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ch.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 resting length after they have been stretched. |
| Epimysium | A connective tissue sheath |
| Fascia | A connective tissue which surrounds and separates muscles |
| Perimysium | Loose connective tissue that surrounds the muscle fasciculi |
| Fibers | Single muscle cells which make up the fasciculi |
| Muscle fasciculi | Visible bundles which make up the muscle |
| Endomysium | A connective tissue sheath which surrounds the fibers |
| Myofibrils | A threadlike structure that extends from one end of the fiber to the other. |
| Actin myofilaments | Thin filaments; resemble 2 minute strands of pearls twisted together |
| Myosin myofilaments | Thick filaments; resemble bundles of minute golf clubs |
| Sarcomeres | Highly ordered units formed by actin & myosin myofilaments; basic structural and functional unit of the muscle |
| Resting membrane potential | The charge difference across the 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 |
| Motor unit | A single motor neuron and all the skeletal fibers it innervates |
| Presynaptic terminal | The enlarged nerve terminal |
| Synaptic cleft | The space between the presynaptic terminal and the muscle cell |
| Postsynaptic terminal | The muscle fiber |
| Synaptic vessels | in the postsynaptic terminal, secretes a neurotransmitter called acetylcholine |
| Sliding filament mechanism | The 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 muscle fibers |
| Threshold | The level at which point the muscle fiber will contract maximally |
| 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 |
| Tetany | When the muscle remains contracted without relaxing |
| Recruitment | The increase in number of motor units being activated |
| ATP (adenosine triphosphate) | Needed for energy for muscle contraction |
| Creatine phosphate | A high energy molecule that ATP can store |
| 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 in the muscle cells |
| Isometric | The length of the muscle does not change but the amount of tension increases during the contraction process |
| Isotonic | The 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 long periods of time |
| 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. They are better suited for aerobic metabolism |
| Origin | The most stationery end of the muscle |
| Insertion | The end of the muscle undergoing the greatest movement |
| Belly | The portion of the muscle between the origin and insertion |
| Synergists | Muscles that work together to accomplish specific movements |
| Antagonists | Muscles that work in opposition to one another |
| Prime mover | One muscle that plays a major role in accomplishing a desired movement |
| Occipitofrontalis | Raises the eyebrows |
| Orbicularis oculi | Closes the eyelids and causes crows feet wrinkles |
| Orbicularis oris | Puckers the lips |
| Buccinator | Flattens the 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 |
| Platysma | Sheetlike muscle that covers the anterolateral neck |
| Erector spinae | Group of muscles on each side of the back |
| Linea alba | A tendinous area of the abdominal wall |
| Rectus abdominis | On each side of the linea alba |
| 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 |
| Deltiod | Attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb |
| Triceps brachii | Extends the forearm |
| Biceps brachii | Flexes the forearm |
| Flexor carpi | Flexes the wrist |
| Extensor carpi | Extends the wrist |
| Flexor digitorum | Flexes the fingers |
| Extensor digitorum | Extends the fingers |
| Quadriceps femoris | Extends the leg |
Created by:
skfreem1
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