Lecture 7 Flashcards
the spinal cord has a ______ structure
laminar
geographical terms that will be helpful in descriptions
posterior anterior lateral medial dorsal ventral
each vertebrae has a ______ and a _____.
body and a spinous process
Peripheral information gets into the spinal cord through ________.
dorsal roots.
Efferent signals are sent from the spinal through the _______.
ventral roots
Starting with the skull, vertebrae are numbered from ____ to ____ and then end with the sacrum.
C1 to L5
Spinal segments are numbered from _____ to ______ but this classification does not correspond exactly to the vertebrae classification.
C5 to L1
A synapse consists of:
a presynaptic membrane, a synaptic cleft, and a postysynaptic membrane
Inhibition means _____ in the efficacy of the synapse and may occur as a result of events on the presynaptic or postsynaptic membrane
decrease
An excitatory synapse leads to a:
depolarization on the postsynaptic membrane
An inhibitory synapse leads to a:
hyper polarization on the postsynaptic membrane
Postsynaptic Inhibition
when one neuron hyper polarized the cell body (or dendrites) of another cell body.
Postsynaptic Inhibition will hyperpolarize the entire postsynaptic membrane, essentially __________
shutting down that cell for a period of time to all incoming stimuli.
Postsynaptic inhibition is a more _____ type of inhibition
general
A postsynaptic inhibitory synapse hyper polarizes the postsynaptic membrane and _________.
decreases its responsiveness to excitatory synapses.
Axons of alpha-motorneurons branch very close to the cell body and make______.
excitatory synapses on Renshaw cells
Renshaw cells make _________ on alpha motorneurons
renshaw cells make inhibitory synapses on alpha motoneurons of the same pool as well as on y-motoneurons, sending their axons to spindles in the SAME muscle.
Recurrent Inhibition
Basically, alpha motoneurons excite the cells (Renshaw cells) that inhibit the same alpha motoneurons
Why is recurrent inhibition beneficial?
Henshaw cells help stabilize the firing rate of motor neurons.
In Reciprocal Inhibition, Ia interneurons receive ______ inputs from Ia afferents & make _______ synapses on motoneurons innervating the antagonist muscle
excitatory; inhibitory
In Reciprocal Inhibition, The INs are inhibited by Renshaw cells and also receive _________ inputs.
descending
In Recurrent Inhibition, alpha motoneurons send axon branches to small ________ interneurons (Renshaw cells) in the ventral horns of the spinal cord
inhibitory
Renshaw cells ______ all motoneurons of the same pool.
inhibit
In Reciprocal Inhibition, __________ are activated by primary spindle afferent fingers.
small interneurons (Ia interneurons)
In Reciprocal Inhibition, the Ia interneurons _________ motoneurons of the antagonist muscle
inhibit.
