Biochemistry
2 questionsWhat is the classification of Carcinoembryonic Antigen (CEA)?
Which of the following is not a part of extracellular matrix (ECM)?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 431: What is the classification of Carcinoembryonic Antigen (CEA)?
- A. Glycoprotein (Correct Answer)
- B. Lipoprotein
- C. Phosphoprotein
- D. Nucleoprotein
Explanation: ***Glycoprotein*** - Carcinoembryonic Antigen (CEA) is classified as a **glycoprotein** due to its structure, which consists of both **carbohydrate** and **protein** components. - This glycosylation is crucial for its function as a cell adhesion molecule and its recognition in diagnostic assays. *Lipoprotein* - **Lipoproteins** are complexes of lipids and proteins that function primarily in **lipid transport** in the blood. - CEA's primary role and structure are not related to lipid transport or being predominantly lipid-based. *Phosphoprotein* - A **phosphoprotein** is a protein that has been **covalently modified by the addition of a phosphate group**, a process crucial for cell signaling. - While proteins can be phosphorylated, the defining characteristic and major classification of CEA is its extensive glycosylation rather than phosphorylation state. *Nucleoprotein* - **Nucleoproteins** are proteins that are **structurally associated with nucleic acids** (DNA or RNA), such as histones or ribosomal proteins. - CEA does not have a structural or functional association with nucleic acids.
Question 432: Which of the following is not a part of extracellular matrix (ECM)?
- A. Lectins (Correct Answer)
- B. Fibronectin
- C. Laminin
- D. Proteoglycans
Explanation: ***Lectins*** - **Lectins** are carbohydrate-binding proteins involved in various cellular processes but are typically found **on cell surfaces** or within cells, not as a major structural component of the ECM. - While they can interact with ECM components, they are not considered a direct structural element of the extracellular matrix itself. *Fibronectin* - **Fibronectin** is a critical **glycoprotein** in the ECM, playing a vital role in cell adhesion, growth, migration, and differentiation. - It links cells to collagen fibers and other ECM components, forming an essential scaffold. *Laminin* - **Laminin** is a major **glycoprotein** component of the **basal lamina**, a specialized layer of the ECM found beneath epithelial cells. - It helps in cell attachment, differentiation, and migration. *Proteoglycans* - **Proteoglycans** are macromolecules consisting of a **core protein** covalently linked to one or more **glycosaminoglycan (GAG) chains**. - They are abundant in the ECM, where they contribute to its structural integrity, hydration, and can regulate the diffusion of molecules.
Internal Medicine
1 questionsIn which non-neoplastic condition is CEA commonly elevated?
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 431: In which non-neoplastic condition is CEA commonly elevated?
- A. Pancreatitis
- B. Inflammatory bowel disease (Correct Answer)
- C. Hemolytic anemia
- D. Liver disease
Explanation: ***Inflammatory bowel disease*** - **Carcinoembryonic antigen (CEA)** levels can be elevated in conditions involving active inflammation and rapid cell turnover within the gastrointestinal tract, such as **inflammatory bowel disease (IBD)** [1]. - While CEA is primarily a tumor marker, its elevation in IBD reflects the extensive mucosal inflammation and repair processes, rather than malignancy. *Hemolytic anemia* - **Hemolytic anemia** involves the destruction of red blood cells and does not typically lead to elevated CEA levels. - Elevated CEA is associated with certain epithelial conditions, not primary hematologic disorders. *Pancreatitis* - While **pancreatitis** can cause elevated levels of other markers like amylase and lipase, it is not consistently associated with elevated CEA. - CEA elevation in pancreatic conditions usually points towards a **pancreatic malignancy**. *Liver disease* - **Liver disease**, particularly severe inflammation or cirrhosis, can sometimes cause a mild elevation in CEA due to impaired clearance or increased production in damaged tissue. - However, levels are typically not as high or consistently elevated as in IBD, and significant elevation often prompts investigation for **primary hepatic or metastatic malignancy**.
Pathology
1 questionsCarcinoma originating from glands is called?
NEET-PG 2015 - Pathology NEET-PG Practice Questions and MCQs
Question 431: Carcinoma originating from glands is called?
