NEET-PG 2015 Practice Questions

Q: Which Brodmann's area is primarily associated with motor speech?

Area 44. Area 44 - **Brodmann Area 44** is primarily known as **Broca's area**, which is critical for **motor speech production** and language processing [1]. - Damage to this area typically results in **Broca's aphasia**, characterized by non-fluent speech and difficulty forming complete sentences [1]. Area 1, 2, 3 - These Brodmann areas constitute the **primary somatosensory cortex**, responsible for processing **tactile and proprioceptive information** from the body. - They are involved in sensory perception, not directly with motor speech production. Area 4, 6 - **Brodmann Area 4** is the **primary motor cortex**, involved in executing voluntary movements [2]. **Brodmann Area 6** is the **premotor and supplementary motor cortex**, involved in planning and coordinating movements [2]. - While these areas are crucial for motor control, they are not specifically associated as the primary center for motor speech in the same way Broca's area is. Area 40 - **Brodmann Area 40**, also known as the **supramarginal gyrus**, is part of the **parietal lobe** and is involved in phonological processing, language perception, and spatial cognition. - While it plays a role in language, it is not the primary area for motor speech production.

Q: Calcium absorption is hampered by

Phytates. ***Phytates*** - **Phytates** (phytic acid) found in whole grains, legumes, nuts, and seeds bind to calcium, forming an insoluble complex that significantly **reduces its absorption** in the intestines. - This binding prevents the free calcium ions from crossing the intestinal wall into the bloodstream. *Protein* - **Protein** generally *enhances* calcium absorption, especially when consumed in moderate amounts, as some amino acids can form soluble calcium complexes. - However, very high protein intake, particularly from animal sources, *may* slightly increase urinary calcium excretion in the long term, but it does not directly hamper intestinal absorption. *Lactose* - **Lactose**, a sugar found in milk, is known to *enhance* calcium absorption. - It does so by creating a more acidic environment in the small intestine and by forming soluble complexes with calcium, making it more bioavailable. *Acid* - **Stomach acid** (hydrochloric acid) is crucial for calcium absorption as it helps to solubilize calcium salts from food. - A *reduced* acidic environment, such as from antacid use or certain medical conditions, would hamper calcium absorption, but acid itself is beneficial.

Q: Aortic valve closure occurs in which part of cardiac cycle?

Beginning of isovolumetric relaxation. ***Beginning of isovolumetric relaxation*** - Aortic valve closure marks the end of **ventricular systole** and the start of **isovolumetric relaxation**, as blood ceases to be ejected and the ventricle begins to relax while remaining closed. - This event corresponds to the **second heart sound (S2)** and signifies the beginning of a period where ventricular volume remains constant, but pressure drops. *Beginning of isovolumetric contraction* - This phase begins with the closure of the **mitral and tricuspid valves** (first heart sound, S1), as ventricular pressure rises but volume remains constant before ejection. - The aortic valve is still closed at this point, as ventricular pressure is not yet high enough to open it. *Beginning of ventricular ejection* - This phase begins when the **aortic valve opens** as ventricular pressure exceeds aortic pressure, allowing blood to be ejected from the left ventricle. - Aortic valve closure occurs *after* ejection, not at its beginning. *During rapid ventricular filling* - Rapid ventricular filling occurs when the **mitral valve opens** (following isovolumetric relaxation), allowing blood to flow from the atria into the ventricles. - During this phase, the aortic valve is closed, but its closure happened earlier, at the beginning of isovolumetric relaxation.

Q: Which of the following neurons in the cerebellar cortex is primarily excitatory?

Granule cells. ***Granule cells*** - **Granule cells** are the only neurons in the cerebellar cortex that are **excitatory**, utilizing glutamate as their neurotransmitter. - They receive input from **mossy fibers** and project their parallel fibers to Purkinje cells and other interneurons. *Purkinje* - **Purkinje cells** are the primary output neurons of the cerebellar cortex and are **inhibitory**, releasing GABA. - They integrate vast amounts of information and project to the **deep cerebellar nuclei**. *Basket* - **Basket cells** are **inhibitory interneurons** located in the molecular layer of the cerebellum. - They synapse on the somata of **Purkinje cells**, providing potent inhibition. *Golgi* - **Golgi cells** are **inhibitory interneurons** found in the granular layer of the cerebellum. - They receive excitatory input from **parallel fibers** and inhibit granule cells, forming an important feedback loop.

