Describe me answes to prepare for viva in best way
Reading File
Running Command
cd /tmp/workspace/attachments/e8c8b3bf-7441-4106-a91b-d59a3c32fca5/ && python3 -c " import pdfplumber with pdfplumber.open('EXAM QUESTIONS PHYSIOLOGY.pdf') as pdf: print(f'Total pages: {len(pdf.pages)}') for i, page in enumerate(pdf.pages): text = page.extract_text() if text: print(f'--- PAGE {i+1} ---') print(text) "
I've read all 109 pages of your Physiology exam questions. Here are comprehensive, viva-ready answers organized by system:
🩺 Physiology Viva Preparation Guide
🔬 SECTION 1: EXCITABLE TISSUES
Q: What is the resting membrane potential and how is it maintained?
RMP is ~-70 mV in neurons. It is maintained by:
- Na⁺/K⁺ ATPase pump (pumps 3 Na⁺ out, 2 K⁺ in)
- High K⁺ permeability (K⁺ leaks out)
- Negatively charged intracellular proteins
Q: Describe the phases of an action potential.
- Depolarization - Na⁺ influx through voltage-gated channels; membrane goes from -70 to +30 mV
- Repolarization - K⁺ efflux; membrane returns toward RMP
- Hyperpolarization - Brief overshoot below RMP; absolute then relative refractory period
Q: What are refractory periods?
- Absolute refractory period - No AP possible regardless of stimulus strength (Na⁺ channels inactivated)
- Relative refractory period - AP possible only with a stronger-than-normal stimulus
Q: What is the All-or-Nothing Law?
A stimulus either exceeds threshold and generates a full AP, or fails to generate any AP. There is no partial response.
Q: Define Rheobase and Chronaxie.
- Rheobase - Minimum current strength needed to excite a tissue
- Chronaxie - Minimum time needed for twice the rheobase to excite; a measure of tissue excitability
Q: What is Parabiosis (Vvedensky's stages)?
Gradual depression of excitability under constant stimulation:
- Increased excitability
- Paradoxical phase - weak stimuli fail; strong stimuli cause inhibition
- Ultraparadoxical phase
- Inhibition (extinction)
🧠 SECTION 2: CNS PHYSIOLOGY
Q: What are the properties of nerve centers?
- Summation (spatial and temporal)
- Post-tetanic potentiation
- Fatigue on overstimulation
- Low lability (slower conduction than nerves)
- Sensitivity to drugs and hypoxia
Q: Describe the reflex arc.
Receptor → Afferent neuron → CNS (integration) → Efferent neuron → Effector
The reflex ring adds feedback from the effector (reverse afferentation).
Q: What is Anokhin's Functional System?
A group of organs/structures that work together to produce a goal-directed adaptive result. Key feature: the final result triggers feedback to regulate the system.
Q: What is the ARAS and its function?
The Ascending Reticular Activating System originates in the brainstem reticular formation and projects to the thalamus and cortex. It maintains consciousness, wakefulness, and attention.
Q: What are the functions of the Hypothalamus?
- Regulates body temperature, hunger, thirst, circadian rhythms
- Controls ANS output (both sympathetic and parasympathetic)
- Neuroendocrine regulation via the hypothalamic-pituitary axis
- Mediates stress response (HPA axis)
- Emotions and motivation (part of limbic system)
Q: What are the functions of the Limbic System?
- Hippocampus - declarative/episodic memory (Papez circuit)
- Amygdala - emotional regulation (fear, aggression), emotional memory
- Hypothalamus - autonomic regulation
- Papez circuit: Hippocampus → Fornix → Mammillary bodies → Anterior thalamus → Cingulate gyrus → Hippocampus
Q: Describe neocortical layers and their functions.
| Layer | Name | Function |
|---|---|---|
| I | Molecular | Nerve fibers |
| II-III | External granular/pyramidal | Intracortical communication |
| IV | Internal granular | Thalamic input |
| V | Internal pyramidal | Motor output (corticospinal tract) |
| VI | Multiform | Various connections |
⚡ SECTION 3: AUTONOMIC NERVOUS SYSTEM
Q: Compare Sympathetic vs Parasympathetic effects.
