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the muscular system

the ability of skeletal muscle to shorten with force contractility
the capability of skeletal muscle to respond to a stimulus excitability
the ability to be stretched extensibility
ability to recoil to their original resting length after they have been stretched elasticity
help to produce heat essential for maintenance of normal body temperature muscles
each skeletal muscle is surrounded by a connective tissue sheath called the perimysium
another connective tissue located outside the epimysium fascia
surrounds and separates muscles fascia
a muscle is composed of numerous visible bundles called muscle fasciculi (fascicle)
muscle fasciculi are surrounded by loose connective tissue called the perimysium
the fasciculi are composed of single muscle cells called fibers
each fiber is a single cylindrical cell containing several nuclei
each fiber is surrounded by a connective sheath called the endomysium
the cytoplasm of each fiber is filled with myofibrils
a thread like structure that extends from one end of the fiber to the other myofibrils
what two kinds of protein fibers do myofibrils consist of actin myofilaments and myosin myofilaments
thin myofilaments actin
thick myofilaments myosin
actin and myosin myofilaments form highly ordered units called sarcomeres
sarcomeres are joined end to end to form the myofibril
the ________ is the basic structural and functional unit of the muscle sarcomere
each sarcomere extends from one z line to another z line
the arrangement of actin and myosin give a banded appearance
the i band is ______ and contains _______ light and actin
the a band extends the length of the myosin
the a band is darker
in the center of each sarcomere is a light area called the H zone
the H zone consists of only myosin
the myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called the M line
the outside of most cell membranes is positively charged
the inside of cell membranes is negatively charged
the charge difference across the membrane is called the resting membrane potential
the brief reversal back of the charge is called action potential
nerve cells that carry action potentials to skeletal muscle fibers motor neurons
each branch that connects to the muscle forms a ______ near the center of the cell neuromuscular junction or synapse
a single muscle neuron and all the skeletal muscle fibers it innervates are called a motor unit
__________ is formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane a neuromuscular junction
the enlarged nerve terminal is the presynaptic terminal
the space between the presynaptic terminal and the muscle cell is the synaptic cleft
the muscle fiber is the postsynaptic terminal
each presynaptic terminal contains __________ that secrete a neurotransmitter synaptic vesicles
synaptic vesicles secrete a neurotransmitter called acetylcholine
muscle cell is rapidly broken down by an enzymes called acetylcholinesterase
occurs as actin and myosin myofilaments slide past one another causing sarcomere s to shorten muscle contraction
the sliding of actin myofilaments past myosin myofilaments during contraction is called sliding filament mechanism
a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers muscle twitch
a muscle fiber will not respond to stimulus until that stimulus reaches a level called _________ at which point the muscle fiber will contract maximally. threshold
muscle fibers maximally contracted all-or-none response
the time between application of a stimulus to a motor neuron and the beginning of a contraction is the lag phase
time of contraction contraction phase
time during which muscles relax relaxation phase
where the muscle remains contracted without relaxing tetany
the increase in number of motor units being activated is called recruitment
__________ is needed for energy for muscle contraction ATP (adenosine triphosphate)
ATP is 1) 2) 1) produced in the mitochondria 2) short lived and unstable
it is necessary for muscle cells to constantly produce ATP
when at rest they cant stockpile ATP but they can store another high-energy molecule, called creatine phosphate
without oxygen anaerobic respiration
with oxygen aerobic respiration
the ____________ is 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. oxygen debt
results when ATP is used during muscle contraction faster than it can be produced in the muscle cells muscle fatigue
the length of the muscle does not change, but the amount of tension increases during the contraction process isometric
the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes isotonic
costant tension produced by the muscles of the body for long periods of time muscle tone
contract quickly and fatigue quickly and fatigue quickly fast-twitch fibers
contract more slowly and are more resistant to fatigue slow-twitch fibers
the points of attachment of each muscle are its origin and insertion
the ________ is the most stationary end of the muscle origin
the __________ is the end of the muscle undergoing the greatest movement insertion
the portion of the muscle between the origin and the insertion is the belly
muscles that work together to accomplish specific movements are called synergists
muscles that work in opposition to one another are called antagonists
among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the prime mover
muscles are named according to their location, size, orientation of fibers, shape, origin, insertion, and function
raises eyebrows occipitofrontalis
closes the eyelids and causes " crows feet" wrinkles in the skin at the lateral corners of the eye orbicularis oculi
puckers the lips orbicularis oris
flattens the cheeks trumpeter's muscle buccinator
kissing muscles orbicularis and buccinator
smiling muscle zygomatius
sneering levator labii superioris
frowning depressor anguli oris
Created by: kailiebellomy