L6 - Graded Potentials Flashcards
Why is the nervous system so complex? Why not “hardwire” the nervous system?
because we do not want to react with the same reflex for the same input every time (allows for adaptability of communication between neurons)
If the afferent neuron is excitatory, and the interneuron is inhibitory, increasing the firing frequency of the afferent neuron would _______ (increase/decrease/not change) the firing frequency of the interneuron?
because the inhibitory neuron is inhibiting the efferent neuron, this means that although it is an inhibitory neuron, its own firing frequency will still increase
If the afferent neuron is excitatory, and the interneuron is inhibitory, increasing the firing frequency of the afferent neuron would _______ (increase/decrease/not change) the firing frequency of the efferent neuron?
because the inhibitory neuron is inhibiting the efferent neuron, this means that the firing frequency of the efferent neuron will decrease
What is a divergent pathway?
one presynaptic neuron branches to affect a larger number of postsynaptic neurons
What is a convergent pathway?
many presynaptic neurons converge to influence a smaller number of postsynaptic neurons
What is an EPSP?
an excitatory postsynaptic potential (depolarizing)
What is an IPSP?
an inhibitory postsynaptic potential (hyperpolarizing)
What is spatial summation in a circumstance when an action potential is generated?
when three excitatory neurons fire resulting in the summed potentials amounting to above threshold resulting in the generation of an action potential
What is spatial summation in a circumstance when an action potential is not generated?
when two excitatory neurons fire and one inhibitory neuron fires resulting in the summed potentials amounting to below threshold resulting in no action potential being generated
What is temporal summation in a circumstance when an action potential is generated?
when two graded potentials occur in quick succession and are able to sum and create an action potential
What is temporal summation in a circumstance when an action potential is not generated?
when two graded potentials do not occur in quick succession and therefore are not able to sum together to reach above threshold
What is the likelihood of an action potential being fired as a result of a signal coming from a presynaptic neuron which is far away from the postsynaptic axon hillock?
low chance as graded potentials decrease in charge over a distance
What is the likelihood of an action potential being fired as a result of a signal coming from a presynaptic neuron which is very close to the postsynaptic axon hillock?
high chance as graded potentials will not decrease in charge as much over the short distance to the axon hillock
Depolarising signals generated by CNS synapses are called…
excitatory postsynaptic potentials
How can EPSPs and IPSPs interact?
by occurring in a postsynaptic cell close together in time, by occurring in a postsynaptic cell close together in space, through intracellular charge interaction in a postsynaptic cell and because they are both graded potentials
