Chapter: Endocrinology
Topic: Adrenal Medulla
Subtopic: Adrenaline and Insulin Interaction
Keyword Definitions:
• Adrenaline – Hormone released from adrenal medulla, acts on alpha and beta adrenergic receptors.
• Insulin – Pancreatic hormone that lowers blood glucose by promoting uptake and storage.
• Alpha cells – Pancreatic islet cells secreting glucagon.
• Beta cells – Pancreatic islet cells secreting insulin.
• Adrenergic receptors – G-protein coupled receptors mediating adrenaline/noradrenaline effects.
Lead Question - 2012
Adrenaline effects insulin by?
a) Stimulation of alpha cells
b) Stimulation of beta cells
c) Stimulation of delta cells
d) Stimulation of g cells
Explanation:
Adrenaline decreases insulin secretion predominantly via stimulation of alpha adrenergic receptors on pancreatic beta cells. This helps increase blood glucose availability during stress or fight-or-flight response. Therefore, the correct answer is stimulation of alpha cells.
Guessed Questions for NEET PG
1. Epinephrine reduces insulin secretion predominantly through?
a) Alpha receptor action
b) Beta receptor action
c) Both alpha and beta
d) Muscarinic receptors
Explanation:
The suppression of insulin release is mainly mediated by alpha adrenergic receptor activation on pancreatic beta cells. Beta receptors may increase insulin slightly, but the dominant effect is inhibition. Correct answer: Alpha receptor action.
2. During stress, blood glucose rises due to?
a) Increased insulin secretion
b) Increased adrenaline secretion
c) Increased somatostatin secretion
d) Increased glucagon binding
Explanation:
Stress activates sympathetic nervous system causing adrenaline release. Adrenaline decreases insulin secretion and enhances glycogenolysis and gluconeogenesis, raising blood glucose. Correct answer: Increased adrenaline secretion.
3. Which adrenergic receptor stimulates insulin release?
a) Alpha-1
b) Alpha-2
c) Beta-2
d) Muscarinic
Explanation:
Beta-2 adrenergic receptor activation enhances insulin release, whereas alpha-2 receptors inhibit it. The balance determines final insulin levels. Correct answer: Beta-2.
4. Adrenaline’s effect on insulin is important for?
a) Hypoglycemia prevention
b) Hyperglycemia prevention
c) Increasing insulin stores
d) Enhancing protein synthesis
Explanation:
By inhibiting insulin secretion, adrenaline prevents hypoglycemia during stress, ensuring glucose availability to muscles and brain. Correct answer: Hypoglycemia prevention.
5. Patient with pheochromocytoma shows low insulin levels because?
a) Excess glucagon
b) Excess cortisol
c) Excess adrenaline
d) Excess GH
Explanation:
Pheochromocytoma secretes excess adrenaline/noradrenaline, which suppresses insulin release via alpha-adrenergic activity, causing hyperglycemia. Correct answer: Excess adrenaline.
6. Which pancreatic cells are directly inhibited by adrenaline?
a) Alpha
b) Beta
c) Delta
d) G cells
Explanation:
Adrenaline directly inhibits pancreatic beta cells, lowering insulin release. This conserves glucose for vital organs during stress. Correct answer: Beta cells.
7. Adrenaline effect on blood sugar is mainly due to?
a) Insulin inhibition + Glycogenolysis
b) Insulin stimulation
c) Protein breakdown
d) Fatty acid oxidation
Explanation:
Adrenaline inhibits insulin secretion and simultaneously promotes glycogenolysis and gluconeogenesis, raising blood glucose. Correct answer: Insulin inhibition + Glycogenolysis.
8. Which receptor subtype is responsible for decreased insulin during sympathetic activation?
a) Alpha-2
b) Beta-1
c) Beta-2
d) Dopaminergic
Explanation:
Alpha-2 adrenergic receptors on pancreatic beta cells suppress insulin secretion when activated by adrenaline. Correct answer: Alpha-2.
9. In hypoglycemia, adrenaline secretion is important because?
a) It raises insulin
b) It lowers glucose
c) It raises glucose
d) It blocks glucagon
Explanation:
Adrenaline is a counter-regulatory hormone that raises glucose by inhibiting insulin and stimulating glycogenolysis. Correct answer: It raises glucose.
10. Which mechanism explains adrenaline-induced hyperglycemia?
a) Increased insulin uptake
b) Increased insulin secretion
c) Decreased insulin + Increased hepatic glucose output
d) Decreased glucagon
Explanation:
Adrenaline causes hyperglycemia by inhibiting insulin secretion and stimulating hepatic glycogenolysis and gluconeogenesis. Correct answer: Decreased insulin + Increased hepatic glucose output.
Chapter: Physiology
Topic: Muscle Physiology
Subtopic: Smooth vs Skeletal Muscle
Keyword Definitions:
• Smooth muscle – Involuntary muscle controlled by autonomic nervous system and hormones.
• Skeletal muscle – Voluntary muscle controlled by somatic nervous system.
• Calcium ions – Required for contraction in both smooth and skeletal muscle, though mechanism differs.
• Troponin – Regulatory protein present in skeletal but absent in smooth muscle.
• Myosin – Thick filament protein essential for contraction in all muscles.
Lead Question - 2012
Smooth muscle physiology different from skeletal muscle
a) K⁺ requires for contraction
b) Ca²⁺ required for contraction
c) Troponin is absent
d) Myosin is required for contraction
Explanation:
Smooth muscle differs from skeletal muscle mainly due to the absence of troponin. Instead, smooth muscle contraction is regulated by calmodulin–myosin light chain kinase pathway. Calcium still plays a key role, but the regulatory protein troponin is absent. Correct answer: Troponin is absent.
Guessed Questions for NEET PG
1. Smooth muscle contraction is regulated by?
a) Troponin
b) Calmodulin
c) Tropomyosin
d) Titin
Explanation:
Unlike skeletal muscle, smooth muscle lacks troponin. Instead, contraction is controlled by calcium–calmodulin complex which activates myosin light chain kinase. Correct answer: Calmodulin.
