Anatomy
3 questionsA surgeon removes a part of the liver located to the left of the falciform ligament. Which segments of the liver are removed?
What is the number of muscles in the middle ear?
Which of the following is NOT a content of the occipital triangle?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 271: A surgeon removes a part of the liver located to the left of the falciform ligament. Which segments of the liver are removed?
- A. Segments I & IV
- B. Segments V & VI
- C. Segments VII & VIII
- D. Segments II & III (Correct Answer)
Explanation: ***Segments II & III*** - The liver segments are defined by their **vascular supply** originating from the **portal vein** and **hepatic artery**, and their **biliary drainage** [1]. - The **falciform ligament** separates the **left lobe** of the liver into **medial** and **lateral** sections. The portion to its left corresponds to the lateral left lobe, which includes **segments II and III** [1, 2]. *Segments I & IV* - **Segment I** (`caudate lobe`) is located **posteriorly**, independent of the falciform ligament, and is supplied by both the left and right portal and hepatic arterial systems [1]. - **Segment IV** (`quadrate lobe`) is part of the **medial left lobe** and is situated to the **right of the falciform ligament** [1]. *Segments V & VI* - These segments are located in the **right lobe** of the liver, which is to the **right of the main portal fissure**, and are not associated with the falciform ligament's immediate left. - **Segment V** is **anterior** and **inferior**, and **Segment VI** is **posterior** and **inferior** within the right lobe. *Segments VII & VIII* - These segments are also located in the **right lobe** of the liver, specifically in the **superior** aspects [1]. - **Segment VII** is **posterior** and **superior**, while **Segment VIII** is **anterior** and **superior** in the right lobe, far from the falciform ligament.
Question 272: What is the number of muscles in the middle ear?
- A. One
- B. Two (Correct Answer)
- C. Three
- D. Four
Explanation: ***Two*** - The middle ear houses two muscles: the **tensor tympani** and the **stapedius muscle** [1]. - These muscles play a crucial role in the **acoustic reflex**, protecting the inner ear from loud sounds. *One* - This option is incorrect as there are two muscles, not one, involved in middle ear function [1]. - Specifying one muscle would neglect the complementary role of the other in the acoustic reflex. *Three* - This option is incorrect because the middle ear only contains two muscles [1]. - There are no additional muscles associated with the ossicles or tympanic membrane. *Four* - This option is incorrect as the middle ear is only comprised of the **tensor tympani** and **stapedius** muscles [1]. - The number four is not associated with the muscular anatomy of the middle ear.
Question 273: Which of the following is NOT a content of the occipital triangle?
- A. Lesser occipital nerve
- B. Occipital artery
- C. Suprascapular nerve (Correct Answer)
- D. Great auricular nerve
Explanation: Suprascapular nerve - The **suprascapular nerve** originates from the brachial plexus and supplies the supraspinatus and infraspinatus muscles; it travels through the suprascapular notch and is not found within the occipital triangle. - Its primary course and innervation are associated with the shoulder, entirely separate from the neck region defining the occipital triangle. *Great auricular nerve* - The **great auricular nerve** emerges from the cervical plexus and supplies sensory innervation to the skin over the parotid gland, mastoid process, and auricle, courses superficially across the sternocleidomastoid in the region of the occipital triangle. - It is a recognized content of the posterior triangle of the neck, which encompasses the occipital triangle. *Lesser occipital nerve* - The **lesser occipital nerve** arises from the cervical plexus at C2 and C3, providing sensory innervation to the skin of the neck and scalp posterior to the auricle. - It ascends along the posterior border of the sternocleidomastoid muscle, placing it within the boundaries of the occipital triangle. *Occipital artery* - The **occipital artery** is a branch of the external carotid artery that supplies blood to the posterior scalp. - It traverses the apex of the posterior triangle (including the occipital triangle) as it ascends to the back of the head.
