NEET-PG 2015 Practice Questions

Q: What structure passes through the quadrangular space?

Axillary nerve. Axillary nerve - The axillary nerve and the posterior circumflex humeral artery are the primary structures that pass through the quadrangular space. - Compression or injury within this space can lead to deficits in the axillary nerve's distribution, affecting the deltoid and teres minor muscles. *Radial nerve* - The radial nerve passes through the triangular interval, not the quadrangular space. - It supplies the triceps muscle and all muscles in the posterior compartment of the forearm. *Median nerve* - The median nerve travels through the cubital fossa and then down the anterior forearm, supplying most of the forearm flexors and some hand muscles. - It does not pass through any of the posterior axillary spaces. *Brachial Artery* - The brachial artery is the main arterial supply to the arm and runs anteriorly in the arm, deep to the biceps brachii muscle. - It does not pass through the quadrangular space; rather, the posterior circumflex humeral artery (a branch of the axillary artery) traverses this space.

Q: Which of the following structures does NOT pass through Calot's triangle?

Portal vein. ***Portal vein*** - The **portal vein** is located within the **porta hepatis** and does not pass through Calot's triangle, making it the correct answer to this question. - It carries venous blood from the **gastrointestinal tract** and **spleen** to the liver and is positioned medial and posterior to the structures within Calot's triangle. *Right hepatic artery* - The **right hepatic artery** is a key structure that passes through Calot's triangle and forms one of its boundaries. - It typically gives rise to the **cystic artery** within or near the triangle, making it an important anatomical landmark during **cholecystectomy**. *Lymph node of Lund* - The **lymph node of Lund** (cystic lymph node) is consistently found within Calot's triangle and serves as an important landmark. - Its presence helps surgeons identify the **boundaries of the triangle** and assess for inflammation or malignancy related to the gallbladder. *Cystic artery* - The **cystic artery** is a consistent structure within Calot's triangle, typically arising from the **right hepatic artery**. - It is routinely **ligated during cholecystectomy** and is one of the key structures surgeons must identify within the triangle.

Q: Spleniculi are most commonly found in which of the following locations?

Hilum of the spleen. No relevant citations could be added to the explanation as the provided text passages did not contain information regarding spleniculi (accessory spleens), their location, or their embryology. ***Hilum of the spleen*** - **Spleniculi** (accessory spleens) are most commonly found at the **hilum of the spleen**, accounting for approximately **75% of cases**. - During **embryonic development**, the spleen forms from mesenchymal tissue in the dorsal mesogastrium, and small fragments of splenic tissue can separate and persist as accessory spleens. - The **splenic hilum** is the most frequent location due to the close proximity during development, followed by the gastrosplenic ligament, tail of pancreas, and greater omentum. - Accessory spleens are found in **10-30% of the population** and are clinically significant in conditions requiring complete splenectomy (e.g., ITP, hereditary spherocytosis). *Colon* - The colon is part of the **gastrointestinal tract** with a completely different embryological origin (endodermal). - Splenic tissue development occurs in the **dorsal mesogastrium** (mesodermal origin), making the colon an anatomically and embryologically implausible location for spleniculi. *Liver* - The liver develops from the **ventral foregut endoderm** and is anatomically distant from the spleen's developmental region. - **Splenosis** (traumatic implantation) could theoretically occur, but congenital spleniculi in the liver are exceptionally rare and not a recognized common location. *Lungs* - The lungs are part of the **respiratory system**, developing from the foregut endoderm in the thoracic cavity. - There is no embryological connection between lung and splenic tissue development, making this an impossible location for congenital accessory spleens.

Q: Trigone of bladder is derived from?

Mesonephric duct. The trigone of the bladder is formed from the caudal ends of the **mesonephric ducts**, which are absorbed into the primitive bladder wall [1]. This mesenchymal origin explains why the trigone has a smooth lining [1] and is less prone to infection compared to the rest of the bladder. *Paramesonephric duct* - The **paramesonephric ducts** (Müllerian ducts) are involved in forming the female reproductive organs, specifically the fallopian tubes, uterus [2], and upper vagina. - They do not contribute to the formation of the urinary bladder or its trigone. *Absorbed anal membrane* - The **anal membrane** separates the endoderm-derived hindgut from the ectoderm-derived anal pit. - Its absorption is relevant to the development of the anus, not the urinary bladder. *Mullerian duct* - The **Müllerian ducts** are synonymous with the paramesonephric ducts and are primarily involved in the development of the female reproductive tract [2]. - They play no role in the development of the urinary bladder or its trigone.