2. Which protein is absent in smooth muscle fibers?
a) Actin
b) Troponin
c) Myosin
d) Tropomyosin
Explanation:
Actin, myosin, and tropomyosin are present in smooth muscle. Troponin, however, is absent, which differentiates it from skeletal muscle. Correct answer: Troponin.
3. Calcium in smooth muscle binds to?
a) Troponin C
b) Calmodulin
c) Tropomyosin
d) Actinin
Explanation:
In skeletal muscle, calcium binds troponin C, but in smooth muscle it binds to calmodulin, initiating contraction via MLCK. Correct answer: Calmodulin.
4. Patient with asthma receives bronchodilator. Relaxation of airway smooth muscle occurs by?
a) Increased cAMP
b) Increased IP₃
c) Increased calcium
d) Decreased cAMP
Explanation:
β₂ agonists increase cAMP, which inhibits MLCK, leading to relaxation of smooth muscle in bronchi. Correct answer: Increased cAMP.
5. Dense bodies in smooth muscle are functionally similar to?
a) T-tubules
b) Z-lines
c) Sarcoplasmic reticulum
d) Myosin heads
Explanation:
Dense bodies in smooth muscle anchor thin filaments, serving a role similar to Z-lines in skeletal muscle. Correct answer: Z-lines.
6. Which of the following best describes latch phenomenon in smooth muscle?
a) Sustained contraction with high ATP
b) Sustained contraction with low ATP
c) Rapid relaxation
d) Skeletal-type tetany
Explanation:
Latch phenomenon allows smooth muscle to maintain tension for long periods with minimal ATP use. Correct answer: Sustained contraction with low ATP.
7. In smooth muscle, myosin light chain kinase (MLCK) is activated by?
a) Troponin C
b) Calcium–calmodulin
c) Tropomyosin
d) ATP alone
Explanation:
Calcium binds calmodulin which activates MLCK, phosphorylating myosin light chains to initiate contraction. Correct answer: Calcium–calmodulin.
8. Clinical: A hypertensive patient takes a calcium channel blocker. Effect on vascular smooth muscle?
a) Increased contraction
b) Decreased contraction
c) Increased MLCK activity
d) Increased calcium influx
Explanation:
Calcium channel blockers reduce calcium influx into smooth muscle, lowering contraction and relaxing vessels. Correct answer: Decreased contraction.
9. Skeletal and smooth muscle differ because skeletal muscle contraction is?
a) Involuntary and calmodulin-mediated
b) Voluntary and troponin-mediated
c) Involuntary and troponin-mediated
d) Voluntary and calmodulin-mediated
Explanation:
Skeletal muscle is voluntary and regulated by troponin–tropomyosin complex, unlike smooth muscle. Correct answer: Voluntary and troponin-mediated.
10. Which structural arrangement is absent in smooth muscle compared to skeletal?
a) Sarcomere
b) Myosin
c) Actin
d) Intermediate filaments
Explanation:
Smooth muscle lacks sarcomere arrangement, hence appears non-striated. Myosin, actin, and intermediate filaments are present. Correct answer: Sarcomere.
Chapter: Neurology
Topic: Peripheral Nerve Injuries
Subtopic: Types of Nerve Damage
Keyword Definitions:
• Neuropraxia – Temporary conduction block without axonal damage.
• Axonotmesis – Axonal disruption with intact connective tissue sheaths, recovery possible.
• Neurotmesis – Complete nerve transection with poor prognosis.
• Motor march – Sequential return of motor power in regenerating nerves.
• Nerve regeneration – Repair process after injury involving axonal sprouting.
Lead Question - 2012
Motor march is seen in ?
a) Axonotmesis
b) Neurotmesis
c) Neuropraxia
d) Nerve regeneration
Explanation:
Motor march refers to the sequential recovery of muscles supplied by a regenerating nerve, starting from proximal to distal. It is characteristic of nerve regeneration, particularly following axonotmesis. Correct answer: Nerve regeneration.
Guessed Questions for NEET PG
1. In neuropraxia, which of the following is true?
a) Axons are disrupted
b) Myelin sheath conduction block
c) Endoneurium destroyed
d) Recovery not possible
Explanation:
Neuropraxia is the mildest form of nerve injury with myelin sheath block but intact axons. Conduction resumes within weeks. Correct answer: Myelin sheath conduction block.
2. Wallerian degeneration occurs in?
a) Neuropraxia
b) Axonotmesis
c) Myasthenia gravis
d) Multiple sclerosis
Explanation:
When axons are disrupted (axonotmesis or neurotmesis), the distal segment undergoes Wallerian degeneration. It does not occur in neuropraxia. Correct answer: Axonotmesis.
3. Clinical: A patient with complete transection of the radial nerve shows no recovery after months. Likely diagnosis?
a) Neuropraxia
b) Neurotmesis
c) Axonotmesis
d) Neuritis
Explanation:
Neurotmesis is complete nerve transection with disruption of connective tissue sheaths. Spontaneous recovery is poor without surgical repair. Correct answer: Neurotmesis.
4. First sign of nerve regeneration is?
a) Return of sensation
b) Motor march
c) Tinel’s sign
d) Muscle hypertrophy
Explanation:
Tinel’s sign, tingling on percussion over the regenerating nerve, indicates axonal sprouting and is the earliest sign of regeneration. Correct answer: Tinel’s sign.
5. Clinical: A young man with wrist drop after humeral fracture recovers completely in 6 weeks. Likely nerve injury?
a) Neuropraxia
b) Neurotmesis
c) Axonotmesis
d) Axonopathy
Explanation:
Rapid, complete recovery without surgery suggests neuropraxia, a conduction block without axonal disruption. Correct answer: Neuropraxia.
6. Axonotmesis differs from neurotmesis because?
a) Axons preserved
b) Connective tissue sheath preserved
c) No Wallerian degeneration
d) Requires surgical repair
Explanation:
In axonotmesis, axons are destroyed but connective tissue sheaths remain intact, allowing axonal regrowth. Neurotmesis disrupts both. Correct answer: Connective tissue sheath preserved.
