Anatomy
4 questionsAt which level do the somites initially form?
Double inferior vena cava is formed due to?
Which muscle is derived from the third pharyngeal arch?
Collecting part of kidney develops from ?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 71: At which level do the somites initially form?
- A. Lumbar level
- B. Sacral level
- C. Cervical level (Correct Answer)
- D. Thoracic level
Explanation: Cervical level - Somites, which are segmented blocks of paraxial mesoderm, initially appear in the **occipital/cranial cervical region** of the developing embryo around day 20 of development. - The first somite pair forms at the **occipital level**, and subsequent somites develop in a **cranio-caudal sequence**. - Development proceeds both cranially (forming occipital somites) and caudally (forming cervical, thoracic, lumbar, and sacral somites) from this initial formation. - By the end of the 5th week, approximately **42-44 somite pairs** are present. *Thoracic level* - Thoracic somites form subsequent to the initial occipital/cervical somites, as the segmentation process extends caudally. - The formation of somites is a sequential process along the **cranio-caudal axis**. *Lumbar level* - Lumbar somites develop later in the embryological timeline, after the cervical and thoracic regions have undergone somite formation. - The **caudal regions** receive somites progressively as development continues. *Sacral level* - Sacral somites are among the last to form, representing the caudal extent of somite development. - Their formation follows the cranio-caudal progression of somite appearance.
Question 72: Double inferior vena cava is formed due to?
- A. Persistence of both supracardinal and subcardinal veins
- B. Persistence of sacrocardinal veins
- C. Persistence of subcardinal veins
- D. Persistence of supracardinal veins (Correct Answer)
Explanation: ***Persistence of supracardinal veins*** - A double inferior vena cava (IVC) results from the **persistence of the left supracardinal vein**, which normally regresses. - This malformation causes the IVC to be duplicated below the level of the renal veins, creating two parallel venous channels ascending to join the normal IVC or renal veins. *Persistence of sacrocardinal veins* - The sacrocardinal veins are involved in the development of the **iliac veins** and the distal part of the IVC, but their independent persistence does not lead to a double IVC. - Abnormalities in sacrocardinal vein development are more commonly associated with conditions like **agenesis of the infrarenal IVC**. *Persistence of subcardinal veins* - The subcardinal veins mainly contribute to the formation of the **renal segment** of the IVC and the gonadal veins. - Their persistence or malformation can lead to a **retrocaval ureter** or other venous anomalies, but not a double IVC. *Persistence of both supracardinal and subcardinal veins* - While both supracardinal and subcardinal veins are crucial for IVC development, their **simultaneous persistence** in a way that creates a double IVC is not the direct mechanism [1]. - A double IVC is specifically attributed to the **persistence of the left supracardinal vein**, with the right supracardinal vein forming the normal right IVC [1].
Question 73: Which muscle is derived from the third pharyngeal arch?
- A. Tensor tympani
- B. Stylopharyngeus (Correct Answer)
- C. Cricothyroid
- D. Stapedius
Explanation: ***Stylopharyngeus*** - The **stylopharyngeus muscle** is uniquely derived from the **third pharyngeal arch**. - It is innervated by the **glossopharyngeal nerve (CN IX)** and plays a role in elevating the pharynx and larynx during swallowing. - This is the **only muscle** derived from the third pharyngeal arch, making it a key anatomical landmark. *Tensor tympani* - The **tensor tympani muscle** is derived from the **first pharyngeal arch**. - It is innervated by the **mandibular nerve (V3)** and dampens sound by tensing the tympanic membrane. *Cricothyroid* - The **cricothyroid muscle** is derived from the **fourth and sixth pharyngeal arches**. - It is innervated by the **external branch of the superior laryngeal nerve (CN X)** and tenses the vocal cords. *Stapedius* - The **stapedius muscle** is derived from the **second pharyngeal arch**. - It is innervated by the **facial nerve (CN VII)** and dampens sound by stabilizing the stapes bone.
Question 74: Collecting part of kidney develops from ?
- A. Mesonephros
- B. Metanephros
- C. Ureteric bud (Correct Answer)
- D. Pronephros
Explanation: ***Ureteric bud*** - The **ureteric bud** (also known as the metanephric diverticulum) is an outgrowth of the **mesonephric duct** that develops into the collecting system of the kidney. - It gives rise to the **ureter**, **renal pelvis**, major and minor calyces, and all collecting ducts. *Pronephros* - **Pronephros** is the earliest, most rudimentary, and transient excretory structure that appears in human embryos. - It is non-functional in humans and **degenerates completely** by the fourth week of gestation. *Mesonephros* - The **mesonephros** develops after the pronephros and functions as a temporary kidney during the early fetal period (weeks 4-8). - Its tubules primarily contribute to the **male reproductive system** (e.g., epididymis, ductus deferens) and **degenerate** in females. *Metanephros* - The **metanephros** is the definitive kidney in mammals and gives rise to the **nephrons** (glomeruli, Bowman's capsule, proximal and distal convoluted tubules, loop of Henle). - While it's crucial for kidney development, the **collecting part** specifically originates from the ureteric bud, which interacts with the metanephric mesenchyme.
