| A | B |
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| The cell membrane of a skeletal muscle fiber is called the __________. | sarcolemma |
| The sarcoplasmic reticulum of a muscle fiber forms dilated sacs which are called _______ _________ and store calcium. | terminal cisternae |
| Tropomyosin molecules block the binding sites located on the _____ filaments. | actin |
| The functional contractile unit of a muscle fiber is called the _________. | sarcomere |
| Each motor neuron and all of the muscle fibers it innervates is collectively called a _____ ____. | motor unit |
| The ___ band is bisected by a Z disc and appears as the light region of the striations on a muscle fiber. | I |
| The ratio of muscle fibers per neuron varies depending upon the need for strength or ____ _______. | fine control |
| Large motor units which contain many muscle fibers per motor neuron are designed for ________. | strength |
| The functional connection between a nerve fiber and a muscle fiber is called a ____________. | synapse (or neuromuscular junction) |
| The depression on the muscle fiber which communicates with a neuron is called the _____ ___ _____. | motor end plate |
| The difference in electrical charge between the inside and the outside of a resting muscle cell is called the resting ________ _________. | membrane potential |
| During muscle contraction, calcium ions released into the sarcoplasm bind to ________. | troponin |
| The minimum voltage necessary to produce a contraction is called the _________. | threshold |
| A rapid series of stimuli do not allow muscle fibers to relax, and consequently produce the smooth, prolonged contractions of everyday activities called _______. | tetanus |
| ________ muscle contraction increases tension without changing muscle length. | Isometric |
| When muscle tension overcomes resistance, for example when your arm lifts a book, it is called ________ contraction. | isotonic |
| _________ is an enzyme that uses 2 ADP to produce 1 ATP. | Myokinase |
| When a muscle can no longer contract, in spite of continued stimulation, this is called _______. | fatigue |
| Once the phosphagen system is exhausted, the muscles use _________ ____________ to produce ATP for short-term energy of 30 - 40 seconds maximum activity. | anaerobic fermentation |
| Dark meat is composed mostly of ____ twitch fibers. | slow |
| Resistance training such as weight lifting, stimulates muscle growth due to ___________ __ ________ __ ____ ____ | hypertrophy or increase in cell size |
| Name two factors that affect the strength of muscle contraction. | Recruitment - number of muscle fibers stimulated; Frequency of stimulation (twitch, treppe, summation, tetanus) |
| Describe three characteristics of fast twitch fibers. | Adapted for anaerobic respiration; Few mitochondria, little myoglobin - white meat; Fatigues easily |
| Describe three characteristics of slow twitch fibers | Adapted to aerobic respiration; Many mitochondria, lots of myoglobin - dark meat; Resistant to fatigue |
| Name two ways that shortened or contracted sarcomeres are returned to their original resting length. | Series-elastic components stretch muscle; Contraction of antagonistic muscle |