- A. Basal cell carcinoma
- B. Squamous cell carcinoma
- C. Adenocarcinoma (Correct Answer)
- D. Fibrosarcoma
Explanation: ***Adenocarcinoma*** - Carcinoma that arises from **glandular epithelium** is specifically classified as adenocarcinoma [1]. - It often presents in organs like the **breast**, **prostate**, and **gastrointestinal tract** [4,5]. *Fibrosarcoma* - This is a **malignant tumor** derived from **fibrous connective tissue**, not glands. - Typically occurs in **soft tissues**, and is distinct from epithelial tumors like adenocarcinoma. *Squamous cell carcinoma* - Originates from **squamous epithelial cells** and primarily affects areas such as the **skin** and **mucous membranes** [2]. - It is not associated with glandular structures, differing markedly from adenocarcinoma. *Basal cell carcinoma* - Arises from **basal cells** in the **epidermis** (skin), not from glandular tissue. - It is the most common type of skin cancer and is largely not relevant to glandular origin. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 335-336. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 777-778. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 348-349.
Pharmacology
4 questionsMost common renal sequela of lithium toxicity is?
Antidepressant drug used in nocturnal enuresis is:
What is the primary mechanism of action of zonisamide?
Buprenorphine is a partial agonist at which opioid receptor?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 431: Most common renal sequela of lithium toxicity is?
- A. Renal tubular acidosis
- B. Glycosuria
- C. MPGN
- D. Nephrogenic Diabetes Insipidus (Correct Answer)
Explanation: ***Nephrogenic Diabetes Insipidus*** - **Lithium** interferes with the action of **ADH** on the renal tubules, specifically at the **collecting ducts**, leading to an inability to concentrate urine. - This results in **polyuria** (excessive urination) and **polydipsia** (excessive thirst), characteristic symptoms of **nephrogenic diabetes insipidus**. *Renal tubular acidosis* - While lithium can affect tubular function, **renal tubular acidosis** is less common than nephrogenic diabetes insipidus. - RTA involves impaired acid excretion or bicarbonate reabsorption, leading to **metabolic acidosis**. *Glycosuria* - **Glycosuria** (glucose in urine) is primarily associated with **diabetes mellitus** or other conditions affecting glucose reabsorption in the proximal tubule. - Lithium toxicity does not typically cause glycosuria. *MPGN* - **Membranoproliferative glomerulonephritis (MPGN)** is a type of glomerular injury characterized by specific changes in the glomerulus. - MPGN is not directly caused by **lithium toxicity**; lithium primarily affects tubular function rather than glomerular structure.
Question 432: Antidepressant drug used in nocturnal enuresis is:
- A. Imipramine (Correct Answer)
- B. Fluoxetine
- C. Trazodone
- D. Sertraline
Explanation: ***Imipramine*** - **Imipramine**, a **tricyclic antidepressant (TCA)**, is frequently used off-label for **nocturnal enuresis** in children [1]. - Its mechanism of action in enuresis is thought to involve a combination of anticholinergic effects (which relax the bladder detrusor muscle) and central nervous system effects (which may increase bladder capacity and arousal from sleep) [1]. *Fluoxetine* - **Fluoxetine** is a **selective serotonin reuptake inhibitor (SSRI)** and is primarily used for depression, anxiety disorders, and OCD [2]. - It is not indicated for the treatment of nocturnal enuresis and does not have the same bladder-relaxing or arousal-modulating properties as imipramine in this context. *Trazodone* - **Trazodone** is a **serotonin antagonist and reuptake inhibitor (SARI)**, commonly prescribed for depression and insomnia due to its prominent sedative effects. - It is not used for nocturnal enuresis and its mechanism of action does not confer benefits for bladder control. *Sertraline* - **Sertraline** is another **selective serotonin reuptake inhibitor (SSRI)** used for a wide range of psychiatric conditions, including depression, anxiety, and panic disorder [2]. - Like fluoxetine, it is not an appropriate treatment for nocturnal enuresis and lacks the specific known effects beneficial for this condition.
Question 433: What is the primary mechanism of action of zonisamide?
- A. GABA receptors
- B. Cl- channels
- C. Sodium channels (Correct Answer)
- D. T-type calcium channels
Explanation: ***Sodium channels (Correct Answer)*** - Zonisamide's primary mechanism involves **blocking voltage-sensitive sodium channels**, which stabilizes neuronal membranes and inhibits repetitive neuronal firing. - This action helps to prevent the propagation of **seizure activity** in the brain. *GABA receptors* - While zonisamide has some weak effects on GABA, it is not its **primary mechanism of action** for antiepileptic efficacy. - Drugs like **benzodiazepines** and **barbiturates** primarily act by enhancing GABAergic transmission. *T-type calcium channels* - Zonisamide also blocks T-type calcium channels, contributing to its broad-spectrum antiepileptic activity, but this is a **secondary mechanism** compared to its sodium channel blockade. - **Ethosuximide** is a classic example of a drug primarily acting on T-type calcium channels, especially for absence seizures. *Cl- channels* - Zonisamide does not primarily act on **chloride channels**; these are often modulated by GABA receptors. - Drugs that act directly on chloride channels are not typically used as **antiepileptics** in the same way.
