RPF increases GFR

Answer

An increase in sympathetic function increases GFR

Answer

Afferent arteriolar constriction increases GFR

Answer

A decrease in RPF increases GFR

Question 4

A new resident to a high-altitude area develops hypoxia. What is the causative factor?

Accepted Answer

Low partial pressure of O2

Answer

Low hemoglobin levels

Answer

Low blood lactate levels

Answer

High partial pressure of CO2

Question 5

Which of the following is an orexigenic hormone?

Accepted Answer

Ghrelin

Answer

Melanocyte-stimulating hormone

Answer

Cholecystokinin

Answer

Leptin

Question 6

Which of the following clotting factor participates in the extrinsic pathway of coagulation?

Accepted Answer

Factor VII

Answer

Factor VIII

Answer

Factor XI

Answer

Factor IX

Question 7

Which of the following is the principal constituent of serum osmolality?

Accepted Answer

Sodium

Answer

Potassium

Answer

Bicarbonate

Answer

Hydrogen ions

Question 8

What is the function of utricle and saccule?

Accepted Answer

Linear acceleration

Answer

Hearing high-frequency sounds

Answer

Hearing low-frequency sounds

Answer

Angular acceleration

Question 9

What is the cause of LH (Luteinizing Hormone) surge?

Accepted Answer

Estradiol

Answer

LH

Answer

Progesterone

Answer

FSH

Question 10

Which of the following cells is responsible for destroying bacterial foreign bodies in liver sinusoids?

Accepted Answer

Kupffer cells

Answer

Hepatocytes

Answer

Sinusoidal endothelial cells

Answer

Ito cells

FMGE 2023 — Physiology