Pathology
1 questionsWhich of the following statements is true regarding light microscopy findings in minimal change disease?
NEET-PG 2013 - Pathology NEET-PG Practice Questions and MCQs
Question 71: Which of the following statements is true regarding light microscopy findings in minimal change disease?
- A. Foot process effacement is observed under electron microscopy, not light microscopy.
- B. Anti-GBM antibodies are associated with Goodpasture syndrome, not minimal change disease.
- C. No significant changes are seen under light microscopy. (Correct Answer)
- D. IgA deposits are characteristic of IgA nephropathy, not minimal change disease.
Explanation: ***No change seen*** - In minimal change disease, **light microscopy** typically shows no significant changes, which is a key characteristic of the condition [1]. - The disease primarily affects the **podocytes** leading to **nephrotic syndrome**, while light microscopy does not reveal any abnormalities [1]. *Loss of foot process seen* - Loss of foot processes is actually observed under **electron microscopy**, not light microscopy. - Light microscopy remains normal, differentiating minimal change disease from other glomerular diseases. *IgA deposits seen* - IgA deposits are associated with **IgA nephropathy**, which is a different condition characterized by mesangial deposition. - Minimal change disease does not have **immunofluorescence** findings, and thus shows no such deposits on light microscopy [1]. *Anti GBM Abs seen* - Anti-GBM antibodies are characteristic of **Goodpasture syndrome**, which presents with significant changes in glomerular structure. - In minimal change disease, there are no **anti-GBM antibodies** or major changes visible under light microscopy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 927-928.
Pharmacology
5 questionsWhich of the following is not a cardioselective beta blocker?
Which of the following is not a recognized use of alpha-2-agonists?
Which dopamine receptor is known for its inhibitory action in the central nervous system?
Which of the following is classified as an antispasmodic agent?
Which beta-1 antagonist is used in congestive cardiac failure?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 71: Which of the following is not a cardioselective beta blocker?
- A. Nebivolol
- B. Atenolol
- C. Betaxolol
- D. Oxprenolol (Correct Answer)
Explanation: ***Oxprenolol*** - **Oxprenolol** is a non-selective beta-blocker with **intrinsic sympathomimetic activity (ISA)**, meaning it blocks both β1 and β2 receptors and partially stimulates them. - Its non-selective action means it affects both the heart (β1) and other organs like the lungs (β2), making it less suitable for patients with respiratory conditions. *Nebivolol* - **Nebivolol** is a highly cardioselective beta-blocker that primarily blocks **β1 receptors** and also has **vasodilatory properties** due to nitric oxide release. - Its high selectivity translates to fewer β2-mediated side effects, such as bronchoconstriction. *Atenolol* - **Atenolol** is a **cardioselective beta-blocker** that predominantly blocks **β1 receptors** at therapeutic doses. - This selectivity makes it a common choice for cardiovascular conditions, reducing the risk of bronchospasm compared to non-selective agents. *Betaxolol* - **Betaxolol** is a **cardioselective beta-blocker** primarily used for the treatment of hypertension and glaucoma. - It selectively blocks **β1 adrenergic receptors**, minimizing effects on the lungs compared to non-selective beta-blockers.
Question 72: Which of the following is not a recognized use of alpha-2-agonists?
- A. Glaucoma
- B. Hypertension
- C. Sedation
- D. Benign Hyperplasia of prostate (Correct Answer)
Explanation: ***Correct Answer: Benign Hyperplasia of prostate*** - Alpha-2-agonists are **NOT** used to treat **benign prostatic hyperplasia (BPH)**; this condition is typically managed with **alpha-1-blockers** (e.g., tamsulosin, alfuzosin) or 5-alpha-reductase inhibitors. - Alpha-1-blockers relax the smooth muscle in the prostate and bladder neck, improving urine flow, which involves a different receptor mechanism than alpha-2-agonists. - Alpha-2-agonists would not provide therapeutic benefit for BPH. *Incorrect: Glaucoma* - Alpha-2-agonists (e.g., **brimonidine**, **apraclonidine**) **are** used to treat **glaucoma** by reducing aqueous humor production and increasing uveoscleral outflow. - This action helps to **lower intraocular pressure**, a primary goal in glaucoma management. *Incorrect: Hypertension* - Central-acting alpha-2-agonists (e.g., **clonidine**, **methyldopa**) **are** used as **antihypertensive agents**. - They reduce sympathetic outflow from the central nervous system, leading to decreased heart rate, vasodilation, and consequently, **lower blood pressure**. *Incorrect: Sedation* - Alpha-2-agonists like **dexmedetomidine** and **clonidine** **are** commonly used for **sedation** in critically ill patients, especially in intensive care units. - They produce sedation, analgesia, and anxiolysis without causing significant respiratory depression, making them valuable in certain clinical settings.
