lecture_notes_15_(ta) - Lecture 15: Muscle Physiology...

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Lecture 15: Muscle Physiology Reading: chapter 8, section: skeletal muscle, pgs 253-259 (pgs 257-263, if using 5 th edition) (TA N OTES IN R ED ) Types of Muscle (3 types) ( MUSCLES APPROACH 1//2 OF OUR BODY WEIGHT , MOSTLY SKELETAL MUSCLES ) ( MUSCLE CELLS ( FIBERS ) ARE 10-100 MICRONS WIDE AND UP TO 2.5 FEET IN LENGTH ) skeletal muscle – striated ( B ANDING , OR STRIPED ) , voluntary cardiac muscle – striated, involuntary ( ABOUT 10% OF OUR BODY WEIGHT ) smooth muscle – unstriated, involuntary ( EXAMPLE : DIGESTIVE ) ( F OUR ROLES OF MUSCLES : PURPOSFUL MOVEMENT , MANIPULATION OF OBJECTS , PROPULSION OF OBJECTS THROUGH THE BODY , AND EMPTYING CONTENTS OF CERTAIN ORGANS ) Skeletal Muscle Neuromuscular Junction, sequence of events: 1) Action potential propagates into the presynaptic terminal 2) Depolarization of the presynaptic terminal opens voltage-gated Ca++ channels 3) Ca++ ions trigger vesicles of Ach to fuse with the plasma membrane 4) ACh diffuses across the synaptic cleft and binds with receptors in the motor endplate 5) ACh binding with the receptor leads to the opening of cation channels. Na++ enters and depolarizes the end plate (EPP) 6) Depolarizing current flows to adjacent membrane that contains voltage-gated Na++ channels (action potential)
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This note was uploaded on 05/02/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.

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lecture_notes_15_(ta) - Lecture 15: Muscle Physiology...

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