What determines if Ach will act in an excitatory or inhibitory manner?
the type of ion channel on the post synaptic membrane
i.e
sodium--excitatory
chloride--inhibitory
Source of Ach in the CNS?
Nucleus Basalis
Degeneration of Nucleus Basalis leads to/?
Dementia/Alzeimers
What happens in Presynaptic Facilitation?
nt decreases k+permeability, trapping k+inside the cell..effectively depolarizing the membrane so upon AP the membrane is dopolarized to +45 instead of +35
Short-term memory is characterized by what?
Presynaptic Ca +2
What happens in presynaptic inhibition?
Cl - permeability increased...hyperpolarizing the membrane...no depolarization
Ion channels are exclusively present where on the neuron?
On the Axon
What limits the frequency of AP?
Absolute Refractory Period
Post synaptic potentials are voltage or ligand gated?
Ligand gated
What nt is always excitatory in the CNS?
Glutamate
Whats the difference between an Ionotropic and metabotropic nt receptor?
Ionotropic--nt binding opens an ion channel--quick
Metabotropic--nt binding activates a series of 2nd messengers which opens the ion channel..long activation..long duration
Polio selectively affects what?
LMN in Lamina 9
What is the mode of action of a botulism toxin?
B. toxin prevents release Ach from the presynaptic membrane
A tumore in the cerebropontine angle affects what CN?
CN VIII-vestibulocochlear
Myesthenia Gravis?
Auto-immune--ab against Ach receptors...paralysis..