Anatomy
3 questionsVertebral arteries of both sides unite to form
What anatomical structure does the pineal gland form part of?
Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 431: Vertebral arteries of both sides unite to form
- A. Anterior spinal artery
- B. Posterior spinal artery
- C. Medullary artery
- D. Basilar artery (Correct Answer)
Explanation: Basilar artery - The paired vertebral arteries ascend through the neck via the transverse foramina of cervical vertebrae and enter the skull through the foramen magnum. - At the level of the pontomedullary junction, the two vertebral arteries merge to form a single basilar artery. Anterior spinal artery - The anterior spinal artery is formed by the union of two small branches derived from each vertebral artery near their intracranial origin. - It supplies the anterior two-thirds of the spinal cord, running along the anterior median fissure. Posterior spinal artery - The posterior spinal arteries are typically two vessels, one arising from each vertebral artery (or less commonly from the posterior inferior cerebellar artery). - They supply the posterior one-third of the spinal cord and do not form a single major merged vessel in the brainstem. Medullary artery - There is no single major artery termed the "medullary artery" formed by the union of the vertebral arteries. - The medulla oblongata is supplied by branches directly from the vertebral arteries and the basilar artery, such as the posterior inferior cerebellar artery (PICA) and direct medullary branches.
Question 432: What anatomical structure does the pineal gland form part of?
- A. Part of the anterior wall of the third ventricle
- B. Part of the roof of the third ventricle (Correct Answer)
- C. Part of the floor of the third ventricle
- D. Part of the posterior wall of the third ventricle
Explanation: **_Part of the roof of the third ventricle_** - The **pineal gland** is a small, pinecone-shaped endocrine gland that forms part of the **roof of the third ventricle** [1]. - It is attached to the roof by the **pineal stalk** and projects posteriorly from the **epithalamus**. - The roof of the third ventricle consists of the **tela choroidea**, the **pineal gland**, and the **choroid plexus** [1]. - The pineal gland regulates circadian rhythms through **melatonin** secretion. *Part of the posterior wall of the third ventricle* - The **posterior wall** of the third ventricle is formed by the **posterior commissure**, the **pineal recess**, and the **habenular commissure**. - While the pineal gland is located posteriorly, it is anatomically classified as part of the roof, not the posterior wall itself. *Part of the anterior wall of the third ventricle* - The **anterior wall** is formed by the **lamina terminalis**, **anterior commissure**, and columns of the fornix. - This is located at the opposite end of the third ventricle from the pineal gland. *Part of the floor of the third ventricle* - The **floor** is formed by structures of the **hypothalamus**, including the **optic chiasm**, **tuber cinereum**, **infundibulum**, and **mammillary bodies**. - The pineal gland is situated dorsally (superiorly), not in the floor.
Question 433: Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
- A. Intralaminar
- B. Anterior
- C. Pulvinar (Correct Answer)
- D. None of the options
Explanation: ***Pulvinar*** - The **pulvinar nucleus** is the largest thalamic nucleus and has the most extensive **妥reciprocal connections** with the **association cortices** of the parietal, temporal, and occipital lobes. - It plays a crucial role in **visual attention**, integration of visual and other sensory information, and facilitating cortico-cortical communication. - The pulvinar is unique in its dense, bidirectional connectivity with higher-order association areas, distinguishing it from other thalamic nuclei. *Intralaminar* - **Intralaminar nuclei** (centromedian, parafascicular) project **diffusely and non-specifically** to widespread cortical areas and the striatum [1]. - They are involved in arousal, attention, and consciousness but lack the **specific, reciprocal connections** with association cortices that characterize the pulvinar. - Their projections are more related to generalized cortical activation rather than specific sensory or cognitive processing [1]. *Anterior* - The **anterior nuclear group** (anteromedial, anterodorsal, anteroventral) projects primarily to the **cingulate gyrus** as part of the limbic system [1]. - While the cingulate is cortical tissue, it is **limbic cortex** with specific emotional and memory functions, not association neocortex involved in higher-order sensory integration. - Receives input from mammillary bodies and is part of the Papez circuit for memory and emotion. *None of the options* - This is incorrect because the **pulvinar nucleus** has well-established, extensive reciprocal connections with association areas of the neocortex. - The pulvinar is considered a "higher-order" thalamic nucleus specifically connecting cortical areas to each other via the thalamus.
Biochemistry
1 questionsWhich protein hormone is often referred to as the 'guardian angel against obesity' due to its role in regulating metabolism?
NEET-PG 2013 - Biochemistry NEET-PG Practice Questions and MCQs
Question 431: Which protein hormone is often referred to as the 'guardian angel against obesity' due to its role in regulating metabolism?
