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What are proprioceptors?
Receptors in muscle fibers that contain sensory nerves.
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What do the muscle spindles do?
They signal changes in length. Specifically to stretch. When the muscle stretches if fires signals to the brain that causes it to contract after stretching.
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What kind of neurons control muscle spindles?
gamma motor neurons.
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What do the golgi tendon organs do?
It signals changes in tension. When the muscle contracts the tendon organ will fire to inhibit and stop the muscle from contracting.
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What tract conveys information from the cortex to spinal cord?
Corticospinal tract.
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What are the largest cells in the cortical spinal tract and what do they do?
Betz cells. They communicate with motoneurons in the spinal cord.
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What areas in the motor cortex plan movement?
Supplemental area and premotor area.
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In the lateral corticospinal tract where does information cross over?
Medulla.
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In the anterior corticospinal tract where does information cross over?
In the spinal cord.
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What percent of signals will crossover at the medulla?
80%
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What part of the brain executes the muscle action?
primary motor cortex.
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How many layers are in the motor cortex?
6
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What do lesions in the premotor cortex do, supplementary motor, and posterior parietal areas do?
impair the ability to make purposeful movement.
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What do lesions in the primary motor cortex do?
impairs the ability to develop an appropriate strategy for movement.
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What does the cerebellum do?
It is the error detector, monitors fine motor control, and cognitive tasks. It regulates movement and posture indirectly by adjusting the output of major descending motor systems.
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How many layers are in the cerebellum and what are they called?
molecular layer, purkinje-cell layer, granule cell layer, white matter layer.
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What is in the moleculer layer of the cerebellum?
few neurons mainly fibers.
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What is in the purkinje-cell layer?
a 1 cell layer of large purkinje-cells.
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What is in the granule-cell layer?
Many neurons that are small.
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What is in the white matter layer?
axons entering or leaving the cerebellum.
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What are the effects of lesions in the cerebellum?
loss of fine coordination, posture changes, ataxia (can't walk straight)
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What is the purpose of the basil ganglia?
select movements and prepare for movements. It plans movements and remembers sequences of movement.
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Together the caudate and putamen make up the?
neostriatum or striatum
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What is the purpose of the globus pallidus?
Receives input from the striatum. It then passes these signals to the sumthamic nuclues or the thalamus.
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What is the purpose of the subthalamic nucleus?
it receives information from the globus pallidus and the motor and premotor cortices.
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What is the purpose of the substantia nigra?
It has dopamine containing neurons that sends dopamine to striatum.
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What is the main output of the basal ganglia?
to the thalamus and then to the cortex.
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What two parts of the basal ganglia send outputs to the thalamus?
The globus pallidus and substantia nigra.
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What is the cause of wilson's disease?
alteration to coppermetbolism degrades parts of the basil ganglia.
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What is the cause of parkinson's disease?
loss of dopaminergic cells in the basil ganglia.
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How does L-DOPA treat parkinsons?
L-dopa does not treat parkinsons it can only relieve some symptoms by giving the brain some dopamine.
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What is the problem with L-DOPA treatment?
Can cause tardive dyskinesias and it can become useless.
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What is grafting?
Taking stem cells and placing them in the substantia nigra to create dopamine neurons.
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What is pallidotomy?
Making a lesion in part of the globus pallidus to stop some tremors.
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What is deep brain stimulation?
electrically stimulate the subthalmic nucleus or the globus pallidus to inactivate neurons that are firing abnormally.
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How is Huntington's disease caused?
It is domintant genetic and it causes neuronal degenration in th striatum and cortex.
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What chromosome is affected by huntington's disease?
Chromosome 4
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What is hemiballism?
Damage to the subthalamic nucleus. Causes uncontrolled movements.
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