| A | B |
|---|
| which muscles are voluntary? | skeletal |
| myofibrils | hundreds of tiny little threads; contain sarcomeres |
| myofilaments | actin and myosin |
| sarcomere | the functional unit of a muscle |
| what is the role of calcium in skeletal muscle? | calcium binds to troponin and uncovers bindig sites |
| sarcolemma | the membrane that surounds the muscle cell |
| endomysium | covers individual muscle cells; covering becomes the tendon |
| perimysium | surrouns a group of muscle cells |
| epimysium | covers entire muscle cell |
| actin | individual kidney shaped molecules twisted into a helix |
| tropomysium and troponin | long fibrous protein that wraps around actin across the myosin binding sites |
| how are skeletal muscles stimulated to contract? | by a nerve |
| how is the motor endplate depolarized? | sodium enters and depolarizes it |
| what is the purpose of Ach? | allows muscle to become permeable to sodium (like opening a gate) |
| what is the purpose of pyruvic acid? | to generate ATP |
| whathappens when a muscle gets fatigued? | it builds up lactic acid |
| what is muscle tone? | involuntary activation of a small # of motor units, causes sustained,small contractions that give a firmness to a relaxed skeletal muscle |
| what kind of fillament is actin? | thin |
| what kind of fillament is myosin? | thick |
| which muscles are involuntary | cardiac and smooth |
| what is a fascicle? | a bundle of muscle cells; covered in perimyisum |