7. Rate of peripheral nerve regeneration is approximately?
a) 1 cm/day
b) 1 mm/day
c) 1 mm/week
d) 1 cm/week
Explanation:
Peripheral nerve regeneration typically occurs at a rate of about 1 mm per day, depending on patient age and injury site. Correct answer: 1 mm/day.
8. Clinical: Recovery of biceps before finger flexors after musculocutaneous nerve injury is due to?
a) Proximal-first regeneration
b) Motor march
c) Collateral sprouting
d) Sensory recovery faster
Explanation:
Motor march explains sequential recovery from proximal to distal muscles in nerve regeneration. Correct answer: Motor march.
9. Sunderland classification grade V corresponds to?
a) Neuropraxia
b) Axonotmesis
c) Neurotmesis
d) Demyelination only
Explanation:
Grade V injury in Sunderland classification represents neurotmesis, complete transection of axons and sheaths. Correct answer: Neurotmesis.
10. In nerve regeneration, Schwann cells mainly provide?
a) Structural myelin
b) Pathway for axonal growth
c) Motor endplate repair
d) Sensory transduction
Explanation:
Schwann cells form bands of Büngner, guiding regenerating axons along preserved endoneurial tubes. Correct answer: Pathway for axonal growth.
Chapter: Muscle Physiology
Topic: Length–Tension Relationship
Subtopic: Muscle Fibre Mechanics
Keyword Definitions:
• Optimum length – Muscle fibre length at which maximum tension is generated.
• Equilibrium length – Resting length without external load.
• Initial length – Starting length before contraction begins.
• Sarcomere – Basic contractile unit of a muscle fibre.
• Active tension – Force produced by cross-bridge cycling.
• Passive tension – Force developed when muscle is stretched beyond resting length.
Lead Question - 2012
When the tension in a muscle fibre is maximum, its length is called as ?
a) Equilibrium length
b) Optimum length
c) Initial length
d) None
Explanation:
Maximum muscle tension occurs at the optimum length, where actin–myosin overlap allows maximal cross-bridge formation. Too much shortening or stretching reduces tension. Hence, the correct answer is Optimum length.
Guessed Questions for NEET PG
1. At optimum length, sarcomere overlap is?
a) Complete overlap
b) Partial overlap allowing maximal cross-bridges
c) No overlap
d) Overlap beyond actin filaments
Explanation:
At optimum length, actin and myosin filaments overlap ideally, allowing maximum cross-bridge formation without hindrance. This ensures maximal tension development. Correct answer: Partial overlap allowing maximal cross-bridges.
2. Clinical: A patient with muscle spasm shows reduced force at very short length. Why?
a) Decreased calcium release
b) Overlap of actin filaments
c) Increased ATP consumption
d) Sarcomere hyperextension
Explanation:
At very short sarcomere lengths, actin filaments overlap excessively, blocking cross-bridge binding and reducing force generation. Correct answer: Overlap of actin filaments.
3. Passive tension in muscle arises mainly from?
a) Myosin heads
b) Actin filaments
c) Titin protein
d) Sarcoplasmic reticulum
Explanation:
When a muscle is stretched beyond resting length, passive tension develops due to titin and connective tissue elasticity. Correct answer: Titin protein.
4. Clinical: During physiotherapy, stretching muscles beyond resting length increases?
a) Active tension
b) Passive tension
c) Both active and passive equally
d) No change
Explanation:
Excessive stretching does not increase active tension but raises passive tension through elastic elements like titin. Correct answer: Passive tension.
5. Initial length of cardiac muscle fibres determines?
a) Contractility
b) Preload and stroke volume
c) Afterload
d) Heart rate
Explanation:
In the heart, initial muscle length (preload) sets sarcomere stretch, influencing stroke volume via the Frank–Starling mechanism. Correct answer: Preload and stroke volume.
6. In skeletal muscle, maximum active tension is observed at?
a) 1.6 µm sarcomere length
b) 2.0–2.2 µm sarcomere length
c) 3.5 µm sarcomere length
d) 1.0 µm sarcomere length
Explanation:
Studies show skeletal muscle develops maximal active tension when sarcomere length is 2.0–2.2 µm. Correct answer: 2.0–2.2 µm sarcomere length.
7. Clinical: Reduced cardiac contractility in dilated cardiomyopathy occurs because?
a) Sarcomeres overstretched
b) Increased overlap
c) ATP deficiency
d) Titin rupture
Explanation:
In dilated cardiomyopathy, sarcomeres are excessively stretched, reducing actin–myosin overlap and contractile efficiency. Correct answer: Sarcomeres overstretched.
8. What happens to active tension when muscle is stretched beyond optimum length?
a) Increases further
b) Decreases
c) Remains same
d) Shifts to passive
Explanation:
Beyond optimum length, overlap reduces, leading to fewer cross-bridges and decreased active tension, while passive tension increases. Correct answer: Decreases.
9. In isometric contraction at optimum length?
a) Tension is maximum
b) Length shortens maximally
c) Passive tension decreases
d) ATP consumption is minimal
Explanation:
During isometric contraction, muscle length is fixed but tension peaks at optimum sarcomere length. Correct answer: Tension is maximum.
10. Clinical: After immobilization, muscles lose optimum length efficiency due to?
a) Reduced sarcomere number
b) Increased titin length
c) Hyperplasia of fibres
d) Myelin degeneration
Explanation:
Immobilization leads to sarcomere loss, altering optimum length and reducing force output. Correct answer: Reduced sarcomere number.
Keyword Definitions
• Tetanic contraction: Sustained maximal muscle tension produced by rapid repetitive stimulation.
• Calcium (Ca2+): Intracellular ion that enables cross-bridge cycling by binding to regulatory proteins.
• Summation: Successive twitches adding to increase tension when stimuli arrive before full relaxation.
• Sarcoplasmic reticulum: Organelle storing Ca2+ in muscle fibres and releasing it on stimulation.
• Excitation–contraction coupling: Sequence linking membrane depolarization to Ca2+ release and contraction.
