Final answer:
The Golgi Tendon Organ is the mechanoreceptor responsible for sensing changes in muscle tension and initiating relaxation to prevent damage.
Step-by-step explanation:
The mechanoreceptor that is sensitive to changes in muscular tension and the rate of that tension change, causing the muscle to relax and preventing excessive stress and possible injury, is the Golgi Tendon Organ.
These sensory receptors are critical for proprioception, translating mechanical stimulus into nerve impulses that communicate to the brain about the level of tension in the muscles and tendons.
When the Golgi tendon organs sense a high level of tension, they initiate a reflex that leads to muscle relaxation, safeguarding the muscle from potential damage.