Q: Which type of glial cell is derived from mesodermal origin?

Microglial cells. ***Microglial cells*** - **Microglial cells** are unique among glial cells as they originate from **mesoderm**, specifically from **monocyte/macrophage precursors** in the bone marrow [1]. - They function as the **immune cells of the central nervous system (CNS)**, scavenging for plaques, damaged neurons, and infectious agents [1]. *Macroglial cells* - This is a broad category that includes **astrocytes, oligodendrocytes, and ependymal cells**, all of which are derived from **neuroectoderm**, not mesoderm [1]. - They perform various supportive roles but are distinct in origin from microglial cells [1]. *Oligodendrocytes* - **Oligodendrocytes** are derived from **neuroectoderm** and are responsible for forming the **myelin sheath** around axons in the CNS [2]. - Myelination is crucial for rapid and efficient nerve impulse conduction. *Ependymal cells* - **Ependymal cells** are derived from **neuroectoderm** and line the **ventricles of the brain** and the **central canal of the spinal cord**. - They play a role in the production and circulation of **cerebrospinal fluid (CSF)**.

Q: Epinephrine increases free fatty acid levels by causing which of the following?

Increasing lipolysis. ***Increasing lipolysis*** - Epinephrine activates **hormone-sensitive lipase** in adipose tissue through a **cAMP-dependent mechanism**, leading to the breakdown of stored triglycerides into free fatty acids and glycerol. - This process, known as **lipolysis**, directly increases the release of free fatty acids into the bloodstream. *Increased fatty acid synthesis* - **Fatty acid synthesis** is a process that builds fatty acids, which would decrease, not increase, free fatty acid levels in the blood. - Epinephrine's primary action is to mobilize energy reserves, which involves breaking down stored fats rather than synthesizing new ones. *Increasing cholesterol catabolism* - While cholesterol metabolism is important, epinephrine does not directly or significantly increase **cholesterol catabolism** as a primary mechanism for raising free fatty acid levels. - The catabolism of cholesterol primarily involves its conversion to bile acids and steroid hormones, which is distinct from fatty acid release. *None of the options* - This option is incorrect because increasing lipolysis is a direct and well-established mechanism by which epinephrine raises free fatty acid levels.

Q: How many molecules of Acetyl CoA are produced from β-oxidation of palmitic acid?

8 acetyl CoA. ***8 acetyl CoA*** - Palmitic acid is a **16-carbon saturated fatty acid (C16:0)**. During β-oxidation, each cycle cleaves two carbons as **acetyl CoA**. - The formula for acetyl CoA produced is **n/2**, where n = number of carbons. For palmitic acid: 16/2 = **8 acetyl CoA molecules**. - Alternatively: Palmitic acid undergoes **7 cycles of β-oxidation** [(n/2) - 1 = 7], each producing 1 acetyl CoA (7 total), plus the final 2-carbon fragment forming the 8th acetyl CoA. *3 acetyl CoA* - This number is too low for a 16-carbon fatty acid. **Short-chain fatty acids** would produce fewer acetyl CoA molecules. - This value corresponds to β-oxidation of a **6-carbon fatty acid** (hexanoic acid), not palmitic acid. *6 acetyl CoA* - This number is also too low for a 16-carbon fatty acid. - This quantity would be produced from a **12-carbon fatty acid** (lauric acid), not palmitic acid. *16 Acetyl CoA* - This number is too high and would incorrectly imply that each carbon forms an acetyl CoA independently. - Sixteen acetyl CoA molecules would be produced from a **32-carbon fatty acid**, which is extremely rare in biological systems.

Q: What primarily forms the core of chylomicrons?

