nervous transmission Flashcards
what do leakage channels do
lets K+ through easily and Na+ poorly
what is an action potential
series of active events, channels actively open and close
name the 2 phases after the arrival of a stimulus
depolarizing phase
repolarizing phase
describe the depolarizing phase
membrane potential rises and becomes positive
describe the repolarizing phase
potential restored to resting valuve
what happens if stimulus is strong enough to reach threshold
Na+ channels open
K+ channels then open
Sodium/potassium pump restores ion concentrations
how does caffeine effect the nervous transmission
acts as a stimulant, lowers the threshold level of the nerve, increases the possibility of a stimulus to result in a nerve potential
how does alcohol effect the nervous system
acts as a depressant, increases nerve threshold level
how does local anesthetics effect the nervous system
nerve action potentials prevented
what is the sending neuron called
presynaptic
what is the receiving neuron called
postsynaptic
what is a neurotransmitter
chemical that carries signal across a synaptic cleft
name the presynaptic events in order
1) action potential arrives at the presynaptic end bulb
2) open voltage gated Ca2+ channels
3) neurotransmitter released into cleft
4) NT binding at postsynaptic receptors
5) chemical trigger of ion channels
6) may depolarize or hyperpolarize postsynaptic cell membrane
7) `if threshold reached at axon hillock then postsynaptic cell action potential results
how are neurotransmitters removed from the cleft
diffusion
destroyed by enzymes in cleft
transported back into presynaptic cell
destroyed by neuroglia
