Anatomy and Physiology in Physical Education

 

   A motor unit (Figure 1) consists of a nerve, and the muscle fibers that it conducts an electrical impulse to. Activation of a motor nerve stimulates muscle fibers to contract, and thereby, causing movement of a body part. This is a simplified illustration as there are many intermediate steps that are not shown.

 

Figure 1: Simplified illustration of a motor unit

 

   A reflex action involves the motor unit and spinal cord (Figure 2). This is an involuntary muscular contraction in that the signal does not travel to the brain, and therefor, is not under your control. This provides for a faster than normal reaction than if you used your brain to control the reflex. When you use your brain to control a reaction, such as when you need to dodge an in-coming projectile, it is referred to as a mechanical reaction, and is not the same as a reflex action.

 

Figure 2: Illustration of an involuntary reflex conduction pathway

 

HOMEWORK QUESTION:

 

1. Identify a real-life scenario that would stimulate the reflex mechanism described above.

 

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