Motor Nervous System Flashcards
excitation-contraction coupling
action potential from a motor neuron (excitation) causes contraction
efferent motor neuron pathway
generation of action potential in the motor neuron, originated at the CNS integration center. Contraction happens when an action potential releases Ach at neuromuscular junction
sliding filament theory
sliding of actin and myosin filaments past them, shortens the sarcomere
reflexes
involuntary muscle contractions, include arc reflex of afferent, integration, and efferent pathways. integration to spinal cord only
contralateral reflex
activated on one side of the body, causes reaction (muscle contraction) on other side of the body
ipsilateral reflex
stimulus and response on the same side of the body
stretch reflex
monosynaptic reflex, involves sensory neuron and motor neuron with only one synapse between them (no interneurons)
withdraw reflex
several interneurons, contraction or flexing of muscles
pupillary light reflex
irises of both eyes constrict when light is shined in only one eye, changes diameter of pupil allowing more/less light into the eye
What causes the opening of sodium ion channels? Step 1
Ach binds to nicotinic receptors on sarcolemma
What alters DHP receptor conformation? Step 2
T-tubules, linked to SR
Where is calcium released? Step 3
Sarcoplasmic reticulum
What does calcium bind to? Step 4
troponin
What does the troponin-Ca2+ complex do? Step 5
pulls tropomyosin away from myosin binding site on actin, exposes binding site
What tightly binds to actin? Step 6
myosin
