EMG, Myasthenia gravis, Lymphatic circulation, Comparison of skeletal, cardiac & smooth muscle, periodic breathing & drowning, physiology deep sea diving & applied, pineal gland& thymus physiolog diabetes mellitus, sex determination & differentiation, puberty & applied, infertility causes & role of IV in infertility, physiology of menopause. Give mcq based information

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physiology MCQ deep sea diving periodic breathing lymphatic circulation sex determination menopause infertility IVF

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📚 MCQ-Based Physiology Notes — Comprehensive Guide

1. 🔬 ELECTROMYOGRAPHY (EMG)

Key Facts for MCQs:

Q1. EMG records electrical activity of muscles via:

(A) Surface electrodes only
(B) Needle electrodes only
(C) Surface or needle electrodes ✅
(D) Ultrasound

Q2. A CMAP (Compound Motor Action Potential) represents:

(A) Summated sensory neuron activity
(B) Summated electrical activity of muscle cells innervated by a motor nerve ✅
(C) Single motor unit potential
(D) Autonomic nerve conduction

Q3. In nerve conduction studies, SNAP (Compound Sensory Nerve Action Potential) is PRESERVED in lesions:

(A) Distal to dorsal root ganglia
(B) Proximal to dorsal root ganglia ✅
(C) In peripheral neuropathy
(D) In Guillain-Barré syndrome

Q4. Slow repetitive stimulation (2-3 Hz) in EMG depletes:

(A) Postsynaptic AChRs
(B) Presynaptic ACh stores ✅
(C) Myelin
(D) Ca²⁺ channels

Q5. Decreased SNAP amplitude indicates:

(A) Demyelination
(B) Axonal damage ✅
(C) NMJ disorder
(D) Myopathy

Q6. Normal nerve conduction velocity (NCV) in upper limbs is approximately:

(A) 20–30 m/s
(B) 35–45 m/s
(C) 50–70 m/s ✅
(D) 80–100 m/s

Source: Neuroanatomy through Clinical Cases 3rd Edition

2. 💉 MYASTHENIA GRAVIS (MG)

Q1. Myasthenia gravis is caused by antibodies against:

(A) Voltage-gated Ca²⁺ channels
(B) Nicotinic ACh receptors (AChR) ✅
(C) Voltage-gated Na⁺ channels
(D) NMDA receptors

Q2. The main immunogenic region (MIR) targeted in MG is on which subunit of AChR?

(A) α subunit ✅
(B) β subunit
(C) γ subunit
(D) δ subunit

Q3. Bimodal peak incidence of MG — early onset is associated with:

(A) Young women with thymic hyperplasia ✅
(B) Old men with thymoma
(C) Children with congenital myasthenic syndrome
(D) Men with thymoma

Q4. Electrophysiological hallmark of MG:

(A) Increased amplitude of MEPP
(B) Decreased amplitude of MEPP with normal quantal frequency ✅
(C) Complete abolition of MEPP
(D) Increased quantal frequency

Q5. First-line pharmacological treatment of MG:

(A) Atropine
(B) Pyridostigmine (AChE inhibitor) ✅
(C) Succinylcholine
(D) Neostigmine methylsulfate IV only

Q6. Thymectomy in MG patients with thymoma results in clinical improvement in:

(A) 25%
(B) 50%
(C) ~75% ✅
(D) 100%

Q7. MG crisis vs. Cholinergic crisis — cholinergic crisis is caused by:

(A) Insufficient AChE inhibitor
(B) Overdose of AChE inhibitor ✅
(C) Autoimmune flare
(D) Thymic hyperplasia

Q8. MG is differentiated from Lambert-Eaton syndrome because in MG:

(A) Strength improves with repeated activity
(B) Strength worsens with repeated activity (fatigable weakness) ✅
(C) Reflexes are absent
(D) Autonomic features dominate

Q9. Treatment targeting the immunological attack in MG includes:

(A) Pyridostigmine
(B) Plasmapheresis + corticosteroids ✅
(C) Atropine
(D) Calcium gluconate

Source: Medical Physiology (Boron & Boulpaep); Neuroanatomy through Clinical Cases