- A. Adiponectin (Correct Answer)
- B. Fibronectin
- C. High-Density Lipoprotein (HDL)
- D. Insulin
Explanation: ***Adiponectin*** - **Adiponectin** is a hormone secreted by **adipose tissue** that plays a crucial role in regulating glucose and fatty acid metabolism, increasing **insulin sensitivity**, and decreasing inflammation. - Its levels are inversely correlated with body fat percentage; individuals with obesity tend to have lower adiponectin levels, leading to its nickname as the 'guardian angel against obesity'. *Fibronectin* - **Fibronectin** is a glycoprotein involved in cell adhesion, growth, migration, and differentiation, and is a key component of the **extracellular matrix**. - It does not primarily function in metabolic regulation or body weight control, unlike adiponectin. *High-Density Lipoprotein (HDL)* - **HDL** is a type of lipoprotein that transports cholesterol from peripheral tissues back to the liver, a process known as **reverse cholesterol transport**. - While beneficial for cardiovascular health, HDL is a lipid-carrying particle, not a protein hormone, and its primary role is not in metabolic regulation or direct obesity prevention. *Insulin* - **Insulin** is a peptide hormone produced by the pancreas that regulates carbohydrate and fat metabolism, primarily by facilitating glucose uptake from the blood into cells. - While essential for metabolism, high levels of insulin in the context of insulin resistance can contribute to obesity, rather than act against it.
Internal Medicine
1 questionsType 3 respiratory failure occurs due to ?
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 431: Type 3 respiratory failure occurs due to ?
- A. Post-operative atelectasis (Correct Answer)
- B. Kyphoscoliosis
- C. Flail chest
- D. Pulmonary fibrosis
Explanation: ***Post-operative atelectasis*** - **Type 3 respiratory failure**, also known as **perioperative respiratory failure**, is characterized by hypoxemia occurring typically after surgery. - **Atelectasis**, the collapse of lung tissue, is a common cause of hypoxemia in the post-operative period due to shallow breathing, pain, and anesthesia affecting lung volumes. *Kyphoscoliosis* - This condition leads to a **restrictive lung disease** due to chest wall deformity, causing chronic respiratory failure. [1] - It more typically results in **Type 2 respiratory failure** (hypercapnic) due to impaired ventilation over time. [1] *Flail chest* - Flail chest is a severe chest wall injury causing paradoxical movement, leading to **acute respiratory failure**. - It is often associated with **Type 1 (hypoxemic)** or **Type 2 (hypercapnic)** respiratory failure due to trauma-induced lung injury and impaired mechanics. *Pulmonary fibrosis* - This is a progressive interstitial lung disease causing **restrictive ventilatory defect** and impaired gas exchange. - It leads to chronic **Type 1 respiratory failure** (hypoxemic) as the lung tissue becomes stiff and scarred.
Pharmacology
3 questionsWhat is the mechanism of action of Warfarin?
Which of the following is a parenteral direct thrombin inhibitor?
Which of the following drugs inhibits the activation of plasminogen?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 431: What is the mechanism of action of Warfarin?
- A. Inhibition of Vitamin K epoxide reductase (Correct Answer)
- B. Inhibition of gamma glutamyl carboxylase
- C. Activation of Vitamin K epoxide reductase
- D. Activation of gamma glutamyl carboxylase
Explanation: ***Inhibition of Vitamin K epoxide reductase*** - Warfarin blocks **Vitamin K epoxide reductase (VKORC1)** [1, 2, 3], an enzyme essential for recycling oxidized vitamin K into its active reduced form [1, 3]. - This reduction prevents the activation of **vitamin K-dependent clotting factors** (II, VII, IX, X), leading to anticoagulation [1, 3]. *Inhibition of gamma glutamyl carboxylase* - **Gamma-glutamyl carboxylase** uses reduced vitamin K as a cofactor to carboxylate specific glutamic acid residues on clotting factors [1, 3]. - While essential for clotting factor activation, this enzyme itself is **not directly inhibited by warfarin** [1, 3]. *Activation of Vitamin K epoxide reductase* - Activating **VKORC1** would increase the production of reduced vitamin K, thereby **promoting coagulation** rather than inhibiting it [1, 2]. - This is the opposite of warfarin's intended therapeutic effect. *Activation of gamma glutamyl carboxylase* - Activating **gamma-glutamyl carboxylase** would enhance the carboxylation and activation of **clotting factors**, leading to procoagulant effects [1, 3]. - This mechanism contradicts warfarin's role as an **anticoagulant**.
Question 432: Which of the following is a parenteral direct thrombin inhibitor?