| Target | Sympathetic | Parasympathetic |
|---|---|---|
| Heart rate | ↑ (β1) | ↓ (M2, vagus) |
| Bronchi | Dilation (β2) | Constriction (M3) |
| Pupils | Dilation - mydriasis (α1) | Constriction - miosis (M3) |
| GI motility | ↓ (α, β) | ↑ (M3) |
| Bladder | Relaxation (β2, β3) | Contraction (M3) |
| Salivation | Thick saliva (α1) | Watery saliva (M3) |
| Erection | Ejaculation (α1) | Erection (NO, M3) |
Q: What is the autonomic reflex arc structure?
Receptor → Sensory neuron → CNS integration center → Preganglionic neuron → Autonomic ganglion → Postganglionic neuron → Effector (smooth muscle/gland/cardiac muscle)
Q: Describe dopamine receptor subtypes and effects.
- D1/D5 (D1-like): ↑ cAMP - increase renal blood flow, motor activity, cognitive enhancement
- D2 (D2-like): ↓ cAMP - inhibit movement (loss → Parkinsonism), ↓ prolactin, reward/addiction
- D3 - limbic system, addiction
- D4 - frontal cortex, ADHD/schizophrenia
Q: Describe muscarinic receptor subtypes.
| Receptor | Location | Effect |
|---|---|---|
| M1 | CNS, autonomic ganglia | ↑ cognition, ↑ gastric acid |
| M2 | Heart (SA/AV nodes) | ↓ HR, feedback inhibition |
| M3 | Smooth muscle, glands, eye | Bronchoconstriction, secretion, miosis, bladder contraction |
Q: What are nicotinic receptor types?
- Nn (neuronal) - autonomic ganglia, adrenal medulla, CNS → impulse transmission, catecholamine release
- Nm (muscle) - neuromuscular junction → skeletal muscle contraction
❤️ SECTION 4: CARDIOVASCULAR PHYSIOLOGY
Q: What are the properties of cardiac muscle?
- Automaticity - spontaneous impulse generation (pacemaker cells)
- Conductivity - transmits impulses
- Contractility - force generation
- Excitability - responds to stimuli
- Rhythmicity - regular impulse generation
Q: Describe the cardiac conduction system and pacemaker rates.
| Region | Rate |
|---|---|
| SA node (primary pacemaker) | 60-80 bpm |
| AV node | 40-60 bpm |
| Bundle of His / Purkinje fibers | 20-40 bpm |
Q: What are the phases of the cardiac cycle?
- Atrial systole - atria contract, fill ventricles
- Isovolumetric contraction - pressure rises, all valves closed
- Ejection - semilunar valves open, blood ejected
- Isovolumetric relaxation - pressure drops, all valves closed
- Ventricular filling - AV valves open, passive filling
Q: Explain the Frank-Starling Law.
The force of ventricular contraction increases with increased end-diastolic volume (preload). The heart pumps out exactly what it receives. Clinical consequence: overstretching leads to heart failure.
Q: Describe the cardiac action potential phases (contractile cardiomyocytes).
| Phase | Event | Ionic change |
|---|---|---|
| Phase 0 | Rapid depolarization | Fast Na⁺ influx |
| Phase 1 | Brief repolarization | Transient K⁺ efflux |
| Phase 2 | Plateau | L-type Ca²⁺ influx balances K⁺ efflux |
| Phase 3 | Final repolarization | Ca²⁺ channels close, ↑ K⁺ efflux |
| Phase 4 | Resting potential | Na⁺/K⁺-ATPase maintains -90 mV |
Q: What is the ECG and how do you analyze it?
Step-by-step ECG analysis:
- Heart rate - 300 ÷ number of large squares between R waves
- Rhythm - regular RR intervals? P before every QRS?
