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Muscles Ch. 6
| Question | Answer |
|---|---|
| 4 characteristics of muscles? | contractility, excitability, extensibility, elasticity |
| what is an epimysium? | connective tissue sheath surrounding each skeletal muscle |
| myofibrils | threadlike structure that extends from one end of the fiber to the other |
| 2 major kinds of protein fibers | actin myofilaments and myosin myofilaments |
| actin | thin myofilaments |
| myosin | thick myofilaments |
| sacromeres | joined end to end to form the myofibril; formed by actin and myosin; basic structural and functional unit of muscle |
| I band | on each side of the Z line; consists of actin |
| A band | extends the length of the myosin |
| H zone | in the center of each sarcomere. |
| positive and negative charge? | positive- outside of cell membrane. negative- inside of cell membrane |
| resting membrane potential | charge difference across the membrane |
| action potential | brief reversal of back of the charge |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers. |
| synapse (neuromuscular junction) | near center of cell; formed by each branch that connects to the muscle. |
| fascia | connective tissue outside the epimysium |
| perimysium | surrounds fasciculi; is loose connective tissue |
| fibers | single muscle cells that create fasciculi |
| endomysium | connective tissue sheath surrounding each muscle fiber |
| cytoplasm of each fiber | myofibrils |
| resting membrane potential | charge difference across the membrane |
| Action potential | brief reversal of the charge |
| motor nuerons | nerve cells that carry action potentials to skeletal muscle fibers |
| Synapse | near center of cell |
| another word for synapse | neuromuscular junction |
| motor unit | single motor neuron and all skeletal muscle fibers it innervates |
| how is a synapse formed? | an enlarged nerve terminal resting in an indentation of the muscle cell membrane. |
| presynaptic terminal | enlarged nerve terminal |
| synaptic cleft | space between the presynaptic terminal and the muscle cell |
| muscular fiber | postsynaptic terminal |
| what does each presynaptic terminal include? | synaptic vessels |
| synaptic vessels secret a neurotransmitter called what? | acetylcholine |
| what does acetylcholine do? | diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell. |
| acetylcholinesterase | enzyme that breaks down acetylcholine |
| what happens when sarcomeres shorten? | the muscle shortens |
| how does muscle contraction occur? | actin and myosin myofilaments slide past each other |
| sliding filament mechanism | sliding of actin myofilaments past myosin myofilaments during contraction |
| What bands shorten? | H and I |
| What bands stay the same? | A bands |
| Muscle Twitch | contraction of an entire muscle in response to a stimulus |
| tetany | muscle remains contracted without relaxing |
| threshold | a muscle fiber won't contract until it reaches this level |
| all-or-none-response | a muscle fiber won't contract, but when it does, it does maximally |
| lag phase | time between application of the stimulus to a motor neuron and the beginning of a contraction |
| contraction phase | time of contraction |
| relaxation phase | time where muscles relax |
| recruitment | increase in number of motor units being activated |
| ATP is needed for what | needed for energy for muscle contraction |
| where is atp produced? | in the mitochondria |
| What is ADP | adenosine diaphosphate |
| True or False? It is necessary for muscle cells to constantly produce ATP | true |
| creatine phosphate | high-energy molecule stored when at rest |
| Can muscles store ATP at rest | no |
| energy contained in ATP is used to synthesize what? | creatine phosphate |
| anaerobic respiration | without oxygen |
| aerobic respiration | with oxygen |
| anaerobic example | lifting weights |
| aerobic example | swimming |
| oxygen debt | amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells |
| muscle fatigue | when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
| fast-twitch fibers | contract quickly and fatigue quickly |
| slow-twitch fibers | contract more slowly and are more resistant to fatigue |
| origin | most stationary end of muscle |
| insertion | end of muscle undergoing the greatest movement |
| belly | portion of muscle between the origin and the insertion |
| true or false? Some muscles have multiple origins or head | true |
| synergists | muscles that work together to accomplish specific movements |
| anatgonists | muscles that work in opposition to each other |
| prime mover | in a group of synergists, it's one muscle that plays a major role in accomplishing the desired movement |
| how are muscles named? | according to location, size, shape, orientation of fibers, origin, insertion, and function |
| occipitofrontalis | raises eyebrows |
| orbicularis oculi | closes eyelids and causes "crows feet" |
| orbicularis oris | puckers the lips |
| zygomaticus | smiling muscle |
| levator labii superioris | sneering |
| depressor anguli oris | frowning |
| mastication | chewing |
| sternocleidomastoid | lateral neck muscle and prime mover |
Created by:
arnelso8