Muscle

Active tissue is secondary in the functional hierarchy because it acts under regulation from the nervous system. Muscle mass index is presented as a stronger longevity predictor than body weight or BMI. Muscle is the primary active tissue, capable of changing shape and performing action in the body. Muscle is described as a metabolic organ that absorbs glucose, stores energy, releases myokines, and provides amino acids during stress. Inadequate protein during a compressed eating window can create negative protein balance and accelerate sarcopenia. Muscle is involved in all forms of movement and mechanical regulation, including limb movement, heartbeat, and blood pressure changes through vessel wall constriction.