MBBS Physiology Syllabus

Physiology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Physiology in MBBS, not a summary of it.

1. 1

   Cellular Physiology

   4 topics

   • Cell membrane structure and function
   • Membrane transport
     • Passive and active transport
     • Facilitated diffusion
     • Osmosis
   • Resting membrane potential, action potential, and synaptic transmission
   • Neurotransmitters and their receptors
2. 2

   Nervous System

   4 topics

   • Structure and functions of neurons
   • Central nervous system (CNS): Brain and spinal cord
   • Peripheral nervous system (PNS): Cranial and spinal nerves
   • Autonomic nervous system: Sympathetic and parasympathetic divisions
3. 3

   Endocrine System

   4 topics

   • Hormones
     • Classification
     • Synthesis
     • Storage
     • Release
   • Hypothalamic-pituitary axis
   • Thyroid, parathyroid, adrenal, pancreas, and gonadal hormones
   • Regulation of hormone secretion
4. 4

   Cardiovascular System

   4 topics

   • Heart
     • Structure
     • Cardiac Cycle
     • Electrical Conduction System
   • Blood vessels
     • Arteries
     • Veins
     • Capillaries
     • Lymphatics
   • Regulation of Cardiac Output, Blood Pressure, and Regional Blood Flow
   • Hemodynamics
     • Blood Flow
     • Resistance
     • Viscosity
5. 5

   Respiratory System

   4 topics

   • Structure and function of the respiratory system
   • Mechanics of breathing: Lung volumes and capacities, pulmonary ventilation
   • Gas exchange: Diffusion, transport of oxygen and carbon dioxide
   • Regulation of respiration: Neural and chemical control mechanisms
6. 6

   Renal Physiology

   4 topics

   • Structure and function of the kidney
   • Glomerular filtration, tubular reabsorption, and secretion
   • Renal blood flow and glomerular filtration rate regulation
   • Acid-base balance and electrolyte regulation
7. 7

   Gastrointestinal System

   3 topics

   • Digestive processes
     • Motility
     • Secretion
     • Absorption
     • Digestion
   • Regulation of gastrointestinal functions
     • Neural control
     • Hormonal control
   • Liver function
     • Metabolism
     • Detoxification
     • Bile secretion
8. 8

   Muscle Physiology

   3 topics

   • Muscle types
     • Skeletal muscle
     • Cardiac muscle
     • Smooth muscle
   • Mechanism of muscle contraction
     • Sliding filament theory
   • Neuromuscular junction and excitation-contraction coupling
9. 9

   Special Senses

   2 topics

   • Vision
     • Structure of the eye
     • Visual pathways
     • Accommodation
   • Hearing and Balance
     • Structure of the ear
     • Auditory pathways
     • Equilibrium

Physiology flashcards for MBBS

22 of 60 cards from the Physiology deck — real questions with worked answers.

1. What is the fluid mosaic model of the cell membrane?

   It describes the membrane as a dynamic phospholipid bilayer in which proteins (integral and peripheral) float and move laterally, interspersed with cholesterol and carbohydrate chains. The bilayer is amphipathic: hydrophilic phosphate heads face outward, hydrophobic fatty-acid tails face inward.

2. What are the four main classes of lipids in the plasma membrane, and what is cholesterol's role?

   Phospholipids, glycolipids, and cholesterol (sphingomyelin being a key phospholipid type). Cholesterol modulates membrane fluidity: it stiffens the membrane at high temperatures and prevents tight packing (keeps it fluid) at low temperatures.

3. Distinguish integral (intrinsic) from peripheral (extrinsic) membrane proteins.

   Integral proteins span the bilayer (transmembrane) and require detergents to extract; they act as channels, carriers, and receptors. Peripheral proteins are loosely bound to membrane surfaces by electrostatic/hydrogen bonds and are easily removed by changes in pH or ionic strength.

4. Compare simple diffusion and facilitated diffusion.

   Both are passive (no ATP) and move solutes down their electrochemical gradient. Simple diffusion crosses the lipid bilayer directly (lipophilic/small molecules, $\ce{O2}$, $\ce{CO2}$) and does not saturate. Facilitated diffusion uses carrier or channel proteins, is specific, saturable ($T_{max}$), and shows competition.

5. What is the difference between primary and secondary active transport?

   Primary active transport directly hydrolyzes ATP to move solutes against their gradient (e.g. $\ce{Na+/K+}$-ATPase, $\ce{Ca^2+}$-ATPase). Secondary active transport uses the energy stored in an ion gradient (usually $\ce{Na+}$) created by primary transport, coupling it via symport (co-transport) or antiport (counter-transport).

6. Describe the stoichiometry and function of the $\ce{Na+/K+}$-ATPase pump.

   For each ATP hydrolyzed it extrudes $3\,\ce{Na+}$ out and imports $2\,\ce{K+}$ in, against their gradients. It is electrogenic (net $+1$ charge moved out per cycle), maintains low intracellular $\ce{Na+}$/high $\ce{K+}$, sustains cell volume, and powers secondary active transport.

7. Give an example of a symporter and an antiporter in human physiology.

   Symporter (co-transport, same direction): $\ce{Na+}$-glucose transporter SGLT in the intestine/kidney. Antiporter (counter-transport, opposite directions): $\ce{Na+}/\ce{Ca^2+}$ exchanger and $\ce{Na+}/\ce{H+}$ exchanger.