Triglycerides. ***Triglycerides*** - Chylomicrons are primarily responsible for transporting **dietary triglycerides** from the intestines to other tissues. - Their large core, composed mainly of **triglycerides**, allows efficient transport of these hydrophobic molecules. *Triglycerides and Cholesterol together* - While **cholesterol** is present in chylomicrons, it is less abundant than **triglycerides** and primarily exists as **cholesterol esters** in the core. - The core is not an equal mixture; **triglycerides** overwhelmingly dominate the volume. *Free fatty acids* - **Free fatty acids** are transported in the blood primarily bound to **albumin**, not within the core of chylomicrons. - Chylomicrons typically carry **esterified fatty acids** as part of triglycerides. *Triglyceride, Cholesterol and Phospholipids* - **Phospholipids** form the outer monolayer of the chylomicron, along with apoproteins, making them **amphipathic**. - They do not constitute a core component but rather the **surface interface** with the aqueous environment.

Q: Energy source used by brain in later days of starvation is

Ketone bodies. ***Ketone bodies*** - During **prolonged starvation**, the liver produces **ketone bodies** (acetoacetate and β-hydroxybutyrate) from fatty acid breakdown. - The brain adapts to utilize these ketone bodies as a primary energy source, reducing its reliance on **glucose**. *Glucose* - While **glucose** is the primary energy source for the brain under normal conditions, its availability diminishes significantly during prolonged starvation. - The brain attempts to conserve glucose for essential functions by switching to alternative fuels. *Glycogen* - The brain stores very limited amounts of **glycogen**, which are rapidly depleted within minutes of glucose deprivation. - It is not a sustainable or significant energy source during extended periods of starvation. *Fatty acids* - **Fatty acids** cannot directly cross the **blood-brain barrier** to a significant extent, thus they are not a direct fuel source for brain cells. - They are, however, used by the liver to synthesize ketone bodies, which then serve as brain fuel.

Question 1

What structure passes through the quadrangular space?

Accepted Answer

Axillary nerve

Answer

Radial nerve

Answer

Median nerve

Answer

Brachial Artery

Question 2

Which of the following structures does NOT pass through Calot's triangle?

Accepted Answer

Portal vein

Answer

Right hepatic artery

Answer

Lymph node of Lund

Answer

Cystic artery

Question 3

Spleniculi are most commonly found in which of the following locations?

Accepted Answer

Hilum of the spleen

Answer

Colon

Answer

Liver

Answer

Lungs

Question 4

Trigone of bladder is derived from?

Accepted Answer

Mesonephric duct

Answer

Paramesonephric duct

Answer

Absorbed anal membrane

Answer

Mullerian duct

Question 5

Which type of glial cell is derived from mesodermal origin?

Accepted Answer

Microglial cells

Answer

Macroglial cells

Answer

Oligodendrocytes

Answer

Ependymal cells

Question 6

Epinephrine increases free fatty acid levels by causing which of the following?

Accepted Answer

Increasing lipolysis

Answer

Increasing fatty acid synthesis

Answer

Increasing cholesterol catabolism

Answer

None of the options

Question 7

How many molecules of Acetyl CoA are produced from β-oxidation of palmitic acid?

Accepted Answer

8 acetyl CoA

Answer

3 acetyl CoA

Answer

16 Acetyl CoA

Answer

6 acetyl CoA

Question 8

What primarily forms the core of chylomicrons?

Accepted Answer

Triglycerides

Answer

Triglycerides and Cholesterol together

Answer

Free fatty acids

Answer

Triglyceride, Cholesterol and Phospholipids

Question 9

Energy source used by brain in later days of starvation is

Accepted Answer

Ketone bodies

Answer

Glucose

Answer

Glycogen

Answer

Fatty acids

Question 10

Which of the following statements about Niemann-Pick disease is false?

Accepted Answer

Type B Niemann-Pick disease is characterized by severe neurological symptoms.

Answer

Due to deficiency of sphingomyelinase.

Answer

CNS symptoms are present in type A.

Answer

Histiocytes show PAS positive inclusions, and Type A is more severe.

NEET-PG 2015

Anatomy

Biochemistry

Pathology