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Question Answer
Contractility the ability of skeletal muscle to shorten with force
Excitability the capacity of skeletal muscle to respond to a stimulus
Extensibility the ability to be stretched
Elasticity ability to recoil to their original resting length after they have been stretched.
Each skeletal muscle is surrounded by a connective tissue sheath called Epimysium
Fascia connective tissue found outside the epimysium and surrounds and separates muscles.
Perimysium A muscle composed of numerous visible bundles called muscle fasciculi, which is surrounded by.
The fasciculi are composed of single muscle cells called Fibers
Each fiber is surrounded by a connective tissue sheath called Endomysium
the cytoplast of each fiber is called Myofibrils which is a thread like structure that extends from one end of the fiber to another.
myofibrils consist of 2 major kinds of protein fibers actin myofilaments and myosin myofilaments
actin myofilaments thin myofilaments. they resemble 2 minute strands of pearls twisted together
myosin myofilaments thick myofilaments. they resemble bundles of minute golf clubs.
actin and myosin myofilaments form highly ordered units called sarcomeres, which are joined end to end to form the myofibril
the outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged. The charge difference across the membrane is called. Resting membrane potential
When a muscle cell is stimulated the membrane characteristics change briefly. The brief reversal back of the charge is called action potential
Motor neurons nerve cells that carry action potentials to skeletal muscle fibers.
each branch that connects to the muscle forms neuromusclular junction
motor unit a single motor neuron and all the skeletal muscle fibers it innervates
The enlarged nerve terminal presynaptic terminal
the space between the presynaptic terminal and the muscle cell synaptic cleft
the sliding of actin myofilaments past myosin myofilaments during contraction sliding filament mechanism
muscle twitch a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers.
a muscle fiber will not respond to stimulus until that stimulus reaches a level called threshold
the time between application of a stimulus to a motor neuron and the beginning of a contraction is the lag phase
the time of contraction is contraction phase
the time during which the muscle relaxes is the relaxation phase
tetany where the muscle remains contracted without relaxing
the increase in number of motor units being activated is recruitment
when at rest they cant stockpile ATP but they can store another high energy molecule called creatine phosphate
anaerobic respiration without oxygen
aerobic respiration with oxygen
oxygen debt 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
muscle fatigue results when ATP is used during muscle contraction faster than it can be produced in the muscle cells.
2 types of muscle contractions isotonic and isometric
isometric the length of the muscle does not change, but the amount of tension increases during the contraction phase
isotonic the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes
muscle tone muscle tone refers to constant tension produced by muscles of the body for long periods of time
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. they are better suited for aerobic metabolism.
origin the most stationary end of the muscle
insertion the end of the muscle undergoing the greatest movement.
belly the portion of the muscle between the origin and the insertion.
synergists muscles that work together to accomplish specific movements
anatagonists muscles that work in opposition to one another
prime mover among a group of synergists, if one muscle plays the major role in accomplishing the desired movement.
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids
orbicularis oris puckers the lips
buccinator flattens the cheeks
zygomatics 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
4 pairs of mastication muscles 2 pairs of pterygoids, temporalis, and masseter
thoracic muscles muscles that move the thorax
external intercostals elevate the ribs during inspiration
internal intercostals contract during forced expiration
diaphragm accomplishes quiet breathing, dome shaped muscle, aids in breathing
linea alba consists of white connective tissue rather than muscle
on each side of the linea alba is the rectus abdominis
tendinous inscriptions cross the rectus abdominis at three or more locations, causing the abdominal wall of a well muscled person to appear segmented
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
triceps brachii extends the forearm
biceps brachii flexes the forearm. occupies the anterior compartment of the arm.
brachiallis flexes forearm
brachioradialis flexes and supinates the forearm
flexor carpi flexes the wrist
extensor carpi extends the wrist

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