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
