NEET-PG 2021 — Physiology

Q: A child presented with dehydration and was supplemented with ORS solution for management. Which of the following transporters help in the absorption of glucose from GIT?

SGLT 1. ***SGLT 1*** - **SGLT1 (Sodium-Glucose Co-transporter 1)** is responsible for the **active transport of glucose and galactose** from the intestinal lumen into the enterocytes, coupled with sodium. - The principle of **oral rehydration solutions (ORS)** relies on this co-transport mechanism, as glucose (or other carbohydrates like sucrose, which is broken down into glucose and fructose) facilitates the absorption of sodium and water across the intestinal wall. *GLUT 2* - **GLUT2** is primarily located on the **basolateral membrane of enterocytes** and facilitates glucose transport out of the cell into the bloodstream. It also plays a role in glucose uptake in the liver and pancreatic beta cells. - While involved in glucose handling, **GLUT2 does not absorb glucose from the intestinal lumen** into the enterocytes; rather, it transports glucose out of them. *SGLT 2* - **SGLT2 (Sodium-Glucose Co-transporter 2)** is predominantly found in the **proximal tubules of the kidneys**, where it is responsible for the reabsorption of the vast majority of filtered glucose back into the bloodstream. - It is not involved in **intestinal glucose absorption**. Selective SGLT2 inhibitors are used as antidiabetic drugs to promote glucose excretion via the kidneys. *GLUT 1* - **GLUT1 (Glucose Transporter 1)** is a ubiquitous glucose transporter found in nearly all cell types, particularly important for basal glucose uptake by tissues like the **brain** and **red blood cells**. - While essential for glucose transport in many tissues, **GLUT1 plays a negligible role in glucose absorption from the gastrointestinal tract**. [Practice more Physiology PYQs on OnCourse]

Q: The body fluid compartments of a patient were measured, showing the following ion concentrations: - Sodium (Na): $10 \mathrm{mEq} / \mathrm{L}$ - Potassium (K): $140 \mathrm{mEq} / \mathrm{L}$ - Chloride (Cl): $15 \mathrm{mEq} / \mathrm{L}$ Based on these values, which fluid compartment is being described?

ICF. ***ICF*** - The measured ion concentrations, especially **high potassium (140 mEq/L)** and **low sodium (10 mEq/L)**, are characteristic of the **intracellular fluid (ICF)**, where potassium is the primary cation and sodium is kept low by the Na+/K+-ATPase pump. - **Chloride levels (15 mEq/L)** are also significantly lower in the ICF compared to extracellular fluids. *Plasma* - Plasma typically has **high sodium (around 140 mEq/L)** and **low potassium (around 4 mEq/L)**, which contradicts the given measurements. - Chloride levels in plasma are usually much higher, around **100-105 mEq/L**. *Interstitial fluid* - Interstitial fluid has an electrolyte composition very similar to plasma, with **high sodium** and **low potassium**, differing mainly in protein content. - This composition is not consistent with the given measurements. *ECF* - The ECF (extracellular fluid), which includes both plasma and interstitial fluid, is characterized by **high sodium** and **low potassium**. - The given ion concentrations, particularly the very **high potassium** and **low sodium**, are directly opposite to the typical ECF profile. [Practice more Physiology PYQs on OnCourse]

Q: A young patient presents with muscle spasms, numbness in the hands and feet, seizures, and difficulty in breathing due to laryngospasm. His blood work reveals an electrolyte imbalance. What is the most likely cause of these manifestations?

Respiratory Alkalosis. ***Respiratory Alkalosis*** - **Hyperventilation** (the likely underlying cause) leads to decreased partial pressure of carbon dioxide (**PCO2**), causing an increase in pH and **respiratory alkalosis**. - This **alkalosis** decreases **ionized calcium** levels by increasing calcium binding to albumin, leading to **hypocalcemia**. - **Hypocalcemia** causes increased neuromuscular excitability, resulting in **muscle spasms, numbness** (paresthesias), **seizures**, and **laryngospasm** (difficulty breathing). - This is the classic presentation of **hypocalcemic tetany** secondary to respiratory alkalosis. *Metabolic Alkalosis* - This imbalance is primarily characterized by an increase in **bicarbonate (HCO3-)** concentration, often due to **vomiting** or diuretic use. - While it can also cause alkalosis leading to **hypocalcemia** and similar neurological symptoms, the acute and severe presentation with prominent tetany and laryngospasm is more characteristic of **respiratory alkalosis**. - Metabolic alkalosis typically has a more gradual onset. *Respiratory Acidosis* - Caused by **hypoventilation**, leading to an increase in **PCO2** and a decrease in pH (acidosis). - **Acidosis increases ionized calcium**, so this would not cause hypocalcemic symptoms. - This condition typically manifests as **somnolence, confusion**, or CNS depression, not the neuromuscular excitability seen in this patient. *Metabolic Acidosis* - Characterized by a decrease in **bicarbonate (HCO3-)** and a decrease in pH, often due to conditions like **diabetic ketoacidosis** or **renal failure**. - **Acidosis increases ionized calcium**, making hypocalcemic tetany unlikely. - Symptoms usually include **Kussmaul breathing** (compensatory hyperventilation) and potential cardiac arrhythmias, which do not match this patient's presentation of tetany and laryngospasm. [Practice more Physiology PYQs on OnCourse]

