Lesson 20 - Muscle Activation through a NEURON

In LESSON 19, we talked about myosin and actin. Now we will talk about the neuron activating the muscle cell.

    Ok. We will start off with a neuron. Neurons usually communicate with another neuron, but in this scenario, we will be talking about a motor neuron. A motor neuron activates muscle cells and causes muscle contraction.

http://bcrc.bio.umass.edu/courses/spring2009/biol/biol101section2/review/20090306/TTubeSarcoRetic.GIF

    Ok. Let's continue.
    1. The first step in this occurs when a action potential (signal) travels down the motor neuron and to the synapse.
    2. Then sodium is released near the synapse. The sodium binds to the neurotransmitters (chemical signals that are used in communication) which then cross the synaptic cleft.
    3. The sodium then triggers another action potential in the muscle cell.
    4. The sodium goes through voltage channels (channels that allow ions to pass through based on the state of voltage) and then they enter also through the T-tubules.
    5. Then a protein complex which is made up of proteins like triadin and calsequestrin is activated by the sodium entering the cell and then activates the sarcoplasmic reticulum.
    6. Inside the sarcoplasmic reticulum in a resting muscle cell, there is a lot of calcium on the inside of the cell. But during muscle contraction calcium is diffuses out of the sarcoplasmic reticulum. So this protein complex activates the calcium ions and causes them to diffuse out.
    7. This calcium goes to bind with the troponin protein which we talked about in Lesson 19.

I HOPE YOU NOW KNOW MORE ABOUT
YOUR MUSCLES THAN BEFORE.

Thanks for reading this post!