8. What is the Nernst equation and what does it calculate?

   It calculates the equilibrium (reversal) potential for a single ion across a membrane: $$E_{ion} = \frac{RT}{zF}\ln\frac{[\text{ion}]_{out}}{[\text{ion}]_{in}}$$ At $37^\circ$C for a monovalent cation this simplifies to $E_{ion} = 61.5\log_{10}\frac{[\text{ion}]_{out}}{[\text{ion}]_{in}}$ mV.

9. What are the approximate Nernst equilibrium potentials for $\ce{Na+}$, $\ce{K+}$, and $\ce{Cl-}$ in a typical neuron?

   $E_{Na} \approx +60$ mV, $E_{K} \approx -90$ mV, $E_{Cl} \approx -70$ mV (values vary slightly by cell).

10. What is the Goldman-Hodgkin-Katz (GHK) equation used for?

    It calculates the resting membrane potential accounting for the permeability ($P$) and concentrations of multiple ions simultaneously: $$V_m = 61.5\log_{10}\frac{P_{K}[\ce{K+}]_o + P_{Na}[\ce{Na+}]_o + P_{Cl}[\ce{Cl-}]_i}{P_{K}[\ce{K+}]_i + P_{Na}[\ce{Na+}]_i + P_{Cl}[\ce{Cl-}]_o}$$

11. Why is the resting membrane potential (about $-70$ mV) closer to $E_K$ than to $E_{Na}$?

    At rest the membrane is far more permeable to $\ce{K+}$ (open $\ce{K+}$ leak channels) than to $\ce{Na+}$, so $V_m$ is dominated by and lies near $E_K$ ($-90$ mV), pulled slightly positive by small $\ce{Na+}$ leak and the electrogenic pump.

12. List the phases of a typical neuronal action potential.

    1) Resting state; 2) Depolarization (threshold reached, voltage-gated $\ce{Na+}$ channels open, rapid upstroke); 3) Repolarization ($\ce{Na+}$ channels inactivate, voltage-gated $\ce{K+}$ channels open); 4) Hyperpolarization/undershoot (slow $\ce{K+}$ channel closure); 5) Return to resting potential.

13. What is the 'all-or-none' principle of the action potential?

    Once a stimulus reaches threshold, an action potential of fixed amplitude and shape is generated; a stronger stimulus does not produce a larger AP. Sub-threshold stimuli produce no AP. Stimulus strength is encoded by AP frequency, not amplitude.

14. Differentiate the absolute and relative refractory periods.

    Absolute refractory period: no stimulus, however strong, can trigger another AP because voltage-gated $\ce{Na+}$ channels are inactivated. Relative refractory period: a stronger-than-normal stimulus can trigger an AP because some $\ce{Na+}$ channels have recovered but $\ce{K+}$ permeability is still high (membrane hyperpolarized).

15. What is saltatory conduction and why is it faster?

    In myelinated axons the AP 'jumps' from one node of Ranvier to the next, where voltage-gated $\ce{Na+}$ channels are concentrated, because myelin insulates the internodes. This increases conduction velocity and conserves energy compared with continuous conduction in unmyelinated fibers.

16. Outline the steps of chemical synaptic transmission.

    1) AP reaches presynaptic terminal; 2) voltage-gated $\ce{Ca^2+}$ channels open, $\ce{Ca^2+}$ enters; 3) synaptic vesicles fuse with membrane and release neurotransmitter by exocytosis; 4) transmitter diffuses across the cleft and binds postsynaptic receptors; 5) postsynaptic potential (EPSP/IPSP) generated; 6) transmitter removed by reuptake, enzymatic degradation, or diffusion.

17. Contrast an EPSP with an IPSP.

    EPSP (excitatory postsynaptic potential): depolarizing, moves $V_m$ toward threshold, typically via $\ce{Na+}$/$\ce{Ca^2+}$ influx (e.g. glutamate). IPSP (inhibitory): hyperpolarizing, moves $V_m$ away from threshold, typically via $\ce{Cl-}$ influx or $\ce{K+}$ efflux (e.g. GABA, glycine).

18. Define temporal and spatial summation.

    Temporal summation: rapid successive impulses from a single presynaptic terminal add together before each potential decays. Spatial summation: simultaneous inputs from multiple presynaptic terminals add together. Both can bring the postsynaptic membrane to threshold.

19. Name the main excitatory and inhibitory neurotransmitters of the CNS.

    Main excitatory: glutamate. Main inhibitory: GABA (gamma-aminobutyric acid) in the brain and glycine in the spinal cord/brainstem.

20. Distinguish ionotropic from metabotropic receptors.

    Ionotropic receptors are ligand-gated ion channels producing fast, direct, brief responses (e.g. nicotinic ACh, $\ce{NMDA}$, $\ce{GABA_A}$). Metabotropic receptors are G-protein-coupled, act via second messengers, and produce slower, longer-lasting, often modulatory effects (e.g. muscarinic ACh, $\ce{GABA_B}$, adrenergic).

21. Compare nicotinic and muscarinic acetylcholine receptors.

    Nicotinic: ionotropic (ligand-gated cation channel), fast; found at neuromuscular junction, autonomic ganglia, adrenal medulla, CNS. Muscarinic: metabotropic (G-protein coupled), slower; found at parasympathetic effector organs and CNS. Acetylcholine is degraded by acetylcholinesterase.

22. What are the structural components of a typical neuron?

    Cell body (soma) containing the nucleus and Nissl substance; dendrites (receive input); axon hillock (site of AP initiation); axon (conducts AP); myelin sheath with nodes of Ranvier; and axon terminals (synaptic boutons) for transmitter release.

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