Lecture 7 Flashcards
What kind of structure does the spinal cord have
laminar
What do the grey and white matter represent in the spinal cord
cell bodies, pathways (respectively)
Directional term for top of head
rostral
Directional term for tail
caudal
What two things do each vertebra have
a body and a spinous process
Peripheral information gets into the spinal cord through the _______
dorsal roots
Efferent signals are sent to the spinal cord through the ________
ventral roots
Starting from the skull, vertebrae are numbered from ____ to ____ and then end with the _____
C1-L5, end with the sacrum
Spinal segments are numbered from ____ to ____, but this classification does not correspond exactly to the vertebrae classification.
C1-S5
The spinal cord ends at what vertebra
L1, or top of L2
A synapse consists of what three things
presynaptic membrane, synaptic cleft, postsynaptic membrane
What means a decrease in the efficacy of the synapse and may occur as a result of events on the pre or postsynaptic membrane
inhibition
An excitatory synapse leads to a _______ of the postsynaptic membrane (bringing it closer to threshold)
depolarization
An inhibitory synapse leads to a _______ of the postsynaptic membrane
hyperpolarization
When one neuron hyperpolarizes the cell body or dendrites of another cell body
postsynaptic inhibition
What will hyperpolarize the entire postsynaptic membrane, essentially shutting down that cell for a period of time to all incoming stimuli
postsynaptic inhibition
During postsynaptic inhibition, a postsynaptic inhibitory synapse hyperpolarizes the postsynaptic membrane and _______ its responsiveness to excitatory synapses
decreases
What causes axons of alpha motor neurons to branch very close to make excitatory synapses on renshaw cells
recurrent inhibition
Motor neurons always have what type of effect
excitatory
What cell does the inhibition during recurrent inhibition
renshaw cells
If a renshaw cell is inhibited and then excited what will happen
nothing at all
Why is it beneficial for alpha motoneurons to excite renshaw cells that will inhibit the same alpha motoneurons and gamma motoneurons
this is a mechanism controlling the amount of force produced during movement
What do renshaw cells help stabilize
the firing rate of motor neurons
What is it called when Ia interneurons receive excitatory inputs from Ia afferents and make inhibitory synapses on motoneurons innervating the antagonist muscle
reciprocal inhibition
Ia interneurons are inhibited by what
renshaw cells and descending inputs
What must happen to the renshaw cell before it can do inhibition
it must be excited
Ia interneurons can be inhibited by renshaw cells to stop what
reciprocal inhibition
What is occurring when a neuron contacts the axon terminal rather than the cell body of another neuron
presynaptic inhibition
Presynaptic inhibition will reduce the amount of ________ released by the second neuron onto the third cell
neurotransmitter
Presynaptic inhibition is more _____ than postsynaptic inhibition
specific or selective
An excitatory synapse acting on the presynaptic membrane, inducing its subthreshold depolarization, thus decreasing the amount of mediator released in response to a single presynaptic action potential
presynaptic inhibition
