Muscles are composed of... ✔️✔️- muscle fibers or muscle cells
Muscle cells are made of... ✔️✔️- myofibrils
myofibrils are made of... ✔️✔️- sarcomeres
sarcomeres are made of... ✔️✔️- myofilaments which are thick myosin filaments and thin actin
filaments
- functional units of skeletal muscle
Actin and Myosin ✔️✔️- contractile proteins
- smallest units of contraction with in the muscle fiber
Thick filaments are made of... ✔️✔️- contractile protein, myosin
- reach from one side of A band to the next side of the A band
Thin filaments are made of... ✔️✔️- contractile protein actin
- regulatory proteins, troponin and tropomyosin
myosin heads ✔️✔️- tiny knobs that project from the thick filaments toward the binding sites on the
thin filaments to form cross bridges
Cross Bridges ✔️✔️- join the thick and thin filaments together during contraction
- thin filaments are attached at one end to the z line, the other end of the filament does not reach all the
way across to the A band
, A Band ✔️✔️- lighter in the middle because only thick filaments are present, the H band
H Band ✔️✔️- lighter area in the middle of the A band where only thick filaments are present
I Band ✔️✔️- area of sarcomere that is comprised of only thin filaments
During contraction the thin filaments are... ✔️✔️- pulled closer together, causing the filaments to slide
over each other, shortening the sarcomere
motor unit ✔️✔️- the neuron and the muscle it stimulates
neuromuscular junction ✔️✔️- the space between the nerve endings and the muscle cells
Sliding Filament Theory ✔️✔️- the cross bridges pull on the actin filaments, sliding them closer
together, changing the fibers' position and not length
- results in the shortening of the sarcomere and contraction of the muscle fiber
Relaxation ✔️✔️- reuptake of calcium ions into the SR occurs and the filaments return to their original
position
Twitch ✔️✔️- results from a single action potential
Tetanus ✔️✔️- a strong sustained contraction that occurs when stimuli are delivered so quickly that
no relaxation occurs
Skeletal Muscles are composed of hundreds of muscle cells called... ✔️✔️- fibers
What is the basic unit of contractility in a muscle cell, extending from Z line to Z line? ✔️✔️-
sarcomere