Q: Which transporter is responsible for the absorption of glucose in the intestine when a person is given Oral Rehydration Solution (ORS)?

SGLT-1. ***SGLT-1 (Sodium-Glucose cotransporter 1)*** - **SGLT-1** is the primary transporter responsible for the **active absorption of glucose** and galactose from the intestinal lumen into enterocytes, utilizing the electrochemical gradient of sodium. - The mechanism of **ORS** relies on the co-transport of sodium and glucose via SGLT-1, which also facilitates the osmotic movement of water, making it effective for rehydration. *GLP-1 (Glucagon-like peptide-1)* - **GLP-1** is an **incretin hormone** that stimulates insulin secretion and inhibits glucagon release from the pancreas, playing a role in glucose homeostasis. - It is not a transporter for glucose absorption from the intestine but rather a **signaling molecule** involved in metabolic regulation. *SGLT-2 (Sodium-Glucose cotransporter 2)* - **SGLT-2** is predominantly found in the **renal tubules**, where it is responsible for the majority of glucose reabsorption from the filtrate back into the bloodstream. - While it is a glucose transporter, its primary role is in the **kidney**, not in intestinal glucose absorption. *GLUT-1 (Glucose Transporter 1)* - **GLUT-1** is found in all cell types and is primarily responsible for **basal glucose uptake** by cells, particularly high in red blood cells and at the blood-brain barrier. - It is a **facilitated diffusion transporter** and is not the primary mechanism for glucose absorption from the intestinal lumen. [Practice more Physiology PYQs on OnCourse]

Q: A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

Respiratory alkalosis. ***Respiratory alkalosis*** - The pH of 7.53 indicates **alkalemia**, and the low pCO2 (20 mmHg) is the primary driver, signifying **respiratory alkalosis** - A hyperventilating patient exhales more CO2, leading to a decrease in its partial pressure in the blood and a subsequent rise in pH - The HCO3 is within normal range (26 mEq/L), indicating **uncompensated respiratory alkalosis** *Metabolic alkalosis* - This would be characterized by a high pH and an elevated **HCO3**, but the HCO3 is within the normal range (26 mEq/L) - While it causes alkalemia, the primary disturbance here is respiratory, not metabolic *Metabolic acidosis* - This would present with a **low pH** and a low **HCO3**, which is contrary to the given ABG values - The patient's pH is elevated, indicating an alkalotic state, not acidotic *Respiratory acidosis* - This would be defined by a **low pH** and an elevated **pCO2**, which is the exact opposite of the provided ABG results - The patient's high pH and low pCO2 rule out respiratory acidosis [Practice more Physiology PYQs on OnCourse]

6 Previous Year Questions with Answers & Explanations

Questions

A child presented with dehydration and was supplemented with ORS solution for management. Which of the following transporters help in the absorption of glucose from GIT?

The body fluid compartments of a patient were measured, showing the following ion concentrations: - Sodium (Na): $10 \mathrm{mEq} / \mathrm{L}$ - Potassium (K): $140 \mathrm{mEq} / \mathrm{L}$ - Chloride (Cl): $15 \mathrm{mEq} / \mathrm{L}$ Based on these values, which fluid compartment is being described?

A young patient presents with muscle spasms, numbness in the hands and feet, seizures, and difficulty in breathing due to laryngospasm. His blood work reveals an electrolyte imbalance. What is the most likely cause of these manifestations?

Which transporter is responsible for the absorption of glucose in the intestine when a person is given Oral Rehydration Solution (ORS)?

A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

What is the function of the umbilical artery in fetal circulation?

NEET-PG 2021 - Physiology NEET-PG Practice Questions and MCQs

Question 1: A child presented with dehydration and was supplemented with ORS solution for management. Which of the following transporters help in the absorption of glucose from GIT?

