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ch.6 muscles


Contractility Ability of skeletal muscle to shorten with force
Extensibility ability to be stretched
Excitability ability to respond to stimuli
Elasticity ability to recoil to their original resting length after they have been stretched
Epimysium connective tissue that surrounds the entire muscle
Fascia Connective tissue located outside the epimysium and surrounds/separates muscles.
Perimysium Loose connective tissue that surrounds fascicle
muscle cells muscle fibers
Each muscle fiber is surrounded by endomysium
Cytoplasm of each fiber is filled with muofibrils
Myofibris consist of 2 major kinds of protien fibers called actin myofilaments and myosin myofilaments
Actin myofilaments thin myofilaments. look like pearls twisted together
myosin myofilaments thick filaments. look like bundles of golf clubs
sacromeres The Actin and Myosin filaments in skeletal muscles are organized into sections
the basic structrural and functional unity of the muscle sacromere
Resting Membrane Potential (RMP) charge difference across the membrane
Action Potential (AP) brief reversal back of the charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
neuronmuscular junction or synapse the link between an axon terminal and a muscle fiber and is near the center of the cell
motor unit a single motor neuron and all the muscle fibers it innervates
the enlarged nerve terminal presynaptic terminal
the space between the presynaptic terminal and the muscle cell synaptic cleft
Each presynaptic terminal contains ___________, which secrete a neurotransmitter called__________. synaptic vesicles, acetylcholine
The acetylcholine released into the synaptic cleft between the neuron and the muscle cell is rapidly broken down by enzymes or __________ acetylcholinesterase
sliding filament mechanism the sliding of actin and myofilaments past myson myofilaments during contraction
muscle twitch contraction of a whole muscle in response to a single stimulus
threshold the level of stimulation required to trigger a neural impulse
all-or-none response A phenomenon at which point the muscle fiber will contract maximally.
The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase. lag
the time of contraction contraction phase
The time during which the muscle relaxes relation phase
tetany where the muscle remains contracted without relaxing
the increase in number of motor units being activated is called________. recruitment
ATP (adenosine triphosphate) main energy source that cells use for most of their work
ATP is produced in the _______ mitochondria
ATP is short-lived and degenerates to the more stable ______. ADP (adenosine diphosphate) and phosphate
A high-energy molecule stored by muscle cells creatine phosphate
anaerobic respiration Does not use oxygen
aerobic uses oxygen
oxygen debt the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose
muscle fatigue Results when ATP is used during muscle contraction faster than it can be produced.
isometric Equal distance
Isometric (equal distance) the length of the muscle does not change, but the amount of tension increases during the contraction process.
isotonic equal tension
isotonic (equal tension) the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes.
muscle tone refers to the constant tension produced by the muscles of the body for long periods of time. Keeps head up and back straight.
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. Better suited for aerobic metabolism.
origin The most stationary end of a muscle
Insertion The end of the muscle undergoing the greatest movement.
the portion of the muscle between the origin and the insertion is the ________ belly
T/F: some muscles have multiple origins or head true
muscles that work together to accomplish specific movements are called _______ synergists
Antagonist muscles that work in opposition to one another
among a group of synergists, if one muscle plays the major role in accomplishing the desired movement prime mover
Occipitofrontalis raises eyebrows
Orbicularis oculi closes 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, trumpeter's muscle
zygomaticus smiling muscle
levator labii superioris sneering
depressor anguli oris frowning
mastication chewing
intrinsic tongue muscles change the shape of the tongue
extrinsic tongue muscles move the tongue
Sternocleidomastoid lateral neck muscle and prime mover. Rotates and abducts the head
errector spinae group of muscles on each side of the back. Responsible for keeping the back straight and the body erect.
thoracic muscles muscle that moves the thorax
most involved in breathing external intercostals, diaphragm and internal intercostals
external intercostals elevates ribes during inspiration
internal intercostals contract during forced expiration
Diaphragm accomplishes quiet breathing. Dome shaped muscle and aids in breathing
abdominal wall muscles linea alba, rectus abdominis, and tendinous inscriptions
scapular movements trapezius and serratus anterior
trapezius rotates scapula
serratus anterior pulls scapula anteriorly
Created by: megx