Lead Question - 2012
Tetanic contraction is due to accumulation of ?
a) Na+
b) Ca2+
c) K+
d) Cl-
Explanation:
Tetanic contraction results when repeated stimuli cause intracellular calcium to accumulate because release from the sarcoplasmic reticulum outpaces reuptake; sustained Ca2+ keeps cross-bridges cycling and prevents relaxation. This leads to fused tetanus. Correct answer: Ca2+ (option b). Clinically relevant in high-frequency stimulation and some toxins.
Guessed Questions for NEET PG
1. Which process increases during unfused tetanus compared with single twitch?
a) Ca2+ reuptake
b) Summation of tension
c) Complete relaxation
d) Decreased cross-bridge cycling
Explanation:
Unfused tetanus arises when stimuli occur before full relaxation, so individual twitches summate producing increased mean tension. This summation occurs because residual Ca2+ persists between stimuli, increasing cross-bridge availability; it differs from fused tetanus where relaxation is absent. Correct answer: Summation of tension.
2. A toxin that blocks Ca2+ release would cause?
a) Enhanced tetanus
b) Flaccid paralysis
c) Spastic paralysis
d) Increased muscle tone
Explanation:
Blocking Ca2+ release from the sarcoplasmic reticulum prevents actin-myosin interaction, producing inability to generate force and flaccid paralysis. Without Ca2+, tetanic contraction cannot occur. Clinically, agents that prevent Ca2+ release produce muscle weakness rather than spasm. Correct answer: Flaccid paralysis.
3. Which ionic change primarily terminates contraction between twitches?
a) Increased intracellular Na+
b) Decrease in intracellular Ca2+ via reuptake
c) Increase in intracellular K+
d) Chloride influx
Explanation:
Contraction ends when Ca2+ is actively pumped back into the sarcoplasmic reticulum, lowering cytosolic Ca2+ and allowing regulatory proteins to inhibit cross-bridge formation, enabling relaxation. Efficient reuptake is essential to prevent summation. Correct answer: Decrease in intracellular Ca2+ via reuptake.
4. Which clinical condition produces sustained involuntary tetanic contractions?
a) Hypocalcemia increasing neuronal excitability
b) Hyperkalemia causing flaccidity
c) Botulism blocking ACh release
d) Myasthenia gravis reducing receptor sensitivity
Explanation:
Hypocalcemia lowers threshold for neuronal firing, potentially increasing neurotransmitter release and producing muscle hyperexcitability and tetany. These involuntary sustained contractions differ from tetanic contraction produced experimentally by high-frequency stimulation. Correct answer: Hypocalcemia increasing neuronal excitability.
5. During high-frequency stimulation fused tetanus occurs because?
a) SR reuptake accelerates
b) Cytosolic Ca2+ remains elevated between stimuli
c) Sarcomeres shorten beyond overlap optimum
d) ATP becomes unavailable instantly
Explanation:
Fused tetanus results when stimuli arrive so rapidly that cytosolic Ca2+ remains high continuously, preventing relaxation. Sustained cross-bridge cycling produces maximal, smooth contraction until fatigue or stimulus stops. Correct answer: Cytosolic Ca2+ remains elevated between stimuli.
6. Which mechanism contributes to muscle fatigue during prolonged tetanic contraction?
a) Unlimited ATP supply
b) Accumulation of inorganic phosphate and H+ impairing Ca2+ release and cross-bridges
c) Increased Ca2+ sensitivity of troponin
d) Enhanced SR Ca2+ content
Explanation:
Fatigue during sustained tetanus involves metabolic changes including inorganic phosphate and proton accumulation, which reduce calcium release and cross-bridge function, and impair ATPase activity, leading to declining force despite continued stimulation. Correct answer: Accumulation of inorganic phosphate and H+.
7. Which drug would reduce tetanic contraction by decreasing available Ca2+?
a) Ryanodine receptor agonist opening SR Ca2+ release
b) Dantrolene reducing SR Ca2+ release
c) ACh esterase inhibitor increasing ACh
d) Ca2+ ionophore increasing cytosolic Ca2+
Explanation:
Dantrolene inhibits calcium release from the sarcoplasmic reticulum, reducing intracellular Ca2+ and preventing sustained contractions, clinically used to treat malignant hyperthermia by suppressing excessive muscle contraction. Correct answer: Dantrolene reducing SR Ca2+ release.
8. In skeletal muscle physiology, accumulation of which ion extracellularly tends to reduce excitability rather than cause tetanus?
a) Extracellular K+ accumulation causing depolarization and inactivation of Na+ channels
b) Extracellular Ca2+ accumulation increasing contraction
c) Extracellular Na+ accumulation causing tetanus
d) Extracellular Cl- causing summation
Explanation:
Prolonged activity can raise extracellular K+, depolarizing the membrane and inactivating Na+ channels, reducing excitability and causing weakness, not tetanic contraction; tetanus arises from intracellular Ca2+ accumulation and high-frequency stimulation. Correct answer: Extracellular K+ accumulation causing depolarization and inactivation.
9. Which structural element directly binds Ca2+ to initiate contraction in skeletal muscle?
a) Troponin C on thin filaments
b) Myosin light chain kinase
c) Titin
d) Nebulin
Explanation:
In skeletal muscle, Ca2+ binds to troponin C in the thin filament regulatory complex causing conformational changes that allow myosin–actin interaction and force production; increased Ca2+ concentration from SR release initiates contraction and tetanus under repetitive stimuli. Correct answer: Troponin C.
10. Which experimental manipulation would most directly create fused tetanus in an isolated muscle preparation?
a) Low-frequency single pulses
b) High-frequency electrical stimulation preventing relaxation between pulses
c) Cooling the muscle to stop enzymatic activity
d) Blocking ACh receptors at the neuromuscular junction
Explanation:
Fused tetanus is produced experimentally by applying high-frequency stimuli such that Ca2+ accumulation prevents relaxation between pulses, resulting in sustained maximal tension, an established method to study contractile properties in isolated muscle. Correct answer: High-frequency electrical stimulation.
Chapter: Central Nervous System
Topic: Cerebrospinal Fluid
Subtopic: Properties and Clinical Importance of CSF
Keyword Definitions:
CSF: Clear fluid cushioning brain and spinal cord, circulating within ventricles and subarachnoid space.
