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Ch. 6 Muscles
| Question | Answer |
|---|---|
| Ability of skeletal muscle to shorten with force | contractility |
| Capacity of skeletal muscle to respond to a stimulus | excitability |
| The ability to be stretched | elasticity |
| Skeletal muscle is surrounded by this connective tissue sheath | epimysium |
| Connective tissue located outside the epimysium that surrounds and separates muscles | fascia |
| Loose connective tissue that surrounds the visible bundles in muscle | perimysium |
| Visible bundles in muscle | fasciculi |
| Single muscle cells | fibers |
| Each fiber is surrounded by a connective tissue sheath called this | endomysium |
| Cytoplasm of each fiber is filled with this | myofibrils |
| 2 major protein fibers | actin & myosin |
| Actin | thin |
| Myosin | thick |
| Actin and myosin myofilaments form highly ordered units called | sarcomeres |
| Sarcomeres join together to form the | Myofibril |
| Basic structural and functional unity of the muscle | sarcomere |
| Each sarcomere extends from what to what? | Z line to Z line |
| Zline | actin |
| What gives the "banded" appearance? | the arrangement of actin and myosin |
| Space on each side of the Z line | i band |
| i band | actin, light |
| extends the length of the myosin | A band |
| A band | Dark, myosin |
| H zone | located in the center of each sarcomere, light area |
| M line | Myosin myofilaments are anchored in the center of the sarcomere at the m line |
| Charge difference across the membrane | resting membrane potential |
| Brief reversal back of the charge | action potential |
| Nerve cells that carry action potentials to skeletal muscle fibers | motor neurons |
| Each branch that connects to the muscle forms a | neuromuscular junction or synapse |
| Single motor neuron and all the skeletal muscle fibers it innervates are called | motor unit |
| many of these form a single muscle | motor unit |
| formed by a enlarged nerve terminal resting in an indentation of the muscle cell membrane | neuromuscular junction |
| presynaptic terminal | enlarged nerve terminal |
| space between the the presynaptic terminal and the muscle cell | synaptic cleft |
| muscle fiber | postsynaptic terminal |
| each presynaptic terminal contains | synaptic vesicles |
| synaptic vesicles secrete this neurotransmitter | acetylcholine |
| breaks down acetylcholine | acetylcholinesterase |
| muscle contraction occurs when... | actin and myosin myofilaments slide past one another causing the sarcomeres to shorten |
| when sarcomeres shorten it... | causes the muscle to shorten |
| sliding of actin myofilaments past myosin myofilaments during contractions | sliding filament mechanism |
| sliding filament mechanism | h & I bands shorten. |
| muscle twitch | contraction of an entire muscle |
| threshold | level that a muscle fiber will respond to a stimulus |
| this is called the all or none affect | threshold |
| lag phase | time between application and occurrence of a contraction |
| contraction phase | actual time of contraction |
| relaxation phase | time of relaxation between contractions |
| tetany | muscle remains contracted without relaxing |
| recruitment | increase in number of motor units being activated |
| atp | energy needed for muscle contractions |
| atp | produced in the mitochondria |
| atp | shortlived and unstable |
| atp | cannot be stockpiled |
| ADP | adenosine diphosphate |
| creatine phosphate | can be stored |
| anaerobic respiration | without oxygen |
| aerobic respiration | with oxygen |
| which is more efficient | aerobic |
| oxygen debt | amount of oxygen needed to replenish |
| muscle fatigue | atp is used faster than it can be made |
| isometric | length does not change |
| isotonic | length of muscle changes |
| muscle tone | constant tension |
| fast twitch | wears down easily |
| slow twitch | can go for a long time |
| origin | head |
| insertion | end of the muscle undergoing the greatest movement |
| belly | portion of the muscle between the origin and the insertion |
| some muscles have multiple origins or head | true |
| synergists | muscles that work together to complete a specific task |
| antagonists | muscles that work against eachother |
| prime mover | main muscle used in any one specific movement |
| most muscles have names that are descriptive | true |
| dark bands | A bands |