Anatomy
1 questionsWhich organ receives dual blood supply with both sources contributing to its primary metabolic function?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 231: Which organ receives dual blood supply with both sources contributing to its primary metabolic function?
- A. Heart
- B. Liver (Correct Answer)
- C. Kidney
- D. Lung
Explanation: ***Liver*** - The liver receives blood from two sources: the **hepatic artery** (supplying oxygenated blood, ~25% of blood flow) and the **hepatic portal vein** (supplying nutrient-rich, deoxygenated blood from the gastrointestinal tract, ~75% of blood flow). - Both blood supplies are essential for the liver's primary metabolic functions, detoxification, and nutrient processing [1]. - This is the classic example of dual blood supply in medical education. *Heart* - The heart receives its blood supply primarily from the **coronary arteries**, which branch off the aorta. - While it has an extensive arterial network, it has a single primary source of blood supply. *Kidney* - The kidneys receive their blood supply exclusively from the **renal arteries**, which branch directly from the aorta. - Each kidney typically has a single renal artery supplying it for high-pressure filtration. *Lung* - The lungs do receive blood from two sources: **pulmonary arteries** (deoxygenated blood for gas exchange) and **bronchial arteries** (oxygenated blood for tissue nourishment, <5% of flow). - However, the primary function (gas exchange) is served by pulmonary circulation alone, while bronchial circulation only nourishes lung tissue. - The liver is the standard answer for dual blood supply where both sources serve the organ's primary function.
Biochemistry
2 questionsConverging point of both pathways in coagulation is at:
Which of the following statements about adiponectin is incorrect?
NEET-PG 2015 - Biochemistry NEET-PG Practice Questions and MCQs
Question 231: Converging point of both pathways in coagulation is at:
- A. Factor VIII
- B. Stuart factor X (Correct Answer)
- C. Factor IX
- D. Factor VII
Explanation: ***Stuart factor X*** [1][2] - It is the main **converging point** of the coagulation cascade, where both the intrinsic and extrinsic pathways meet to initiate the common pathway [1]. - Activated factor X leads to the conversion of **prothrombin to thrombin**, pivotal for clot formation [2]. *Factor VII* [2] - Primarily involved in the **extrinsic pathway** of coagulation, activating factor X, but does not serve as a converging point. - Its function is limited to starting the coagulation cascade, particularly upon tissue injury. *Factor IX* [2] - A key component of the **intrinsic pathway**, it leads to the activation of factor X but is not the point where both pathways converge. - It requires **factor VIII** for its activation, further illustrating its role within a specific pathway. *Factor VIII* - Also part of the **intrinsic pathway**, it acts as a cofactor for factor IX but does not integrate both pathways into a common point. - Its deficiency is associated with **Hemophilia A**, underscoring its specific pathway involvement. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 128-130. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 582-583.
Question 232: Which of the following statements about adiponectin is incorrect?
- A. Secreted by adipose tissue
- B. Increases FFA oxidation
- C. Lowers glucose
- D. Positive Correlation with BMI (Correct Answer)
Explanation: ***Positive Correlation with BMI (INCORRECT STATEMENT)*** - Adiponectin levels are **inversely correlated with BMI**, NOT positively correlated; as BMI increases, adiponectin levels generally decrease. - This inverse relationship is significant because lower adiponectin levels are associated with increased insulin resistance and **metabolic syndrome**. - This statement is **false**, making it the correct answer to this question. *Secreted by adipose tissue (Correct statement)* - Adiponectin is a **hormone primarily secreted by adipocytes** (fat cells). - It plays a crucial role in regulating glucose and lipid metabolism, and its secretion is altered in conditions like obesity. - This statement is **true**. *Lowers glucose (Correct statement)* - Adiponectin **enhances insulin sensitivity** in peripheral tissues like skeletal muscle and liver, leading to increased glucose uptake and utilization. - This action helps to **lower blood glucose levels** and improve glycemic control. - This statement is **true**. *Increases FFA oxidation (Correct statement)* - Adiponectin **promotes fatty acid oxidation** in muscle and liver, reducing intracellular lipid accumulation. - By increasing fatty acid burning, it helps to **decrease circulating free fatty acid (FFA) levels**, which can contribute to insulin resistance if elevated. - This statement is **true**.
Physiology
7 questionsWhich of the following structures contains baroreceptors that detect changes in blood pressure?
Broca's area is primarily involved in which of the following functions?
Vibrations are detected by which types of receptors?
