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Chapter 6 muscles

Contractility the ability of a skeletal muscle to shorten with force
Excitability the capacity of a skeletal muscle to respond to stimulus
Extensibility the ability to be stretched
Elasticity the ability to recoil to original shape after being stretched
Fascia outermost layer of muscles, separates muscles from each other
Epimysium connective tissue sheath around outside of a muscle
Perimysium surrounds fasicles
Endomysium surrounds muscle fibers
myofibrils threadlike structure that extends from one end of the fiber to the other
Actin thin, resemble pearls, light band
Myosin thick, resemble golf clubs, dark band
Myofilaments Actin, Myosin
Sarcomere organization of myofilaments from Zline to Zline
Resting membrane potential charge difference across a cell membrane
action potential brief reversal back of charge when a muscle is stimulated
Motor neurons nerve cells that carry action potentials to muscle fibers
nueromuscular junction (synapse)Where a nerve cell branches into a muscle
motor unit a motor nueron and all the muscle fibers it innervates
presynaptic terminal enlarged nerve terminal
postsynaptic terminal muscle fiber below presynaptic terminal
synaptic cleft space between presynaptic terminal and muscle fiber
acetylcholine nuerotransmitter secreted by synaptic vesicles
acetylcholinesteracse enzyme that breaks down acetylcholine
sliding filament mechanism sliding of actin myofilaments past myosin myofilaments
muscle twitch contraction of an entire muscle in response to stimuli
threshold level of stimulus in which muscles will contract
all-or-none response maximal contraction of a muscle
lag phase time lapse between application of a stimulus and beginning of a contraction
contraction phase time of contraction
relaxation phase time when a muscle relaxes
tetany muscle remains contracted without relaxing
recruitment increase in number of motor units being activated
ATP adenosine triphosphate
ADP adenosine diphosphate
creatine phosphate can be stockpiled when a muscle is at rest
anaerobic respiration without oxygen
aerobic respiration with oxygen
oxygen debt amount of oxygen needed to convert lactic acid to glucose and replenish depleted stores of creatine phosphate in muscle fibers
muscle fatigue tiredness of muscles, results when ATP is used during muscle contraction faster than it can be produced
isometric length of muscle doesn't change, tension increases
isotonic amount of tension doesn't change, length changes
muscle tone constant tension produced by muscles for long periods of time
fast-twitch contract quickly and fatigue quickly
slow-twitch contract slowly and fatigue slowly
origin stationary end of a muscle
insertion end of muscle undergoing greatest movement
belly portion of muscle between origin and insertion
synergists muscles that work together to accomplish movements
antagonists muscles that work against each other to create movement
prime mover one muscle playing a major role in a group of synergists
trunk muscles muscles that move the vertebral column
thoracic muscles muscles that move the thorax
abdominal wall muscles The muscles of the anterior abdominal wall flex and rotate the vertebral column, compress the abdominal cavity, and hold in the abdominal viscera.
trapezius rotates scapula
serratus anterior pulls scapula anteriorly
pectoralis major adducts and flexes the arm
latissimus dorsi medially rotates, adducts, and powerfully extends the arm. “Swimmer muscles”
deltoid attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb.
hamstrings posterior thigh muscles
linea alba tendinous area of the abdominal wall
rectus abdominis On each side of the linea alba
Tendinous inscriptions cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented.
frontalis raises eyebrows
orbicularis oculi closes eyelids
buccinator flattens cheek
zygomaticus smiling muscles
lavator labil superovis sneering
depressor anguli oris frowning
mastication chewing
mastication muscles temporalis, masseter
tongue muscles intrinsic, extrinsic
neck muscles sternocleidomastoid, prime mover rotates the head
kissing muscles orbicularis oris, buccinator
triceps brachii extends the forearm
biceps brachii flexes the forearm
Created by: auraluna