Briefly explain hypertrophy and atrophy.

Explanation

Hypertrophy : Increase in the size of muscles is called hypertrophy . Increase in the size of muscle may occur due to exercise. Due to repeated and forcefule contraction of muscles, mass of muscle increases. Increase in number of mitochondria, filaments in sarcoments and amount of sarcoplasm increases : mass of muscle with hypertrophy which also increases strength.
Atrophy : Decrease in the size of muscle is called atrophy. Atrophy is due to immobilization of muscles. Mass of muscles decreases due to decrease in number of mitochondria, filaments in sarcomeres and amount of sarcoplasm. An injury to a nerve which supplies a muscle can cause atrophy.