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Human Physiology

Digestion, circulation, respiration, excretion, nervous system

Key Concepts
  • Digestive system: mechanical and chemical digestion; absorption mainly in small intestine
  • Circulatory system: double circulation; SA node is pacemaker; blood groups ABO and Rh
  • Respiratory system: tidal volume ~500 mL; vital capacity = IRV + TV + ERV
  • Excretory system: nephron is structural unit; GFR ~125 mL/min; ADH controls water reabsorption
  • Nervous system: neuron with resting potential −70 mV; action potential propagation
Important Formulae
Cardiac output CO = Heart rate × Stroke volume
Glomerular filtration rate GFR ≈ 125 mL/min (180 L/day filtered)
Haemoglobin O₂ carrying capacity Each Hb carries 4 O₂; 1 g Hb carries ~1.34 mL O₂
Quick Tips
  • RBC lifespan: 120 days; WBC: days to years; platelets: 10 days.
  • Insulin (from β-cells of islets of Langerhans) lowers blood glucose; glucagon raises it.
  • Resting membrane potential maintained by Na⁺/K⁺ ATPase pump.
Sample Practice Questions

  1. Adrenal medulla secretes:

    • Cortisol only
    • Adrenaline (epinephrine) and noradrenaline
    • Insulin
    • Testosterone
    Show answer

    Answer: Adrenaline (epinephrine) and noradrenaline

  2. Normal resting heart rate of an adult is approximately:

    • 40 beats/min
    • 72 beats/min
    • 100 beats/min
    • 120 beats/min
    Show answer

    Answer: 72 beats/min

  3. Peristalsis is the rhythmic contraction of:

    • Cardiac muscle
    • Skeletal muscle
    • Smooth muscle of GI tract
    • Diaphragm
    Show answer

    Answer: Smooth muscle of GI tract

  4. Breathing is controlled by the respiratory centre in:

    • Cerebrum
    • Cerebellum
    • Medulla oblongata
    • Pons only
    Show answer

    Answer: Medulla oblongata

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Practice Questions

Practice 20 randomly selected NEET questions on Human Physiology. Answers are revealed after each question.

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