Neurons, action potentials, synapses, neurotransmitters, synaptic plasticity, CNS/PNS organization.
Nervous System Physiology
Neuron
Excitable cell transmitting information via electrical (action potentials) + chemical (neurotransmitter) signals. Compartmentalised:…
Resting membrane potential
Steady-state voltage across plasma membrane (~-70 mV in neurons) set by differential ion permeability + Na+/K+ ATPase gradients.…
Action potential
All-or-none (~100 mV) voltage spike propagating along axon: Na+ influx (depolarisation) → K+ efflux (repolarisation) → hyperpolarisation →…
Hodgkin-Huxley model
Hodgkin-Huxley 1952: quantitative model of squid axon action potential using voltage-dependent Na+ and K+ conductances with gating…
Synapse
Specialised junction for signal transmission between neurons. Chemical (neurotransmitter-mediated, most common) or electrical…
Neurotransmitter
Chemical messenger released from presynaptic terminal, diffuses across cleft, binds postsynaptic receptors. Classes: amino-acid (glutamate,…
Synaptic plasticity
Activity-dependent changes in synaptic strength — biological substrate of learning + memory. Hebbian: 'neurons that fire together wire…
Long-term potentiation (LTP)
Persistent (hours-days) enhancement of synaptic strength after high-frequency stimulation. NMDA-receptor Ca²+ influx → CaMKII →…
Excitatory/inhibitory balance
Glutamate (excit.) + GABA (inhib.) dominate fast synaptic transmission. E/I balance required for normal cortical function; imbalance…
Neurovascular coupling & BOLD
Active neurons trigger local vasodilation (astrocyte + interneuron signalling). Basis of fMRI BOLD signal. Coupling can break down in…
Cable equation axonal propagation
Linear cable equation τ ∂V/∂t = λ² ∂²V/∂x² - V (Kelvin 1855 / Rall 1959) with τ=R_m C_m, λ=√(R_m d/4 R_i) governs sub-threshold passive…
Rall equivalent-cylinder dendritic theorem
Rall 1962: a branching dendritic tree obeys an equivalent-cylinder reduction iff sum of daughter diameters^(3/2) at each branch point…
HH-physiology
Hodgkin-Huxley 1952 (Nobel 1963) action-potential ionic currents; modern compartmental-models + cardiac-electrophysiology.
Synaptic transmission (Katz 1962)
B Katz 1962 (Nobel 1970) quantal-release + miniature-EPSPs; modern Sudhof 2013 (Nobel 2013) SNARE-vesicle-fusion.
LTP (Bliss-Lomo 1973)
T Bliss-T Lomo 1973 long-term-potentiation hippocampus; modern AMPA + NMDA + memory-consolidation foundation.
Dendritic integration (Magee 2000)
J Magee 2000 dendritic-integration; backpropagating-AP + dendritic-spikes; modern multi-compartmental computational models.
Baroreflex (Cyon-Ludwig 1866)
Cyon-Ludwig 1866 carotid-sinus baroreceptors; modern bedside HRV-analysis + clinical autonomic-evaluation.
ANS (Langley 1903)
J Langley 1903 sympathetic + parasympathetic + enteric ANS; modern enteric-nervous-system 'second brain' research.
Quantal release (Katz 1969)
B Katz 1969 quantal-release theory; modern Sudhof 2013 SNARE molecular machinery; basis of synaptic-physiology.
Na-K electrochemical gradient
Goldman-Hodgkin-Katz 1949 GHK voltage equation; modern Nernst + Donnan + active-transport ATPase combined model.
Axonal transport (Allen 1982)
R D Allen 1982 video-enhanced microscopy axonal-transport; modern fast-anterograde kinesin + retrograde dynein.
Nerve regeneration (Cajal 1928)
S R y Cajal 1928 'Degeneration and Regeneration'; modern PNS-Schwann-cell vs CNS-myelin-inhibitory recovery.
BBB (Ehrlich 1885)
P Ehrlich 1885 dye-exclusion blood-brain-barrier; modern tight-junction + transporter ATP-binding-cassette.
Tripartite synapse (Haydon 2001)
P Haydon 2001 + Araque 1999 tripartite-synapse; modern astrocyte-mediated gliotransmission + neurovascular coupling.