action potentials and synaptic tranmission Flashcards
amplitude
peak (not determined by strength)
- specific to neuron
strength
how frequently they fire
active transport
move ions against their concentration gradient
ion channels
- leakage channels
- gated channels
gated channel types
- voltage gated
- ligand gated
- mechanically gated
voltage gated ion channels
change in membrane potential causes channel to open
- crucial for generation and conduction of AP
ligand gated ion channels
chemical stimulus open and closes the channel
- G protein coupled and starts secondary process
mechanically gated ion channels
forces distort the channel which opens the gate
graded potentials
- small deviation from resting membrane potential
- can be in either hyper polarize or depolarize
- usually result of ligand gated or mechanically gated ion channels opening or closing
- most common in dendrites and cell bodies of neurons
- amplitude is determined by strength of stimulus
- not all or none
absolute refractory period
- unable to generate an AP even with a very strong stimulus
- inactivated Na channels cannot reopen
relative refractory period
- need a suprathreshold stimulus to generate another AP
- voltage gated K+ channels are still open, but Na channels have returned to resting state
electrical synapses
- ionic current passes directly from one cell to another cell through connexions in gap junctions
- fast
- synchronization
- two way transmission
chemical synapses
- 2 neurons separated by synaptic cleft
- voltage gated Ca channels open, Ca flows into presynaptic neuron
EPSP
depolarizes the postsynaptic cell to create an AP
IPSP
hyper polarizes the postsynaptic cell to inhibit generation of AP
spatial summation
several presynaptic end bulbs release NT
temporal summation
NT released from a single presynaptic end bulb in rapid succession
diffusion
diffuse down concentration gradient
enzymatic degradation
eat neurotransmitter
uptake by cells
primarily glial cells or reuptake by the neuron that released them
