Anatomy
1 questionsWhich nucleus is primarily involved in the Papez circuit?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 221: Which nucleus is primarily involved in the Papez circuit?
- A. Pulvinar nucleus
- B. Intralaminar nucleus
- C. Anterior nucleus of the thalamus (Correct Answer)
- D. Ventral posterolateral (VPL) nucleus
Explanation: ***Anterior nucleus of the thalamus*** - The **anterior nucleus of the thalamus** is a key relay station in the Papez circuit [1], receiving input from the mamillary bodies and projecting to the cingulate gyrus. - This circuit is crucial for **memory formation** [2] and emotional processing. *Pulvinar nucleus* - The pulvinar nucleus is primarily involved in **visual processing**, attention, and eye movements. - It does not form a direct part of the classic Papez circuit for emotion and memory. *Intralaminar nucleus* - The intralaminar nuclei are involved in **arousal**, attention, and pain perception, with widespread projections to the cerebral cortex [1]. - They are not considered a primary component of the Papez circuit. *Ventral posterolateral (VPL) nucleus* - The VPL nucleus is a major **somatosensory relay** in the thalamus, transmitting touch, proprioception, and vibration information from the body to the cortex. - It has no direct role in the Papez circuit or limbic functions.
Internal Medicine
1 questionsCryoprecipitate is useful in which of the following conditions?
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 221: Cryoprecipitate is useful in which of the following conditions?
- A. Hemophilia A
- B. Thrombosthenia
- C. Warfarin reversal
- D. Afibrinogenemia (Correct Answer)
Explanation: ***Afibrinogenemia*** - Cryoprecipitate is rich in **fibrinogen**, factor VIII, factor XIII, von Willebrand factor, and fibronectin. It is the only blood product with a substantial concentration of fibrinogen. - **Afibrinogenemia** (or hypofibrinogenemia) is a condition characterized by low or absent levels of fibrinogen, a critical clotting factor that cryoprecipitate replaces effectively. *Hemophilia A* - Hemophilia A is a deficiency of **Factor VIII**. While cryoprecipitate contains factor VIII, **recombinant Factor VIII concentrates** are the preferred treatment due to better safety (reduced risk of viral transmission) and more precise dosing [1]. - Cryoprecipitate was historically used for Hemophilia A before the availability of safer, more specific factor concentrates [2]. *Thrombosthenia* - Thrombasthenia is a platelet function disorder characterized by defective **glycoprotein IIb/IIIa receptors** on platelets, leading to impaired platelet aggregation. - Cryoprecipitate does not contain platelets or factors that directly correct platelet function, making **platelet transfusions** the treatment of choice for severe bleeding in thrombasthenia. *Warfarin reversal* - Warfarin reversal is primarily achieved using **Vitamin K**, which restores levels of functional clotting factors II, VII, IX, and X. - For rapid reversal in emergencies, **prothrombin complex concentrate (PCC)** is preferred because it contains high concentrations of these vitamin K-dependent factors, addressing the primary deficiency caused by warfarin [1].
Pediatrics
1 questionsAt what age does the tonic neck reflex typically disappear?
NEET-PG 2013 - Pediatrics NEET-PG Practice Questions and MCQs
Question 221: At what age does the tonic neck reflex typically disappear?
- A. 1 month
- B. 2 months
- C. 3 months
- D. 4 months (Correct Answer)
Explanation: ***Correct Answer: 4 months*** - The **tonic neck reflex**, also known as the **asymmetrical tonic neck reflex (ATNR)**, typically disappears around **4 to 6 months of age**. - Persistence beyond this age can be a sign of **neurological dysfunction** and may interfere with motor development such as rolling or bringing hands to midline. *Incorrect: 1 month* - While the tonic neck reflex is present at 1 month, it does not typically disappear at this early stage. - At 1 month, infants are still relying on a variety of **primitive reflexes** for survival and early motor patterns. *Incorrect: 2 months* - The tonic neck reflex is still usually clearly present at 2 months of age. - This reflex contributes to early **eye-hand coordination** and helps develop unilateral body movements. *Incorrect: 3 months* - While starting to integrate, the tonic neck reflex is not fully integrated or gone by 3 months. - Its presence is normal at this age, and its integration is a gradual process as **voluntary motor control** emerges.
Pharmacology
3 questionsWhich of the following statements is true regarding omalizumab?
Which of the following is a second-generation beta blocker?
