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Chapter 6: Muscles
| Term | Definition |
|---|---|
| Contractility | The ability of skeletal muscle to shorten with force |
| Excitability | The capacity of skeletal muscle to respond to stimulus. |
| Extensibility | The ability to be stretched |
| Elasticity | Ability to recoil to their original resting length after they have been stretched. |
| Yes | Do muscles help to produce heat essential for maintenance of normal body temperature |
| Epimysium | connective tissue sheath that surrounds each skeletal muscle |
| Fascia | connective tissue located outside the epimysium. surrounds and separates muscles |
| fascicle | numerous visible bundles |
| perimysium | loose connective tissue surrounds fascicle |
| fibers | single muscle cells |
| endomysium | connective tissue sheath surrounding each fiber |
| myofibrils | threadlike structure that extends from one end of the fiber to the other |
| 2 major kinds of protein | actin myofilaments myosin myofilaments |
| actin myofilaments | thin myofilaments - resemble 2 minute strands of pearls twisted together |
| myosin myofilaments | thick myofilaments - resemble bundles of minute golf clubs |
| sarcomeres | joined end to end to form the myofibril basic structural and functional unity of the muscle |
| resting membrane potential | the charge difference across the membrane |
| action potential | brief reversal back of the charge |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| neuromuscular junction | branch that connects to the muscle near the center of the cell |
| synapse | another name for neuromuscular junction |
| motor unit | a single motor neuron and all the skeletal muscle fibers it innervates |
| presynaptic terminal | the enlarged nerve terminal |
| synaptic cleft | the space between the presynaptic terminal and the muscle cell |
| postsynaptic terminal | muscle fiber |
| synaptic vesicles | located in the presynaptic terminal;secretes a neurotransmitter called acetylcholine |
| acetylcholine | secretion from the synaptic vesicles |
| sarcolemma | acetylcholine diffuses across the synaptic cleft and binds to receptor molecules in the muscle cell membrane |
| acetylcholinesterase | the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzymes |
| sliding filament mechanism | sliding of actin myofilament past myosin myofilaments during contraction |
| muscle contraction | occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten |
| muscle twitch | a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers |
| threshold | point the muscle fiber will contract maximally |
| all-or-none response | threshold phenomenon |
| lag phase | the time between application of a stimulus to a motor neuron and the beginning of a contraction |
| contraction phase | the time of contraction |
| relaxation phase | the time during which the muscle relaxes |
| recruitment | the increase in number of motor units being activated |
| ATP (adenosine triphosphate) | needed for muscle contraction;produced in the mitochondria; short lived |
| Yes | is it necessary for muscle cells to constantly produce ATP? |
| creatine phosphate | when at rest they can't stockpile ATP but they can store another high-energy molecule |
| anaerobic respiration | without oxygen |
| aerobic respiration | with oxygen (more efficient) |
| 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 |
| isometric(equal distance) | the length of the muscle does not change, but the amount increases during the contraction process |
| isotonic(equal tension) | 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. keeps head up and back straight |
| 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. better suited for aerobic metabolism |
| Ex. white meat of a chickens breast | fast-twitch fibers |
| Ex. dark meat of a duck's breast or the legs of a chicken | slow-twitch fibers |
| origin(head) | the most stationary end of the muscle |
| insertion | the end of the muscle undergoing the greatest movement |
| belly | portion of the muscle between the origin and the insertion |
| synergists | muscles that work together to accomplish specific movements |
| antagonists | muscles that work in opposition to one another |
| prime mover | synergists;the major role in accomplishing the desired movement |
| erector spinae | group of muscles on each side of the back; responsible for keeping the back straight and the body erect. |
| thoracic muscles | muscles that move the thorax |
| external intercostals | elevate the ribs during inspiration |
| internal intercostals | contract during forced expiration |
| diaphragm | accomplished quiet breathing; dome-shaped muscle |
| abdominal wall muscles | the muscles of the anterior abdominal wall flex and rotate the vertebral column, compress the abdominal activity, and hold in the abdominal viscera |
| linea alba | tendinous area of the abdominal wall which consists of white connective tissue rather than muscle |
| rectus abdominis | on each side of the linea alba |
| 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 and latissimus dorsi muscles | attatches arm to the thorax |
| pectoralis major | adducts and flexes the arm |
| latissimus dorsi | medially rotates, adducts, and powerfully extends the arm "swimmer arm" |
| deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb |
| triceps brachii | extends forearm |
| biceps brachii | flexes the forearm |
| brachioradialis | flexes and supinates the forearm |
| tetany | where the muscle remains contracted without relaxing |
Created by:
jaaybroooke
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