University:
Kentucky State University
Course:
BIO 303 | Human Physiology
Academic year:

2023
Views:

185

Pages:

12
Author:

palangresq3v

MUSCLE PHYSIOLOGY Classification of muscle Muscle Type Voluntary/Involuntary Striated/Non-Striated Location Skeletal Voluntary Striated Limbs Cardiac Involuntary Striated Heart Smooth Involuntary Non-striated Viscera Note: Striated refers to the appearance of the muscle tissue under a microscope. It is characterized by alternating light and dark bands. human figure with highlighted muscle groups skeletal muscle cell cardiac muscle cell smooth muscle cell • There are three kinds of muscle tissue: skeletal, cardiac, and smooth. • These three kinds of muscle tissue compose about 50 percent of a human's body weight. • Skeletal muscle tissue is striated and subject to voluntary control. • The skeletal muscles are innervated by the somatic nervous system. Skeletal muscle fibers A muscle fiber is a skeletal muscle cell. • It is large, elongated, and cylinder-shaped. • The fibers extend the entire length of a skeletal muscle. Muscle fiber and its sub structure responsible for Contraction Action potentials arrive to terminal it release acetylcholine that bind to its receptor then it open cation channel (Na) depolarization & excitation Then it arrive to t tubules that trigger lateral sac of sacroplasmic reticulum which release Ca troponin to slip tropomyosin Exit of Ca from lateral sac Passive Move it back active • Relaxation of a skeletal muscle depends on the reuptake of calcium ions, from the cytosol into the SR. • With the absence of calcium, troponin and tropomyosin can resume their blocking role. • However, calcium can be released again from the SR into the cytosol if a somatic efferent neuron signals the muscle cell with another action potential. (If ATP and metabolise fatigue • A muscle fiber contains contractile elements called myofibrils . A myofibril contains thick filaments called myosin and thin filaments called actin. • Actin and myosin are arranged in units called sarcomeres. A sarcomere is found between two Z lines. Thin Myofibrils Thick The sarcomere • The sarcomere is the functional unit of the muscle Its regions are: • A band - myosin (thick) filaments stacked along with parts of the actin (thin) filaments. • H zone - middle of the A band where actin does not reach. • M line - extends vertically down the center of the A band. • I band - part of actin that do not project into A band.