Chapter 8: Control of Movement Flashcards
Ultimate function of nervous system:
control of behavior
_______ muscles move us around and are responsible for physical actions.
Skeletal
Strong bands of CT that fasten muscle to bones
Tendons
Flexion is the contraction of a flexor muscle that moves the limb toward/away from the body.
Toward
Extension is the contraction of an extensor muscle that moves the limb toward/away from the body.
Away from
The extrafusal/intrafusal muscle fibers provide the force of the muscle.
Extrafusal
Several extrafusal muscle fibers are served by a single axon of an _______ _____ ______.
alpha motor neuron
The intrafusal muscle fiber is served by _ axons: ________.
2; sensory and motor
Which part of the intrafusal muscle fiber contains the sensory endings sensitive to stretching?
Capsule
Which neuron causes the intrafusal muscle fiber to contract (albeit minimally)?
Gamme motor neuron
What does a motor unit consist of?
Alpha motor neuron
Axon
Associated extrafusal muscle fibers
Fine motor muscles such as the eyes or fingers will have more/less extrafusal muscle fibers per alpha motor neuron.
less
Gross motor muscles such as the limbs or butt will have more/less extrafusal muscle fibers per alpha motor neuron.
more
A muscle fiber is made up of a bundle of ______.
myofibrils (actin and myosin)
What are myosin cross bridges?
Little motile elements on the myosin that interact with actin and produce muscular contractions
_______ occur where the actin and myosin overlap on a muscle fiber
Striations
The synapse between the terminal button of an efferent neuron and the membrane of a muscle fiber:
Neuromuscular junction
In the neuromuscular junction, the terminal buttons synapse on _____ _________.
motor endplates
True or false: the endplate potential always causes muscle fibers to fire.
True
The depolarization of the postsynaptic membrane caused by the liberation of acetylcholine by the terminal buttons when an axon fires is called the _____ ______.
endplate potential
The endplate potential is a hyperpolarization/depolarization of the postsynaptic membrane
depolarization
The strength of a muscular contraction is determined by the _____ ____ ____ ________ of various motor units
average rate of firing
When the average rate of firing of various motor neurons is high, the contraction is strong/weak.
Strong
When the average rate of firing of various motor neurons is low, the contraction is strong/weak.
weak
True or false: intrafusal muscle fibers are stretch receptors that detect the total amount of stretch exerted by the muscle.
FALSE: they are stretch receptors that serve as muscle length detectors
Receptors on the intrafusal muscle fibers detect muscle _____, not tension
length
The golgi tendon organs encode the stretch degree by the ______ __ _______.
rate of firing
______ receptors detect the total amount of stretch exerted by muscle and are located within ______.
Stretch; tendons
The golgi tendon organ, monitoring the strength of contraction, fires in proportion to the stress on the muscle. Therefore, if weight was added to your hand, the firing increases/decreases.
increases
The monosynaptic stretch reflex controls ______ movements.
limb
During a monosynaptic stretch reflex, the muscle contracts in respond to being quickly ______ in reaction to a stimulus.
stretched
The monosynaptic stretch reflex helps to maintain _____ and adjusts to maintain ____ ______.
Posture; body position
Explain what happens during a monosynaptic stretch reflex:
Muscle lengthens, muscle spindle fires to the terminal buttons in gray matter of spinal cord, which synapse on the alpha motor neuron, innervating extrafusal muscle fibers and causing the muscle to move.
When gamma motor neurons are active,
muscle spindles become longer/shorter and are more/less sensitive to change
shorter; more
__________ reflexes involve multiple synapses involved in more complex reflexive behavior
Polysynaptic
Examples of a polysynaptic reflexes:
Pain; startle reflexes
True or false: You can’t control the polysynaptic reflex AT ALL.
False – we can kinda inhibit them thanks to context and learning.
Where is the primary motor cortex?
Posterior frontal lobe