3. 🩸 LYMPHATIC CIRCULATION

Q1. The largest lymphatic vessel in the body is:

(A) Right lymphatic duct
(B) Thoracic duct ✅
(C) Cisterna chyli
(D) Subclavian trunk

Q2. Thoracic duct drains into:

(A) Right subclavian vein
(B) Junction of left subclavian and left internal jugular vein ✅
(C) Superior vena cava
(D) Azygos vein

Q3. Lymph capillaries are permeable to large molecules because they have:

(A) Tight junctions
(B) Fenestrations
(C) Overlapping endothelial cells with no basement membrane (anchoring filaments) ✅
(D) Gap junctions

Q4. The main driving force for lymph flow is:

(A) Cardiac output
(B) Skeletal muscle contractions + respiratory movements + intrinsic lymphatic vessel contraction ✅
(C) Osmotic pressure
(D) Gravity alone

Q5. Edema in lymphatic obstruction is called:

(A) Lymphedema ✅
(B) Pitting edema
(C) Anasarca
(D) Hydrothorax

Q6. Lymph from the lower extremities first passes through:

(A) Inguinal lymph nodes ✅
(B) Axillary nodes
(C) Mesenteric nodes
(D) Thoracic duct directly

Q7. Chyle is lymph rich in fat absorbed from:

(A) Stomach
(B) Small intestine via lacteals ✅
(C) Colon
(D) Liver

Q8. Lymph does NOT contain:

(A) Lymphocytes
(B) Proteins
(C) RBCs (under normal conditions) ✅
(D) Lipids

4. 💪 COMPARISON: SKELETAL vs. CARDIAC vs. SMOOTH MUSCLE

Feature	Skeletal	Cardiac	Smooth
Nuclei	Multinucleate	Single (central)	Single (central)
Striations	Yes	Yes	No
Control	Voluntary	Involuntary	Involuntary
T-tubules	Wide, at A-I junction	Narrow, at Z-disc	Absent/rudimentary
Intercalated discs	No	Yes	No
SR development	Extensive	Less developed	Poorly developed
Pacemaker	None	SA node (intrinsic)	Some (interstitial cells)
Ca²⁺ source	Mainly SR	SR + extracellular	Mainly extracellular
Ca²⁺ mediator	Troponin	Troponin	Calmodulin-MLCK
Action potential	All-or-none	Plateau (phase 2)	Slow, graded
Fatigue	Yes	No	No
Regeneration	Limited (satellite cells)	None	Yes
Length of fiber	Long (few cm)	Short, branched	Short, spindle

Q1. Cardiac muscle is unique because it has:

(A) Intercalated discs with gap junctions ✅
(B) Multiple nuclei
(C) No T-tubules
(D) Voluntary control

Q2. Ca²⁺ in smooth muscle acts through:

(A) Troponin-C
(B) Calmodulin → MLCK (myosin light chain kinase) ✅
(C) Troponin-I
(D) Actin directly

Q3. The refractory period of cardiac muscle is:

(A) Very short (allows tetanus)
(B) Long (prevents tetanic contraction) ✅
(C) Same as skeletal muscle
(D) Absent

Q4. Smooth muscle contraction involves phosphorylation of:

(A) Actin
(B) Myosin light chain ✅
(C) Troponin
(D) Tropomyosin

Q5. T-tubules in skeletal muscle are located at:

(A) M-line
(B) A-I junction (junction of A and I bands) ✅
(C) Z-disc
(D) H-zone

5. 🌊 PERIODIC BREATHING & DROWNING

Periodic Breathing:

Q1. Cheyne-Stokes breathing is characterized by:

(A) Rapid regular breathing
(B) Waxing and waning tidal volume with apneic episodes ✅
(C) Deep, slow regular breathing
(D) Inspiratory stridor

Q2. Commonest cause of Cheyne-Stokes breathing:

(A) Left heart failure (increased circulation time) ✅
(B) Right heart failure
(C) Pulmonary embolism
(D) Asthma

Q3. The underlying mechanism of Cheyne-Stokes breathing is:

