What is a motor unit?
There are two components that make up a motor unit and you need to know both of these ready for your level 2 anatomy exam. In short, a motor unit is a motor neuron and all the muscle fibres that it innervates.
Let’s look at the motor neuron first.
What is a Motor Unit? Component 1: Motor Neuron
We have two different types of neurons in our body. The first one is the sensory neuron. This neuron carries information from our senses up to our central nervous system.
The second neuron carries information from the central nervous system to the muscles. It’s this neuron that we are focusing on today!
Let’s start exploring.
The second component of the motor unit is the muscle fibre.
What is a Motor Unit? Component 2: Muscle Fibre
There are a couple of differences between a muscle fibre, myofilament and a muscle belly. You’ll need to know these for your level 2 anatomy exam.
To help with these differences, watch this video as well. In this video you’ll learn everything about the muscle structure and anatomy.
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Muscle fibres can only switch on or off, there are no half measures. And for that reason, it’s called the, “all or none law,” when we’re talking about muscle contraction. As a result, there is only one variable that will change the intensity of muscle contraction. We need to engage and recruit more motor units, not more muscle fibres.
So, if you imagine or remember back to a time when you had to lift up a heavy box but you thought it was quite light. So, you think it’s a light box, you go up to it, you go to pick it up and you can’t lift it, it doesn’t move.
The reason for this is that you’ve recruited enough motor units to be able to lift what you deemed as a light box. When you try again, you can actually lift it because at that point, you’ve recruited enough motor units.
To recap, the motor unit is the motor neuron and all the muscle fibres that it innervates.
Together, the motor unit causes a muscle contraction.
Now you know everything there is to know about motor units ready for your level 2 anatomy exam.
Question: Are you prepared for your level 2 anatomy exam?
and would you know how to answer the questions?
To help, download the 88 mock questions. These will help you prepare for your level 2 anatomy and Physiology exam.
All you need to do is click the link below:
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