synapses (e2) Flashcards
who is charles sherrington?
nobel prize in 1932; synaptic delay
how did sherrington come up with the synaptic delay?
study of the reflex arc; the delay occurs where one neuron communicates with another
presynaptic neurons
send signals
postsynaptic neurons
receive the signal
what are graded potentials?
unlike action potentials, they can be either depolarizations (excitatory) or hyperpolarizations (inhibitory)
what are EPSPs?
temporary graded depolarization of postsynaptic membrane
how do EPSPs happen?
caused by entrance of sodium ions into the cell
what is the function of EPSPs?
make the cell more likely to fire an action potential
what are IPSPs?
temporary graded hyperpolarization of postsynaptic membrane
how do IPSPs happen?
caused by the exit of potassium ions outside the cell or chloride ions (-) inside
they increase the negative charge within the neuron
what is the function of IPSPs?
makes the cell less likely to fire an action
what is spatial summation?
synaptic inputs from separate locations combine their effects on a neuron
what is temporal summation?
repeated stimuli within a brief time have a cumulative effect
what is the spontaneous firing rate?
a periodic production of action potentials even without synaptic input
ongoing activity in the absence of a task or stimulation
the ____ increase the frequency of action potentials above the spontaneous rate whereas the ____ decrease it
EPSPs, IPSPs
