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chapter 6 muscles
muscles
| Question | Answer |
|---|---|
| the ability of skeletal muscle to shorten with force | contractility |
| the capacity of skeletal to respond to a stimulus | excitability |
| the ability to be stretched | extensibility |
| the ability to recoil to their original resting length after they have been stretched | elasticity |
| connective tissue sheath surrounding each skeletal muscle | epimysium |
| outside the epimysium. surrounds and separates muscles | fascia |
| a muscle is composed of numerous visible bundles called _____ ______. | muscle fasciculi (fascicle) |
| loose connective tissue surrounding the fasciculi | perimysium |
| the connective tissue sheath surrounding each muscle fiber | endomysium |
| the cytoplasm of each fiber is filled with _____. | myofibrils |
| thin myofilaments | actin |
| thick myofilaments | myosin |
| highly ordered units formed by actin and myosin myofilaments | sarcomeres |
| basic structural and functional unit of the muscle | sarcomere |
| 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 |
| an enlarged nerve terminal resting in an indentation of the muscle cell membrane | neuromuscular junction |
| 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 and the postsynaptic terminal | synaptic cleft |
| the muscle fiber | postsynaptic terminal |
| each presynaptic terminal contains | synaptic vesicles |
| synaptic vesicles secrete a neurotransmitter called | acetylcholine |
| the enzyme that breaks down the acetylcholine | acetylcholinesterase |
| a contraction of an entire muscle in response to a stimulus | muscle twitch |
| the time between application of a stimulus to a motor neuron and the beginning of a contraction | lag time |
| 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 | adenosine triphosphate |
| ATP is needed for | energy for muscle contraction |
| ATP is produced in the | mitochondria |
| ATP is | short-lived and unstable |
| another high-energy molecule stored when muscles are at rest | creatine phosphate |
| without oxygen | anaerobic respiration |
| with oxygen (more efficient) | aerobic respiration |
| the amount of oxygen needed in chemical reactions | oxygen debt |
| when ATP is used faster than it can be produced by muscle fibers | muscle fatigue |
| the length of the muscle does not change, but the tension increases during the contraction phase | isometric contraction |
| the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes | isotonic contraction |
| constant tension produced by muscles of the body for long periods of time | muscle tone |
| contract quickly and fatigue quickly | fast twitch fibers |
| contract slowly and are more resistant to fatigue | slow twitch fibers |
| points of attachment | origin and insertion |
| the most stationary end of the muscle | origin |
| the end of the muscle undergoing the greatest movement | insertion |
| the portion 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 |
| the one muscle that plays the major role in a group of synergists | prime mover |
| occipitofrontalis | raises the eyebrows |
| orbicularis oculi | closes the eyelids and causes "crows feet" |
| orbicular oris | puckers the lips |
| buccinator | flattens the cheeks |
| zygomaticus | smiling muscle |
| levator labii superioris | sneering |
| depressor anguli oris | frowning |
| mastication | chewing |
| intrinsic tongue muscle | change the shape of the tongue |
| extrinsic tongue muscle | move the tongue |
| lateral neck muscle and prime mover | sternocleidomastoid |
| sheetlike muscle that covers the anterolateral neck | platysma |
| group of muscles on each side of the back | erector spinae |
| muscles that move the thorax | thoracic muscles |
| most involved in breathing | external and internal intercostals |
| external intercostals | elevate the ribs during inspiration |
| internal intercostals | contract during forced expiration |
| accomplishes quiet breathing. dome shaped | diaphragm |
| tendinous area of the abdominal wall, consists of white connective tissue rather than muscle | linea alba |
| on each side of the linea alba | rectus abdominis |
| cross the rectus abdominis at three or more locations | tendinous inscriptions |
| trapecius | 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 humerous to the scapula and clavicle |
| triceps brachii | extends the forearm |
| biceps brachii | flexes the forearm |
| brachialis | flexes forearm |
| brachioradialis | flexes and supinates the forearm |
| strong band of fibrous connective tissue that covers the flexor and extensor tendons | retinaculum |
| flexor carpi | flexes the wrist |
| extensor carpi | extends the wrist |
| flexor digitorum | flexes the fingers |
| extensor digitorum | extends the fingers |
| 19 hand muscles | intrinsic hand muscles |
| located between the metacarpals | interossi muscles |
| gluteus maximus | buttocks |
| gluteus medius | hip muscle |
| quadriceps femoris | extends the leg |
| sartorius | "tailors muscle", flexes the thigh |
| posterior thigh muscles, extends the leg and extends the thigh | hamstring muscle |
| forms the calf muscle | gastroncnemius and soleus |
| flex the foot and toes | calcaneal tendon (achilles tendon) |
| lateral muscles of the leg | peroneus muscles |
| 20 muscles located within the foot | intrinsic foot muscles |