A. GLUT 2
B. SGLT 1 (Correct Answer)
C. SGLT 2
D. GLUT 1

Explanation: ***SGLT 1*** - **SGLT1 (Sodium-Glucose Co-transporter 1)** is responsible for the **active transport of glucose and galactose** from the intestinal lumen into the enterocytes, coupled with sodium. - The principle of **oral rehydration solutions (ORS)** relies on this co-transport mechanism, as glucose (or other carbohydrates like sucrose, which is broken down into glucose and fructose) facilitates the absorption of sodium and water across the intestinal wall. *GLUT 2* - **GLUT2** is primarily located on the **basolateral membrane of enterocytes** and facilitates glucose transport out of the cell into the bloodstream. It also plays a role in glucose uptake in the liver and pancreatic beta cells. - While involved in glucose handling, **GLUT2 does not absorb glucose from the intestinal lumen** into the enterocytes; rather, it transports glucose out of them. *SGLT 2* - **SGLT2 (Sodium-Glucose Co-transporter 2)** is predominantly found in the **proximal tubules of the kidneys**, where it is responsible for the reabsorption of the vast majority of filtered glucose back into the bloodstream. - It is not involved in **intestinal glucose absorption**. Selective SGLT2 inhibitors are used as antidiabetic drugs to promote glucose excretion via the kidneys. *GLUT 1* - **GLUT1 (Glucose Transporter 1)** is a ubiquitous glucose transporter found in nearly all cell types, particularly important for basal glucose uptake by tissues like the **brain** and **red blood cells**. - While essential for glucose transport in many tissues, **GLUT1 plays a negligible role in glucose absorption from the gastrointestinal tract**.

Question 2: The body fluid compartments of a patient were measured, showing the following ion concentrations: - Sodium (Na): $10 \mathrm{mEq} / \mathrm{L}$ - Potassium (K): $140 \mathrm{mEq} / \mathrm{L}$ - Chloride (Cl): $15 \mathrm{mEq} / \mathrm{L}$ Based on these values, which fluid compartment is being described?

A. Plasma
B. ICF (Correct Answer)
C. Interstitial fluid
D. ECF

Explanation: ***ICF*** - The measured ion concentrations, especially **high potassium (140 mEq/L)** and **low sodium (10 mEq/L)**, are characteristic of the **intracellular fluid (ICF)**, where potassium is the primary cation and sodium is kept low by the Na+/K+-ATPase pump. - **Chloride levels (15 mEq/L)** are also significantly lower in the ICF compared to extracellular fluids. *Plasma* - Plasma typically has **high sodium (around 140 mEq/L)** and **low potassium (around 4 mEq/L)**, which contradicts the given measurements. - Chloride levels in plasma are usually much higher, around **100-105 mEq/L**. *Interstitial fluid* - Interstitial fluid has an electrolyte composition very similar to plasma, with **high sodium** and **low potassium**, differing mainly in protein content. - This composition is not consistent with the given measurements. *ECF* - The ECF (extracellular fluid), which includes both plasma and interstitial fluid, is characterized by **high sodium** and **low potassium**. - The given ion concentrations, particularly the very **high potassium** and **low sodium**, are directly opposite to the typical ECF profile.

Question 3: A young patient presents with muscle spasms, numbness in the hands and feet, seizures, and difficulty in breathing due to laryngospasm. His blood work reveals an electrolyte imbalance. What is the most likely cause of these manifestations?

A. Respiratory Alkalosis (Correct Answer)
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Metabolic Acidosis

Explanation: ***Respiratory Alkalosis*** - **Hyperventilation** (the likely underlying cause) leads to decreased partial pressure of carbon dioxide (**PCO2**), causing an increase in pH and **respiratory alkalosis**. - This **alkalosis** decreases **ionized calcium** levels by increasing calcium binding to albumin, leading to **hypocalcemia**. - **Hypocalcemia** causes increased neuromuscular excitability, resulting in **muscle spasms, numbness** (paresthesias), **seizures**, and **laryngospasm** (difficulty breathing). - This is the classic presentation of **hypocalcemic tetany** secondary to respiratory alkalosis. *Metabolic Alkalosis* - This imbalance is primarily characterized by an increase in **bicarbonate (HCO3-)** concentration, often due to **vomiting** or diuretic use. - While it can also cause alkalosis leading to **hypocalcemia** and similar neurological symptoms, the acute and severe presentation with prominent tetany and laryngospasm is more characteristic of **respiratory alkalosis**. - Metabolic alkalosis typically has a more gradual onset. *Respiratory Acidosis* - Caused by **hypoventilation**, leading to an increase in **PCO2** and a decrease in pH (acidosis). - **Acidosis increases ionized calcium**, so this would not cause hypocalcemic symptoms. - This condition typically manifests as **somnolence, confusion**, or CNS depression, not the neuromuscular excitability seen in this patient. *Metabolic Acidosis* - Characterized by a decrease in **bicarbonate (HCO3-)** and a decrease in pH, often due to conditions like **diabetic ketoacidosis** or **renal failure**. - **Acidosis increases ionized calcium**, making hypocalcemic tetany unlikely. - Symptoms usually include **Kussmaul breathing** (compensatory hyperventilation) and potential cardiac arrhythmias, which do not match this patient's presentation of tetany and laryngospasm.

