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