action potentials
what are the 4 classifications of synapses?
1) axospinous 2) axodendritic 3) axosomatic 4) axoaxonic
neuron membrane properties (2) that affect ion flow
1) conductance 2) capacitance
AP speed and propagation factors
1) myleinated or not 2) diameter of axon (bigger = faster)
neuron special anatomical features (2)
1) shape of the body - long and skinny - ideal for sending messages 2) specialized end for receiving, specialized end for sending messages
nerve cell membranes have 3 types of channels
1) voltage gated 2) ligand gated - with a G protein and second messenger 3) nongated ion channels (always open)
saltatory conduction
AP jumping from node to node faster conduction
channelopathies
Alterations in voltage-gated sodium and potassium channels, as well as in voltage-gated calcium and chloride channels, are now known to be the basis of several diseases of nerve and muscle
action potential definition
an electrical signal that propagates over a long distance without a change in amplitude
voltage gated channels found where on neuron
axon
the action potential is generated at the ____ and conducted along the _____
axon hillock; axon
how are synapses classified?
based on their site of contact
part of neuron lacking voltage gated channels (mostly)
dendrites and soma (do not conduct action potentials)
axon hillock
location on axon that has the highest density of voltage gated channels AKA trigger zone
Capacitance
membrane's ability to store an electrical charge
location of synapses
mostly in the dendritic and somatic part of the cell axon contains some synapses as well
nodes of Ranvier
nodes in between mylenated axons (like sasauges) where AP is generated - hops from node to node Na+ channels concentrated here
function of synapses
on the dendrite: receive and integrate incoming info on the axon: conducts information in the form of electrical signal
importance of myelination
segments activated instead of each individual channel being activated
absolute refractory period
the axon is resetting absolutely NO action potential can be generated
relative refractory period
the axon is still resetting, but an action potential can still be genereated - just has a higher threshold and the amplitude will be lower
conductance
the ease at which ions flow through their channels greater the conductance, the greater the ion flow
all or none concept
the initiation of an action potential must pass a threshold to be generated; if the threshold is not met there is no AP it's either successful or its not
