PDF containing notes from Neurophysiology Action Potential lecture. Content discusses ion channels/ concentrations, steps in action potential, stages in depolarisation etc
For A-level/ first year uni students
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Neurophysiology Action
Potential
Created @January 21, 2025 12:13 PM
Class Principles to Neuroscience and Pharmacology
Ion Distribution:
Plasma membrane is impermeable to ions, enabling big differences in ion
concentration to occur
Na+ is less concentrated inside of the cell
K+ is more concentrated on the inside of the cell
Concentrations are a must for neuronal signalling
Ion Concentration Differences:
Differences across the membrane are generated by low permeability of
cell membrane, ion channels and sodium/potassium pumps
This makes it difficult to create the resting and action potential
Ion Channels:
Formed by proteins that cover the cell membrane to synthesis a water
filled pore
Leaky channels are always open and sets the cells resting potential
Neurophysiology Action Potential 1
, Ion channels are usually closed until they respond to certain stimulus
Voltage-gated sodium and potassium channels open if there’s a change to
the membrane potential
Voltage- gated calcium channels triggers neurotransmitter release at
synapses
Ligand Gated channels are responsible for synaptic transmission
Sodium Potassium Pump:
Transports Na+ out of cells against concentration gradient, this process
requires ATP that is produced by mitochondria
K+ is exchanged and enters the cell
Na+ is generated and K+ concentration gradients occur across the
membrane, but gradients are only possible because the cell membrane is
very permeable to ions
Why It’s Important
Neuron works to maintain K+
Na+/ K+ pump uses ATP for concentration gradient maintenance
Both of the pumps generates concentration gradients that are required for
neuronal activity
BRAIN NEEDS CONSTANT SUPPLY OF ENERGY AND OXYGEN TO KEEP THE
PUMPS GOING
K+ Setting Resting Potential:
K+ Concentration is higher inside of the cell
K+ moves down the concentration through the leaky potassium channels
Neurophysiology Action Potential 2
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