Neural introduction Flashcards
What 4 processes does the nervous system need to carry out
sense
process - distinguish between relevant/not
react
memorise - adapt i.e. habituation, LTP, LTD
How is an action potential described
Fixed size
All or nothing
What sort of channels does an action potential open
Cation permeable
What happens when a threshold is reach in an AP
Sufficient VG Na+ channels open
Permeability/conductance to Na+>K+
What phase follows threshold in AP
Rising phase Depolarisation Na+ into neurone down electrochemical gradient Shifts Vm -->ENa Vm = positive
What phase follows rising phase in AP
Overshoot
Vm = above zero approx. +40mV
What phase follows overshoot phase in AP
FALLING PHASE Repolarisation VG Na+ close VG K+ open Perm/conductance K+> Na+ K+ diffuses out of neuron down conc grad Vm --> Ek
What phase follows falling phase in AP
Undershoot Hyperpolarisation below resting Vm Vm --> Ek VG K+ add to resting K+ mem perm
When does undershoot wear off
As VG K+ close
Why is conduction unidirectional despite Na+ diffusing in both ways
VG Na+ closed and inactive behind
Membrane needs to hyperpolarise first
Cannot depolarised
Area where an AP cannot be depolarised is called
Refractory period
How is an AP conducted
Non-decremental manner
Max speed of an AP
10m/s
What occurs at synapses
Docking of NT
where does docking occur
At active zone of terminal membrane before an AP
What does docking ensure
Rapid release
Are synapses or ligand gated ion channels faster
Ligand
Describe EPSP
Transmitter release at a fast excitatory chemical synapse generates excitatory post-synaptic potential e.g. nAChR
Describe IPSP
Transmitter release at a fast inhibitory chemical synapse generates inhibitory post-synaptic potential e.g. GABAAR
Where is glutamate found
CNS
glutamate acts on
Ionotropic R
metabotropic R
glutamate is an example of
NT
3 receptors glutamate acts on
AMPA
Kainate
NMDA
AMPA
Na+ selective
K+ selective
EPSP
NMDA
Works with AMPA
Mg2+ block
Ca2+/Na+
Describe GABAaR
Ionotropic
High Cl- out
Low Cl- in
Hyperpolarisaton
Where is LTD
Cerebellum
Describe LTD
not hyperpolarisation
Decrease in depolarisation from decrease in efficacy of neuronal synapses