Question 4: Which transporter is responsible for the absorption of glucose in the intestine when a person is given Oral Rehydration Solution (ORS)?

A. GLP-1
B. SGLT-2
C. SGLT-1 (Correct Answer)
D. GLUT-1

Explanation: ***SGLT-1 (Sodium-Glucose cotransporter 1)*** - **SGLT-1** is the primary transporter responsible for the **active absorption of glucose** and galactose from the intestinal lumen into enterocytes, utilizing the electrochemical gradient of sodium. - The mechanism of **ORS** relies on the co-transport of sodium and glucose via SGLT-1, which also facilitates the osmotic movement of water, making it effective for rehydration. *GLP-1 (Glucagon-like peptide-1)* - **GLP-1** is an **incretin hormone** that stimulates insulin secretion and inhibits glucagon release from the pancreas, playing a role in glucose homeostasis. - It is not a transporter for glucose absorption from the intestine but rather a **signaling molecule** involved in metabolic regulation. *SGLT-2 (Sodium-Glucose cotransporter 2)* - **SGLT-2** is predominantly found in the **renal tubules**, where it is responsible for the majority of glucose reabsorption from the filtrate back into the bloodstream. - While it is a glucose transporter, its primary role is in the **kidney**, not in intestinal glucose absorption. *GLUT-1 (Glucose Transporter 1)* - **GLUT-1** is found in all cell types and is primarily responsible for **basal glucose uptake** by cells, particularly high in red blood cells and at the blood-brain barrier. - It is a **facilitated diffusion transporter** and is not the primary mechanism for glucose absorption from the intestinal lumen.

Question 5: A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

A. Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory alkalosis (Correct Answer)
D. Respiratory acidosis

Explanation: ***Respiratory alkalosis*** - The pH of 7.53 indicates **alkalemia**, and the low pCO2 (20 mmHg) is the primary driver, signifying **respiratory alkalosis** - A hyperventilating patient exhales more CO2, leading to a decrease in its partial pressure in the blood and a subsequent rise in pH - The HCO3 is within normal range (26 mEq/L), indicating **uncompensated respiratory alkalosis** *Metabolic alkalosis* - This would be characterized by a high pH and an elevated **HCO3**, but the HCO3 is within the normal range (26 mEq/L) - While it causes alkalemia, the primary disturbance here is respiratory, not metabolic *Metabolic acidosis* - This would present with a **low pH** and a low **HCO3**, which is contrary to the given ABG values - The patient's pH is elevated, indicating an alkalotic state, not acidotic *Respiratory acidosis* - This would be defined by a **low pH** and an elevated **pCO2**, which is the exact opposite of the provided ABG results - The patient's high pH and low pCO2 rule out respiratory acidosis

Question 6: What is the function of the umbilical artery in fetal circulation?

A. Provide nutrients
B. None of the options
C. Carry oxygenated blood from the placenta to the fetus
D. Carry deoxygenated blood from the fetus to the placenta (Correct Answer)

Explanation: ***Carry deoxygenated blood from the fetus to the placenta*** - The **umbilical arteries** are responsible for transporting **deoxygenated blood** and waste products away from the fetal circulation to the placenta. - There are typically **two umbilical arteries** that branch off the internal iliac arteries of the fetus. *Provide nutrients* - **Nutrient delivery** to the fetus is primarily a function of the **umbilical vein**, which carries oxygenated and nutrient-rich blood from the placenta. - The umbilical arteries carry metabolic waste products away from the fetus, not nutrients to it. *None of the options* - This option is incorrect because one of the provided options accurately describes the function of the umbilical artery. - The specific role of the umbilical artery is distinct from other fetal circulatory components. *Carry oxygenated blood from the placenta to the fetus* - This function is performed by the **umbilical vein**, which brings **oxygen-rich blood** and nutrients from the placenta to the fetus. - The umbilical arteries carry blood in the opposite direction and with a different oxygenation status.