Describe the events that occur at the neuromuscular junction. (mechanism of action of neuromuscular junction)
Here are a number of sites that have information on that.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=mechanism+of+action+of+neuromuscular+junction&btnG=Google+Search
look over it, it not provide much information
The neuromuscular junction is a specialized synapse connecting a motor neuron to skeletal muscle fibers. Let's break down the events that occur at the neuromuscular junction:
1. Arrival of Action Potential: When an action potential reaches the end of the motor neuron, it triggers the release of a neurotransmitter called acetylcholine (ACh) from small vesicles within the neuron terminal.
2. Binding to Receptors: Acetylcholine molecules diffuse across the synaptic cleft and bind to specific receptors located on the motor end plate, which is a specialized region on the muscle fiber membrane.
3. Generation of Muscle Action Potential: The binding of acetylcholine to its receptors initiates a series of events that leads to the generation of a muscle action potential. This occurs as the receptors open channels in the muscle fiber membrane, allowing an influx of positively charged ions such as sodium (Na+), which results in depolarization of the muscle fiber.
4. Release of Calcium: The depolarization of the muscle fiber membrane triggers the opening of voltage-gated calcium channels located on the membrane of the muscle fiber's sarcoplasmic reticulum (a calcium reservoir within the muscle fiber). Calcium ions (Ca2+) rapidly diffuse into the sarcoplasm (cytoplasm of the muscle fiber).
5. Contraction of Muscle Fiber: The increased concentration of calcium ions in the sarcoplasm enables the interaction between actin and myosin, the two proteins responsible for muscle contraction. This process leads to the sliding of actin and myosin filaments and ultimately the shortening (contraction) of the muscle fiber.
6. Termination of Neurotransmission: After acetylcholine has fulfilled its role, it needs to be rapidly removed from the synaptic cleft to terminate muscle fiber stimulation. The enzyme acetylcholinesterase breaks down acetylcholine into acetic acid and choline. The choline is then taken up by the motor neuron to form new acetylcholine molecules.
In summary, the mechanism of action at the neuromuscular junction involves the release of acetylcholine, its binding to receptors on the muscle fiber, the generation of a muscle action potential, the release of calcium ions, the contraction of the muscle fiber, and the termination of neurotransmission through the breakdown of acetylcholine by acetylcholinesterase.