- P wave - atrial depolarization; <0.12 sec
- PR interval - 0.12-0.20 sec; prolonged = AV block
- QRS complex - ventricular depolarization; <0.12 sec
- ST segment - should be isoelectric; elevation = infarction; depression = ischemia
- T wave - ventricular repolarization; inversion = ischemia
- QT interval - prolonged = risk of Torsades de Pointes
Q: What are cardiac reflexes and their clinical significance?
| Reflex | Stimulus | Effect | Significance |
|---|---|---|---|
| Baroreceptor | ↑ arterial pressure | ↓ HR, ↓ contractility | Maintains BP homeostasis |
| Bainbridge | ↑ venous return | ↑ HR | Prevents blood pooling |
| Chemoreceptor | Low O₂/high CO₂ | ↑ HR | Assists in hypoxia |
| Cushing | ↑ intracranial pressure | ↑ BP, ↓ HR | Indicates brain injury |
🫁 SECTION 5: RESPIRATORY PHYSIOLOGY
Q: What are the four stages of respiration?
- Pulmonary ventilation (breathing)
- External respiration (alveolar gas exchange)
- Gas transport (in blood)
- Internal respiration (tissue gas exchange)
Q: Describe the respiratory center structure.
| Part | Location | Function |
|---|---|---|
| Inspiratory center | Medulla | Controls inhalation |
| Expiratory center | Medulla | Controls forced exhalation |
| Pneumotaxic center | Pons | Stops inhalation, starts exhalation |
| Apneustic center | Pons | Prolongs inhalation |
Q: How is oxygen transported?
- 98-99% bound to hemoglobin as oxyhemoglobin (HbO₂)
- 1-2% dissolved in plasma
- Oxygen capacity of blood: ~20 mL O₂ per 100 mL blood
Q: Describe the oxyhemoglobin dissociation curve.
S-shaped (sigmoid) curve:
- In lungs (PO₂ ~100 mmHg) → Hb ~100% saturated
- In tissues (PO₂ ~40 mmHg) → Hb releases O₂
- Right shift (easier O₂ release): ↑CO₂, ↓pH, ↑temperature (during exercise)
- Left shift (holds O₂ tighter): ↓CO₂, ↑pH, ↓temperature
Q: How is CO₂ transported?
- As bicarbonate HCO₃⁻ (~70%) - via carbonic anhydrase in RBCs
- Bound to Hb as carbaminohemoglobin (~20-23%)
- Dissolved in plasma (~5-7%)
Carbonic anhydrase catalyzes: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻
Q: What causes pneumothorax and what happens?
Air enters the pleural cavity → vacuum (negative pressure of ~-4 mmHg) is lost → lung collapses → breathing becomes difficult. Causes: chest trauma, spontaneous rupture, iatrogenic.
Q: What are lung volumes?
| Volume | Amount | Description |
|---|---|---|
| Tidal Volume (TV) | ~500 mL | Normal breathing |
| IRV | ~3000 mL | Extra air after normal inhalation |
| ERV | ~1100 mL | Extra air after normal exhalation |
| Residual Volume (RV) | ~1200 mL | Cannot be exhaled |
| Vital Capacity | TV+IRV+ERV | Max air moved |
🩸 SECTION 6: BLOOD PHYSIOLOGY
Q: What are the blood constants?
| Parameter | Normal Range |
|---|---|
| pH | 7.35 - 7.45 |
| Hematocrit | 40-45% |
| Hemoglobin | 12-17.5 g/dL |
| Osmolality | 280-295 mOsm/kg |
| Volume | ~5 liters |
Q: Describe hemostasis and blood coagulation.
- Vascular phase - vasoconstriction reduces blood flow
- Platelet phase - platelets adhere, activate, aggregate → temporary plug
- Coagulation phase - intrinsic/extrinsic pathways → common pathway → fibrinogen → fibrin mesh = stable clot
Accelerators: Vitamin K, Ca²⁺, Factors VIII, IX
Inhibitors/Anticoagulants: Heparin, antithrombin III, Protein C, aspirin
Q: Blood groups and transfusion rules?
