Muscular Terms

Muscle fibers

basic muscular cell; multinucleate

Fascicles

cluster of muscle fibers

Fascia

thick connective tissue surrounding fascicles

Intercalated disks

junctions between cardiac muscle cells allowing for quick signal transmission

Autonomic nervous system

system that controls involuntary muscle contractions

Hormones

chemicals that can cause smooth muscle contractions

Sarcolemma

Plasma membrane surrounding muscle fibers

Myofibril

contractile muscle fibers made up of actin and myosin

Z-line

transverse structure holding actin filaments in place

Sarcomere

contractile element between z-lines

Myosin filament

long filament comprised of two polypeptide chains with a club-shaped head at both ends

Actin filament

long filament comprised of two helical strands of actin

Tropomyosin and troponin complex

actin-binding proteins; covers myosin-binding sites on actin

Acetylcholine

hormone released from neurons onto sarcolemma

T-tubules

transmitter of depolarisation from sarcolemma to sarcoplasmic reticulum

Sarcoplasmic reticulum

structure surrounding muscle fibers that releases calcium around myofilaments