Final answer:
The term for the wasting away or lack of development of muscle is atrophy, which includes the reduction of muscle mass due to factors like diseases, aging, and lack of physical activity. Atrophy particularly affects skeletal muscle, with sarcopenia being the age-related form, and can be somewhat mitigated by regular exercise.
Step-by-step explanation:
The term for the wasting away or no development of muscle is atrophy. Muscle atrophy refers to a decrease in muscle mass, which can occur for a variety of reasons, including lack of physical activity, aging, and diseases such as cancer and AIDS. This condition is characterized by a reduction in the size and number of muscle fibers, leading to a decline in muscle strength and function. Atrophy can affect skeletal muscle and is often seen in situations of extended immobilization, like bed rest or space flight, as well as with aging, a process known as sarcopenia.
Regular exercise can mitigate some effects of atrophy by adding structural proteins and causing cellular changes that maintain muscle mass and strength. However, muscle atrophy can have significant impacts on quality of life, contributing to difficulties with locomotion, balance, and posture, increasing the risk of falls and other injuries.