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Ch. 6 Muscles

QuestionAnswer
Contractility ability of skeletal muscle to shorten with force
Excitability capacity of skeletal muscle to respond to a stimulus
Elasticity ability to recoil to original resting length after been stretched
Epimysium connective tissue sheath surrounded by each skeletal muscle
Fascia connective tissue located outside the epimysium; surrounds and separates the muscles
Perimysium loose connective sheath that surrounds muscle fasciculi
endomysium connective tissue sheath that surrounds each fiber
myofibrils threadlike structure that extends from one end of the fiber to the other
Actin myofilaments thin and resemble 2 minute strands of pearls twisted together
myosin myofilaments thick and resemble bundles of minute golf clubs
Sarcomere highly ordered units formed from actin and myosin. Extends from one Z line to another Z line
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 also called a synapse and forms when each branch connects to the muscle
motor unit single motor neuron and all the skeletal muscle fibers it innervates
presynaptic terminal the enlarged nerve terminal
synaptic cleft space between the presynaptic terminal and the muscle cell
postsynaptic terminal the muscle fiber
synaptic vesicles located in the presynaptic terminal and secrete a neurotransmitter
acetylcholine neurotransmitter and it diffuses across the synaptic cleft and binds to the postsynaptic terminal
exocytosis process when an action potential reaches the nerve terminal, it causes the synaptic vesicles to release acetylcholine into the synaptic cleft
acetylcholinesterase enzymatic breakdown that happens when acetylcholine is released into the synaptic cleft between the neuron and muscle cell
sliding filament mechanism sliding of actin past myosin during contraction
muscle twitch contraction of an entire muscle in response to a stimulus
threshold a level the stimulus has to reach in order for the muscle fiber to respond to the stimulus
lag phase time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase the time of contraction
relaxation phase time during which the muscle relaxes
tetany when the muscle remains contracted without relaxing
recruitment increase in number of motor units being activated
anaerobic respiration without oxygen
aerobic respiration with oxygen
oxygen debt amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the stored creatine phosphate stored 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 contraction
isotonic amount of tension produced by the muscle is constant during contraction but the length of the muscle changes
muscle tone refers to constant tension produced by muscles of the body for long periods of time
fast-twitch fibers contract and fatigue quickly
slow-twitch fibers contract more slowly and are more resistant to fatigue
origin the most stationary end of the muscle
insertion end of the muscle undergoing the greatest movement
belly portion of muscle between the origin and the insertion
synergists muscles that work together to accomplish specific movements
antagonist muscles that work together in opposition to one another
prime mover among group of synergists, one muscle plays the major role in accomplishing the desired movement
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids and causes crows feet wrinkles in the skin at the lateral corners of the eye
orbicularis oris puckers the lips
buccinator flattens the cheeks
zygomaticus smiling muscle
levator labii superioris sneering
depressor anguli oris frowning
mastication chewing
intrinsic tongue muscles changes the shape of the tongue
extrinsic tongue muscles moves the tongue
sternocleidomastiod lateral neck muscle and prime mover; rotates and abducts the head
platysma sheetlike muscle that covers the anterolateral neck
erector spinae Group of muscles on each side of the back; responsible for keeping the back straight and the body erect
thoracic muscles muscles that move the thorax
external intercostals elevate the ribs during inspiration
internal intercostals contract during forced expiration
linea alba tendinous area of the abdominal wall that extends from the sternum through the navel to the pubis
trapezius rotates the scapula
serratus anterior pulls scapula anteriorly
pectoralis major abducts and flexes the arm
latissimus dorsi medially rotates, adducts, and powerfully extends the arm
deltoid attaches the humerus to the scapula and the clavicle and is the major abductor of the upper limb
triceps brachii extends the forearm
biceps brachii flexes the forearm
brachialis flexes forearm
brachioradialis flexes and supinates the forearm
flexor carpi flexes the wrist
Extensor carpi extends the wrist
flexor digitorum flexes the fingers
Created by: Tessa22