Neural Activity 2

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Neural Activity 2

Neurotransmitters and Receptors

Metabotropic receptors

Activation of second messanger without opening channel

Activation of G-protein.

Ionotropic receptors

GABA receptor

ISPS

Hyperpolarisation of neuron from influx chloride

Glutamate receptor (NMDA & AMPA)

ESPS

Depolarises neuron from influx of positive ions causing action potential

Receptor binding immediately opens ion channels

Channels & Pumps

Voltage-gated channels

Gap junctions

Active transport pump

sodium-potassium pump

Transports sodium out of the cell and potassium into the cell.

Ligand Gated channel

Properties of Synapses

Spatial Summation

Combination of effects of two or more synapses into single neuron

Temporal Summation

Cumulative effect of repeated stimuli within brief time

Synapse Steps

5. post synaptic ion channel results in EPSP or IPSP

Inhibitory post synaptic potential

Excitatory post synaptic potential

Depolarisation

4. neurotransmitter bins on ligand gated ion channels

3. neurotransmitter released into synaptic cleft

2. increased calcium lets synaptic vesicles fuse with terminal membrane

1. AP arrives at synapse

chemicals stored in vesicles of pre-synaptic terminal

Opens calcium ions

Calcium evokes release of neurotransmitter into cleft

Myelin Sheath

Refractory Period

Absolute Refractory Period

Unable to produce action potential

Relative Refractory Period

Time after absolute refractory period that requires stronger stimulus to initiate action potential

time when cell resists production of further action potential

Saltatory conduction

Action potential

Resting State

- 40mV

Threshold

minimum amount of membrane depolarisation necessary to trigger action potential (-55mV)

Depolarise

Reduce polarisation toward zero across membrane (+40mV)

Hyperpolarisation

Increased polarisation across membrane