Arachnoid Villi: Microscopic projections of arachnoid membrane into venous sinuses, allowing CSF absorption.
Intracranial Pressure: Pressure inside the skull regulated by CSF volume and brain compliance.
CSF pH: Slightly lower (7.33) than plasma (7.40).
Dural Tap: Lumbar puncture procedure for diagnostic/therapeutic collection of CSF.
Lead Question – 2012
Which of the following is NOT TRUE about CSF?
a) Removal of CSF during dural tap causes intense intracranial headache
b) Normally contain no neutrophils
c) Formed by arachnoid villi within the ventricles
d) pH is less than that of plasma
Explanation: The false statement is (c). CSF is formed by the choroid plexus, not arachnoid villi. Arachnoid villi function in absorption into venous circulation. CSF removal during tap causes headache due to traction on meninges. Normal CSF has no neutrophils and a slightly lower pH than plasma. Correct answer: c.
Guessed Question 1
Which structure produces most CSF in adults?
a) Choroid plexus
b) Arachnoid villi
c) Dural sinuses
d) Astrocytes
Explanation: The majority of CSF is secreted by the choroid plexus in lateral, third, and fourth ventricles. Arachnoid villi only absorb it. Production rate is about 500 ml/day. Answer: a.
Guessed Question 2
Which condition is associated with elevated neutrophils in CSF?
a) Viral meningitis
b) Bacterial meningitis
c) Tuberculous meningitis
d) Fungal meningitis
Explanation: Presence of neutrophils in CSF indicates bacterial meningitis. Viral causes lymphocytic predominance, while TB and fungal show mononuclear cells. Thus, neutrophils are highly suggestive of bacterial etiology. Answer: b.
Guessed Question 3
A patient develops severe headache after lumbar puncture. The mechanism is?
a) Rise in CSF pressure
b) Fall in CSF pressure with meningeal traction
c) Dural nerve irritation
d) Arachnoid inflammation
Explanation: Post-lumbar puncture headache results from fall in CSF pressure causing traction on meninges and intracranial structures when upright. It improves on lying down. Answer: b.
Guessed Question 4
Normal CSF pressure in an adult lying on the side is?
a) 30–50 mm H₂O
b) 60–150 mm H₂O
c) 180–250 mm H₂O
d) 300–400 mm H₂O
Explanation: Normal CSF pressure in lateral decubitus position is 60–150 mm H₂O. Above this suggests raised intracranial pressure. Answer: b.
Guessed Question 5
Which of the following is true about CSF circulation?
a) Flows from subarachnoid space to ventricles
b) Produced in arachnoid villi
c) Passes from lateral to third ventricle via foramen of Monro
d) Absorbed in spinal cord
Explanation: CSF flows from lateral ventricles to third ventricle via foramen of Monro. It is produced in choroid plexus and absorbed by arachnoid villi into venous sinuses. Answer: c.
Guessed Question 6
A patient with suspected subarachnoid hemorrhage but normal CT should undergo?
a) EEG
b) Lumbar puncture
c) MRI
d) Skull X-ray
Explanation: In suspected subarachnoid hemorrhage, if CT scan is negative, lumbar puncture to detect xanthochromia in CSF is diagnostic. Answer: b.
Guessed Question 7
CSF glucose is normally?
a) Equal to plasma glucose
b) Two-thirds of plasma glucose
c) Half of plasma glucose
d) Higher than plasma glucose
Explanation: Normal CSF glucose is about two-thirds of plasma glucose. Low glucose levels suggest bacterial, TB, or fungal meningitis. Answer: b.
Guessed Question 8
In tuberculous meningitis, CSF typically shows?
a) High neutrophils, high glucose
b) Lymphocytes, low glucose, high protein
c) Neutrophils, high glucose, low protein
d) Normal findings
Explanation: Tuberculous meningitis is characterized by lymphocytic pleocytosis, low glucose, and high protein. This pattern helps distinguish it from viral or bacterial causes. Answer: b.
Guessed Question 9
Which of the following substances does NOT normally cross the blood-CSF barrier easily?
a) CO₂
b) Oxygen
c) Glucose
d) Plasma proteins
Explanation: The blood-CSF barrier prevents entry of large proteins while allowing gases and glucose. Hence plasma proteins do not cross easily. Answer: d.
Guessed Question 10
Increased opening pressure during lumbar puncture is seen in?
a) Intracranial hypertension
b) Normal pressure hydrocephalus
c) Spinal anesthesia
d) Hypovolemia
Explanation: Raised opening pressure during lumbar puncture is diagnostic of intracranial hypertension. This may result from tumors, hemorrhage, meningitis, or venous sinus thrombosis. Answer: a.
Chapter: Environmental Physiology
Topic: Acclimatization
Subtopic: Thermoregulation
Keyword Definitions:
Acclimatization: Physiological adaptation to environmental stress such as high altitude or heat.
Sweating: Mechanism of heat loss through evaporation of sweat from the skin surface.
Down Regulation: Reduction in receptor number or sensitivity due to prolonged stimulation.
Cholinergic receptors: Receptors activated by acetylcholine, key in sweat gland activity.
Adrenergic receptors: Receptors activated by catecholamines like epinephrine and norepinephrine.
Lead Question - 2012
During acclimatization, decreased sweating is due to down regulation of ?
a) Epinephrine receptors
b) Norepinephrine receptors
c) Acetylcholine receptors
d) Dopamine receptors
Explanation: The correct answer is c) Acetylcholine receptors. In heat acclimatization, sweat production reduces due to down regulation of muscarinic acetylcholine receptors on sweat glands. This conserves body water while maintaining thermoregulation. Adrenergic or dopamine receptors are not directly responsible for sweat gland control in acclimatization.
Guessed Question 1
Which neurotransmitter primarily stimulates sweat gland activity?
a) Acetylcholine
b) Norepinephrine
c) Dopamine
d) Serotonin
Explanation: The correct answer is a) Acetylcholine. Sweat glands are innervated by sympathetic cholinergic fibers, which release acetylcholine to trigger sweat production. Adrenergic transmitters like norepinephrine usually act on blood vessels, not directly on sweat glands. This distinction is essential in understanding thermoregulation physiology.
