NEET-PG 2015 - Physiology Practice Questions

Q: During pregnancy, the increased size of the pituitary gland is primarily due to the enlargement of which hormone-secreting cells?

Prolactin. ***Prolactin*** - During pregnancy, the number and size of **lactotrophs**, the cells that secrete prolactin, increase significantly due to high **estrogen** levels. - This **hyperplasia** and **hypertrophy** of lactotrophs contribute to the overall enlargement of the pituitary gland, preparing it for lactation. *Growth hormone* - While growth hormone is important, there isn't a primary enlargement of **somatotrophs** (GH-secreting cells) in the pituitary during pregnancy. - Furthermore, most circulating GH during pregnancy is **placental growth hormone**, rather than pituitary-derived. *ACTH* - Adrenocorticotropic hormone (ACTH) is secreted by **corticotrophs**, and these cells do not undergo prominent hypertrophy or hyperplasia during normal pregnancy. - While cortisol levels increase, this is largely due to factors other than increased pituitary ACTH cell size. *TSH* - Thyroid-stimulating hormone (TSH) is secreted by **thyrotrophs**, which do not notably enlarge during pregnancy. - Thyroid gland activity increases during pregnancy, but this is mediated by **hCG** and other mechanisms, not pituitary thyrotroph growth.

Q: Gamma waves of REM sleep are associated with?

Subconscious processing. ***Subconscious processing*** - **Gamma waves (30-100 Hz)** during **REM sleep** represent high-frequency neural oscillations associated with **complex cognitive processing** occurring below the level of conscious awareness. - These waves reflect **integration of neural activity** across different brain regions, facilitating information processing and neural plasticity during sleep. - The term encompasses the underlying **neural mechanisms** that support dream generation and memory consolidation processes. *Dream consciousness and memory consolidation* - While **gamma waves** do correlate with dreaming and memory processes during **REM sleep**, these represent the **experiential and functional outcomes** rather than the primary neurophysiological association. - Dream consciousness is a **manifestation** of the underlying subconscious processing, not the direct association with gamma wave activity itself. *Deep subconscious processing* - The term "deep subconscious" is **non-specific** and lacks precise neurophysiological definition in the context of gamma wave activity. - While directionally correct, this option uses imprecise terminology compared to the more accurate "subconscious processing." *Non-REM sleep* - **Gamma waves** are characteristic of **waking states** and **REM sleep**, not non-REM sleep stages. - **Non-REM sleep** (stages N1, N2, N3) is dominated by **slower wave activity** including theta waves (stage N1), sleep spindles and K-complexes (stage N2), and delta waves (stage N3/deep sleep).

Q: Which of the following is not true about sleep -

REM sleep comes earlier than NREM sleep. ***REM sleep comes earlier than NREM sleep*** - This statement is **incorrect** because the sleep cycle typically begins with **NREM (non-rapid eye movement) sleep**, specifically NREM stage 1, before progressing to NREM stages 2 and 3, and then finally entering REM sleep. - NREM sleep accounts for about **75% of total sleep time** and occurs prior to REM sleep in a typical nocturnal sleep episode. *Dreams come in REM sleep* - This statement is **true** as **vivid, memorable dreams** are most commonly associated with **REM sleep**. - During REM sleep, brain activity significantly increases, mimicking the awake state, which facilitates complex dream formation. *REM sleep is also called paradoxical sleep* - This statement is **true** because **REM sleep** is characterized by **high brain activity** (similar to wakefulness) and rapid eye movements, yet the body experiences **muscle atonia**, leading to a state of profound relaxation. - This paradoxical combination of an active brain and a paralyzed body gives it the name **paradoxical sleep**. *Sleep walking comes in NREM sleep* - This statement is **true** as **sleepwalking (somnambulism)** typically occurs during **slow-wave sleep**, which is **NREM stage 3 (deep sleep)**. - During this stage, arousal thresholds are very high, and complex motor behaviors can occur while the individual remains in a sleep state.

Q: Most recently identified taste sensation is?

Umami. ***Umami*** - **Umami** is the most recently identified **fifth basic taste**, often described as a savory or meaty taste. - Its discovery and recognition as a distinct taste sensation occurred in the **early 20th century** by Kikunae Ikeda, who isolated glutamate from kombu. *Sour* - The sensation of **sourness** is one of the traditionally recognized basic tastes, identified much earlier than umami. - It is typically associated with **acids**, such as those found in lemons or vinegar. *Bitter* - **Bitterness** is another long-standing basic taste that serves an important protective function, often signaling potential toxins. - It is one of the earliest tastes understood and recognized, with receptors for a wide range of bitter compounds. *Sweet* - **Sweetness** is a fundamental and ancient taste, universally recognized as pleasurable and indicating energy-rich foods. - The perception of sweet taste, primarily from sugars, has been understood for centuries.

