Flashcards in Module 3.1 Deck (20)
What is a reflex?
automatic muscular responses to stimuli
What experimental evidence did Sherrington have for synaptic delay?
He found that the velocity of conduction through a reflex was significantly slower than an action potential along an axon.
What experimental evidence did Sherrington have for temporal summation?
Evidence Sherrington found for temporal summation was that repeated stimuli within a brief time have a cumulative effect.
What is an EPSP and what ionic flow is largely responsible for it?
An EPSP (excitatory postsynaptic potential) is a graded depolarization. A sodium ionic flow is responsible for it.
How do spatial and temporal summation differ?
Temporal summation is the combined effect of quickly repeated stimulation at a single synapse. Spatial summation is the combined effect of several nearly simultaneous stimulations at several synapses onto one neuron.
What is an IPSP and what ionic flows will produce it?
IPSP (inhibitory postsynaptic potential) is a temporary hyperpolarization of a membrane; potassium
What influence do EPSP's and IPSPs have on neurons with spontaneous firing rates?
ESPS's increase the rate of action potentials about the spontaneous rate and IPSP's decrease it below the spontaneous rate.
*****What factors influence a cell's decision whether or not to produce an action potential?
A synapse decides whether or not to send a message.
an electrical charge that shoots the axon due to rapid influx of Na+
stimuli (NT) causes the inside of the cell to become more positive by opening Na+ channels (makes action potential more likely)
NT causes inside of the neuron becomes more negative due to K+ leaving or Cl- coming in (AP less likely)
When depolarization reaches threshold, __________ Na+ channels at axon hillock fly open
The all-or-none-law means that the ________ strength is the same no matter what
on myelinated axons when the charge jumps to the next Na+ channel
period when the neuron cannot fire again right away
absolute refractory period
period when the neuron will fire if given strong stimulation
relative refractory period
several weak EPSPs in rapid succession can add up to a threshold-level stimulus
several weak EPSPs from different sources can add up to a threshold-level stimulus
______ cancel out ____ in summation