Guessed Question 2
In heat acclimatization, plasma volume usually:
a) Decreases
b) Remains unchanged
c) Increases
d) Fluctuates randomly
Explanation: The correct answer is c) Increases. During heat acclimatization, plasma volume expands to support greater sweating and maintain circulation under thermal stress. This helps preserve cardiovascular stability and prevents dehydration. It is a key adaptive change to allow prolonged work in hot climates.
Guessed Question 3
Which hormone enhances sodium reabsorption during heat acclimatization?
a) Insulin
b) Aldosterone
c) Cortisol
d) Thyroxine
Explanation: The correct answer is b) Aldosterone. Heat exposure activates the renin-angiotensin-aldosterone system, promoting sodium and water retention. This conserves body fluid during excessive sweating. Cortisol has a mild mineralocorticoid effect, but aldosterone is the primary regulator in acclimatization physiology.
Guessed Question 4
Which of the following best describes the heart rate response during early heat acclimatization?
a) Decreased resting and exercise heart rate
b) Increased resting heart rate only
c) Increased exercise heart rate only
d) No significant change
Explanation: The correct answer is a) Decreased resting and exercise heart rate. With acclimatization, cardiovascular efficiency improves, reducing the strain on the heart during both rest and exercise in hot environments. This adaptation supports better endurance under thermal stress.
Guessed Question 5
Which blood parameter decreases significantly during high-altitude acclimatization but not during heat acclimatization?
a) Plasma bicarbonate
b) Plasma sodium
c) Plasma potassium
d) Plasma glucose
Explanation: The correct answer is a) Plasma bicarbonate. At high altitude, respiratory alkalosis develops, leading to renal excretion of bicarbonate. In contrast, heat acclimatization does not significantly affect bicarbonate levels but instead alters plasma volume and electrolytes to support sweating.
Guessed Question 6
In a soldier exposed to desert climate, which adaptation is expected?
a) Reduced sweating rate
b) Increased sweat sodium concentration
c) Decreased sweat sodium concentration
d) Absence of sweating
Explanation: The correct answer is c) Decreased sweat sodium concentration. Acclimatization reduces sodium loss in sweat through aldosterone-mediated sodium reabsorption in sweat ducts. This adaptation conserves electrolytes and prevents hyponatremia during prolonged desert exposure.
Guessed Question 7
During prolonged heat acclimatization, which thermoregulatory change is most evident?
a) Delayed onset of sweating
b) Earlier onset of sweating
c) Cessation of sweating
d) No change in sweating
Explanation: The correct answer is b) Earlier onset of sweating. Acclimatized individuals begin sweating at lower core body temperatures, allowing more effective heat dissipation. This prevents dangerous rises in body temperature during physical activity in hot environments.
Guessed Question 8
Which receptor type is most associated with vasodilation in skin during heat exposure?
a) Alpha-adrenergic
b) Beta-adrenergic
c) Muscarinic
d) Dopaminergic
Explanation: The correct answer is b) Beta-adrenergic. Skin vasodilation during heat stress is mediated in part by beta-adrenergic receptors, enhancing blood flow to the skin for heat dissipation. Alpha receptors usually mediate vasoconstriction.
Guessed Question 9
Which electrolyte disturbance is most likely in excessive sweating without adequate fluid replacement?
a) Hypernatremia
b) Hyponatremia
c) Hyperkalemia
d) Hypercalcemia
Explanation: The correct answer is b) Hyponatremia. Excessive sweating without sodium replacement leads to significant sodium loss, lowering plasma sodium levels. This can cause weakness, confusion, and in severe cases seizures. Acclimatization helps reduce sodium loss per unit sweat volume.
Guessed Question 10
Which is the earliest physiological response in heat acclimatization?
a) Plasma volume expansion
b) Increased red blood cells
c) Reduced basal metabolic rate
d) Increased appetite
Explanation: The correct answer is a) Plasma volume expansion. This occurs within a few days of heat exposure, allowing better cardiovascular stability and sweat production. Other adaptations, such as reduced sweat sodium concentration, take longer to develop. RBC increase is characteristic of altitude acclimatization, not heat adaptation.
Chapter: Renal Physiology
Topic: Renal Handling of Substances
Subtopic: Tubular Reabsorption
Keyword Definitions:
Reabsorption: Movement of substances from tubular fluid back into the blood.
Glucose Reabsorption: Occurs completely in proximal tubule under normal conditions, via sodium-glucose transporters.
Sodium (Na+): Mostly reabsorbed, but not fully; some is excreted.
Potassium (K+): Filtered, reabsorbed, and secreted depending on body needs.
Urea: Partially reabsorbed, contributes to medullary concentration gradient.
Transport Maximum (Tm): Maximum rate at which a substance can be reabsorbed.
Glycosuria: Presence of glucose in urine when plasma glucose exceeds Tm.
Proximal Tubule: Main site of glucose reabsorption in the nephron.
Lead Question - 2012
Substance that is completely reabsorbed from the kidney?
a) Na+
b) K+
c) Urea
d) Glucose
Explanation: The correct answer is d) Glucose. Under normal physiological conditions, glucose filtered by the glomerulus is completely reabsorbed in the proximal tubule. Other substances like sodium, potassium, and urea are only partially reabsorbed. Glycosuria occurs if glucose exceeds the renal threshold, as in uncontrolled diabetes.
Guessed Question 1
Which part of nephron is primarily responsible for complete glucose reabsorption?
a) Proximal tubule
b) Loop of Henle
c) Distal tubule
d) Collecting duct
Explanation: The correct answer is a) Proximal tubule. Glucose reabsorption occurs through sodium-glucose cotransporters (SGLT2 in early proximal tubule, SGLT1 in later segments). Failure leads to glycosuria even without hyperglycemia.