Question 434: Buprenorphine is a partial agonist at which opioid receptor?
- A. Mu (Correct Answer)
- B. Kappa
- C. Delta
- D. ORL-1
Explanation: ***Mu*** - Buprenorphine primarily acts as a **partial agonist** at the **mu opioid receptor**, providing analgesic effects with a ceiling effect on respiratory depression. - Its partial agonism at the mu receptor contributes to its lower potential for respiratory depression and overdose compared to full mu agonists. *Kappa* - While buprenorphine has some antagonist activity at the kappa receptor, its primary therapeutic action is not at this receptor. - **Kappa receptor agonists** like pentazocine can produce dysphoria and psychotomimetic effects. *Delta* - The delta opioid receptor is involved in analgesia and emotional responses, but buprenorphine has very low affinity and activity at this receptor. - **Delta receptor agonists** are not widely used clinically due to limited efficacy and side effects. *ORL-1* - The ORL-1 (Opioid Receptor-like 1) receptor, also known as the nociceptin receptor, is distinct from classical opioid receptors. - Buprenorphine has **no significant activity** at the ORL-1 receptor, which primarily mediates pain, anxiety, and learning.
Physiology
2 questionsDuring the sympathetic fight-or-flight response, what is the primary cardiovascular effect of epinephrine and norepinephrine on skeletal muscle vasculature?
Maximum density of muscle spindle is found in?
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 431: During the sympathetic fight-or-flight response, what is the primary cardiovascular effect of epinephrine and norepinephrine on skeletal muscle vasculature?
- A. Increased blood flow to muscles (Correct Answer)
- B. Increased blood flow to the skin
- C. Bronchoconstriction
- D. Decreased heart rate
Explanation: ***Increased blood flow to muscles*** - **Epinephrine** and **norepinephrine** cause **vasodilation** in skeletal muscle arterioles, shunting blood toward tissues critical for immediate physical action. - This response ensures that muscles have adequate **oxygen** and **nutrients** to support intense activity, enabling a quick escape or confrontation. *Increased blood flow to the skin* - During fight-or-flight, the body prioritizes essential organs, causing **vasoconstriction** in the skin to redirect blood flow away from non-essential areas. - This redirection helps to conserve blood and reduce potential blood loss from surface injuries. *Bronchoconstriction* - **Epinephrine** and **norepinephrine** actually cause **bronchodilation**, leading to the relaxation of airway smooth muscles. - This effect increases the diameter of the airways, allowing more air to enter and exit the lungs, thereby enhancing **oxygen intake** and carbon dioxide expulsion. *Decreased heart rate* - The primary effect of **epinephrine** and **norepinephrine** is to **increase heart rate** and myocardial contractility. - This cardiac acceleration enhances **cardiac output**, ensuring rapid and efficient delivery of oxygenated blood throughout the body to meet the demands of stress.
Question 432: Maximum density of muscle spindle is found in?
- A. Calf muscle
- B. Lumbricals (Correct Answer)
- C. Triceps
- D. Quadriceps muscle
Explanation: ***Lumbricals*** - **Lumbricals** are small, intricate muscles in the hand, responsible for fine motor control and precise movements like grasping and manipulating objects. - The high density of **muscle spindles** in lumbricals allows for extremely accurate feedback on muscle length and tension, crucial for **proprioception** and delicate tasks. *Calf muscle* - **Calf muscles** (gastrocnemius and soleus) are large muscles primarily involved in powerful movements like walking and running. - While they do contain muscle spindles for proprioception, their density is lower compared to muscles involved in fine motor control. *Quadriceps muscle* - The **quadriceps femoris** is a large muscle group in the thigh responsible for knee extension and powerful leg movements. - They contain muscle spindles to monitor muscle stretch, but not with the extreme density seen in muscles with fine motor functions. *Triceps* - The **triceps brachii** is a large muscle on the back of the upper arm, primarily responsible for elbow extension. - It has a moderate density of muscle spindles, sufficient for coordinating arm movements but not as high as muscles designed for precision.