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Cards In This Set
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Motor unit
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A motor neuron and the muscle fibers it connects with
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Relationship between the ventral horn and motor unit
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They originate in the ventral horn of the spinal cord
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Pyramidal neuron relationship with motor neurons
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Signals are sent down the pyramidal neurons coming from the primary cortex
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What is activated when voluntary control is activated
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Primary motor cortex
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1st 4 steps of neuromuscular junction
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1. voltage-gated calcium channels open and calcium enters the cytosol 2. Ca triggers the release by exocytosis of acetylchoine 3. Acetylcholine diffuses and binds to nicotinic, cholinergic receptors at motor end plate, Na enters the cell 4. Na produces an end plate potential that generates current throughout skeletal muscle cell
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2nd 4 steps of neuromuscular junction
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5. cell depolarizes membrane generates action potential 6. Action potential spreads along the skeletal muscle, acetylcholinesterase degrades acetylcholine to produce acetate and choline 7. choline is actively transported into the terminal 8. synthesize more ACh
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What is end plate potential similar to?
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Excitatory post synaptic potential
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Difference between end plate potential and excitatory post synaptic potential
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End plate potentials are normally of great magnitude to depolarize the muscle fiber to threshold-generates action potential
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Process of excitation-contraction coupling
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Action potential propagates through entire sarcolemma and travels thru T tubules. T tubules release Ca from nearby sarcoplasmic reticulus which serves as the signal that initiates the cross bridge cycle and contraction of the muscle
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Structural organization of whole muscle
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Myofibrils are composed of a fundamental unit called sarcomere which repeats over and over
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Each sarcomere is bordered on either end by what
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Z line
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What does a Z line do?
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Which run perpendicular to long axis and anchor the thin filaments at one end
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What connects thick filaments in a sarcomere
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M line
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What is the A band
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Region that is darkes under microscope-whole length of thick filaments.
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H zone
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Region in the center of the A band that appears noticeably lighter
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