Short answers, pulled from the story.
Skeletal muscle comprises approximately 35 percent of the human body by weight. This tissue contains more than 600 distinct muscles in a healthy adult and functions as the most metabolically active tissue in the body.
Skeletal muscle acts as a complex endocrine organ that secretes hundreds of signaling molecules to regulate the health of distant organs. Subsets of 654 different proteins, lipids, amino acids, and small RNAs are found in the secretome of skeletal muscles to mediate the health benefits of exercise.
Muscle contraction occurs through excitation-contraction coupling involving the interaction of actin and myosin filaments within the sarcomere. A motor neuron releases acetylcholine to trigger depolarization, which releases calcium ions that allow myosin heads to pull actin filaments and shorten the sarcomere.
The strongest human muscle by weight is often considered the masseter or jaw muscle, which can exert a bite force of 200 pounds. The myometrial layer of the uterus may be the strongest muscle by weight in the female body, exerting 100 to 400 Newtons of force during childbirth.
Satellite cells are normally quiescent cells that can be activated by exercise or pathology to provide additional myonuclei for muscle growth or repair. These cells migrate to appropriate locations during development and fuse to form elongated, multinucleated cells.