PNB 2264 Lecture Notes - Lecture 5: Voltage-Dependent Calcium Channel, Acetylcholine Receptor, Myocyte
23 Jan 2017
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Tutorial 1
https://quizlet.com/8314385/lab5-emg-pnb2264-flash-cards/
● Skeletal Muscles Anatomy
○ Contractions responsible for supporting and moving the skeleton
○ Each muscle is made up of many individual fibers also known as muscle
cells
■ Organized in bundles called fascicles
○ Each individual muscle fiber is innervated by a branch of a motor
neuron axon
● Motor Unit
○ When action potential is generated by a motor neuron, it innervates the
muscle fibers
○ Motor unit: one motor neuron and all the individual muscle fibers that it
innervates
● The Neuromuscular Junction
○ Action potential propagates axon
○ Voltage gated Ca2+ channels activate
■ Calcium influx
○ ACh released
■ Binds to receptors
○ Ach binds binds nicotinic cholinergic receptor, opening a non specific
monovalent cation (+) channel
■ Open non specific
■ Sodium = in (MORE) → ++
■ Potassium = out
■ DEPOLARIZE
○ Voltage gated Na+ channels open
○ End plate potential (EPP)
■ Can record using EMG
● Electromyogram (EMG)
○ A technique to record electrical signals from muscle fiber during muscle
contraction
■ NOT contractile force of the muscles
○ Electroactivity of muscles
○ EMG Subtypes
■ Intramuscular - electrodes inserted into muscles
■ Surface - electrodes placed on skin surface
● Experiments to be conducted
○ Measure forces changes with increasing demand
○ Reciprocal activation
find more resources at oneclass.com
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Document Summary
Contractions responsible for supporting and moving the skeleton. Each muscle is made up of many individual fibers also known as muscle cells. Each individual muscle fiber is innervated by a branch of a motor neuron axon. When action potential is generated by a motor neuron, it innervates the muscle fibers. Motor unit: one motor neuron and all the individual muscle fibers that it innervates. Ach binds binds nicotinic cholinergic receptor, opening a non specific monovalent cation (+) channel. A technique to record electrical signals from muscle fiber during muscle contraction. Surface - electrodes placed on skin surface. Notice the phenomena of coactivation (active potential depend on nature ex: speed) Bot agonist and antagonist to hold stable position. Size and shape of emg wave provide info on ability of the muscles to respond when the nerves are stimulated. Can be used together with a nerve conduction study to detect neuropathies and myopathies and many others.