Which of the following receptors is stimulated by sustained pressure?
Tetany in muscle occurs in spite of normal serum Ca2+ level. Which ion is responsible?
What is another name for the withdrawal reflex?
Which of the following is the MOST important factor determining whether a substance can be filtered at the glomerulus?
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 231: Which of the following structures contains baroreceptors that detect changes in blood pressure?
- A. Carotid body
- B. Carotid sinus (Correct Answer)
- C. Aortic body
- D. None of the options
Explanation: ***Carotid sinus*** - The **carotid sinus** is a dilation at the bifurcation of the common carotid artery, containing **baroreceptors** sensitive to changes in blood pressure [1]. - These baroreceptors are **mechanoreceptors** that respond to the stretching of the vessel wall due to increased arterial pressure, sending signals to the brainstem to regulate blood pressure. *Carotid body* - The **carotid body** is a chemoreceptor that primarily detects changes in **blood oxygen, carbon dioxide, and pH** levels, not blood pressure [2]. - It plays a crucial role in regulating **respiration** in response to hypoxemia. *Aortic body* - The **aortic body** is a **chemoreceptor** located near the aortic arch that primarily monitors **blood oxygen, carbon dioxide, and pH levels**. - Note: While the aortic body itself is a chemoreceptor, the **aortic arch** (a different structure) does contain baroreceptors [1]. However, this option specifically refers to the aortic body, which is not a baroreceptor. - The aortic body contributes to the regulation of **respiration** in response to hypoxemia, not directly blood pressure. *None of the options* - This option is incorrect because the **carotid sinus** is a well-known site for baroreceptors involved in blood pressure regulation.
Question 232: Broca's area is primarily involved in which of the following functions?
- A. Speech production (Correct Answer)
- B. Language comprehension
- C. Language repetition
- D. Reading ability
Explanation: ***Speech production*** - **Broca's area** is a region in the frontal lobe of the dominant hemisphere, typically the left, that is crucial for the formation of coherent and grammatically correct speech. - Damage to this area leads to **Broca's aphasia**, characterized by **non-fluent speech**, difficulty retrieving words, and impaired syntax. *Language comprehension* - **Wernicke's area**, located in the temporal lobe, is primarily responsible for **language comprehension**. - Patients with **Wernicke's aphasia** can produce fluent speech but have difficulty understanding spoken and written language. *Language repetition* - The **arcuate fasciculus**, a bundle of nerve fibers connecting Broca's and Wernicke's areas, is essential for **language repetition**. - Lesions in this pathway result in **conduction aphasia**, where comprehension and fluency are relatively preserved, but repetition is severely impaired. *Reading ability* - Reading ability involves a complex network of brain regions, including the **angular gyrus** and **visual cortex**, in addition to language areas. - While Broca's area contributes to the motor planning aspects of reading aloud, it is not its primary function.
Question 233: Vibrations are detected by which types of receptors?
- A. Slowly adapting
- B. Rapidly adapting (Correct Answer)
- C. Non-adapting
- D. None of the above
Explanation: ***Rapidly adapting*** - **Rapidly adapting mechanoreceptors**, such as **Pacinian corpuscles** and **Meissner's corpuscles**, are highly sensitive to changes in pressure and movement. - They fire at the **onset and offset of a stimulus**, making them ideal for detecting vibrations, which are rhythmic changes in pressure. *Slowly adapting* - **Slowly adapting mechanoreceptors**, such as **Merkel cells** and **Ruffini endings**, are responsible for sustained pressure and touch. - They continue to fire as long as the stimulus is present, making them less suited for detecting transient vibratory stimuli. *Non-adapting* - The human body does not typically have **truly non-adapting** sensory receptors; most receptors show some form of adaptation to continuous stimuli. - This term is not standard in the classification of mechanoreceptors based on their adaptation rates. *None of the above* - This option is incorrect because rapidly adapting receptors are indeed responsible for detecting vibrations.
Question 234: Which of the following receptors is stimulated by sustained pressure?
- A. Ruffini's end organ (Correct Answer)
- B. Merkel's disc
- C. Hair cells
- D. Meissner Corpuscles
Explanation: ***Ruffini's end organ*** - These are **slowly adapting mechanoreceptors** located deep in the dermis and subcutaneous tissue. - They are responsible for detecting **sustained pressure**, stretch, and position sense. *Merkel's disc* - These are **slowly adapting mechanoreceptors** found in the basal epidermis. - They are crucial for sensing **light touch** and **two-point discrimination**. *Hair cells* - These are **mechanoreceptors** primarily found in the inner ear, responsible for hearing and balance. - They are not involved in the perception of somatosensory stimuli like pressure on the skin. *Meissner Corpuscles* - These are **rapidly adapting mechanoreceptors** located in the dermal papillae, close to the skin surface. - They are primarily involved in detecting **light touch** and **discriminative touch**, especially changes in texture.
