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Shapter 6: Muscles


Contractibility skeletal muscles shorten with force
Excitability skeletal muscle responds to stimulus
Extensibility skeletal muscles stretches
Elasticity skeletal mucles recoilt ooriginal length after being stretched
Epimysium connective tissue that surrounds skeletal muscle
Fascia connective tissue located outside of the epimysium
Fascicle bundles the compose a muscle
Perimysium loose connective tissue that surrounds the fascicle
Myofibrils a structure that extends from one end of a fiber to the other
Actin Myofilaments THIN myofilaments that resemble 2 strands of pearls twisted together
Myosin Myofilaments THICK myfilaments that resemble bundles of golf club
Sarcomeres formed by both actin a myosin myofilaments
Sarcomeres are joined end to end to form the myofibril
Sarcomeres are the basic structural and funtional unit of the muscle
Resting Membrane Potential the difference across the membrane
Action Potential the reversal back of the charge
Motor Neurons nerve cells that carry action potentials to muscle fibers
Neuromusclular Junction formed by each branch the connect to the muscle
Synapse Neuromusclular Junction
Neuromusclular Junction formed near the center of a cell
Motor Unit composed of a single motor neuron and the skeletal muscle fibers it innervates
Motor Unit formed a single muscle
Presynaptic Terminal the enlarged nerve terminal
Synaptic Cleft the space between the presynaptic terminal and the muscle cell
Postsynaptic Terminal the muslce fiber
Synaptic Vesicles secrete a neurotransmitter called Acetylcholine
Acetylcholine diffuses across the synaptic cleft and binds to the postsynaptic terminal
Acetylcholine causes a change in the postsynaptin cell
Acetylcholinesterase rapidly break down the synaptic cleft
Sliding Filament Mechanism the sliding of actin myofilaments past myosin myofilaments during contraction
Muscle Twitch the contraction of an entire muscle in response to a stimulus
Muscle Twitch causes the action potential in one or more muscle fibers
Threshold point at which the muscle fiber will contract maximally
All-or-None Response the action of the muscle fiber contracting maximally
Lag Phase the time between application of a stimulus to a motor neuron
Lag Phase the beginning of a contraction
Contraction Phase the time of contraction
Relaxation Phase time during which the muscle relaxes
Tetany when the muscle remains contracted without relaxing
Recruitment increase in number of motor units being activated
ATP adenosine triphosphate
Adenosine Triphosphate needed for energy for muscle contraction
Adenosine Triphosphate produced in the mitochondria
ATP short-lived and unstable
ADP adenosine diphosphate
Adenosine Diphosphate more stable than ATP
Creatine Phosphate a high energy molecule
Occipitofrontalis raises eyebrows
Orbicularis Oculi closes eyelids
Orbicularis Oris puckers lips
Buccinator smiling
Kissing Muscles orbicularis oris and buccinator
Zygomaticus responsible for smiling
Levator Labii Superioris sneering
Depressor Anguli Oris frowning
Tongue Muscles intrinsic and extrinsic
Extrinsic Tongue Muscle moves the tongue
Intrinsic Tongue Muscle changes shape of the tongue
Masticating another name for chewing
Masticating Muscles Masseter, Temporalis, Pteragoids
Sternocleidomastoid located in the neck
Pectoralis Major located in the upper limb of the body
Trunk Muscles erector spinal
Erector Spinal found on each side of the back
Erector Spinal responsible for erect posture
Thoracic Muscles External Intercostal, Internal Intercostal, Diaphragm
External Intercostal contract during inspiration
Internal Intercostal contract during forced expiration
Diaphragm dome shaped muscles responsible for quiet breaths
Abdominals Rectus Abdominis, Linea Alba, Tendinous Inscriptions, External Abdominal Obliques
Rectus Abdominus abs
Linea Alba white line of connective tissue that extends from the sternum to the pubis
Tendinous Inscriptions cross the rectus abdominis in 3 places & form a segmented look in the abs
External Abdominal Obliques internal and transverse
Origin most stationary end of the muscle
Insertion the end of the muscle undergoing the greatest amount of 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 the muscle in a group of synergists that plays the major role in accomplishing the desired movement
Created by: Donielle



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