Q: Vibration sense is detected by ?

Deep receptors. ***Deep receptors*** - **Vibration sense** is primarily mediated by **Pacinian corpuscles** and **Meissner's corpuscles**, which are considered deep receptors. - **Pacinian corpuscles** are located in the **deep dermis** and **subcutaneous tissue** and are highly sensitive to **high-frequency vibration** (200-300 Hz). - **Meissner's corpuscles** in dermal papillae detect **lower frequency vibration** and are rapidly adapting mechanoreceptors. *Superficial receptors* - **Superficial receptors** like **Merkel cells** primarily detect **sustained touch** and **pressure**, providing information about texture. - While they contribute to tactile sensation, they are **slowly adapting** and not specialized for rapidly oscillating stimuli like vibration. *Free nerve endings* - **Free nerve endings** are unmyelinated or lightly myelinated nerve terminals that detect **pain**, **temperature**, and **crude touch**. - They are not specialized mechanoreceptors and lack the structural organization needed to transduce vibratory stimuli. *Nociceptors* - **Nociceptors** are specialized sensory receptors that detect **noxious (harmful) stimuli** and mediate the sensation of **pain**. - They respond to extreme temperatures, intense mechanical stress, or chemical irritants, not to non-painful vibration.

Q: Stress induced hyperglycemia is mediated through which hormone:

Cortisol. ***Cortisol*** - **Cortisol** is the **primary mediator** of stress-induced hyperglycemia among the counter-regulatory hormones - It promotes **gluconeogenesis** (formation of new glucose from amino acids and glycerol) in the liver - Stimulates **protein catabolism** in muscles, providing substrates for gluconeogenesis - Induces **insulin resistance** in peripheral tissues, reducing glucose uptake - Released as part of the **HPA axis response** to stress, with sustained elevation during prolonged stress - This is the **correct answer** for stress-induced hyperglycemia mediation *Epinephrine* - **Epinephrine** (adrenaline) is a potent hyperglycemic hormone but acts as an **acute, immediate response** to stress - Rapidly increases blood glucose through **glycogenolysis** (breakdown of glycogen) in liver and muscles - Stimulates **gluconeogenesis** and inhibits insulin secretion - Effects are **rapid but short-lived**, making it more of an emergency response rather than the sustained mediator - Works synergistically with cortisol but is not the primary sustained mediator *Growth hormone* - **Growth hormone** does contribute to hyperglycemia through **anti-insulin effects** and promoting lipolysis - Its hyperglycemic effects are **slower and less pronounced** compared to cortisol and epinephrine - Plays a role in **chronic stress** but is not the primary acute mediator - More important for **long-term metabolic adaptation** rather than immediate stress response *Insulin* - **Insulin** is a **glucose-lowering hormone** that facilitates glucose uptake into cells - During stress, insulin secretion is **suppressed** and tissues become **insulin-resistant** due to counter-regulatory hormones - It does **not mediate** stress-induced hyperglycemia; rather, its action is **opposed** by stress hormones - Decreased insulin action contributes to hyperglycemia but insulin itself is not the mediator

Question 1

During pregnancy, the increased size of the pituitary gland is primarily due to the enlargement of which hormone-secreting cells?

Accepted Answer

Prolactin

Answer

Growth hormone

Answer

ACTH

Answer

TSH

Question 2

Gamma waves of REM sleep are associated with?

Accepted Answer

Subconscious processing

Answer

Dream consciousness and memory consolidation

Answer

Deep subconscious processing

Answer

Non-REM sleep

Question 3

Which of the following is not true about sleep -

Accepted Answer

REM sleep comes earlier than NREM sleep

Answer

Dreams come in REM sleep

Answer

REM sleep is also called paradoxical sleep

Answer

Sleep walking comes in NREM sleep

Question 4

Most recently identified taste sensation is?

Accepted Answer

Umami

Answer

Sour

Answer

Bitter

Answer

Sweet

Question 5

Vibration sense is detected by ?

Accepted Answer

Deep receptors

Answer

Superficial receptors

Answer

Free nerve endings

Answer

Nociceptors

Question 6

Stress induced hyperglycemia is mediated through which hormone:

Accepted Answer

Cortisol

Answer

Epinephrine

Answer

Insulin

Answer

Growth hormone

NEET-PG 2015 — Physiology