What Happens When You Stretch?

3/14/16

What Happens When You Stretch

(when you don't see the hw correctly because there's a glare on the board so your submission is a day late :( )

• "When you stretch, the muscle fiber is pulled out to its full length sarcomere by sarcomere, and then the connective tissue takes up the remaining slack"

When I stretch I never though about how the muscle lengthens, I always assumed stretching happened as an entire aunt rather than on a microscopic level. I also never knew that connective tissues worked as part of stretching, but now that I think of it I remember some times where that could of happened.

• "the golgi tendon organ records the change in tension...when this tension exceeds a certain threshold, it triggers the lengthening reaction which inhibits the muscles from contracting and causes them to relax"

I never knew about the golgi tendon of the proprioceptors that send signals of our movements, but its interesting how our muscles are triggered to relax into a stretch, I've always wondered how the muscles knew not to recontract.

• "Proprioceptors are the source of all proprioception: the perception of one's own body position and movement"

I can't believe that our bodies are so complex but I guess it makes us the functioning people we are now. I wonder how the proprioceptors know all this info through just the nervous system.

Relate and Review:

     Stretching is the lengthening of all the individual sarcomeres. It starts with a signal from the proprioceptor that tracks basically all our movement. Intrafusal muscle fibers and extrafusal muscle fibers are 2 types of muscle fibers and golgi tendon organs are near the end of the muscle fiber are responsible for determining which part of the muscle stretches first (middle then outer). Golgi tendon transfers other info like tension to trigger the lengthening reaction which stops muscles from contracting and causes them to relax. Golgi's main function is to protect the muscles, tendons, and ligaments from injury. The opposing motion of the agonist vs. antagonist is called reciprocal inhibition as antagonists are inhibited from contracting. The proprioceptors record the change of length which triggers the stretch reflex which attempts to resist change in muscle length by causing muscles to contract. This is why holding a stretch is very important.