Stimulation of muscle contraction

Stimulation of muscle contraction - 2. Action potential is...

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Stimulation of muscle contraction Neurons, or nerve cells, are stimulated when the polarity across their plasma membrane changes. The polarity change, called an action potential, travels along the neuron until it reaches the end of the neuron. A gap called a synapse or synaptic cleft separates the neuron from a muscle cell or another neuron. If a neuron stimulates a muscle, then the neuron is a motor neuron, and its specialized synapse is called a neuromuscular junction. Muscle contraction is stimulated through the following steps: 1. Action potential generates release of acetylcholine. When an action potential of a neuron reaches the neuromuscular junction, the neuron secretes the neurotransmitter acetylcholine (Ach), which diffuses across the synaptic cleft.
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Unformatted text preview: 2. Action potential is generated on the motor end plate and throughout the T tubules. Receptors on the motor end plate, a highly folded region of the sarcolemma, initiate an action potential. The action potential travels along the sarcolemma throughout the transverse system of tubules. 3. Sarcoplasmic reticulum releases Ca 2+ . As a result of the action potential throughout the transverse system of tubules, the sarcoplasmic reticulum releases Ca 2+ . 4. Myosin cross bridges form. The Ca 2+ released by the sarcoplasmic reticulum binds to troponin molecules on the actin helix, prompting tropomyosin molecules to expose binding sites for myosin cross-bridge formation. If ATP is available, muscle contraction begins....
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This note was uploaded on 12/04/2011 for the course ANTHRO 2000 taught by Professor Monicaoyola during the Fall '10 term at Broward College.

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Stimulation of muscle contraction - 2. Action potential is...

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