Biochemistry
1 questionsGlucagon stimulates
NEET-PG 2013 - Biochemistry NEET-PG Practice Questions and MCQs
Question 271: Glucagon stimulates
- A. Gluconeogenesis (Correct Answer)
- B. Glycogenesis
- C. Fatty acid synthesis
- D. Glycolysis
Explanation: ***Gluconeogenesis*** - **Glucagon** is a hormone that primarily acts to raise **blood glucose levels** by stimulating the production of glucose from non-carbohydrate sources. - This process, **gluconeogenesis**, occurs mainly in the liver and is initiated by glucagon to counteract hypoglycemia. *Glycogenesis* - **Glycogenesis** is the process of synthesizing **glycogen** from glucose and is primarily stimulated by insulin when blood glucose levels are high. - Glucagon's role is to *inhibit* glycogen synthesis and instead promote glycogen breakdown. *Fatty acid synthesis* - **Fatty acid synthesis** is an anabolic process that primarily occurs when there is an excess of energy and glucose, often stimulated by **insulin**. - Glucagon generally has an **inhibitory effect** on fatty acid synthesis, as its main goal is to mobilize energy stores, not create them. *Glycolysis* - **Glycolysis** is the breakdown of glucose to produce energy, and it is stimulated when glucose is abundant and energy is needed. - Glucagon primarily acts to *inhibit* glycolysis in the liver, thereby conserving glucose for use by other tissues and promoting its release into the bloodstream.
Internal Medicine
3 questionsWhich of the following is NOT a feature of Peutz-Jeghers syndrome?
What is the most common location of gastrinoma?
Which of the following does not synthesize von Willebrand factor?
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 271: Which of the following is NOT a feature of Peutz-Jeghers syndrome?
- A. Mucocutaneous pigmentation
- B. Autosomal recessive inheritance (Correct Answer)
- C. Autosomal dominant
- D. Hamartomatous polyp
Explanation: ***High risk of malignancy*** - Peutz-Jeghers syndrome is primarily associated with **benign hamartomatous polyps**, not a **high risk of malignancy**, which distinguishes it from other syndromes. - Although patients may develop cancers [1], the syndrome itself does not inherently denote a high malignancy risk like other syndromes such as familial adenomatous polyposis. *Autosomal dominant* - This syndrome is indeed **autosomal dominant**, caused by mutations in the STK11 gene. - Families with this condition typically show **vertical transmission**, characteristic of autosomal dominant inheritance. *Hamartomatous polyp* - Individuals with Peutz-Jeghers syndrome develop **hamartomatous polyps**, which are a hallmark feature of the condition [1]. - These polyps can occur in the gastrointestinal tract and are benign lesions rather than adenomatous type seen in other syndromes [1]. *Mucocutaneous pigmentation* - Mucocutaneous pigmentation, such as **freckling around the lips and buccal mucosa**, is a key clinical feature of Peutz-Jeghers syndrome. - This pigmentation usually appears in childhood and is often a distinguishing sign of the syndrome.
Question 272: What is the most common location of gastrinoma?
- A. Pancreas
- B. Duodenum (Correct Answer)
- C. Jejunum
- D. Gall bladder
Explanation: ***Duodenum*** - The **duodenum** is the most common site for gastrinomas, accounting for over **half of all cases**, particularly in sporadic gastrinoma and Zollinger-Ellison syndrome. - These tumors are often **small** and **multiple** in the duodenum, making them challenging to locate. *Pancreas* - Pancreatic gastrinomas are also common, representing approximately **25-40% of cases**, but are less frequent than duodenal gastrinomas. - Pancreatic gastrinomas tend to be **larger** and more amenable to surgical resection when compared to duodenal gastrinomas. *Jejunum* - Gastrinomas found in the jejunum are **rare**, accounting for only a small percentage of cases. - The small intestine distal to the duodenum is an **uncommon site** for primary gastrinoma formation. *Gall bladder* - The **gallbladder** is not a typical location for gastrinoma development. - Gastrinomas are neuroendocrine tumors that arise from **gastrin-producing cells**, which are not found in the gallbladder.
Question 273: Which of the following does not synthesize von Willebrand factor?
- A. Endothelial cells
- B. Hepatocytes (Correct Answer)
- C. Megakaryocytes
- D. None of the options
Explanation: ***Hepatocytes*** - Von Willebrand factor (vWF) is primarily synthesized by **endothelial cells** and **megakaryocytes** [1], not hepatocytes. - Hepatocytes are responsible for synthesizing other proteins like **clotting factors**, but not vWF. *Megakaryoctyes* - Megakaryocytes play a crucial role in the synthesis of **platelet-derived factors**, including von Willebrand factor (vWF) [1]. - They release vWF into the bloodstream, facilitating platelet adhesion, especially in vascular injury sites. *None* - The option implies all listed cell types synthesize vWF, which is incorrect, as **only endothelial cells and megakaryocytes** produce it [1]. - Suggests a misunderstanding of the synthesis of coagulation-related factors, as hepatocytes do not produce vWF. *Endothelial cells* - Endothelial cells are the primary source of **von Willebrand factor** [1], releasing it to assist in platelet aggregation and clotting. - They are essential for the body's response to vascular injury, facilitating hemostasis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 669-670.
