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muscle notes
| Term | Definition |
|---|---|
| contractility | the ability of skeletal muscle to shorten with force |
| excitability | 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 | skeletal muscle is surrounded by a connective tissue sheath |
| fascia | another connective tissue located outside the epimysium |
| perimysium | a muscle is composed of numerous visible bundles called muscle fasciculi, which are surrounded by loose connective tissue |
| fibers | fasciculi are composed of single muscle cells |
| endomysium | each fiber is surrounded by a connective tissue sheath |
| myofibers | a threadlike structure that extends from one end of the fiber to the other |
| actin myofilaments | thin myofilaments, they resemble 2 minute strands of pearls twisted together |
| myosin myofilaments | thick myofilaments, they have resemble bundles of minute golf clubs |
| sarcomeres | actin myosin myofilaments form highly ordered units |
| resting membrane potential | the change difference across the membrane |
| action potential | when a muscle cell i stimulated the membrane characteristics change briefly |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| neuromuscluar junction or synapse | near the center of the cell |
| motor joint | a single motor neuron and all the skeletal muscle fibers innervates |
| presynaptic terminal | the enlarged nerve terminal |
| synaptic cleft | the space between the presynaptic terminal |
| postsynaptic terminal | the muscle fiber |
| acetylcholine | the secrete a neurotransmitter |
| synaptic vesicles | what each presynaptic terminal contains |
| acetylcholinesterase | the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by this enzyme |
| sliding filament mechanism | the sliding of actin myofilaments past myosin myofilaments during contraction |
| muscle twitch | a contraction of an entire muscle is response to a stimulus that causes the action potential in one or more muscle fibers |
| threshold | the point to which the muscle fibers will contract maximally |
| all- or- none response | the 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 a contraction |
| relaxation phase | the time during which the muscle relaxes |
| tetany | where the muscle remains contracted without relaxing |
| recruitment | the increase in number of motor units being activated |
| creatine phosphate | when at rest they cant stockpile atp but they can store another 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 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 | muscle tone refers to constant tension produced by muscle of the body for long periods of time |
| fast-twitch fibers | contract quickly and fatigue guickly |
| slow-twitch fibers | contract more slowly and are more resistant to fatigue |
| origin | (head) is the most stationary end of the muscle |
| insertion | the end of the muscle undergoing the greatest movement |
| belly | the 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 | if one muscle plays the major role in accomplishing the desired movement |
| 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 |
| buccinator | flattens the cheeks |
| Zygomaticus | smiling muscle |
| Levator labii superioris | sneering |
| Depressor anguli oris | frowning |
| Intrinsic Tongue Muscles | change the shape of the tongue |
| Extrinsic Tongue Muscles | move the tongue |
| Sternocleidomastoid | lateral neck muscle and prime mover. Rotates and abducts the head |
| Erector spinae | group of muscles on each side of the back. Responsible for keeping the back straight and the body erect |
| External intercostals | elevate the ribs during inspiration |
| Internal intercostals | contract during forced expiration |
| Diaphragm | accomplishes quiet breathing. Dome-shaped muscle. Aids in breathing. |
| linea alba | The tendinous area of the abdominal wall |
| rectus abdominis | it is 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 | how the arm is attached to the thorax |
| Pectoralis major | adducts and flexes the arm |
| Latissimus dorsi | medially rotates, adducts, and powerfully extends the arm. “Swimmer muscles” |
| Deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb. |
| Triceps brachii | extends the forearm. Occupies the posterior compartment of the arm |
| Biceps brachii | flexes the forearm. Occupies the anterior compartment of the arm |
| Brachialis | flexes forearm |
| Brachioradialis | flexes and supinates the forearm |
Created by:
Bnbevin2
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