Question | Answer |
the ability to shorten with force | contractility |
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 temp. | muscles |
skeletal muscle is surrounded by a connective tissue sheath called | epimysium |
another connective tissue located outside the epimysium | fascia |
a muscle is composed of numerous visible bundles called | muscle fasciculi (fascicle) |
fiber is surrounded by connective tissue sheath called | endomysium |
cytoplasm of each fiber is filled with | myofibrils |
myofibrils consist of 2 major kinds of protein fibers | actin myofilament
myosin myofilament |
actin & myosin myofilaments form highly ordered units called | sarcomeres |
thin myofilaments resembles 2 minute strands of pearls twisted together | actin myofilament |
thick myofilamenys resembles bundles of minute golf clubs | myosin myofilament |
the arrangement of actin & myosin give a | banded appearance |
on each side of Z line is a light area | I band |
the darker central region in each sarcomere is called | A band |
center of each sarcomere is another light area called | H zone |
myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called | M line |
each sarcomere extends from | one Z line (disc) to another Z line (disc) |
the charge difference across the membrane is called | resting membrane potential |
the brief reversal back of the charge is called | action potenial |
nerve cells that carry action potentials to skeletal muscle fibers | motor neurons |
each branch that connects to the muscle forms | neuromusclular junction |
near the center of the cell | synapse |
a single motor neuron & all the skeletal muscle fibers it innervates are called | motor unit |
enlarged nerve terminal | presynaptic terminal |
the space between the presynaptic terminal & the muscle cell | synaptic cleft |
the muscle fiber | postsynaptic terminal |
each presynaptic terminal contains | synapyic vesicles |
secretes a neurotransmitter called | acetylcholine |
the acetylcholine diffuses across the synaptic cleft & binds to receptor molecules in the muscle cell membrane called | sarcolemma |
acetylcholine released into the synaptic cleft between the neuron & muscle cell is rapidly broken down by enzymes | acetylcholinesterase |
occurs as actin & myosin myofilaments slide past one another causing the sarcomeres 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 | threshold |
the muscle fiber will contract maximally this phenomenon is called | all-or-none response |
the time between application of a stimulus to a motor neuron & the beginning of a contraction | lag phase |
time of contraction | contraction phase |
time during which the muscles relaxes | relaxation phase |
where the muscle remains contracted without relaxing | tetany |
the increase in number of motor units being activated | recruitment |
needed for energy for muscle contraction | ATP (adenosine triphosphate) |
ATP is produced in the | mitochondria |
short-lived & unstable | ATP (adenosine triphosphate) |
ATP degenerates to the more stable called | ADP (adenosine diphosphate) |
it is necessary for muscle cells to constantly produce ATP; when at rest they can't stockpile ATP but they can store another high-energy molecule called | creatine phosphate |
without oxygen | anaerobic respiration |
with oxygen (more efficient) | aerobic respiration |
the amount of oxygen needed in chemical reactions to convert lactic acid to glucose & 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 |
(equal distance) the length of the muscle does not change, but the amount of tension increases during the contraction process | isometric |
(equal tension) the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes | isotonic |
constant tension produced by muscles of the body for long periods of time; keeps head up & back straight | muscle tone |
contract quickly & fatigue quickly; well adapted to perform anaerobic metabolism Ex. white meat | fast-twitch fibers |
contract more slowly 7 more resistant to fatigue; better suited fir aerobic metabolism Ex.dark meat | slow-twitch fibers |
the points of attachment of each muscle are called | origin & insertion |
at these attachment points the muscle is connected to the bone | tendon |
(head) the most stationary end of the muscle | origin |
the end of the muscle undergoing the greatest movement | insertion |
portion of the muscle between the origin & the insertion is called | belly |
muscles that work together to accomplish specific movements are called | synergists |
muscles that work in opposition to one another | antagonists |
among a group of synergists, if one muscle plays the major role in accomplishing the desired movement | prime mover |
most muscles have names that are descriptive, some are named according to their location, size, orientation of fibers, shape, origin, insertion, & function | nomenclature |
raises the eyebrows | occipitofrontalis |
closes eyelids | orbicularis oculi |
2 kissing muscles | orbicularis oris & buccinator |
puckers the lips | orbicularis oris |
flattens the cheeks " trumper"s muscles" | buccinator |
smiling muscle | zygomaticus |
sneering | levator labii superoris |
frowning | depressor anguli oris |
chewing | mastication |
chewing muscles | temporalis & masseter |
tongue muscles | intrinsic & extrinsic |
changes the shape of the tongue | intrinsic |
moves the tongue | extrinsic |
lateral neck; prime mover; rotates and extends the head | strenocleidowastoid |
twisted neck; wry neck | torticollis |
extends the forearm | triceps brachii |
flexes the forearm | biceps brachii |
flexes forearm | brachialis |
flexes and supinates the forearm | brachioraialis |
flexes the wrist | flexor carpi |
extends the wrist | extensor carpi |
flexes the fingers | flexor digitorum |
extends the fingers | extensor digitorum |
buttocks | gluteus maximus |
hip muscle & common injection site | gluteus medius |
extends the leg; anterior thigh muscle | quadriceps femoris |
"tailors muscle", flexes the thigh | sartorius |
flexes the leg and extends the thigh: posterior thigh muscle | hamstring |
form the calf muscle | gastrocnemius and soleus |
flex the foot and toes | calcaneal tendon (Achilles tendon) |
the lateral muscles of the leg | peroneus |
20 muscles within the foot | intrinsic foot |
19 hand muscles | intrinsic hand muscles |
located between the metacarpals; responsible for abduction & adduction of the fingers | interossi |
strong band of fibrous connective tissue that cover the flexor & extensor tendons & holds them in place | retinaculum (bracelet) |
group of muscles on each side of the back | erector spine |
elevate the ribs during inspiration | external intercostals |
contract during forced inspiration | internal intercostals |
tendinous area of the abdominal wall called | linea alba |
on each side of the linea alba is the | rectus abdominis |
cross the rectus abdominis at three or more locations | tendinous inscriptions |
rotates scapula | trapezius |
pulls scapula anteriorly | serratus anterior |
adducts and flexes the arm | pectoralis major |
medially rotates,adducts, & powerfully extends the arm 'swimmer muscles" | latissimus dorsi |
attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb | deltoid |