Somatic Nervous System Flashcards
Skeletal muscle neuron, neurotransmitter, and receptor site
Alpha motor neuron
Acetylcholine
Nicotine
Alpha motor neuron cell body location
CNS, spinal cord
Motor unit definition
One motor neuron and all of the muscle fibers it innervates
Muscle definition
Many motor units together
2 ways the nervous system can increase muscular force
Frequency coding (more during of one motor neuron) Population coding (more motor neurons activated)
Muscle spindles are what type of receptor and where are they located
Stretch
Intrafusal fibers
Intrafusal fibers are innervated by what and where are they located in the fiber
Sensory afferent neurons; middle
Gamma motor neurons; ends at contractile elements
How do muscle spindles respond to stretch
They increase action potentials with stretch
T/F Gama motor neurons and alpha motor neurons do not contact at the same time
False
What happens in accordance to muscle spindles when muscle contracts voluntarily
Both the alpha and gamma motor neurons contract so that the muscle spindle can continue to provide feedback to the CNS regarding the length of the muscle
If there is an unexpected stretch of the muscle, it is sensed by _____ and results in ______. Which muscles relax and contract?
Muscle spindle afferents; reflex CONTRACTION of the alpha motor neuron
contraction of agonist and relaxation of antagonist
Golgi tendon organs are what type of receptor and where are they located
tension
tendon of the muscle
Which causes more activation of the golgi tendon organ: passive stretch or active contraction
active contraction
Cutaneous receptors provide what senses
pain, temperature, pressure, vibration, itch
Knee-jerk Reflex (Myotatic Reflex)
muscle spindle
Inverse Myotatic Reflex
Golgi Tendon Organ
Flexor Withdrawal Reflex
Cutaneous receptors
If there is too much tension of the muscle, it is sensed by ____ and results in ____. Which muscles relax and contrat?
Golgi tendon organs; RELAXATION of the alpha motor neuron
Agonist relaxes, antagonist contracts
Flexor Withdrawal Reflex muscle utilization
reflex contraction of flexor muscles with relaxation of antagonist muscles on side of stimulation.
reflex contraction of extensor muscles with contraction of antagonist muscles on the contralateral side of the stimulation
T/F Interneurons can be either inhibitory or excitatory.
TRUE
Vestibular System sends projections to the brain stem for control of what? What does it detect?
balance and coordination (sense of equilibrium)
position and motion of head in space
What does the Utricle detect?
horizontal head tilt and horizontal acceleration
What does Saccule detect?
vertical head tilt and vertical acceleration
What do Semicircular canals detect?
rotational acceleration
What are the sensory receptors of the vestibular system?
hair cells; kinocilium
Determine activity of hair cell by kinocilium
bending away= depolarize (action potential increases)
bending forward= hyperpolarize
what do the hair cells sit in in the semicircular canals?
cupula
What are the otolithic organs?
utricle and saccule
T/F The utricle and saccule only respond to horizontal and vertical acceleration?
FALSE; they also respond to head tilt- you are going to maintain the effect if you tilt your head and stay there
What are statoconia crystals?
otoliths that move with gravity and cause the hair cells to bend
What does the motor cortex do?
sends projections to the brain stem, spinal interneurons and alpha motor neurons to control movement and to gamma motor neurons to maintain muscle spindle sensitivity (reaching and fine movements)
Sensory information from the motor cortex
to the thalamus, then somatosensory complex
supplemental and premotor areas of the motor cortex are important for __________.
planning and programming movement
Cerebellum participates in:
- planning movement
- controlling posture and equilbrium
- smooth limb movement
Basal ganglia play a role in:
motor, cognitive, and emotional responses
Parkinson’s disease
loss of dopamine (NT) signaling in the basal ganglia
