NEET-PG 2012 - Physiology Practice Questions

Q: Lesion of globus pallidus causes

Athetosis. ***Athetosis*** - **Athetosis** is the **classic movement disorder** associated with lesions of the **globus pallidus**, often occurring with **putamen** involvement. - It is characterized by **slow, writhing, involuntary movements**, particularly affecting the **distal extremities** (hands and feet). - Commonly seen in **kernicterus** (bilirubin-induced damage to basal ganglia), **cerebral palsy**, and **status marmoratus** of the basal ganglia. - When combined with chorea, it forms **choreoathetosis**. *Chorea* - **Chorea** is predominantly associated with dysfunction of the **caudate nucleus** and **putamen**, as seen in **Huntington's disease**. - It involves brief, irregular, unpredictable, **involuntary movements** that flow from one body part to another. *Hemibalismus* - **Hemibalismus** is most commonly caused by a lesion in the **subthalamic nucleus** (nucleus of Luys), often due to a **lacunar stroke**. - It involves large-amplitude, **involuntary flinging movements** of the limbs on **one side of the body**. *Dystonia* - **Dystonia** involves sustained or repetitive muscle contractions leading to twisting movements or abnormal fixed postures. - It results from dysfunction of **multiple basal ganglia structures** including the globus pallidus internal segment, putamen, and thalamus, but is **not the classic presentation** of isolated globus pallidus lesions.

Q: Decidual reaction is due to which hormone?

Progesterone. ***Progesterone*** - The **decidual reaction** is a specific uterine stromal cell differentiation process that prepares the endometrium for **implantation and pregnancy maintenance**. - This process is primarily induced and maintained by **progesterone**, which causes stromal cells to enlarge, accumulate glycogen and lipids, and secrete various factors essential for embryonic development. *Estrogen* - Estrogen plays a crucial role in the **proliferation of the endometrium** during the follicular phase, building up the uterine lining. - While estrogen is essential, it acts in conjunction with progesterone; progesterone is the **primary hormone** responsible for the decidualization process itself. *LH* - Luteinizing hormone (LH) is responsible for triggering **ovulation** and stimulating the corpus luteum to produce progesterone. - LH's direct role is not in the decidual reaction of the endometrium but rather in the **ovarian events** that lead to the production of the hormones that cause decidualization. *FSH* - Follicle-stimulating hormone (FSH) is vital for the growth and maturation of **ovarian follicles** and **estrogen production**. - FSH does not directly induce the decidual reaction but facilitates the production of estrogen, which then contributes to endometrial proliferation, a precursor to progesterone's decidualizing effect.

Q: What is the primary mechanism underlying hyperthermia?

Failure of thermoregulation. ***Failure of thermoregulation*** - **Hyperthermia** is fundamentally caused by the body's inability to dissipate heat effectively, leading to an uncontrolled rise in core body temperature. - This differentiates it from fever, where the **hypothalamic set point** is elevated, and the body actively tries to reach that higher temperature. *Temperature > 41.5°C* - While a temperature exceeding **41.5°C** is often seen in severe hyperthermia, it is a *consequence* of the failure of thermoregulation, not its primary cause. - This extreme temperature indicates a critical state, but the underlying problem is the body's inability to control internal heat. *Temperature > 40°C with autonomic dysfunction* - A temperature above **40°C** combined with **autonomic dysfunction** (e.g., altered mental status, seizures) describes a severe *manifestation* of hyperthermia, often seen in heat stroke. - This is a symptom complex resulting from, rather than the primary cause of, the body's thermoregulatory failure. *No change in hypothalamic set point* - This statement is a *characteristic* of hyperthermia, distinguishing it from fever, where the **hypothalamic set point** is elevated. - However, the *absence* of this change is not the primary cause; rather, the underlying issue is the body's inability to manage its heat load despite a normal set point.

