neurons threshold levels(exam4)

an "all or none principle"

• the neuron transmits a nerve impulse or it does not transmit a nerve impulse
• a) no such thing as 1/4 or 1/2 strength

• a) threshold stimulus or liminal stimulus
• b)subthreshold stimulus or subliminal stimulus
• c)summation of inadequate stimuli

summation of inadequate stimuli

a single stimulus that is strong enough to initiate a nerve impulse in the post-synaptic neuron

a single stimulus that is too weak to initiate a nerve impulse in the post-synaptic neuron

a series of stimuli that are too weak to initiate a nerve impulse b themselves->collectively add together and initiate a nerve impulse in post-synaptic neuron

• a)post
• b)pre

comulative effect of all active pre-synaptic neurons

the "axon hillock"

• 1.excitatory post-synaptic potential (EPSP)
• 2. inhibitory post-synaptic potential(IPSP)

neurotransmitter that moves the post-synaptic closer to threshold level->more likely to initiate a nerve impulse

neurotransmitter that moves the post synaptic neuron farther from threshold level (hyperpolarizes)-> less likely to initiate a nerve impulse

no

yes