Question 235: Tetany in muscle occurs in spite of normal serum Ca2+ level. Which ion is responsible?
- A. Mg2+
- B. K+
- C. Na+
- D. Ionized Ca2+ (Correct Answer)
Explanation: ***Ionized Ca2+*** - While total serum calcium might be normal, **tetany** is specifically caused by a decrease in the concentration of **ionized (free) calcium** in the extracellular fluid. - Ionized calcium is the physiologically active form of calcium responsible for neuromuscular excitability. *Mg2+* - **Hypomagnesemia** can exacerbate hypocalcemia and contribute to tetany, but it is not the primary ion directly responsible for tetany when **total serum calcium is normal**. - A deficiency in Mg2+ can impair the release of **parathyroid hormone** and reduce target organ responsiveness to PTH. *K+* - Abnormalities in **potassium levels** (hypokalemia or hyperkalemia) primarily affect cardiac and muscular excitability, leading to arrhythmias or muscle weakness/paralysis. - While electrolyte imbalances are interconnected, changes in potassium are not the direct cause of tetany due to calcium's role. *Na+* - **Sodium ions** are crucial for nerve impulse transmission and muscle contraction by establishing the resting membrane potential and initiating action potentials. - However, direct changes in sodium concentration do not typically cause tetany; rather, they can lead to neurological symptoms like seizures (hyponatremia) or altered mental status (hypernatremia).
Question 236: What is another name for the withdrawal reflex?
- A. Golgi tendon reflex
- B. Extension reflex
- C. Stretch reflex
- D. Flexor reflex (Correct Answer)
Explanation: ***Flexor reflex*** - The withdrawal reflex is also known as the **flexor reflex** because it causes the rapid flexion (bending) of a limb to withdraw it from a noxious stimulus. - This reflex is a **polysynaptic reflex** involving interneurons in the spinal cord. *Golgi tendon reflex* - The **Golgi tendon reflex** is a protective reflex that causes muscle relaxation in response to excessive muscle tension. - It involves activation of **Golgi tendon organs**, which are proprioceptors located in the tendons. *Extension reflex* - The **extension reflex** is typically observed in withdrawal reflexes of the opposing limb, known as the **crossed extensor reflex**, to maintain balance. - It involves the extension of the contralateral limb while the ipsilateral limb flexes. *Stretch reflex* - The **stretch reflex** (or myotatic reflex) causes muscle contraction in response to stretching of the muscle. - It is a **monosynaptic reflex** involving muscle spindles and maintaining muscle tone.
Question 237: Which of the following is the MOST important factor determining whether a substance can be filtered at the glomerulus?
- A. Lipid solubility of the substance
- B. Molecular weight of the substance (Correct Answer)
- C. Binding capacity to albumin
- D. None of the options
Explanation: ***Molecular weight of the substance*** - The **glomerular filtration barrier** acts as a size-selective filter, generally permeable to substances with a molecular weight less than 5,000-10,000 Daltons - Larger molecules are typically restricted from filtration due to the **size exclusion** property of the glomerular basement membrane and podocyte slit diaphragms - This is the **primary determinant** of whether a substance can be filtered at all, making it the most important factor among the given options *Lipid solubility of the substance* - **Lipid solubility** is more relevant for reabsorption and secretion in the renal tubules, particularly for passive diffusion across tubular cell membranes - It has minimal direct influence on the initial filtration process at the glomerulus, which is primarily a **pressure-driven, size- and charge-selective ultrafiltration** process - The glomerular capillary wall is not a lipid membrane barrier for the filtration process *Binding capacity to albumin* - Substances bound to **large plasma proteins** like albumin (molecular weight ~67,000 Daltons) cannot pass through the glomerular filtration barrier - While important for determining the *free, filterable fraction* of a substance in plasma, the binding itself is secondary to the fundamental molecular weight/size restriction - Only the **free (unbound) fraction** of a substance is available for filtration, and whether it filters depends primarily on its molecular weight *None of the options* - This option is incorrect because **molecular weight** is indeed the most critical factor among the given options for determining whether a substance can be filtered at the glomerulus