Chapter 3a: The Properties of Synapses, and more
Spontaneous Firing Rate
A periodic production of action potentials even without synaptic input. - most neurons have this
Excitatory Postsynaptic Potential (EPSP)
A postsynaptic potential that depolarizes the neuronal membrane, making the cell more likely to fire an action potential. - occurs when sodium ions enter a cell. - "if the delay between ____'s was short enough, temporal summation occurred." - is a type of Graded Potential
Reflexes
Automatic muscular responses to stimuli. - Sherrington conducted his research on these, and found three propeties of ___" - 1. ____ are slower than conduction along an axon - 2. Several weak stimuli presented at slightly different times or slightly diffferent locations produce a stronger ___ than a single stimulus does - 3. When one set of muscles becomes excited, a different set becomes relaxed
Spatial Summation
Occurs when synaptic inputs from separate locations combine their effects on a neuron. - (summation over space) - "instead of pinching one point twice, he [Sherrington] pinched two points at once. Although neither pinch alone produced a reflex, together they did."
Reflex Arc
The circuit from sensory neuron to muscle response.
Presynaptic Neuron
The neuron that delivers the synaptic transmission.
Postsynaptic Neuron
The neuron that receives the message.
Temporal Summation
The summation of graded potentials from stimuli at different times. - Sherrington found that repeated stimuli within a brief time have a cumulative effect. He referred to this phenomenon as ____ ____. One pinch of dogs foot did not evoke a reflex, but a few rapidly repeated pinches did. Sherrington surmised that single pinch produced a synaptic transmission less than the threshold for the Postsynaptic Neuron. - (summation over time)
Inhibitory Postsynaptic Potential (IPSP)
The temporary Hyperpolarization of a membrane that resembles an EPSP. - 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) - is a type of Graded Potential