Lesson 2: Neural Control of Movement Flashcards
Two parts of the nervous system
CNS
PNS
6 major areas of the brain
Medulla oblongata
Pons
Midbrain
Cerebellum
Encephalon
Cerebrum
3 parts of the brainstem
Medulla
Pons
Midbrain
Fine motor controls have more/less muscle fibers per unit
less
Gross motor controls have more/less muscle fibers per unit
more
Parts of the alpha motor neuron:
Cell body, axon, dendrites
The ______ houses the neuron’s control center for signal transmission
cell body
The ___ extends from the cell body to deliver the signal to the muscle
axon
The _______ are small and short neural branches that receive impulses and conduct them toward the cell body
dendrites
Lipoprotein membrane that wraps around the axon over most of its length
myelin sheath
What is the myelin sheath made from?
Lipoprotein
Fat
What is the purpose of the myelin sheath?
Insulates and speeds up nerve transmission
What is the thin/outermost layer that covers the myelin sheath?
Neurilemma
Nodes that interrupt the myelin sheath every 1 to 2 mm and allow the neuron to depolarize (provide stimulus for movement)
Nodes of Ranvier
What is the purpose of the nodes of Ranvier on the axon?
Allow the neuron to depolarize and provide a stimulus for movement
Conduction speed of a nerve fiber is directly related to the _______ and the _________.
muscle fiber’s diameter
Thickness of the myelin sheath
The bigger the nerve fiber, the bigger/smaller the muscle fiber
bigger
Another name for the neuromuscular junction is the _____ ______
motor endplate
Where does excitation typically occur?
The neuromuscular junction
The post-synaptic membrane (on muscle fiber) involve “folds” that allow for ________
greater surface area of transmission
The electrical stimulus at the post-synaptic membrane creates an ______ _______
Action potential
Threshold for excitation
change in voltage on the post synaptic membrane required to produce an action potential
What is spatial summation?
simultaneous “summing’” of stimuli from surrounding terminals (“space”)
What is temporal summation?
Simultaneous “summing” of stimuli from repeated stimulation (“time”)
The larger the motor unit, the more/less force it can produce
MORE
Type _ muscle fibers have the smallest motor units
I
Type _ muscle fibers have the largest motor units
IIx & IIb
Type _ muscle fibers have larger but not the largest motor units
IIa
What is the reflex arc?
the nerve pathway involved in a reflex action including at its simplest a sensory nerve and a motor nerve with a synapse between
Arrangement of the reflex arc:
1) afferent neurons transmit sensory input from peripheral receptors and enter through the dorsal region of the spinal cord
2) afferent neurons synapse (interconnect) with efferent neurons through interneurons in the spinal cord
3) efferent neurons exit the cord through ventral region and provide signaling to muscles
Does the reflex arc directly involve the spinal cord?
Yes
Does the reflex arc directly involve the brain?
No
Muscles and tendons have highly specialized sensory receptors sensitive to _____, _____, and ______
stretch, tension, pressure
The receptors in the muscles and tendons that are sensitive to stretch, tension, and pressure are called _________
proprioceptors
2 types of proprioceptors
Muscle Spindles
Golgi Tendon Organs
Muscle spindles provide mechano-sensory information about change in ____ _____ ____
muscle fiber length
Where are the muscle spindles located?
In the muscle fiber
the process by which a muscle spindle detects, responds to, and modulates change in the length of muscle fibers
Stretch reflex
What triggers the stretch reflex?
Change in the length of muscle fiber
Three main components of the stretch reflex:
1) Muscle spindle that responds to stretch
2) Afferent nerve fiber that carries the sensory impulse from the spindle to the spinal cord
3) Efferent spinal cord motor neuron that activates the attached muscle fiber
What does the muscle spindle of the stretch reflex do?
Responds to the stretch
What does the afferent nerve fiber of the stretch reflex do?
Carries the sensory impulse from the muscle spindle to the spinal cord
What does the efferent spinal cord motor neuron of the stretch reflex do?
Activates the attached muscle fiber
Does the stretch reflex involve interneuron?
No
Example of the stretch reflex
heavier weight added will have an initial reflex response; patellar tap reflex
The GTO responds to _____/____ ____
tension; force production
sensory receptors that detect differences in the tension generated by active muscles
GTO
Where are GTOs located?
In the tendon (which attaches muscle to bone, FYI)
GTOS respond to tension created in the muscle when it lengthens/shortens and tension when the muscle _______ _______
shortens; stretches passively
What does the GTO do when responding to EXCESSIVE tension?
Elicits reflex inhibition of the muscle cells they supply
Protect the muscle against excessive force
Protect the muscle and surrounding tissue from injury during an unaccustomed movement or excessive load
True or False: The GTO aims to limit damage, like a golf cart governor.
True
Explain the three steps of the GTO reflex arc
1) excessive tension on the tendon provides an afferent stimulus to the spinal cord
2) an inhibitory interneuron connects the afferent and efferent pathways
3) efferent neuron sends signal to decrease tension/inhibit force
Does the GTO reflex arc involve an interneuron?
Yes