Pharmacology
2 questionsWhich drug has the highest plasma protein binding?
What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 271: Which drug has the highest plasma protein binding?
- A. Warfarin (Correct Answer)
- B. Verapamil
- C. Aspirin
- D. GTN
Explanation: ***Warfarin*** - **Warfarin** exhibits very **high plasma protein binding**, typically greater than 99%, primarily to albumin. - This high binding capacity means that only a small fraction of the drug is free and pharmacologically active. - Due to high protein binding, warfarin is susceptible to drug interactions when displaced from albumin. *Verapamil* - **Verapamil** has a relatively high plasma protein binding, around 90%, but it is not as high as warfarin. - Its binding is predominantly to **albumin** and alpha-1-acid glycoprotein. *Aspirin* - **Aspirin** (acetylsalicylic acid) has moderate plasma protein binding, usually between 50-90%, depending on the dosage. - It binds to **albumin** and can displace other protein-bound drugs. *GTN* - **Glyceryl trinitrate (GTN)** has moderate plasma protein binding, approximately 60%. - Its rapid onset and short duration of action are primarily due to its extensive first-pass metabolism and quick redistribution, rather than protein binding characteristics.
Question 272: What is the mechanism of metabolism for alcohol, aspirin, and phenytoin at high doses?
- A. First pass kinetics
- B. First order kinetics
- C. Zero order kinetics (Correct Answer)
- D. Second order kinetics
Explanation: ***Zero order kinetics*** - This mechanism occurs when the **metabolic enzymes become saturated at high drug concentrations**, leading to a constant amount (not a constant percentage) of drug being eliminated per unit time. - Alcohol, aspirin, and phenytoin are examples of drugs that exhibit **saturable metabolism**, transitioning from first-order to zero-order kinetics at higher doses. *First pass kinetics* - This describes the **metabolism of a drug by the liver or gut wall enzymes before it reaches systemic circulation** after oral administration. - While relevant to the oral bioavailability of these drugs, it does not describe the specific mechanism of elimination at high doses. *First order kinetics* - In this mechanism, a **constant fraction or percentage of the drug is eliminated per unit of time**, meaning the rate of elimination is directly proportional to the drug concentration. - Most drugs follow first-order kinetics at therapeutic doses because metabolizing enzymes are not saturated. *Second order kinetics* - This is a **less common pharmacokinetic model** where the rate of elimination is proportional to the square of the drug concentration or involves two reactants. - It does not typically describe the common elimination patterns of most drugs, including alcohol, aspirin, and phenytoin.
Physiology
1 questionsMechanism of action of cholecystokinin?
NEET-PG 2013 - Physiology NEET-PG Practice Questions and MCQs
Question 271: Mechanism of action of cholecystokinin?
- A. Activation of adenylyl cyclase
- B. Opening of ion channels
- C. Through IP3- DAG system (Correct Answer)
- D. Transcription factors
Explanation: ***Through IP3- DAG system*** - Cholecystokinin (CCK) primarily acts via **Gq protein-coupled receptors**, leading to the activation of **phospholipase C**. - This activation results in the hydrolysis of **PIP2 into IP3 and DAG**, which then mediate intracellular signaling cascades, causing actions like gallbladder contraction and pancreatic enzyme secretion. *Activation of adenylyl cyclase* - This mechanism is typically associated with **Gs protein-coupled receptors**, leading to increased levels of **cyclic AMP (cAMP)**. - Hormones like **glucagon** and **epinephrine** often utilize this pathway, which is distinct from CCK's primary signaling. *Opening of ion channels* - While ion channels are crucial for many cellular processes, CCK's direct mechanism of action typically involves **intracellular second messengers** rather than direct gating of ion channels. - Neurotransmitters like **acetylcholine** can directly open ion channels, but this is not the main signaling pathway for CCK. *Transcription factors* - Transcription factors regulate **gene expression** by binding to DNA, which is a slower, more long-term cellular response. - While CCK can eventually influence gene expression, its direct and immediate effects (e.g., gallbladder contraction) are mediated by **rapid second messenger systems**, not primary transcription factor modulation.