- Type A - A antigen, anti-B antibodies
- Type B - B antigen, anti-A antibodies
- Type AB - both antigens, no antibodies (universal recipient)
- Type O - no antigens, both antibodies (universal donor)
- Rh⁻ recipients must NOT receive Rh⁺ blood
Q: Leukocyte formula (normal percentages)?
| Type | % |
|---|---|
| Neutrophils | 54-62% (phagocytosis, first responders) |
| Lymphocytes | 25-33% (B cells = antibodies; T cells = cell-mediated immunity) |
| Monocytes | 3-7% (phagocytosis, become macrophages) |
| Eosinophils | 1-3% (parasites, allergies) |
| Basophils | 0.5-1% (histamine release in allergy) |
🧬 SECTION 7: ENDOCRINOLOGY (HORMONES)
Q: What is the difference between membrane vs nuclear hormone receptors?
- Membrane receptors (water-soluble hormones - peptides, catecholamines): activate second messengers (cAMP, IP3/DAG, Ca²⁺) → rapid response (seconds-minutes)
- Nuclear/cytoplasmic receptors (lipid-soluble - steroids, thyroid hormones): bind DNA at hormone response elements (HREs) → alter gene transcription → slow response (hours-days)
Q: What are pituitary hormones and their target glands?
Anterior pituitary: GH, ACTH (→ cortisol), TSH (→ T3/T4), FSH, LH, Prolactin
Posterior pituitary (stores hypothalamic hormones): ADH (water retention), Oxytocin (uterine contractions, milk ejection)
Q: What is the hypothalamic-pituitary axis?
- Hypothalamus releases releasing/inhibiting hormones → via hypothalamo-hypophyseal portal system → anterior pituitary
- Target gland hormones feed back negatively to suppress hypothalamus and pituitary (negative feedback)
- Example: Low cortisol → CRH ↑ → ACTH ↑ → cortisol ↑ → feedback suppresses CRH/ACTH
Q: What are pancreatic hormones?
| Cell | Hormone | Trigger | Main Effect |
|---|---|---|---|
| Beta | Insulin | High glucose | ↓ Blood glucose (uptake, glycogenesis) |
| Alpha | Glucagon | Low glucose | ↑ Blood glucose (glycogenolysis, gluconeogenesis) |
| Delta | Somatostatin | Various | Inhibits insulin and glucagon |
Q: What are adrenal hormones?
- Cortex → Mineralocorticoids (aldosterone: Na⁺/K⁺ balance), Glucocorticoids (cortisol: metabolism, anti-inflammatory, stress), Androgens
- Medulla → Epinephrine/Norepinephrine (fight-or-flight: ↑HR, ↑BP, ↑blood glucose)
Q: What are thyroid hormones?
- T3 and T4: ↑ basal metabolic rate, protein synthesis, growth, brain development, body temperature
- Calcitonin (parafollicular cells): ↓ blood calcium (inhibits bone resorption)
Q: What does PTH do?
- Bone: ↑ osteoclast activity → ↑ Ca²⁺ release
- Kidney: ↑ Ca²⁺ reabsorption, ↓ phosphate reabsorption, ↑ calcitriol (active Vit D)
- Intestine (indirect via calcitriol): ↑ Ca²⁺ absorption
- Net effect: ↑ blood calcium
🌡️ SECTION 8: METABOLISM & THERMOREGULATION
Q: What is the difference between anabolism and catabolism?
- Anabolism - building up (uses ATP): amino acids → proteins
- Catabolism - breaking down (releases ATP): glucose → CO₂ + H₂O + ATP
Q: What is nitrogen balance?
| Type | Meaning | Example |
|---|---|---|
| Positive | Protein intake > loss | Growth, pregnancy, healing |
| Negative | Protein loss > intake | Starvation, illness |
Q: What factors affect BMR?
Age (↓ with age), Sex (men > women), Body size, Thyroid hormones (↑ BMR), Cold temperature (↑ BMR)
Q: How does the body regulate temperature?
- Thermoreceptors (cold/warm) in skin and tissues → signal hypothalamus
- Anterior hypothalamus - heat dissipation (↑ sweating, vasodilation)
- Posterior hypothalamus - heat conservation (shivering, vasoconstriction)
- 4 physical mechanisms of heat loss: Radiation, Conduction, Convection, Evaporation (only method when ambient temp > body temp)
🫘 SECTION 9: RENAL / EXCRETORY PHYSIOLOGY
Q: Describe the nephron structure and function.
