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Chapter 6: Muscles
| Question | Answer |
|---|---|
| contractility | ability to shorten with force |
| Excitability | responding to stimulus |
| extensibility | ability to be stretched |
| elasticity | ability to recoil |
| epimysium | connective tissue that surrounds skeletal muscle |
| fascia | tissue surrounds & separates muscles |
| perimysium | surrounds muscle fascicle |
| endomysium | covers muscle fibers |
| muscle cells | muscle fibers |
| myofibrils | thread like structure |
| actin myofilaments | thin myofilaments |
| myosin myofilaments | thick myofilaments |
| sacromere | basic structural & functional unit of muscles |
| Z line | attachment site for actin |
| I band | light side of the Z line |
| A band | darker central region, filled with myosin. |
| H zone | center of each sacromere |
| M line | dark staining band |
| Resting Membrane Potential | charge difference across the membrane |
| Action Potential | reversal of a charge. |
| Motor Neurons | nerve cells that carry action potentials to skeletal muscle fibers. |
| Neuromusclular junction/ Synapse | formed when branches connect to muscle, near center of cell. |
| Motor Unit | Single motor neuron & all skeletal muscle fibers operating |
| Presynaptic Terminal | Enlarged nerve terminal |
| Synaptic Cleft | space between the presynaptic terminal & the muscle cell. |
| Postsynaptic Terminal | muscle fiber |
| Synaptic Vesicles | secrete a neurotransmitter called acetylcholine |
| Acetylcholine | Binds to the postsynaptic terminal causing a in postsynaptic cell. |
| Acetylcholinesterase | Enzyme that breaks down muscle cells |
| Muscle contraction | When the sarcomere shortens, it cause the muscle to shorten. |
| Sliding Filament Mechanism | When actin and myosin myofilaments glide past one another. |
| Muscle twitch | contraction of a muscle ins response to s stimulus |
| Threshold | when the muscle fiber will contract maximally. |
| Lag phase | time between response to a stimulus & actual contraction |
| Contraction phase | the time of contraction |
| Relaxation Phase | the time when muscle relaxes fully |
| Tetany | where the muscle remains contraction without relaxing. |
| Recruitment | increase in number of motor units being activated |
| Adenosine Triphosphate (ATP) | is needed for energy to contract muscles |
| Creatine Phosphate | high-energy molecule, used to replace ATP |
| Anareobic Respiration | without oxygen |
| Aerobic Respiration | with oxygen |
| Oxygen Debt | amount of oxygen needed to replenish the depleted store of CP stores in muscle cells |
| Muscle Fatigue | results when you use more muscle cells faster than you can reproduce. |
| 2 types of muscle contractions | isometric & isotonic |
| Isometric | when length doesn't change but the tension increases. |
| Isotonic | tension doesn't change, but length does. |
| Muscle Tone | constant tension produced by muscles of the body for long periods of time. |
| Fast-Twitch Fibers | Contract quickly & fatigue quickly |
| Slow-twitch Fibers | contract slowly & are more resistant to fatigue. |
| Muscle is connected to the ____ by the ______. | bone ; tendon |
| Origin (head) | most stationary end of the muscle |
| Insertion | end of muscle undergoing most movement |
| Belly | portion of muscle between the origin & insertion |
| Some muscles have multiple _____. | origins |
| Synergists | muscles that work together to accomplish a specific movement |
| Antagonists | muscles that work in opposition to each other. |
| Prime mover | In a group of synergists, one muscle that plays the major role |
| Muscles help produce ____ essential for maintenance of body temperature. | heat |
| Muscle fasciculi (fascicle) | numerous visible bundles |
| Muscle fibers | single cylindrical cell containing several nuclei |
| 2 major kinds of protein fibers | actin & myosin |