Question | Answer |
muscle cells | muscle fibers |
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 the ____ | epimysium |
____ is another connective tissue located outside the epimysium | fascia |
muscle fasciculi are surrounded by loose connective tissue called the ____ | perimysium |
each fiber is surrounded by a connective tissue sheath called the ____ | endomysium |
the cytoplasm of each fiber is filled with ___ | myofibrils |
thin myofilaments (pearls twisted) | actin myofilaments |
thick myofilaments (golf balls) | myosin myofilaments |
joined end to end to form the myofibril | sarcomeres |
the charge difference across the membrane | resting membrane potential |
the brief reversal back of the charge | action potential |
nerve cells that carry action potentials to skeletal muscle fibers | motor neurons |
Each branch that connects to the muscle forms a _____ _____, or _____ near the center of the cell. | neuromusclular junction ; synapse |
a single motor neuron | motor unit |
enlarged nerve terminal | presynaptic terminal |
the space between the presynaptic terminal and the muscle cell | synaptic cleft |
postsynaptic terminal | muscle fiber |
secrete a neurotransmitter | synaptic vesicles |
neurotransmitter | acetylcholine |
enzyme that breaks down muscle cells | acetylcholinesterase |
the sliding of actin myofilaments past myosin myofilaments during contraction | sliding filament mechanism |
___ ___ is 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 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 |
where the muscle remains contracted without relaxing | tetany |
the increase in number of motor units being activated | recruitment |
ATP is produced in the _______ | mitochondria |
adenosine triphosphate | ATP |
adenosine diphosphate | ADP |
high-energy molecule ATP stores | 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 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 muscle contraction |
the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes | isotonic muscle contraction |
Muscle tone refers to constant tension produced by muscles of the body for long periods of time. Keeps head up and back straight | muscle tone |
contract quickly and fatigue quickly | fast twitch fibers |
contract more slowly and are more resistant to fatigue | slow twitch fibers |
At these attachment points the muscle is connected to the bone by ____ | a tendon |
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 | the belly |
muscles that work together to accomplish specific movements | synergists |
muscles that work in opposition to one another | antagonists |
if one muscle plays the major role in accomplishing the desired movement it is the _____ | prime mover |
Occipitofrontalis | raises the eyebrows |
Orbicularis oculi | closes the eyelids |
Orbicularis oris | puckers lips |
Buccinator | flattens cheeks |
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 |
Erector spinae | group of muscles on each side of the back. Responsible for keeping the back straight and the body erect |
muscles that move the thorax | thoracic muscles |
elevate the ribs during inspiration | External intercostals |
contract during forced expiration | Internal intercostals |
accomplishes quiet breathing | diaphragm |
tendinous area of the abdominal wall | linea alba |
On each side of the linea alba is the ____ | rectus abdominis muscle |
______ cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled
person to appear segmented | Tendinous inscriptions |
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 |
Deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb |
Triceps brachii | extends the forearm |