Muscles

Front 1

Skeletal Muscle

Back 1

Responsible for voluntary movement and is therefore innervated by somatic nervous system.

Front 2

Red Fibers

Back 2

Slow-twitch fibers of skeletal muscle that have high myoglobin content and derive energy aerobically, and lots of mitochondria.

Front 3

White Fibers

Back 3

Fast-twitch fibers that contain much less myoglobin.

Front 4

Smooth Muscle

Back 4

Responsible for involuntary actions, controlled by autonomic nervous system. Can contract without nervous input (myogenic activity).

Front 5

Tonus

Back 5

Sustained state of low-level contraction (such as in blood vessels) of smooth muscles.

Front 6

Cardiac Muscle

Back 6

Primarily uninucleated, involuntary, striated. Connected by intercalated discs with many gap junctions connecting cytoplasm of adjacent cells.

Front 7

Myofibrils

Back 7

Sarcomeres laid end to end, and surrounded by a covering called the sarcoplasmic reticulum (modified ER with high Ca+2 concentration).

Front 8

Sarcoplasm

Back 8

Modified cytoplasm located just outside the sarcoplasmic reticulum.

Front 9

Sarcolemma

Back 9

Cell membrane of a myocyte/muscle cell. Capable of propagating an action potential via transverse (T) tubules.

Front 10

Myocyte

Back 10

Muscle cells. Contain many myofibrils arranged in parallel in a muscle fiber. Polynucleated.

Front 11

Latent Period

Back 11

Time between reaching threshold and onset of contraction. During this time, action potential spreads along muscle and allows for calcium to be released from sarcoplasmic reticulum.

Front 12

Frequency Summation

Back 12

When muscle fiber is exposed to frequent and prolonged stimulation with insufficient time to relax, contractions will combine, become stronger, and more prolonged.

Front 13

Oxygen Debt

Back 13

Difference between amount of oxygen needed, and actual amount present.