Chapter3 Flashcards
What directs the coordinated actions of muscles?
Central nervous system
What are the two main components of the central nervous system?
Brain and spinal cord
What do we adapt and improve through practice?
Motor skills
What are skeletal muscles?
Muscles that attach to the skeleton
What is the function of flexors?
Bend a joint
What is the function of extensors?
Straighten a joint
What is the role of flexors and extensors?
Work in opposition
What muscle contracts to bend the elbow?
Biceps
What muscle relaxes when bending the elbow?
Triceps
What are muscles called that promote movement?
Agonists
What are muscles called that oppose or inhibit movement?
Antagonists
What allows rapid movements like throwing a dart?
Agonists and antagonists
What is co-contraction?
Simultaneous contraction
What does co-contraction stabilize?
Movement control
Who controls skeletal muscle movement?
Central nervous system
What is a skeletal muscle made up of?
Muscle fibers
What controls each muscle fiber?
Alpha motor neuron
Where do alpha motor neurons originate?
Spinal cord or brain
What is the link between CNS and skeletal muscles?
Motor unit
What is reciprocal inhibition?
Flexor relaxes, extensor activates
Where do inhibitory interneurons operate?
Within the spinal cord
What activates inhibitory interneurons?
Original sensory stimulus
What does the simplest reflex involve?
Synchronous activation of motor neurons
What is the function of many reflexes?
Protect from injury
What happens during the ‘knee jerk’ reflex?
Lower leg swings forward
How does the reflex help when jumping off a chair?
Promotes knee muscle contraction
What triggers the flexion withdrawal reflex?
Sharp object
What sends a message to the spinal cord in the flexion withdrawal reflex?
Pain receptors
What happens to the leg when the flexion withdrawal reflex occurs?
Leg is lifted
What must be activated in the opposite leg during the reflex?
Extensors
What is the flexion crossed extension reflex?
Prevents falling over
What do muscle spindles provide information about?
Muscle length changes
What type of reflex is the ‘knee jerk’ response?
Stretch reflex
Where are the circuits that control reflexes located?
Spinal cord
What do muscle spindles sense?
Stretch extent and speed
What activates the alpha motor neurons in the stretch reflex?
Signals
What is tested when a doctor taps a muscle tendon?
Reflexes
What do muscle spindle sensory fibers send to the spinal cord?
Impulses
What is flexion withdrawal?
Leg lifted from sharp object
What is the crossed extension reflex?
Opposite leg extends for balance
What do motor neurons do?
Carry instructions from the brain
How long can motor neurons be?
Stretch length of leg
What do tendon feedback systems detect?
Force or tension
What do feedback systems allow the brain to do?
Fine-tune muscle behavior
Examples of tasks using feedback systems?
Sipping, throwing
What do spinal circuits control?
Voluntary behaviors
What generates rhythmic muscle activation for locomotion?
Neurons in spinal circuits
What types of movements are central pattern generators responsible for?
Walking, flying, swimming, breathing
What are central pattern generators?
Spinal circuitry for movement
What is the purpose of studying central pattern generators?
Recover function after paralysis
Where do the most complex movements originate?
Input from the brain
What is the role of higher brain regions?
Initiate motion and coordinate movement
What brain area is essential for voluntary movement?
Motor cortex
What do neurons in the motor cortex control?
Activation of alpha motor neurons
What is the role of neurons controlling functionally related muscles?
Finely tuned motor skills
What can other motor cortex neurons direct?
Coordinated limb movement
Which regions modulate voluntary movement?
Basal ganglia, thalamus, cerebellum
What does the motor cortex work with?
Other brain regions
What do these brain regions influence?
Motor neurons in spinal cord
What is the role of the basal ganglia?
Monitor and adjust motor performance
What disease is associated with degeneration of neurons in the substantia nigra?
Parkinson’s disease
What neurotransmitter is involved in motor control affected in Parkinson’s?
Dopamine
What are the hallmark symptoms of Parkinson’s disease?
Tremor, rigidity, akinesia
What symptoms do individuals with Huntington’s disease display?
Uncontrolled jerking movements
What causes symptoms in Huntington’s disease?
Loss of inhibitory neurons
Which brain region is crucial for coordinating movement?
Cerebellum
What does the cerebellum receive input from?
Sensory receptors and cortex
What role do neurons in the cerebellum play?
Integrate sensory information
What does the cerebellum enable?
Fluid movements
What happens with cerebellar dysfunction?
Poor coordination
What is a common cause of acquired cerebellar degeneration?
Long-term alcohol abuse
What are typical symptoms of acquired cerebellar degeneration?
Poor coordination, unsteady walk
How does the cerebellum assist in physical tasks?
Adapts to the unexpected
What role does the cerebellum play in motor learning?
Refines motor programs
How does the cerebellum help with movement changes?
Recalibrates movements
What tasks does the cerebellum assist with?
Walking, speaking, music
