Chapter 2.1: The Concept of the Synapse Flashcards
Communication at Synapses
reflex arc p. 40
The circuit from sensory neuron to muscle response is called a reflex arc.
reflexes p. 40
Automatic muscular responses
to stimuli.
synapse p. 40
physiologically demonstrated that communication between one neuron and the next differs from communication along a single axon. He inferred a specialized gap between neurons and introduced
the term synapse to describe it.
excitatory postsynaptic potential
(EPSP) p. 41
Action potentials, which are always depolarizations,
graded potentials may be either depolarizations (excitatory) or hyperpolarizations (inhibitory). A graded depolarization is known as an excitatory postsynaptic potential (EPSP). It results from a flow of sodium ions into the neuron. If an EPSP does not cause the cell to reach its threshold, the depolarization decays quickly.
postsynaptic neuron p. 41
The neuron that receives a signal it is the postsynaptic neuron.
presynaptic neuron p. 41
The neuron that delivers transmission is the presynaptic neuron.
spatial summation p. 41
Synapses have the property of spatial summation—that is, summation over space. Synaptic inputs from separate locations combine their effects on a
neuron.
temporal summation p. 41
Repeated stimuli within a brief time have a cumulative effect. He referred to this phenomenon as temporal summation (summation over time).
inhibitory postsynaptic potential
(IPSP) p. 43
That is, it increases the negative charge within the
cell, moving it further from the threshold and ecreasing the probability of an action potential. This temporary hyperpolarization of a membrane—called an inhibitory postsynaptic potential, or IPSP—resembles an EPSP. An IPSP occurs when synaptic input selectively opens the gates for potassium ions to leave the cell (carrying a positive charge with them) or for chloride ions to enter the cell (carrying a negative charge).
spontaneous firing rate p. 45
Most neurons have a spontaneous firing rate, a periodic production of action potentials even without synaptic input. In such cases, the EPSPs increase the frequency of action potentials above the spontaneous rate, whereas IPSPs decrease it.