Guessed Question 2
In uncontrolled diabetes mellitus, presence of glucose in urine is due to?
a) Increased renal clearance
b) Decreased tubular transport maximum
c) Plasma glucose exceeding tubular reabsorptive capacity
d) Enhanced secretion of glucose
Explanation: The correct answer is c) Plasma glucose exceeding tubular reabsorptive capacity. When blood glucose exceeds ~180 mg/dL, tubular transport maximum is overwhelmed, resulting in glucose loss in urine.
Guessed Question 3
Which of the following is reabsorbed both passively and actively in the nephron?
a) Glucose
b) Sodium
c) Urea
d) Potassium
Explanation: The correct answer is c) Urea. Urea undergoes passive reabsorption in proximal tubule and collecting duct, contributing to medullary osmotic gradient for water reabsorption.
Guessed Question 4
Which ion is secreted by distal nephron to maintain potassium balance?
a) Sodium
b) Chloride
c) Potassium
d) Calcium
Explanation: The correct answer is c) Potassium. Potassium is reabsorbed in proximal tubule and loop of Henle but secreted by principal cells in distal tubule and collecting duct under aldosterone influence.
Guessed Question 5
Renal threshold for glucose is approximately?
a) 120 mg/dL
b) 180 mg/dL
c) 220 mg/dL
d) 300 mg/dL
Explanation: The correct answer is b) 180 mg/dL. Above this concentration, glucose transporters saturate and glucose appears in urine. This threshold explains glycosuria in hyperglycemia.
Guessed Question 6
Which hormone promotes sodium reabsorption in the distal nephron?
a) Aldosterone
b) Vasopressin
c) ANP
d) Calcitonin
Explanation: The correct answer is a) Aldosterone. Aldosterone increases sodium reabsorption and potassium secretion in the distal tubule and collecting duct, helping maintain blood pressure and electrolyte balance.
Guessed Question 7
Which of the following is a clinical sign of reduced glucose reabsorption capacity?
a) Polyuria
b) Polydipsia
c) Glycosuria
d) All of the above
Explanation: The correct answer is d) All of the above. Glycosuria leads to osmotic diuresis (polyuria) and increased thirst (polydipsia), classic symptoms of uncontrolled diabetes mellitus.
Guessed Question 8
Which renal transport mechanism is energy-dependent?
a) Passive diffusion
b) Facilitated diffusion
c) Secondary active transport
d) Osmosis
Explanation: The correct answer is c) Secondary active transport. Glucose reabsorption occurs by coupling with sodium gradient, which is maintained by Na+/K+ ATPase pump in proximal tubular cells.
Guessed Question 9
Which factor decreases urea reabsorption in the kidney?
a) Increased ADH
b) Increased urine flow rate
c) Increased medullary concentration
d) Enhanced collecting duct permeability
Explanation: The correct answer is b) Increased urine flow rate. High urine flow reduces time for passive urea reabsorption, leading to increased urea excretion, often seen in osmotic diuresis.
Guessed Question 10
In Fanconi syndrome, renal tubular defect leads to?
a) Increased glucose reabsorption
b) Decreased glucose reabsorption
c) Increased sodium reabsorption
d) Decreased potassium secretion
Explanation: The correct answer is b) Decreased glucose reabsorption. Fanconi syndrome involves proximal tubule dysfunction causing loss of glucose, amino acids, phosphate, and bicarbonate in urine.
Chapter: Renal Physiology
Topic: Renal Handling of Substances
Subtopic: Tubular Secretion and Filtration
Keyword Definitions:
Filtration: Movement of plasma components into Bowman’s capsule at glomerulus.
Secretion: Transfer of substances from blood into tubular fluid.
Uric Acid: Waste product of purine metabolism, filtered and secreted in proximal tubule.
Glucose: Completely reabsorbed in proximal tubule, normally not secreted.
Urea: Partially reabsorbed and contributes to medullary osmotic gradient.
Sodium (Na+): Mostly reabsorbed, not secreted under normal physiology.
Proximal Tubule: Major site of secretion and reabsorption in nephron.
Transporters: Organic anion and cation transporters help secretion of uric acid and drugs.
Lead Question - 2012
Substrate which is both secreted & filtered?
a) Uric Acid
b) Glucose
c) Urea
d) Na+
Explanation: The correct answer is a) Uric Acid. Uric acid is filtered at the glomerulus and actively secreted by proximal tubular cells via organic anion transporters. It also undergoes partial reabsorption. In conditions like gout or renal tubular dysfunction, uric acid handling becomes clinically significant for diagnosis and therapy.
Guessed Question 1
Which transporter system mediates uric acid secretion in the proximal tubule?
a) SGLT2
b) Organic anion transporter
c) Sodium-potassium pump
d) Aquaporins
Explanation: The correct answer is b) Organic anion transporter. These transporters secrete uric acid and drugs into tubular fluid. Dysfunction may cause hyperuricemia or altered drug clearance, which is clinically important in pharmacology and renal disease management.
Guessed Question 2
Increased serum uric acid leading to gout occurs due to?
a) Decreased uric acid secretion
b) Increased glucose excretion
c) Reduced sodium excretion
d) Increased urea absorption
Explanation: The correct answer is a) Decreased uric acid secretion. Impaired tubular secretion of uric acid increases serum uric acid levels, resulting in gout. Drugs like probenecid enhance uric acid excretion and are used in treatment.
Guessed Question 3
Which of the following substances is filtered but almost completely reabsorbed?
a) Glucose
b) Uric acid
c) Urea
d) Creatinine
Explanation: The correct answer is a) Glucose. Normally, all filtered glucose is reabsorbed in the proximal tubule via sodium-glucose cotransporters. Presence of glucose in urine (glycosuria) indicates hyperglycemia or proximal tubular dysfunction.
Guessed Question 4
Which clinical drug increases uric acid secretion to manage gout?
a) Allopurinol
b) Probenecid
c) Furosemide
d) Thiazides
Explanation: The correct answer is b) Probenecid. Probenecid inhibits tubular reabsorption of uric acid, enhancing its secretion and urinary clearance. It is used in chronic gout but contraindicated in renal impairment.