Question 73: Which dopamine receptor is known for its inhibitory action in the central nervous system?
- A. Dopamine Receptor D5
- B. No inhibitory dopamine receptor present
- C. Dopamine Receptor D2 (Correct Answer)
- D. Dopamine Receptor D1
Explanation: ***Dopamine Receptor D2*** - The **D2 receptor** is a member of the D2-like family (D2, D3, D4), which are **G-protein coupled receptors** that inhibit adenylyl cyclase activity. - Its activation typically leads to a **decrease in neuronal excitability** and neurotransmitter release, providing an inhibitory effect in the CNS. *Dopamine Receptor D5* - The **D5 receptor** belongs to the D1-like family (D1, D5), which are **G-protein coupled receptors** that stimulate adenylyl cyclase activity. - Activation of D5 receptors typically leads to **excitatory effects** rather than inhibitory ones in the CNS. *No inhibitory dopamine receptor present* - This statement is incorrect as specific dopamine receptor subtypes, particularly the **D2-like family**, are well-established to exert inhibitory actions in the CNS. - These inhibitory effects are crucial for various physiological processes, including motor control and reward pathways. *Dopamine Receptor D1* - The **D1 receptor** is part of the D1-like family (D1, D5) and is known for its **excitatory effects** in the CNS. - Activation of D1 receptors leads to an **increase in intracellular cAMP** and generally enhances neuronal activity.
Question 74: Which of the following is classified as an antispasmodic agent?
- A. Dicyclomine (Correct Answer)
- B. Physostigmine
- C. Tropicamide
- D. None of the options
Explanation: ***Dicyclomine*** - **Dicyclomine** is an **anticholinergic** medication that works by blocking muscarinic receptors, thereby reducing smooth muscle spasm in the gastrointestinal tract. - It is commonly used to treat symptoms of **irritable bowel syndrome (IBS)**, such as abdominal pain and cramping. *Physostigmine* - **Physostigmine** is a **cholinesterase inhibitor** that increases the concentration of acetylcholine at the synaptic cleft. - It is used to treat **anticholinergic poisoning** by reversing the effects of anticholinergic drugs, rather than acting as an antispasmodic itself. *Tropicamide* - **Tropicamide** is an **anticholinergic** agent primarily used as a **mydriatic** (pupil dilator) and **cycloplegic** (paralyzes the ciliary muscle) for ophthalmic examinations. - Its action is localized to the eye and it does not have significant systemic antispasmodic effects. *None of the options* - This option is incorrect because one of the listed medications is indeed classified as an antispasmodic agent. - When "None of the options" appears as a choice, it should only be selected if all other options are clearly incorrect.
Question 75: Which beta-1 antagonist is used in congestive cardiac failure?
- A. Atenolol
- B. Metoprolol (Correct Answer)
- C. Esmolol
- D. Bisoprolol
Explanation: ***Metoprolol*** - **Metoprolol succinate** (extended-release formulation) is a selective **beta-1 antagonist** proven to reduce mortality and hospitalizations in **chronic heart failure with reduced ejection fraction (HFrEF)**. - It works by **reducing heart rate, myocardial oxygen demand**, and preventing adverse cardiac remodeling through inhibition of chronic sympathetic activation. - Along with **bisoprolol and carvedilol**, it is one of the **three beta-blockers with proven mortality benefit** in heart failure trials. *Atenolol* - While atenolol is a selective beta-1 antagonist, it **lacks evidence for mortality benefit** in heart failure. - It has **high hydrophilicity** and renal elimination, leading to less favorable pharmacokinetics compared to metoprolol. - More commonly used for **hypertension and angina** rather than heart failure management. *Esmolol* - **Esmolol** is an ultra-short-acting selective beta-1 antagonist used for **acute control of heart rate** in perioperative and critical care settings. - Its **very short half-life (9 minutes)** makes it unsuitable for chronic management of heart failure. - Administered only **intravenously** and requires continuous infusion. *Bisoprolol* - While **bisoprolol is also approved** for heart failure and has proven mortality benefit (CIBIS-II trial), this question likely expects **metoprolol** as the answer given the historical context. - Both bisoprolol and metoprolol are acceptable answers, but **metoprolol** has been more widely studied and is more commonly cited in Indian medical exams. - Bisoprolol has **greater beta-1 selectivity** than metoprolol but similar clinical outcomes in heart failure.