Q: Tetany is seen in

Respiratory alkalosis. ***Respiratory alkalosis*** - **Respiratory alkalosis** is caused by **hyperventilation**, which leads to a decrease in arterial partial pressure of carbon dioxide (**PaCO2**). - This decrease in PaCO2 causes an increase in pH (alkalemia) and a shift in the albumin-bound calcium equilibrium, reducing the amount of **ionized calcium** in the blood, leading to symptoms of **hypocalcemia** such as tetany. *Respiratory acidosis* - **Respiratory acidosis** is characterized by an increase in PaCO2 and a decrease in pH due to inadequate ventilation, which would not typically cause tetany. - In fact, the acidosis would tend to increase **ionized calcium** levels, thereby counteracting any tendency towards symptoms of hypocalcemia. *Metabolic acidosis* - **Metabolic acidosis** involves a decrease in bicarbonate concentration and pH, often due to conditions like diabetic ketoacidosis or lactic acidosis. - Similar to respiratory acidosis, the acidic environment of **metabolic acidosis** tends to increase **ionized calcium** levels, making tetany unlikely. *Hyperkalemia* - **Hyperkalemia** refers to elevated potassium levels in the blood, which primarily affects cardiac and neuromuscular function. - While it can cause muscle weakness and cardiac arrhythmias, it does not directly lead to **tetany**, which is a sign of **hypocalcemia**.

Q: Unable to consolidate long-term memory. Which lobe of the brain is involved?

Temporal. ***Temporal*** - The **temporal lobe**, particularly the **hippocampus** within it, is critically involved in the formation and consolidation of new long-term memories [1]. - Damage to the temporal lobe can result in **anterograde amnesia**, the inability to form new memories after the injury [1]. *Frontal* - The **frontal lobe** is primarily responsible for executive functions, **planning**, decision-making, and working memory [1]. - While it contributes to memory retrieval and strategic memory processes, it is not the primary site for the consolidation of long-term memories. *Parietal* - The **parietal lobe** is involved in processing **sensory information**, spatial awareness, and navigation. - It plays a role in attention and short-term memory, but not in the consolidation of long-term memory. *Occipital* - The **occipital lobe** is dedicated to **visual processing** and interpretation of visual information. - It has no direct primary role in the consolidation of long-term memories.

Q: Narcolepsy is due to abnormality in ?

Hypothalamus. **Hypothalamus** - Narcolepsy is primarily caused by the loss of **orexin (hypocretin)** producing neurons in the **hypothalamus**, which are crucial for maintaining wakefulness. - This deficiency leads to dysregulation of **sleep-wake cycles**, causing excessive daytime sleepiness and other narcolepsy symptoms. *Neocortex* - The neocortex is involved in higher-level cognitive functions, sensory perception, and voluntary movement, but it is not the primary site of pathology in narcolepsy. - While sleep stages involve cortical activity, the core deficit in narcolepsy does not originate here. *Cerebellum* - The cerebellum is mainly responsible for motor control, coordination, and balance. - Its dysfunction is associated with ataxic gait and coordination problems, not the sleep disturbances characteristic of narcolepsy. *Medulla oblongata* - The medulla oblongata controls vital autonomic functions like breathing, heart rate, and blood pressure. - While involved in sleep regulation pathways, it is not the primary anatomical location affected in narcolepsy.

Q: Which hormone surge indicates the fertile period in females?

LH. ***LH*** - The **luteinizing hormone (LH) surge** triggers **ovulation**, releasing a mature egg from the follicle. - This surge is a key indicator of the **fertile window** in a woman's menstrual cycle. *FSH* - **Follicle-stimulating hormone (FSH)** primarily stimulates the growth and development of **ovarian follicles** early in the menstrual cycle, prior to the fertile period. - While essential for follicle maturation, it does not directly signal the immediate fertile window or ovulation. *Estrogen* - **Estrogen levels peak** just before the LH surge, playing a role in triggering the surge itself through positive feedback. - However, estrogen itself does not directly indicate the onset of the fertile period; rather, the subsequent LH surge does. *Oxytocin* - **Oxytocin** is largely involved in processes like **uterine contractions during childbirth** and **milk ejection during lactation**. - It has no direct role in indicating a female's fertile period or timing of ovulation.

Q: Maximum duration of time is spent in NREM stage:

II. ***II*** - **NREM Stage II** constitutes the largest percentage of total sleep time, typically accounting for about 45-55% of an adult's sleep. - This stage is characterized by the presence of **sleep spindles** and **K-complexes** on an EEG, and it is a relatively stable period of sleep. *I* - **NREM Stage I** is the lightest stage of sleep, representing the transition from wakefulness to sleep. - It is the shortest stage, lasting only a few minutes, and is characterized by slow eye movements and a decrease in muscle tone. *III* - **NREM Stage III** (along with Stage IV in older classifications) is considered **slow-wave sleep** or deep sleep. - While crucial for restorative processes, Stage III does not account for the majority of total sleep time, typically being less than Stage II. *IV* - **NREM Stage IV** is the deepest stage of sleep, now often combined with Stage III as part of **slow-wave sleep**. - It involves the lowest brain wave activity and is difficult to awaken from, but its duration is significantly less than Stage II.

