🧠 Neurobiology: One Night Revision & Cram Sheet
Explain how excitable cells produce a travelling impulse, how synapses turn that impulse into excitation or inhibition, and how sensory, motor, and plastic circuits use those synapses to represent the world, to move the body, and to store a change. Disorders are read as failures of those mechanisms, not as a treatment manual.
🌟 Core Axioms & High-Yield Golden Rules
7 Core PrinciplesNon-negotiable foundational truths frequently tested in direct conceptual and numerical exam questions. Click checkbox to mark as mastered.
Resting Membrane Potential (~ -70 mV): Dominated by resting K+ permeability through inward-rectifier/leak K+ channels, maintained by electrogenic Na+/K+ ATPase (3 Na+ out / 2 K+ in).
💡 RMP close to K+ equilibrium potential (-90 mV)Action potential upstroke is caused by voltage-gated Na+ channels opening rapidly (Hodgkin cycle positive feedback); downstroke is caused by Na+ channel inactivation (inactivation gate) and delayed rectifier K+ channels opening.
💡 Na+ in = Depolarization | K+ out = RepolarizationAbsolute refractory period is caused by voltage-gated Na+ channels being in an INACTIVATED state; relative refractory period is caused by lingering K+ channel opening and hyperpolarization.
💡 Inactivated Na+ channels = Absolute RefractorySynaptic transmission: Presynaptic depolarization opens voltage-gated Ca2+ channels; Ca2+ binds synaptotagmin, triggering v-SNARE (synaptobrevin) and t-SNARE (syntaxin, SNAP-25) fusion pore formation.
💡 Ca2+ + Synaptotagmin + SNARE = Neurotransmitter ReleaseMajor Neurotransmitters: Glutamate is main excitatory in CNS (AMPA, NMDA, Kainate); GABA is main inhibitory in brain (GABA-A is ligand-gated Cl- channel); Glycine is main inhibitory in spinal cord.
💡 GABA-A = Cl- influx = Hyperpolarization (IPSP)NMDA receptor requires TWO coincident signals: Glutamate binding AND membrane depolarization to expel the magnesium block (Mg2+) from the pore; permeable to Ca2+.
💡 NMDA = Coincidence Detector for LTPMyelinated axons exhibit saltatory conduction: action potentials regenerate only at uninsulated Nodes of Ranvier, drastically increasing conduction velocity without increasing axon diameter.
💡 Saltatory = Leaping between nodes📚 Chapter-by-Chapter Rapid Cram Breakdown
10 ModulesHigh-density review of every curriculum chapter. Click any chapter title to view full in-depth lecture notes.
- Master Neuron doctrine: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master structure: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master axonal transport: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master glia: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master myelin: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Ions at rest: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Nernst and Goldman: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master phases: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master voltage-gated channels: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master refractory period: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Synaptic transmission →
- Master Electrical versus chemical synapses: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master vesicle release: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master quanta: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master summation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master neuromuscular junction: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Criteria: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master ionotropic versus metabotropic: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master glutamate, GABA, glycine, acetylcholine, catecholamines, serotonin, peptides, nitric oxide: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master CNS and PNS: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master spinal reflex: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master regions by computation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master maps: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master autonomic nervous system: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Sensory systems →
- Master Labelled lines: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master somatosensation and pain: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master retina and visual path: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master cochlea, canals, and otoliths: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master taste and smell: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Motor systems →
- Master Hierarchy: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master stretch reflex: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master upper and lower motor neurons: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master cerebellar versus basal-ganglia lesions: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master excitation–contraction coupling: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Neural tube and crest: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master migration: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master guidance cues: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master synapse formation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master critical periods: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Facilitation and depression: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master LTP and LTD: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Hebb’s rule: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master consolidation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master explicit and implicit memory: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Demyelination: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master myasthenia gravis: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Parkinson disease: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master epilepsy: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Alzheimer disease: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
⚖️ Must-Know Comparison & Distinction Tables
1 TablesSide-by-side matrices comparing commonly confused biological mechanisms, kinetic types, and pathways.
Action Potential vs. Post-Synaptic Potentials (EPSP / IPSP)
| Feature | Action Potential | Graded Potentials (EPSP / IPSP) |
|---|---|---|
| Magnitude | All-or-none (constant amplitude ~100 mV) | Graded (proportional to stimulus intensity, 1 - 20 mV) |
| Channels Involved | Voltage-gated Na+ and K+ channels | Ligand-gated / ionotropic receptor channels |
| Propagation | Self-propagating, non-decremental over long distance | Passive spread, decremental (decays with distance) |
| Summation | Cannot summate (due to refractory period) | Undergoes spatial and temporal summation at axon hillock |
⚠️ Examiner Traps & Common Student Mistakes
1 PitfallsClassic trap questions designed by examiners to catch uncritical students. Don't lose easy marks here!
Tetanus Toxin vs Botulinum Toxin Mechanism
Assuming both toxins cause identical paralysis.
Both are zinc endopeptidases cleaving SNARE proteins. BUT Tetanus toxin cleaves synaptobrevin in inhibitory interneurons (Renshaw cells in spinal cord), blocking GABA/glycine release and causing SPASTIC paralysis. Botulinum toxin cleaves SNAREs at the neuromuscular junction, blocking Acetylcholine release and causing FLACCID paralysis.
📐 Key Formulas & Numerical Constants
2 FormulasStandard Equilibrium Constant
Keq = [Products] / [Reactants]Determines direction of chemical/biological reactions at dynamic equilibrium.
Relative Quantitative Ratio
Ratio = Experimental_Value / Baseline_ControlStandardizes comparative fold-change in quantitative biological assays.
🏛️ Landmark Scientists & Nobel Discoveries
6 PioneersFrequently tested in historical milestone and match-the-following exam questions.
Karl von Frisch
🏅 Nobel Prize in Physiology or Medicine (1973) for discoveries concerning organization and elicitation of individual and social behavior patternsMajor landmark discoveries
Konrad Zacharias Lorenz
🏅 Nobel Prize in Physiology or Medicine (1973) for discoveries concerning organization and elicitation of individual and social behavior patternsMajor landmark discoveries
Santiago Ramón y Cajal
🏅 Nobel Prize in Physiology or Medicine (1906) in recognition of their work on the structure of the nervous systemMajor landmark discoveries
Camillo Golgi
🏅 Nobel Prize in Physiology or Medicine (1906) in recognition of their work on the structure of the nervous systemMajor landmark discoveries
Sir Charles Scott Sherrington
🏅 Nobel Prize in Physiology or Medicine (1932) for discoveries regarding the functions of neuronsMajor landmark discoveries
Eric Richard Kandel
🏅 Nobel Prize in Physiology or Medicine (2000) for discoveries concerning signal transduction in the nervous systemMajor landmark discoveries
🎯 Rapid-Fire Active Recall Checklist
3 QuestionsTest your memory before stepping into the exam hall. Try to answer mentally, then tap "Reveal Answer" to verify!