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Biol 207 Lab Final Questions And Answers Latest Update
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Biol 207 Lab Final Questions And Answers Latest Update
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2024/2025Biol 207 Lab Final Questions And
Answers Latest Update
Intrafusal fibers (IFs) ANS✔✔ muscle spindle fibers
Sensory neurons: fire if intrafusal fibers stretch ANS✔✔ send message to gamma and alpha motor
neurons in CNS
Gamma motor neuron: ANS✔✔ causes IFs to tighten...↑ spindle sensitivity
Extrafusal fibers (EFs): ANS✔✔ normal muscle fibers outside of spindle responsible for
contraction
Alpha motor neuron: ANS✔✔ stimulates contraction of
EFs
agonist ANS✔✔ primary mover; should be contracted
antagonist ANS✔✔ opposes mover; should be relaxed
Load-Recruitment Relationship ANS✔✔ -Recruitment: ↑ in the # of motor units that are activated
-If ↑ load -> need to ↑ the force of contraction
-More and larger motor units are recruited within the muscle
Contraction of individual muscle fibers ANS✔✔ all or none
Contraction of entire muscle can vary ANS✔✔ graded contraction
, 2024/2025
Each muscle fiber is controlled by.... ANS✔✔ a single axon from a somatic motor neuron
Each motor neuron usually controls.... ANS✔✔ multiple muscle fibers
Tetanus ANS✔✔ smooth, sustained muscle contraction
•Fatigue ANS✔✔ decline in muscle's ability to maintain force after prolonged stimulation
•At threshold, as stimulus frequency.... ANS✔✔ increases, summation occurs until tetanus is
reached
•Summation ANS✔✔ 2nd twitch builds on previous twitch due to the delivery of a 2nd pulse of
stimulation right after 1st pulse of stimulation
•Twitch ANS✔✔ single short contraction due to single pulse of stimulation
muscle contraction ANS✔✔ Ca2+ binds troponin -> shape change causes tropomyosin to shift out
of the way-> Myosin head binds actin
->Power stroke...sarcomere contracts!
beginning of muscle contraction ANS✔✔ Action potential travels down motor neuron axon->
Acetylcholine released-> muscle depolarizes-> at threshold VG Ca2+ channels in plasma
membrane open -> Ca2+ release channels in sarcoplasmic reticulum open
Muscle Fibers ANS✔✔ Contain bundles of protein filaments called myofibril
•Sliding filament model ANS✔✔ actin and myosin filaments DO NOT shorten, but instead slide
past each other during contraction
Tendons ANS✔✔ attach bone to muscle
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