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The ability of skeletal muscle to shorten with force Contractility
The capacity of skeletal muscle to respond to a stimulus Excitability
The ability to be stretched Extensibility
Skeletal muscle is surrounded by this connective tissue sheath Epimysium
Another connective tissue located outside the epimysium Fascia
Loose connective tissue that surrounds the fascicle Perimysium
The fasciculi are composed of single muscle cells called this Fibers
Each fiber is surrounded by this connective tissue sheath Endomysium
The cytoplasm of each fiber is filled with this Myofibrils
Thin myofilaments Actin Myofilaments
Thick myofilaments Myosin Myofilaments
Actin and myosin myofilaments form highly ordered units called this Sarcomeres
The charge difference across the membrane is called this Resting Membrane Potential
The brief reversal back of the charge is called this Action Potential
Nerve cells that carry action potentials to skeletal muscle fibers Motor neurons
Each branch that connects to the muscle Synapse
A single motor neuron and all the skeletal muscle fibers it innervates Motor Unit
The enlarged nerve terminal Presynaptic Terminal
The space between the presynaptic terminal and the muscle cell Synaptic Cleft
The muscle fiber Postsynaptic Terminal
Each presynaptic terminal contains synaptic vesicles that secrete this neurotransmitter Acetylcholine
The acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by this enzyme Acetylcholinesterase
The sliding of actin myofilaments past myosin myofilaments during contraction is called this Sliding Filament Mechanism
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 this Threshold
The time between application of a stimulus to a motor neuron and the beginning of a contraction Lag Phase
The time of contraction Contraction Phase
The time during which the muscle relaxes Relaxation Phase
Muscle remains contracted without relaxing Tetany
The increase in number of motor units being activated Recruitment
Needed for energy for muscle contraction and is produced in the mitochondria ATP(adenosine triphosphate)
ATP reduces to this stable compound ADP (adenosine diphosphate)
Can store another high-energy molecule Creatine Phosphate
Without oxygen Anaerobic Respiration
With oxygen (more efficient) Aerobic Respiration
The increased respiration provides the oxygen to pay back the oxygen debt 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 Isometric
The amount of tension produced by the muscle is constant, but the length of the muscle changes Isotonic
Refers to constant tension produced by muscles of the body for long periods of time Muscle Tone
Contract quickly and fatigue quickly Fast-twitch Fibers
Contract more slowly and are more resistant to fatigue Slow-twitch Fibers
The most stationary end of the muscle Origin
The end of the muscle undergoing the greatest movement Insertion
The portion of the muscle between the origin and the insertion Belly
Muscles that work together to accomplish specific movements Synergists
Muscles that work in opposition to one another Antagonists
In a group of synergists, if this muscle plays the major role in accomplishing the desired movement Prime Mover
Raises the 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 Buccinator
Smiling muscle Zygomaticus
Sneering Levator Labii Superioris
Frowning Depressor Anguli Oris
Chewing Mastication
Change the shape of the tongue Intrinsic Tongue Muscles
Move the tongue Extrinsic Tongue Muscles
lateral neck muscle and prime mover; rotates and abducts the head Sternocleidomastoid
group of muscles on each side of the back; responsible for keeping the back straight and the body erect Erector Spinae
Muscles that move the thorax Thoracic Muscles
Elevate the ribs during inspiration External Intercostals
Contract during forced expiration Internal Intercostals
Accomplishes quiet breathing Diaphragm
The muscles of the anterior abdominal wall flex and rotate the vertebral column Abdominal Wall Muscles
Tendinous area of the abdominal wall Linea Alba
On each side of the linea alba Rectus Abdominis
Cross the rectus abdominis at three or more locations Tendinous Inscriptions
Rotates the scapula Trapezius
Pulls scapula anteriorly Serratus Anterior
Adducts and flexes the arm Pectoralis Major
Medially rotates, adducts, and powerfully extends the arm Latissimus Dorsi
Attaches the humerus to the scapula and clavicle Deltoid
Extends the forearm Triceps Brachii
Flexes the forearm Biceps Brachii
Flexes forearm Brachialis
Created by: aleftyjeffrey