Which antiglaucomatous drug is known to cause spasm of accommodation?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 221: Which of the following statements is true regarding omalizumab?
- A. Anti-IgE
- B. Given subcutaneously
- C. Used as add-on therapy in moderate to severe asthma prophylaxis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** is correct because each statement is true: **Anti-IgE** - Omalizumab is a **humanized monoclonal antibody** that specifically targets and binds to **free IgE** in the circulation - By binding free IgE, it prevents IgE from attaching to **high-affinity receptors** on mast cells and basophils - This reduces the allergic cascade and prevents release of inflammatory mediators **Given subcutaneously** - Omalizumab is administered via **subcutaneous injection** only - Dosing is typically every **2 to 4 weeks** based on patient's body weight and baseline IgE levels - Not available in oral or intravenous formulations for asthma treatment **Used as add-on therapy in moderate to severe asthma prophylaxis** - FDA approved as **add-on maintenance treatment** for patients aged ≥6 years with **moderate to severe persistent allergic asthma** - Indicated when asthma is **inadequately controlled** with inhaled corticosteroids - Reduces frequency of asthma exacerbations and improves asthma control - Also approved for chronic spontaneous urticaria All three statements accurately describe omalizumab's mechanism, administration route, and clinical indication, making **"All of the options"** the correct answer.
Question 222: Which of the following is a second-generation beta blocker?
- A. Timolol
- B. Atenolol (Correct Answer)
- C. Nadolol
- D. Propranolol
Explanation: ***Atenolol*** - **Atenolol** is a **second-generation beta blocker** characterized by its **cardioselectivity**, meaning it primarily blocks beta-1 receptors in the heart. - This selectively reduces heart rate and contractility with fewer respiratory side effects compared to non-selective agents. *Propranolol* - **Propranolol** is a **first-generation non-selective beta blocker**, meaning it blocks both beta-1 and beta-2 adrenergic receptors. - Its non-selective action can cause significant bronchoconstriction, making it less suitable for patients with respiratory conditions. *Timolol* - **Timolol** is also a **first-generation non-selective beta blocker** commonly used in ophthalmic preparations for glaucoma. - It blocks both beta-1 and beta-2 receptors and does not possess the cardioselectivity of second-generation agents. *Nadolol* - **Nadolol** is another **first-generation non-selective beta blocker** with a long duration of action due to its extensive plasma half-life. - Like other first-generation agents, it lacks cardioselectivity and blocks both beta-1 and beta-2 receptors.
Question 223: Which antiglaucomatous drug is known to cause spasm of accommodation?
- A. Timolol
- B. Pilocarpine (Correct Answer)
- C. Dorzolamide
- D. Latanoprost
Explanation: ***Pilocarpine*** - **Pilocarpine** is a **direct-acting muscarinic agonist** that contracts the **ciliary muscle**. - Contraction of the ciliary muscle leads to **accommodation spasm** and a forward movement of the **iris-lens diaphragm**, which also helps to open the **trabecular meshwork**, facilitating aqueous outflow. *Timolol* - **Timolol** is a **beta-blocker** that reduces aqueous humor production by blocking beta-adrenergic receptors on the ciliary epithelium. - It does not directly affect the **ciliary muscle** or cause accommodation spasm. *Dorazolamide* - **Dorzolamide** is a **carbonic anhydrase inhibitor** that reduces aqueous humor production. - Its mechanism of action does not involve the ciliary body's mechanical action and therefore does not cause **accommodation spasm**. *Latanoprost* - **Latanoprost** is a **prostaglandin analog** that increases uveoscleral outflow of aqueous humor. - It does not directly affect the ciliary muscle's contraction or cause **accommodation spasm**.
Physiology
4 questionsWhat is the critical closing pressure in the context of capillary physiology?
All are true about baroreceptors, except?
Integration center of tonic labyrinthine reflex is?
What type of reflex is the righting reflex?
NEET-PG 2013 - Physiology NEET-PG Practice Questions and MCQs
Question 221: What is the critical closing pressure in the context of capillary physiology?