Q: Which of the following is true about NREM sleep?

Teeth grinding. ***Teeth grinding*** - **Bruxism** (teeth grinding) commonly occurs during **NREM sleep stages**, particularly stage N2. - It is an **involuntary motor activity** that can lead to dental issues and jaw pain. *Narcolepsy* - Narcolepsy is a neurological condition characterized by overwhelming daytime sleepiness and involves dysregulation of **REM sleep**. - Patients often experience **sudden REM sleep onset** during waking hours, not typically an NREM sleep phenomenon. *Nightmares* - Nightmares are generally vivid, disturbing dreams that occur during **REM sleep**. - While other sleep disturbances can occur in NREM, classic nightmares are a **REM-related parasomnia**. *Sleep paralysis* - Sleep paralysis is a temporary inability to move or speak that occurs when waking up or falling asleep, often associated with **REM sleep**. - It involves the persistence of **REM atonia** into the waking state.

Q: Hypothalamus increases release of all hormones from the pituitary except ?

Prolactin. ***Prolactin*** - The hypothalamus primarily **inhibits prolactin release** from the anterior pituitary via **dopamine** (prolactin-inhibiting hormone). - All other hormones listed (ACTH, TSH, FSH/LH, GH) are stimulated by their respective hypothalamic releasing hormones. *ACTH* - The hypothalamus **increases ACTH release** by secreting **corticotropin-releasing hormone (CRH)**, which acts on the anterior pituitary. - CRH stimulates corticotrophs to synthesize and release ACTH, which then acts on the adrenal glands. *TSH* - The hypothalamus **increases TSH release** by secreting **thyrotropin-releasing hormone (TRH)**, which stimulates thyrotrophs in the anterior pituitary. - TRH also has a minor stimulatory effect on prolactin release, but its primary role is TSH stimulation. *FSH* - The hypothalamus **increases FSH release** (along with LH) by secreting **gonadotropin-releasing hormone (GnRH)** in a pulsatile manner. - GnRH stimulates gonadotrophs in the anterior pituitary to produce and secrete both FSH and LH.

Question 1

Lesion of globus pallidus causes

Accepted Answer

Athetosis

Answer

Chorea

Answer

Hemibalismus

Answer

Dystonia

Question 2

Decidual reaction is due to which hormone?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

LH

Answer

FSH

Question 3

What is the primary mechanism underlying hyperthermia?

Accepted Answer

Failure of thermoregulation

Answer

Temperature > 40°C with autonomic dysfunction

Answer

Temperature > 41.5°C

Answer

No change in hypothalamic set point

Question 4

Tetany is seen in

Accepted Answer

Respiratory alkalosis

Answer

Respiratory acidosis

Answer

Metabolic acidosis

Answer

Hyperkalemia

Question 5

Unable to consolidate long-term memory. Which lobe of the brain is involved?

Accepted Answer

Temporal

Answer

Frontal

Answer

Parietal

Answer

Occipital

Question 6

Narcolepsy is due to abnormality in ?

Accepted Answer

Hypothalamus

Answer

Neocortex

Answer

Cerebellum

Answer

Medulla oblongata

Question 7

Which hormone surge indicates the fertile period in females?

Accepted Answer

LH

Answer

FSH

Answer

Estrogen

Answer

Oxytocin

Question 8

Maximum duration of time is spent in NREM stage:

Accepted Answer

II

Answer

I

Answer

III

Answer

IV

Question 9

Which of the following is true about NREM sleep?

Accepted Answer

Teeth grinding

Answer

Narcolepsy

Answer

Nightmares

Answer

Sleep paralysis

Question 10

Hypothalamus increases release of all hormones from the pituitary except ?

Accepted Answer

Prolactin

Answer

ACTH

Answer

TSH

Answer

FSH

NEET-PG 2012 — Physiology