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Anatomy
Chapter 6 Muscles
| Term | Definition |
|---|---|
| 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 |
| Epimysium | connective tissue sheath |
| Fascia | connective tissue located outside the epimysium, it surrounds and separates muscles |
| Perimysium | loose connective tissue |
| Fibers | fasciculi are composed of single muscle cells |
| Endomysium | fibers surrounded by a connective tissue stealth |
| myofibrils | a threadlike structure that extends from one end of the fiber to the other |
| actin myofilaments | type of protein fiber, they resemble 2 minute strands of pearls twisted together |
| myosin myofilaments | thick myofilaments |
| sarcomeres | actin and myosin myofilaments from highly ordered units |
| resting membrane potential | charge across membrane |
| action potential | the brief reversal back of the charge |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| neuromuscular junction | each branch that connects to the muscle |
| synapse | near the center of the cell |
| motor unit | a single motor neuron and all 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 in the between the presynaptic terminal |
| synaptic vesicles | each presynaptic terminal contains this |
| acetylcholine | that secrete neurotransmitter |
| acetylcholinesterase | it's released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by enzymes |
| sliding filament mechanism | sliding of actin myofilaments past myosin myofilaments during contraction |
| muscle twitch | a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more fibers |
| threshold | a muscle fiber that will not respond to stimulus reaches a level |
| all-or-none response | threshold phenonmenon |
| 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 the time during which |
| relaxation phase | time during which the muscle relaxes |
| tetany | where the muscle remains contracted without relaxing |
| recruitment | the increase in the number of motor units being activated |
| ATP (adenosine triphosphate) | needed for energy for muscle contraction |
| ATP is produced by | mitochondria |
| ATP is short-lived and | unstable |
| It degenerates to the more stable ADP plus | Phosphate |
| creatine phosphate | can store high energy molecule |
| 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 |
| isometric | length of muscle does not change, but amount of tension increases during contraction process |
| isotonic | amount of tension produced by the muscle is constant during contraction but the length of the muscle changes |
| muscle tone | constant tension produced by muscles of the body for a long period of time |
| fast-twitch fibers | contract quickly and fatigue quickly |
| slow-twitch fibers | contact more slowly and are more resistant to fatigue |
| origin (head) | most stationary end of the muscle |
| insertion | the end of the muscle undergoing the greatest movement |
| belly | where the portion of muscle between the origin and the insertion |
| some muscles have | multiple origins or head |
| synergists | muscles that work together to accomplish specific movements |
| antagonists | muscles that work in opposition to one another |
| most muscles have names that are | descriptive |
| some muscles are named according to | location, size, orientation of fibers, shape, origin, insertion and function, etc. |
| occipitofrontalis | raises the eyebrows |
| orbicularis oculi | closes the eyelids and causes "crows feet" wrinkles in the skin at the lateral corners of the eye |
| orbicularis oris | puckers the lips |
| zygomaticus | smiling muscle |
| levator labii supererioris | sneering |
| 62 buccinator | flattens the cheeks |
| orbicularis oris and buccinator | kissing muscles |
| depressor anguli | frowning |
| intrinsic tongue muscle | change shape of tongue |
| extrinsic tongue muscle | move the tongue |
| sternocleidomastoid | lateral neck muscle and prime mover |
| erector spinae | group of muscle and prime mover. |
| external intercostals | elevate the ribs during inspiration |
| internal intercostals | contract during forced expiration |
| diaphragm | accomplishes quiet breathing |
| 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 |
Created by:
drewcyrus_
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