Guessed Question 5
Which of the following is filtered and secreted but not reabsorbed significantly?
a) Creatinine
b) Sodium
c) Urea
d) Glucose
Explanation: The correct answer is a) Creatinine. Creatinine is freely filtered and slightly secreted, making it a reliable marker for glomerular filtration rate (GFR). Its secretion causes slight overestimation of GFR in clearance studies.
Guessed Question 6
In chronic renal failure, serum uric acid levels increase because?
a) Increased tubular secretion
b) Decreased tubular secretion
c) Increased urea absorption
d) Reduced glucose filtration
Explanation: The correct answer is b) Decreased tubular secretion. Declining renal function reduces secretion and clearance of uric acid, leading to hyperuricemia. This may worsen hypertension, gout, and cardiovascular risk.
Guessed Question 7
Which nephron segment is the major site of drug secretion?
a) Loop of Henle
b) Distal tubule
c) Proximal tubule
d) Collecting duct
Explanation: The correct answer is c) Proximal tubule. The proximal tubule contains organic acid and base transporters that secrete uric acid, creatinine, and drugs like penicillin, making it crucial in pharmacokinetics.
Guessed Question 8
Urea is primarily reabsorbed by?
a) Passive diffusion
b) Primary active transport
c) Secondary active transport
d) Vesicular transport
Explanation: The correct answer is a) Passive diffusion. Urea moves down its concentration gradient. Reabsorption mainly occurs in the proximal tubule and medullary collecting duct, helping in countercurrent multiplication and water conservation.
Guessed Question 9
Which of the following substances best reflects GFR because it is filtered but not secreted or reabsorbed?
a) Urea
b) Creatinine
c) Inulin
d) Uric acid
Explanation: The correct answer is c) Inulin. Inulin clearance accurately measures GFR since it is filtered freely but neither secreted nor reabsorbed. Creatinine is often used clinically but slightly overestimates GFR due to secretion.
Guessed Question 10
A patient on chemotherapy develops tumor lysis syndrome with raised uric acid. The best drug to reduce uric acid production is?
a) Probenecid
b) Febuxostat
c) Furosemide
d) Mannitol
Explanation: The correct answer is b) Febuxostat. Febuxostat, like allopurinol, inhibits xanthine oxidase, reducing uric acid production. It is used to prevent uric acid nephropathy and gout in high-risk patients undergoing chemotherapy.
Chapter: Renal Physiology
Topic: Hormonal Regulation of Kidney Function
Subtopic: Atrial Natriuretic Peptide (ANP)
Keywords:
ANP: Atrial Natriuretic Peptide, hormone secreted by atria in response to stretch.
PCT: Proximal Convoluted Tubule, primary site for reabsorption.
Loop of Henle: Segment important in urine concentration.
Collecting Duct: Final site of regulation of water and sodium.
Glomerulus: Initial filtering structure of nephron.
Lead Question - 2012
ANP acts at which site ?
a) Glomerulus
b) Loop of Henle
c) PCT
d) Collecting duct
Explanation:
ANP acts mainly at the collecting duct to inhibit sodium reabsorption, leading to natriuresis and diuresis. It also dilates afferent arterioles and increases GFR. This helps to reduce blood volume and pressure. Correct answer: d) Collecting duct.
Guessed Question 1
Which hormone primarily reduces sodium reabsorption in the collecting ducts?
a) Aldosterone
b) ADH
c) ANP
d) Renin
Explanation:
ANP opposes the action of aldosterone and reduces sodium reabsorption in the collecting ducts, promoting excretion. Answer: c) ANP.
Guessed Question 2
A patient with atrial stretch due to fluid overload will have elevated?
a) Aldosterone
b) Vasopressin
c) ANP
d) Angiotensin II
Explanation:
Atrial stretch stimulates ANP secretion, reducing blood pressure by promoting natriuresis. This mechanism helps counteract fluid overload. Answer: c) ANP.
Guessed Question 3
ANP increases sodium excretion by?
a) Stimulating renin release
b) Dilating afferent arteriole
c) Constricting efferent arteriole
d) Enhancing aldosterone secretion
Explanation:
ANP dilates the afferent arteriole and inhibits renin and aldosterone, leading to natriuresis. Answer: b) Dilating afferent arteriole.
Guessed Question 4
Which of the following is inhibited by ANP?
a) Renin secretion
b) Aldosterone secretion
c) Sodium reabsorption
d) All of the above
Explanation:
ANP inhibits renin and aldosterone secretion and reduces sodium reabsorption in the collecting duct. Answer: d) All of the above.
Guessed Question 5
Which receptor mediates ANP effects in kidney?
a) GABA receptor
b) Natriuretic peptide receptor-A
c) Beta adrenergic receptor
d) Nicotinic receptor
Explanation:
ANP acts via natriuretic peptide receptor-A, a guanylyl cyclase-linked receptor that increases cGMP. Answer: b) Natriuretic peptide receptor-A.
Guessed Question 6
In heart failure, ANP levels are?
a) Decreased
b) Increased
c) Normal
d) Absent
Explanation:
In heart failure, ANP secretion increases due to atrial distension, but the kidney response is often blunted. Answer: b) Increased.
Guessed Question 7
ANP effect on GFR is?
a) Decrease GFR
b) Increase GFR
c) No effect
d) Transient fall
Explanation:
ANP increases GFR by dilating afferent arteriole and relaxing mesangial cells. Answer: b) Increase GFR.
Guessed Question 8
Which ion excretion is promoted most by ANP?
a) Sodium
b) Potassium
c) Calcium
d) Chloride
Explanation:
ANP strongly increases sodium excretion (natriuresis), which is accompanied by water excretion. Answer: a) Sodium.
Guessed Question 9
ANP secretion is stimulated by?
a) Dehydration
b) Hemorrhage
c) Atrial distension
d) Low blood pressure
Explanation:
ANP secretion occurs in response to atrial distension due to increased venous return. Answer: c) Atrial distension.
Guessed Question 10
ANP counters the effects of which hormone?
a) Aldosterone
b) ADH
c) Cortisol
d) Insulin
Explanation:
ANP directly opposes aldosterone by decreasing sodium reabsorption in the collecting ducts. Answer: a) Aldosterone.