Q: EPSP is due to?

Sodium ion influx. ***Sodium ion influx*** - An **Excitatory Postsynaptic Potential (EPSP)** is caused primarily by the binding of an **excitatory neurotransmitter** to its receptor, leading to the opening of **ligand-gated ion channels** permeable to sodium (Na+) ions. - The **influx of positively charged sodium ions** into the postsynaptic neuron causes a **depolarization** of the membrane potential, making it more likely to reach the threshold for an action potential. *Potassium ion influx* - **Potassium (K+) influx** is not the primary mechanism for generating an EPSP; instead, **potassium efflux** (movement out of the cell) is typically involved in **repolarization** after an action potential or in generating **Inhibitory Postsynaptic Potentials (IPSPs)**. - The movement of K+ into the cell would make the membrane potential more negative, leading to **hyperpolarization** or preventing depolarization. *Sodium ion efflux* - **Sodium (Na+) efflux** is mediated by the **Na+/K+ pump** and is crucial for maintaining the resting membrane potential, but it does **not directly cause an EPSP**. - Pumping Na+ out of the cell would **hyperpolarize** the cell or oppose depolarization, making an action potential less likely. *Calcium ion influx* - While **calcium (Ca2+) influx** is vital for many neuronal processes, including **neurotransmitter release** from the presynaptic terminal, it is **not the primary ionic basis** for generating an EPSP in the postsynaptic neuron itself. - Significant Ca2+ influx can occur during an **action potential** or lead to intracellular signaling, but it's not the main depolarizing current responsible for an EPSP.

Q: During the sympathetic fight-or-flight response, what is the primary cardiovascular effect of epinephrine and norepinephrine on skeletal muscle vasculature?

Increased blood flow to muscles. ***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.

Q: Maximum density of muscle spindle is found in?

Lumbricals. ***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.

Q: Broca's area is primarily involved in which of the following functions?

Speech production. ***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.

Q: Which of the following is the MOST important factor determining whether a substance can be filtered at the glomerulus?

Molecular weight of the substance. ***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

Question 1

Which Brodmann's area is primarily associated with motor speech?

Accepted Answer

Area 44

Answer

Area 1, 2, 3

Answer

Area 4, 6

Answer

Area 40

Question 2

Calcium absorption is hampered by

Accepted Answer

Phytates

Answer

Protein

Answer

Lactose

Answer

Acid

Question 3

Aortic valve closure occurs in which part of cardiac cycle?

Accepted Answer

Beginning of isovolumetric relaxation

Answer

Beginning of isovolumetric contraction

Answer

During rapid ventricular filling

Answer

Beginning of ventricular ejection

Question 4

Which of the following neurons in the cerebellar cortex is primarily excitatory?

Accepted Answer

Granule cells

Answer

Purkinje

Answer

Basket

Answer

Golgi

Question 5

EPSP is due to?

Accepted Answer

Sodium ion influx

Answer

Potassium ion influx

Answer

Sodium ion efflux

Answer

Calcium ion influx

Question 6

During the sympathetic fight-or-flight response, what is the primary cardiovascular effect of epinephrine and norepinephrine on skeletal muscle vasculature?

Accepted Answer

Increased blood flow to muscles

Answer

Increased blood flow to the skin

Answer

Bronchoconstriction

Answer

Decreased heart rate

Question 7

What does the ST Segment of an ECG correspond to?

Accepted Answer

Plateau phase between ventricular depolarization and repolarization

Answer

Ventricular depolarization

Answer

Atrial depolarization

Answer

AV Conduction

Question 8

Maximum density of muscle spindle is found in?

Accepted Answer

Lumbricals

Answer

Calf muscle

Answer

Triceps

Answer

Quadriceps muscle

Question 9

Broca's area is primarily involved in which of the following functions?

Accepted Answer

Speech production

Answer

Language comprehension

Answer

Language repetition

Answer

Reading ability

Question 10

Which of the following is the MOST important factor determining whether a substance can be filtered at the glomerulus?

Accepted Answer

Molecular weight of the substance

Answer

Lipid solubility of the substance

Answer

Binding capacity to albumin

Answer

None of the options

NEET-PG 2015

Anatomy

Biochemistry

Physiology