- Glomerulus + Bowman's capsule - filtration (primary urine formed)
- PCT - reabsorbs 65-70% water, all glucose/amino acids, Na⁺
- Loop of Henle - descending (water); ascending (Na⁺, Cl⁻ - impermeable to water)
- DCT - regulated reabsorption (Na⁺, Ca²⁺) by aldosterone and PTH
- Collecting duct - water reabsorption regulated by ADH
Q: Primary vs secondary urine?
- Primary urine: 180 L/day produced; contains water, glucose, amino acids, urea, ions (NO proteins or cells)
- Secondary (final) urine: ~1.5-2 L/day; 99% of water reabsorbed; contains urea, creatinine, ions; NO glucose or proteins normally
Q: What is GFR and how is it measured?
GFR = ~125 mL/min (normal). Measured by:
- Creatinine clearance (most common clinically)
- Inulin clearance (gold standard)
- eGFR (blood creatinine + age + sex formula)
Q: What is the RAAS?
- Low BP → kidneys release renin
- Renin → angiotensinogen → Angiotensin I
- In lungs via ACE → Angiotensin II
- Angiotensin II → vasoconstriction + stimulates aldosterone (Na⁺ retention → ↑ blood volume → ↑ BP)
Q: Normal urinalysis parameters?
| Parameter | Normal |
|---|---|
| Color | Pale yellow |
| pH | 4.5-8 |
| Glucose | Absent |
| Proteins | Absent or trace |
| Blood | Absent |
| Specific gravity | 1.005-1.030 |
🍽️ SECTION 10: DIGESTIVE PHYSIOLOGY
Q: What are the phases of gastric secretion?
| Phase | Trigger | % of secretion |
|---|---|---|
| Cephalic | Sight, smell, thought of food (vagus nerve) | ~30% |
| Gastric | Food in stomach (distension, gastrin) | ~60% |
| Intestinal | Chyme in duodenum (secretin, CCK) | ~10% - also inhibits |
Q: What is the role of HCl in digestion?
- Creates acidic environment (pH 1-2) to activate pepsinogen → pepsin
- Denatures proteins
- Kills bacteria (antimicrobial)
- Stimulates gastrin secretion
- Aids mineral absorption (iron, calcium)
Q: What are gastrointestinal hormones?
| Hormone | Source | Function |
|---|---|---|
| Gastrin | Stomach G-cells | ↑ gastric acid secretion |
| Secretin | Duodenum | ↑ bicarbonate from pancreas (neutralizes acid) |
| CCK | Duodenum | ↑ pancreatic enzymes, gallbladder contraction |
| GIP | Duodenum | Inhibits gastric secretion, stimulates insulin |
| VIP | Intestine | Relaxes smooth muscle, stimulates secretion |
Q: What is the mechanism of hunger and satiety?
Hunger signals:
- Ghrelin (from empty stomach) → stimulates lateral hypothalamus
- Low blood glucose → hypothalamic neurons → NPY/AgRP release → ↑ appetite
Satiety signals:
- Stretch receptors in stomach → vagus nerve → brain
- CCK, PYY, GLP-1 (intestinal hormones) → suppress hunger
- Leptin (from fat cells) → long-term satiety, suppresses appetite
- VMH (ventromedial hypothalamus) = "satiety center"
💡 TOP VIVA TIPS
- Always state the mechanism, not just the effect - examiners reward explanations
- Link structure to function - e.g., intercalated discs → electrical coupling → synchronous contraction
- Use clinical examples - e.g., ACE inhibitors block RAAS, treating hypertension
- For ECG questions - always follow the 8-step analysis approach
- For reflex questions - always draw/describe the complete arc
- For hormone questions - state: source, trigger, target, mechanism, effect
- For ANS questions - compare sympathetic vs parasympathetic side by side
This covers all topics from your PDF across all 9 physiological systems. Good luck with your viva! 🎓
This is a shared conversation. Sign in to Orris to start your own chat.