- A. Ximelagatran
- B. Dabigatran
- C. Argatroban (Correct Answer)
- D. Heparin
Explanation: ***Argatroban*** - **Argatroban** is a **synthetic direct thrombin inhibitor** administered exclusively via **intravenous infusion**, making it a parenteral drug. - It does not require antithrombin for its action and is primarily used in patients with **heparin-induced thrombocytopenia (HIT)**. *Ximelagatran* - **Ximelagatran** was an **oral direct thrombin inhibitor** but was withdrawn from the market due to concerns about severe **liver toxicity**. - As an oral drug, it is not a parenteral medication. *Dabigatran* - **Dabigatran** is a **direct thrombin inhibitor** that is administered **orally** in capsule form (as dabigatran etexilate, a prodrug). - Therefore, it is not a parenteral medication. *Heparin* - **Heparin** is an **indirect thrombin inhibitor** because it requires binding to **antithrombin** to exert its anticoagulant effect. - Although administered parenterally, its mechanism of action is indirect.
Question 433: Which of the following drugs inhibits the activation of plasminogen?
- A. Streptokinase
- B. Aminocaproic acid (Correct Answer)
- C. Reteplase
- D. Clopidogrel
Explanation: ***Correct Option: Aminocaproic acid*** - **Aminocaproic acid** is an antifibrinolytic drug that acts by competitively inhibiting the activation of **plasminogen** to plasmin. - By preventing the formation of plasmin, it stabilizes blood clots and is used to treat excessive bleeding. *Incorrect Option: Streptokinase* - **Streptokinase** is a **thrombolytic agent** that forms a complex with plasminogen, converting uncomplexed plasminogen into plasmin. - This action promotes the degradation of fibrin clots, making it a **fibrinolytic drug**, not an inhibitor of plasminogen activation. *Incorrect Option: Reteplase* - **Reteplase** is a **recombinant tissue plasminogen activator (tPA)** that directly converts plasminogen to plasmin. - This drug actively promotes **fibrinolysis** and clot breakdown, making it a thrombolytic agent. *Incorrect Option: Clopidogrel* - **Clopidogrel** is an **antiplatelet drug** that inhibits platelet aggregation by irreversibly blocking the P2Y12 adenosine diphosphate (ADP) receptor on platelets. - Its mechanism of action is focused on **platelet function**, not on the plasminogen-plasmin system.
Physiology
2 questionsFever increases water loss by how much for each degree Celsius increase in body temperature?
What is the minimum fluid urine output for neutral solute balance?
NEET-PG 2013 - Physiology NEET-PG Practice Questions and MCQs
Question 431: Fever increases water loss by how much for each degree Celsius increase in body temperature?
- A. 100 ml/day
- B. 200 ml/day (Correct Answer)
- C. 400 ml/day
- D. 800 ml/day
Explanation: ***200 ml/day*** - For every 1-degree Celsius (or 1.8-degree Fahrenheit) increase in body temperature, there is an approximate **200 ml increase in insensible water loss** per day due to increased metabolism and sweating. - This value highlights the importance of **adequate fluid replacement** in febrile patients to prevent dehydration. *100 ml/day* - This value is **insufficient** to account for the increased insensible fluid losses associated with fever. - Using this estimate could lead to **underestimation of fluid requirements** and potential dehydration in febrile patients. *400 ml/day* - This value is **higher than the typical estimated increase** in water loss per degree Celsius of fever. - While extreme fever might cause higher losses, 200 ml/day is the standard clinical approximation for a 1-degree rise. *800 ml/day* - This value represents a **significant overestimation** of the fluid loss per degree Celsius increase in fever. - Such a high estimate would generally be seen only in very severe conditions or with much larger temperature increases.
Question 432: What is the minimum fluid urine output for neutral solute balance?
- A. 300 ml
- B. 750 ml
- C. 500 ml
- D. 400 ml (Correct Answer)
Explanation: ***400 ml*** - The kidneys must excrete approximately **600 mOsm of solutes daily** to maintain neutral solute balance. - With a maximum urine concentrating ability of **1200-1400 mOsm/L**, the minimum volume required is calculated as: 600 mOsm ÷ 1400 mOsm/L = **428 ml**. - Therefore, **400 ml** is the conventionally accepted minimum urine output for neutral solute balance. - Below this volume, even with maximal concentration, solute excretion would be inadequate. *300 ml* - **300 ml** would be insufficient to excrete the 600 mOsm daily solute load even at maximal concentration (300 × 1400 = 420 mOsm only). - This volume would lead to accumulation of solutes and **azotemia** (elevated BUN and creatinine). *500 ml* - While **500 ml** would certainly be adequate for solute excretion, it exceeds the calculated minimum of ~428 ml. - The question asks for the *minimum* volume, making **400 ml** the more precise answer according to standard textbooks. *750 ml* - **750 ml** is well above the minimum required for neutral solute balance. - This volume represents normal physiological urine output but is not the minimum threshold for maintaining solute balance.