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Muscle System
Ch. 6 flashcards
Question | Answer |
---|---|
contractibility | shorten with force |
excitability | respond to a stimulus |
extensibility | ability to be stretched |
elasticity | recoil to original resting length after being stretched |
epimysium | skeletal muscle surrounded by connective tissue sheath |
fascia | connective tissue outside epimysium. surrounds and separates muscle |
perimysium | muscle composed of numerous visible bundles called muscle fasciculi, surrounded by loose connective tissue |
fibers | fasciculi composed of single muscle cells |
endomysium | surrounded by connective sheath |
myofibrils | threadlike structure that extends from one fiber to the other |
actin myofilaments | thin myofilaments |
myosin myofilaments | thick myofilaments |
sarcomeres | actin and myosin myofilaments join end to end to form myofibril |
resting membrane potential | charge difference across the membrane |
action potential | brief reversal back of the charge |
motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
neuromuscular junction | each branch that connects to the muscle near the center of the cell |
synapse | branch that connects to the muscle near the center of the cell |
motor unit | single motor neuron and all the skeletal muscle fibers it innervates |
presynaptic terminal | enlarged nerve terminal |
synaptic terminal | space between the presynaptic terminal and muscle cell |
postsynaptic terminal | muscle fiber |
synaptic cleft | space between the presynaptic terminal and muscle cell |
synaptic vesicles | presynaptic terminal |
acetylcholine | secrete a neurotransmitter |
acetylcholinesterase | acetylcholine released into synaptic cleft between the muscle and neuron and muscle cell, rapidly broken down by enzymes |
sliding filament mechanism | sliding of actin myofilaments past myosin myofilaments during contraction |
muscle twitch | contraction of an entire muscle in response to a stimulus that causes action potential in one or more muscle fibers |
threshold | muscle fiber will not respond to stimulus until that stimulus reaches a level |
all-or-none response | the muscle fiber will contract maximally |
lag phase | time between application of a stimulus to a motor neuron and the beginning of a contraction |
contraction phase | time of contraction |
relaxation phase | time which the muscle relaxes |
tetany | where muscles remain contracted without relaxing |
recruitment | increase in number of motor units being activated |
creatine phosphate | when at rest they cant stockpile ATP but they can store another 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, replenish depleted phosphate in muscle cells |
muscle fatigue | results when ATP is used during muscle contraction faster than it can be produced in muscle cells |
isometric | length of the muscle does not change, but the amount of tension increases during the contraction process |
muscle tone | constant tension produced by muscles of the body for long periods of time |
fast-twitch fibers | contract quickly and fatigue quickly. well adapted to perform anaerobic metabolism |
slow- twitch fibers | contract more slowly and are more resistant to fatigue |
origin | most stationary end of the muscle |
insertion | 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 movement |
antagonists | muscles that work in opposition to one another |
prime mover | if one muscle plays the major role in accomplishing the desired movement |
mastication | chewing |
sternocleidomastoid | lateral neck muscle and prime mover |
erector spinae | group of muscles on each side of the back |
thoracic muscles | muscles that move the thorax |
abdominal wall muscles | muscles of the anterior abdominal wall flex and rotate the vertebral column |
trapezius | rotates scapula |
serratus anterior | pulls scapula anteriorly |
pectorals major | adducts and flexes the arm |
latissimus dorsi | medially rotates, adducts, an powerfully extends the arm |
deltoid | attaches the humerus to the scapula and clavicle, abductor of the upper limb |
Triceps brachii | Extends the forearm |
Biceps brachii | Flexes the forearm |
Brachialis | flexes forearm |
brachioradialis | flexes and supinates the forearm |
retinaculum | strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place around the wrist so that they do not "bowstring" during muscle contraction |
flexor carpi | flexes the wrist |
extensor carpi | extends the wrist |
flexor digitorum | flexes the fingers |
extensor digitorum | extends the fingers |
gluteus Maximus | buttocks |
quadriceps femoris | extends the leg; anterior muscles |
Sartorius | "tailors muscle" ; flexes the thigh |
hamstring muscles | posterior thigh muscles; flexes the leg and extends the thigh |
gastrocnemius and soleus | form the calf muscle |
calcaneal tendon (Achilles tendon) | flex the foot and toes |
intrinsic foot | 20 muscles located within the foot, muscles flex extend, abduct, and adduct the toes |