HBF 7 Membrane potentials and excitability

Leak channels

Selective for specific ion

always open

Ligan gated channels

Ligand receptor embedded in channel

Induces conformational change to open or close channel

Voltage gated ion channels

Voltage sensor in ion channel protein

Changes in membrane potentials induce conformational change to open of close the channel

Maintaining diff conc of ions means that there are

Ion conc gradients and ion charge gradients

What is RMP

Difference in electrical charge across the plasma membrane in the cell at rest

What is RMP in a typical neuron

-70 mV

Electrochemical gradient

Charge gradient + concentration gradient

What happens at equilibrium in an electrochemical gradient

Charge gradient balances out the conc gradient

no net flow of ions across a membrane

What happens if ion channels open in response to a specific stimuli

Ions will move towards their equilibrium potential

What do excitable cells do

Actively induce changes in their membrane potential

How does depolarisation occur

Influx of positively charged ions

Known as excitatory post synaptic potential

Associated with excitation of cells

How does hyperpolarisation occur

Efflux of positively charged ions

Influx of negatively charged ions

This is known as inhibitory post synaptic potential and is associated with the innhibition of cells

What is an action potential

Brief rapid large change in membrane potential during which potential reverses

Serves as long distance signals

What is the refactor period

When a further stimulus will not trigger another action potential

What is postsynaptic response

Combined effect of thousands of synaptic events from many neurons

When AP threshold is reached

Strong stimuli produce action potentials of the same amplitude as weak stimuli