(A) Increased controller gain + increased circulation time → oscillation of CO₂ around the apnea threshold ✅
(B) Peripheral chemoreceptor failure
(C) Brainstem infarct
(D) Hyperthyroidism

Q4. Biot's breathing (ataxic breathing) is seen in:

(A) Cheyne-Stokes
(B) Medullary compression (meningitis, raised ICP) ✅
(C) Metabolic acidosis
(D) Anxiety

Q5. Kussmaul breathing (deep, rapid) is caused by:

(A) Metabolic acidosis (diabetic ketoacidosis) ✅
(B) Respiratory alkalosis
(C) Opioid overdose
(D) Cervical cord lesion

Drowning:

Q6. "Dry drowning" occurs due to:

(A) Massive water aspiration
(B) Laryngospasm preventing water aspiration ✅
(C) Cardiac arrest first
(D) Pulmonary edema

Q7. In wet drowning (fresh water), the major pathophysiology is:

(A) Hemodilution → hemolysis → hyperkalemia → ventricular fibrillation ✅
(B) Hemoconcentration
(C) Hypokalemia
(D) Metabolic alkalosis

Q8. In seawater drowning (hypertonic):

(A) Water moves from blood into alveoli → hemoconcentration → pulmonary edema ✅
(B) Hemolysis occurs
(C) Hyponatremia
(D) Hypervolemia

Q9. "Secondary drowning" (near-drowning syndrome) is characterized by:

(A) Immediate death
(B) Delayed pulmonary edema/ARDS hours after rescue ✅
(C) Bradycardia only
(D) Metabolic alkalosis

6. 🤿 DEEP SEA DIVING — PHYSIOLOGY & APPLIED

Q1. As depth increases by 10 meters of sea water, pressure increases by:

(A) 0.5 atm
(B) 1 atm ✅
(C) 2 atm
(D) 5 atm

Q2. Nitrogen narcosis is also called:

(A) Oxygen toxicity
(B) "Rapture of the deep" — narcotic effect of N₂ under high pressure ✅
(C) Decompression sickness
(D) CO₂ retention

Q3. Decompression sickness ("The Bends") results from:

(A) CO₂ bubble formation
(B) Nitrogen bubble formation in tissues on rapid ascent ✅
(C) O₂ toxicity
(D) Hypercapnia

Q4. Treatment of decompression sickness is:

(A) Hyperbaric oxygen therapy (recompression) ✅
(B) Diuretics
(C) Vasodilators
(D) Mechanical ventilation

Q5. Oxygen toxicity at high partial pressures affects primarily:

(A) Kidneys
(B) CNS (Grand mal seizures — Paul Bert effect) and lungs (Lorrain Smith effect) ✅
(C) Liver
(D) Heart

Q6. Helium is substituted for nitrogen in deep diving mixtures because:

(A) Low solubility in blood, low narcotic effect, low density ✅
(B) It provides more O₂
(C) It prevents hypercapnia
(D) It has high solubility

Q7. Henry's Law states that at constant temperature:

(A) Volume of gas is inversely proportional to pressure
(B) Amount of gas dissolved in liquid is proportional to its partial pressure ✅
(C) Volume is directly proportional to temperature
(D) Pressure × volume = constant

Q8. "Squeeze" injury in diving affects:

(A) Only the eyes
(B) Air-filled body spaces (sinuses, ears, lungs) due to unequal pressure ✅
(C) Only skin
(D) Only joints

Q9. High Pressure Nervous Syndrome (HPNS) occurs at depths:

(A) >10 m
(B) >30 m
(C) >150–200 m ✅
(D) >50 m

Q10. The diving reflex includes:

(A) Bradycardia + peripheral vasoconstriction + blood shift to core ✅
(B) Tachycardia
(C) Vasodilation
(D) Bronchodilation

7. 🌙 PINEAL GLAND PHYSIOLOGY

Q1. Main hormone secreted by the pineal gland:

(A) Serotonin
(B) Melatonin ✅
(C) Dopamine
(D) TSH

Q2. Main cell type of the pineal gland:

(A) Pinealocyte ✅
(B) Astrocyte
(C) Chromaffin cell
(D) Pituicyte

Q3. Melatonin secretion is HIGHEST at:

(A) Noon
(B) 6 PM
(C) 2–4 AM ✅
(D) 8 AM

Q4. Pathway for light suppression of melatonin: retina →

(A) Suprachiasmatic nucleus → intermediolateral cell column → superior cervical ganglion → pinealocyte ✅
(B) Retina → hypothalamus → pituitary → pineal
(C) Retina → thalamus → pineal directly
(D) Retina → optic cortex → pineal

Q5. In darkness, norepinephrine released onto pinealocytes:

(A) Stimulates melatonin synthesis and release ✅
(B) Inhibits melatonin
(C) Stimulates serotonin release only
(D) Has no effect

Q6. Clinical application of melatonin — calcification of pineal gland ("brain sand") is useful for:

(A) Detecting midline shift on X-ray/CT (radiological landmark) ✅
(B) Diagnosing diabetes
(C) Measuring ICP
(D) Diagnosing MG

Q7. Pineal tumors are associated with:

(A) Excess melatonin
(B) Loss of melatonin secretion; precocious puberty (germinoma destroying gland) ✅
(C) Hypothyroidism
(D) Acromegaly

8. 🦋 THYMUS PHYSIOLOGY

Q1. The thymus is the site of maturation for:

(A) B lymphocytes
(B) T lymphocytes ✅
(C) NK cells
(D) Macrophages

Q2. Thymic hormone responsible for T-cell maturation:

(A) Thyroxine
(B) Thymosin (thymopoietin, thymulin) ✅
(C) Thyroglobulin
(D) PTH

Q3. The thymus is LARGEST at:

(A) Birth
(B) Puberty ✅
(C) Middle age
(D) Old age

Q4. After puberty, the thymus undergoes:

(A) Involution (replaced by fat and fibrous tissue) ✅
(B) Hyperplasia
(C) Malignant transformation
(D) Enlargement

Q5. In DiGeorge syndrome, absence of thymus leads to:

(A) B-cell deficiency
(B) T-cell deficiency → recurrent infections with intracellular pathogens ✅
(C) NK cell deficiency
(D) Complement deficiency

Q6. Thymic selection processes:

(A) Positive selection (cortex) + Negative selection (medulla) → self-tolerant T cells ✅
(B) Only positive selection
(C) Only negative selection
(D) Random selection

Q7. MHC restriction of T cells is established during:

(A) Positive selection in thymic cortex ✅
(B) Negative selection
(C) Peripheral activation
(D) Bone marrow development

9. 🍬 DIABETES MELLITUS

Q1. Beta cells of islets of Langerhans constitute approximately ___% of islet cells:

(A) 25%
(B) 60% ✅
(C) 10%
(D) 80%

Q2. Alpha cells secrete:

(A) Insulin
(B) Glucagon ✅
(C) Somatostatin
(D) Amylin

Q3. Hormone that inhibits both insulin AND glucagon secretion:

(A) Amylin
(B) GIP
(C) Somatostatin (from delta cells) ✅
(D) Pancreatic polypeptide

Q4. Type 1 DM is characterized by:

(A) Autoimmune destruction of beta cells → absolute insulin deficiency ✅
(B) Insulin resistance
(C) Gestational hormones
(D) MODY gene mutations

Q5. HbA1c reflects blood glucose over:

(A) 1 week
(B) 1 month
(C) 2–3 months ✅
(D) 6 months

Q6. In DKA (Diabetic Ketoacidosis), breathing pattern is:

(A) Cheyne-Stokes
(B) Kussmaul (deep, labored) ✅
(C) Biot's
(D) Apneusis

Q7. Diagnostic criterion for DM (fasting plasma glucose):

(A) ≥100 mg/dL
(B) ≥126 mg/dL on two occasions ✅
(C) ≥110 mg/dL
(D) ≥200 mg/dL fasting

Q8. GLUT-2 is the glucose transporter in:

(A) Brain
(B) Muscle
(C) Pancreatic beta cells and liver ✅
(D) RBCs

Q9. Insulin promotes all EXCEPT:

(A) Glycogenesis
(B) Lipogenesis
(C) Protein synthesis
(D) Glycogenolysis ✅ (insulin inhibits glycogenolysis)

Q10. Amylin (co-secreted with insulin) functions by:

(A) Stimulating glucagon
(B) Inhibiting insulin secretion, slowing gastric emptying ✅
(C) Increasing appetite
(D) Promoting glycogenolysis

Source: Guyton and Hall Textbook of Medical Physiology

10. 🧬 SEX DETERMINATION & DIFFERENTIATION

Q1. Sex determination is primarily decided by:

(A) Testosterone at conception
(B) Presence or absence of Y chromosome (SRY gene) ✅
(C) Maternal hormones
(D) Gonadotropins

Q2. SRY gene on Y chromosome encodes:

(A) Testis-determining factor (TDF) ✅
(B) Anti-Müllerian hormone
(C) Testosterone
(D) LH receptor

Q3. Without SRY gene, the undifferentiated gonad develops into:

(A) Testis
(B) Ovary ✅
(C) Neither
(D) Adrenal cortex

Q4. Müllerian-inhibiting factor (AMH) is produced by:

(A) Sertoli cells of testis ✅
(B) Leydig cells
(C) Granulosa cells
(D) Theca cells

Q5. In females, the Wolffian duct degenerates because:

(A) Absence of testosterone ✅
(B) Estrogen actively degrades it
(C) AMH destroys it
(D) Progesterone degrades it

Q6. Congenital Adrenal Hyperplasia (CAH) virilizes females because of excess:

(A) Estrogen
(B) Androgens (17-hydroxyprogesterone → androstenedione) ✅
(C) Cortisol
(D) AMH

Q7. 5α-reductase deficiency causes:

(A) Ambiguous genitalia at birth → virilization at puberty in 46,XY males (DHT deficiency) ✅
(B) Complete feminization
(C) Infertility in females
(D) No phenotypic change

Q8. Androgen Insensitivity Syndrome (AIS) — complete form presents as:

(A) 46,XY female phenotype with absent uterus, blind vagina, testes ✅
(B) 46,XX male
(C) Turner's syndrome
(D) Klinefelter's

11. 🧒 PUBERTY & APPLIED

Q1. The first sign of puberty in girls is:

(A) Menarche
(B) Thelarche (breast development — budding) ✅
(C) Pubic hair
(D) Growth spurt

Q2. The first sign of puberty in boys is:

(A) Testicular enlargement (>4 mL or >2.5 cm length) ✅
(B) Pubic hair
(C) Voice change
(D) Growth spurt

Q3. Average age of menarche in girls (in developed countries):

(A) 10 years
(B) 12–13 years ✅
(C) 15 years
(D) 16 years

Q4. GnRH pulse frequency is critical — high-frequency pulses favor secretion of:

(A) FSH
(B) LH ✅
(C) Both equally
(D) Inhibin

Q5. Precocious puberty (central/GnRH-dependent) is caused by:

(A) Adrenal tumor
(B) Ovarian cyst
(C) Early activation of hypothalamic-pituitary-gonadal axis ✅
(D) CAH

Q6. Delayed puberty in boys is defined as no secondary sex characteristics by age:

(A) 12
(B) 13
(C) 14 ✅
(D) 16

Q7. Leptin's role in puberty:

(A) Acts as a permissive signal — adequate fat mass triggers GnRH pulse generator ✅
(B) Inhibits GnRH
(C) Directly stimulates gonads
(D) No role in puberty

Q8. Kallmann syndrome presents with:

(A) Hypogonadotropic hypogonadism + anosmia (absent olfactory bulb) ✅
(B) Hypergonadotropic hypogonadism
(C) Normal puberty + anosmia
(D) Precocious puberty

12. 🏥 INFERTILITY — CAUSES & ROLE OF IVF

Q1. Infertility is defined as failure to conceive after:

(A) 6 months
(B) 1 year of regular unprotected intercourse ✅
(C) 2 years
(D) 3 years

Q2. Most common cause of female infertility:

(A) Uterine fibroids
(B) Ovulatory disorders (PCOS most common) ✅
(C) Tubal factor
(D) Cervical factor

Q3. Normal semen analysis (WHO 2021) — minimum sperm concentration:

(A) 16 million/mL ✅ (revised from 15 million)
(B) 20 million/mL
(C) 5 million/mL
(D) 40 million/mL

Q4. Oligozoospermia is sperm count <:

(A) 16 million/mL ✅
(B) 20 million/mL
(C) 5 million/mL
(D) 40 million/mL

Q5. In IVF, ovulation induction is typically achieved with:

(A) GnRH alone
(B) Gonadotropins (FSH/hMG) with or without GnRH agonist/antagonist suppression ✅
(C) Clomiphene only
(D) Progesterone

Q6. In IVF, oocyte retrieval is performed:

(A) At ovulation spontaneously
(B) ~36 hours after hCG trigger, transvaginally under ultrasound guidance ✅
(C) 72 hours after LH surge
(D) Laparoscopically always

Q7. ICSI (Intracytoplasmic Sperm Injection) is specifically indicated for:

(A) Tubal factor
(B) Severe male factor infertility (low count, motility, or morphology) ✅
(C) Endometriosis only
(D) Recurrent miscarriage

Q8. Asherman's syndrome causes infertility through:

(A) Tubal occlusion
(B) Intrauterine adhesions (synechiae) preventing implantation ✅
(C) Anovulation
(D) Cervical stenosis only

Q9. Antisperm antibodies cause infertility by:

(A) Impairing sperm motility, penetration of cervical mucus, and fertilization ✅
(B) Destroying ova
(C) Blocking tubal transport of embryo
(D) Preventing implantation

Q10. First successful IVF baby was born in:

(A) 1973
(B) 1978 ✅ (Louise Brown — Steptoe & Edwards)
(C) 1985
(D) 1990

13. 🌸 PHYSIOLOGY OF MENOPAUSE

Q1. Average age of natural menopause:

(A) 40–42 years
(B) 45–47 years
(C) 48–52 years (average ~51) ✅
(D) 55–60 years

Q2. Premature ovarian insufficiency (POI) is menopause before age:

(A) 40 years ✅
(B) 45 years
(C) 50 years
(D) 35 years

Q3. FSH levels in menopause:

(A) Decreased
(B) Normal
(C) Markedly elevated (>40 IU/L on two occasions 4 weeks apart) ✅
(D) Fluctuating only

Q4. Primary estrogen in postmenopausal women is:

(A) Estradiol (E2)
(B) Estrone (E1) — from peripheral conversion of androstenedione in adipose ✅
(C) Estriol (E3)
(D) Ethinyl estradiol

Q5. "Hot flashes" in menopause are due to:

(A) Excess progesterone
(B) Estrogen withdrawal → thermoregulatory instability (lowered thermostat set-point) ✅
(C) LH excess directly
(D) Cortisol changes

Q6. Long-term consequence of estrogen deficiency in menopause:

(A) Hypertension alone
(B) Osteoporosis (bone resorption > formation) ✅
(C) Hypoglycemia
(D) Hypothyroidism

Q7. Genitourinary syndrome of menopause (GSM) includes:

(A) Vaginal dryness, dyspareunia, urinary urgency, recurrent UTIs ✅
(B) Hot flashes only
(C) Mood changes only
(D) Only bone changes

Q8. Hormone Replacement Therapy (HRT) is contraindicated in:

(A) Estrogen-receptor positive breast cancer, thromboembolic disease, undiagnosed vaginal bleeding ✅
(B) Osteoporosis
(C) Vasomotor symptoms
(D) Coronary heart disease in young women (not a contraindication per current guidelines)

Q9. After menopause, FSH:LH ratio is:

(A) LH > FSH
(B) FSH > LH ✅
(C) Equal
(D) Both suppressed

Q10. The "menopausal triad":

(A) Vasomotor symptoms + Urogenital atrophy + Osteoporosis ✅
(B) Weight gain + Depression + Acne
(C) Hirsutism + Infertility + Anovulation
(D) Polyuria + Polydipsia + Polyphagia

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