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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 |