intro to muscular system

functions

• produce movement created by contractions

• change position of head, limbs, fingers, etc. and change diameter of heart chambers and blood vessels

• produce heat

• maintain posture

• stabilize joints w/ tendons

fascicles

many muscle fibers arranged together in bundles

fascia

• separates individual muscles

• continues into tendons + aponeuroses

• dense CT

parts of fascia

• endomysium surrounding individual cells

• perimysium surrounding fascicles

• epimysium around entire muscle

parts of a muscle fiber

sarcolemma, sarcoplasm, myofibril, mitochondria (for ATP)

sarcolemma

muscle fiber membrane

sarcoplasm

inner material surrounding fibers

myofibril

• abundant, threadlike structures running parallel in sarcoplasm

• made of myofilaments + responsible for contractions

protein filaments

• actin = thin +light

• myosin = thick + dark

• I and Z lines between each band

sarcomere

• one Z line to another - functional unit of a muscle cell

• lots of sarcomeres make up a myofibril

arrangement of muscle

muscle → fascia → fascicle → muscle fiber → myofibrils → sarcomere → actin/myosin (myofilaments)

sarcoplasmic reticulum

helps control Ca++ concentration

transverse tubules

invaginations (cavity) of sarcolemma that allow for depolarization of the cell’s interior