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Muscles chapter 6


contractility The ability of skeletal muscle to shorten with force
Excitability capacity of skeletal muscle to respond to a stimulus
Extensibility Ability to be stretched
Muscle fiber muscle cell
Epimysium Each skeletal muscle surrounded by connective tissue sheath
Fascia Another connective tissue located outside the epimysium
Fascia surrounds and separates muscles
Fasciculi muscle that is composed of numerous visible bundles
perimysium Fasciculi is surrounded by loose connective tissue
Actin myofilaments thin Myofilaments, which resemble 2 minute strands of pearls twisted together
Myosin myofilaments thick Myofilaments, which resemble bundles of golf clubs
Sarcomeres Actin and Myosin Myofilaments form highly ordered units
Sarcomeres which are joined end to end to form myofibril
sarcomere basic structural and functional unity
sarcomere each one extends from one Z line to another Z line. Each Z line is an attachment site for actin
resting membrane potential outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively the charge difference across the membrane
action potential when muscle cell is stimulated the membrane characteristics change briefly, the brief reversal back of charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
neuromuscular junction axons enter the muscle and branch. Each branch that connects to the muscle
motor unit single motor neuron and all skeletal muscle fibers it innervates
presynaptic terminal enlarged nerve terminal
synaptic cleft space between presynaptic terminal and muscle cell
postsynaptic terminal the muscle fiber in it
Synaptic vessels each presynaptic vessel contains it
acetylocholine secrete a neurotransmitter
acetylocholine diffuses across synaptic cleft and binds to the postsynaptic terminal causing a change in postsynaptic cell
sliding filament mechanism sliding of actin myofilaments past myofilaments during contraction
muscle twitch contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
threshold muscle fiber will not respond to stimulus until the stimulus reaches a level
lag phase time between application of a stimulus to a motor neuron and beginning of contraction
contraction phase time of contraction is
relaxation phase time during which the muscle relaxes
Tetany where the muscle remains contracted without relaxing
recruitment increase of number of motor units being activated
ATP(adensosine triphosphate) is needed for energy for muscle
ATP produced in the mitochondria
Creatine phosphate When rest they cant stockpile ATP but they can store another high end molecule
Anaerobic respiration without oxygen
Aerobic respiration with oxygen(more efficient)
muscle fatigue results of ATP is used during muscle contraction faster than it can be produced in 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 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 and back straight
Fast-twitch fibers contract quickly and fatigue quickly well adapted to perform anaerobic metabolism
slow twitch fibers contract more slowly and is more resistant to fatigue, they are better suited for aerobic metabolism
origin(head) is the most stationary end of the muscle
Insertion end of the muscle undergoing the greatest movement
belly portion of muscle between the origin and insertion
Synergist muscles that work together to accomplish specific movements
antagonist muscles that work in opposition to one another
occipitofrontalis raises the eyebrows
Orbicularis oculi closes the eyelids and causes crows feet, wrinkles skin at lateral corners of eyes
orbicularis oris puckers the lips
Buccinator Flattens cheeks, Trumpeters muscle
Zygomaticus smiling muscle
Levatator Labii superioris sneering
Depressor anguli oris frowning
Mastification chewing
Intrinsic Tongue Muscle change the shape of tongue
Extrinsic Tongue Muscle Move the Tongue
Sternocleidmastoid lateral neck muscle and prime mover, rotates and abducts the head
Platysma sheetlike muscle that covers the anterolateral neck, pulls the corners of mouth inferiorly
Erector spinae group of muscles on each side of the back. Responsible for keeping the back straight and body erect
External intercostals elevate the ribs during inspiration
Internal intercostals contract during forced expiration
Diaphram accomplishes quiet breathing
Trapezius Rotates scapula
serratus anterior pulls scapula anterior
Pectoralis Major adducts and flexes arm
Triceps brachii extends the forearm
Biceps brachii flexes the forearm
Brachialis flexes forearm
Brachioradialis flexes and supinates the forearm
flexor carpi flexes wrist
extensor carpi extends the wrist
flexor digitorium flexes the fingers
Created by: Kbrumfield