- A. Arterial pressure minus venous pressure
- B. Capillary pressure minus venous pressure
- C. Pressure below which capillaries close (Correct Answer)
- D. None of the options
Explanation: ***Pressure below which capillaries close*** - The **critical closing pressure** is the lowest pressure at which blood can flow through a capillary. - When the luminal pressure falls below this threshold, the capillary collapses due to **extrinsic tissue pressure** and intrinsic vascular tone. *Arterial pressure minus venous pressure* - This calculation represents the **arteriovenous pressure gradient**, which drives blood flow through a vascular bed. - It does not directly define the point at which capillaries collapse. *Capillary pressure minus venous pressure* - This difference primarily influences filtration and reabsorption of fluids across the capillary wall. - It is not directly related to the **critical closing pressure** of the capillaries. *None of the options* - This is incorrect as one of the provided options accurately defines the **critical closing pressure**.
Question 222: All are true about baroreceptors, except?
- A. Stimulated when BP decreases (Correct Answer)
- B. Stimulation causes increased vagal discharge
- C. Stimulate nucleus ambiguus
- D. Afferents are through sino-aortic nerves
Explanation: ***Stimulated when BP decreases*** - Baroreceptors are **stretch receptors** located in the walls of the carotid sinus and aortic arch. - They are stimulated by an **increase in blood pressure (BP)**, which causes stretching of the arterial walls, not by a decrease. *Afferents are through sino-aortic nerves* - This statement is **true**. Afferent impulses from the carotid sinus baroreceptors travel via the **glossopharyngeal nerve (IX)**, and those from the aortic arch baroreceptors travel via the **vagus nerve (X)**. - These nerves collectively form the **sino-aortic nerves** that relay information to the brainstem. *Stimulation causes increased vagal discharge* - This statement is **true**. When baroreceptors are stimulated by **increased BP**, they send signals to the cardiovascular center in the medulla. - This leads to increased **parasympathetic (vagal) outflow** to the heart, causing a decrease in heart rate and contractility, and inhibition of sympathetic outflow. *Stimulate nucleus ambiguus* - This statement is **true**. The **nucleus ambiguus** is a brainstem nucleus that contains the cell bodies of preganglionic parasympathetic neurons that contribute to the vagus nerve. - Baroreceptor stimulation leads to activation of the nucleus ambiguus, thereby increasing **vagal output** to the heart.
Question 223: Integration center of tonic labyrinthine reflex is?
- A. Spinal cord
- B. Medulla (Correct Answer)
- C. Midbrain
- D. Cerebral cortex
Explanation: ***Medulla*** - The **tonic labyrinthine reflex** is a primitive reflex originating in the **vestibular system**, specifically the otolith organs, which respond to head position changes. - Its integration center lies in the **medulla oblongata**, a part of the brainstem responsible for essential involuntary functions. *Spinal cord* - The spinal cord integrates simpler reflexes like **stretch reflexes** and **withdrawal reflexes**. - It does not process the complex vestibular input required for the tonic labyrinthine reflex. *Midbrain* - The **midbrain** is involved in integrating reflexes related to visual and auditory stimuli, such as the **startle reflex** and **pupillary light reflex**. - It is superior to the primary integration center for the tonic labyrinthine reflex. *Cerebral cortex* - The **cerebral cortex** is responsible for higher cognitive functions, voluntary movements, and conscious sensation. - Reflexes like the tonic labyrinthine reflex are subcortical and operate without conscious control.
Question 224: What type of reflex is the righting reflex?
- A. Postural reflex (Correct Answer)
- B. Spinal reflex
- C. Ocular reflex
- D. Stretch reflex
Explanation: ***Postural reflex*** - The **righting reflex** is a mechanism that helps an animal or human maintain or regain their upright body position or head orientation in space, which is a key component of **postural control**. - It involves complex inputs from the **vestibular system**, visual system, and proprioceptors to adjust muscle tone and body position against gravity. - Examples include **neck righting reflex**, **body righting reflex**, and **labyrinthine righting reflex**. *Stretch reflex* - A **stretch reflex** is a monosynaptic reflex that causes a muscle to contract in response to being stretched, primarily to maintain muscle length and tone. - It does not encompass the complex, multi-sensory integration required for maintaining overall body orientation. *Spinal reflex* - A **spinal reflex** is any reflex arc whose neural circuit passes through the spinal cord, and it can be either monosynaptic or polysynaptic. - While the righting reflex involves spinal cord components, it is a broader, more integrated reflex that extends beyond a simple spinal cord circuit. *Ocular reflex* - **Ocular reflexes** are involuntary eye movements or responses, such as pupillary light reflex or vestibulo-ocular reflex, that primarily control eye position or pupil size. - They do not directly relate to the maintenance of the entire body's upright posture.