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muscular system
| Question | Answer |
|---|---|
| What's contractility? | the ability of skeletal muscle to shorten with force |
| What's excitability? | the capacity of skeletal muscle to respond to a stimulus |
| What's extensibility? | the ability to be stretched |
| What's elasticity? | ability to recoil to original resting length after being stretched |
| epimysium | connective tissue sheath that surrounds each skeletal muscle |
| fascia | connective tissue located outside the epimysium, surrounds and separates muscles |
| fasciculi | a muscle composed of numerous visible bundles |
| perimysium | loose connective tissue fasciculi is surrounded by |
| fibers | single muscle cells fasciculi is composed of |
| nuclei | each muscle fiber is a single cylindrical cell that contains nuclei |
| endomysium | connective tissue sheath that surrounds each fiber |
| myofibrils | a threadlike structure that extends from one end of the fiber to the other, the cytoplasm of each fiber is filled with it |
| 2 major protein fibers myofibrils consist of | actin myofilaments and myosin myofilaments |
| actin myofilaments | thin myofilaments, resemble 2 minute strands of pearls twisted together |
| myosin myofilaments | thick myofilaments, resemble bundles of minute golf clubs |
| sarcomeres | highly ordered units formed by actin and myosin myofilaments, they are joined end to end to form the myofibril |
| basic structural and functional unit of the muscle | sarcomeres |
| extends from one z line to another z line | sacromere |
| resting membrane potential | the change difference across the membrane, the outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged |
| action potential | the brief reversal back of the charge, when a muscle cell is stimulated and the membrane characteristics change briefly |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| neuromuscular junction | also called synapse, axons enter the muscles and branch, each branch connects to muscle forms |
| motor unit | a single motor neuron and all the skeletal muscle fibers it innervates, they form a single muscle |
| presynaptic terminal | the enlarged nerve neuromuscular junction is formed by |
| synaptic cleft | the space between the presynaptic terminal and muscle cell |
| postsynaptic terminal | the muscle fiber |
| synaptic vesicles | each presynaptic terminal contains it, it secretes a neurotransmitter |
| acetylcholine | the neurotransmitter |
| what diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell | acetylcholine |
| acetylcholinesterase | the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes, the neuron and muscles cell is rapidly broken down by enzymes |
| sliding filament mechanism | the sliding of actin myofilaments past myosin myofilaments during contraction |
| muscle twitch | a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers |
| threshold | a muscle fiber will not respond to stimulus until that stimulus reaches a level called threshold where the muscle fiber contracts, this is called all or none response |
| lag phase | the time between application of a stimulus to a motor neuron and the beginning of a contraction |
| contraction phase | the time of contraction |
| relaxation phase | the time during which the muscle relaxes |
| tetany | where the muscle remains contracted without relaxing |
| recruitment | the increase in number of motor units being activated |
| ATP | adenosine triphosphate, needed for energy for muscle contraction, produced in the mitochondria, short lived and unstable |
| ADP | adenosine diphosphate, plus phosphate, necessary for muscle cells to produce ATP constantly |
| creatine phosphate | when ADP is at rest and cant stockpile ATP they store this high energy molecule |
| Anaerobic respiration | without oxygen |
| aerobic respiration | with oxygen |
| oxygen debt | the 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 its produced |
| Isometric | one type of muscle contraction, the length of the muscle doesn't change but the amount of tension increases |
| Isotonic | one type of muscle contraction, the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes |
| muscle tone | constant tension produced by muscles of the body for long periods of time, keeps head up and back straight |
| fast twitch fibers | contract quickly and fatigue quickly, adapted to perform anaerobic metabolism, Ex- white meat in chicken breast |
| slow twitch fibers | contract slowly and resistant to fatigue, better for aerobic metabolism Ex- dark meat of duck breast or chicken leg |
| origin | point of attachment, the head, the most stationary end of the muscle |
| insertion | the end of the muscle undergoing the greatest movement |
| belly | portion of the muscle between the origin and the insertion |
| synergists | muscles that work together to accomplish specific movements |
| antagonists | muscles that work in opposition to one another |
| prime mover | if one muscle plays the major role in accomplishing the desired movement among synergists |
| nomenclature | most muscles have names that are descriptive, named according to location, size, orientation of fibers, shape, origin, insertion, and function, etc |
| occipitofrontalis | raising eyebrows |
| orbicularis oculi | closes eyelids and causes crow feet |
| orbicularis oris | puckers lips |
| buccinator | flattens cheeks (trumpeters muscle) |
| kissing muscles | orbicularis oris and buccinator |
| zygomaticus | smiling muscle |
| levator labii superioris | sneering |
| depressor anguli oris | frowning |
| mastication | chewing |
| sternocleidomastoid | lateral neck muscle and prime mover, rotates and abducts head |
| erector spinae | group of muscles on each side of back, keeps back straight |
| thoracic muscles | external intercostals and internal intercostals and diaphragm |
| linea alba | tendinous area of abdominal wall |
| rectus absominis | on each side of linea alba |
| tendinous inscriptions | cross the rectus abdomminis at 3 or more locations, causes abdominal wall to appear segmented |
| trapezius | rotates scapula |
| serratus anterior | pulls scapula anteriorly |
| pectoralis major | adducts and flexes arm |
| latissimus dorsi | medially rotates, adducts, and powerfully extends arm |
| deltoid | attaches humerus to scapula and clavicle, major abductor for upper limb |
| tricep brachii | extends forearm |
| biceps branchii | flexes forearm |
| brachialis | flexes forearm |
| brachioradialis | flexes and supinates forearm |
| retinaculum (bracelet) | strong band of fibrous connective tissue that covers flexor and extensor tendons and holds them in place |
| flexor carpi | flexes wrist |
| extensor carpi | extends wrist |
| flexor digitorum | flexes the fingers |
| extensor digitorum | extends fingers |
| gluteus maximus | butt |
| quadriceps femoris | extends legs, anterior thigh muscles |
| sartorius | tailors muscle, flexes thigh |
| hamstring | posterior thigh muscles, flexes leg and extends thigh |
| gastrocnemius and soleus | form the calf muscle, joins calcaneal tendon, flexes foot and toes |
| peroneus | lateral muscles of leg, primarily everters of foot |
| intrinsic foot | 20 muscles in foot, they flex extend, abduct, and adduct toes |
Created by:
brea.hatten
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