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71 Cards in this Set
- Front
- Back
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Myofibril
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make up the contractile components in muscles. The smallest complete contractile system. Densely packed cells with contractile proteins, energy storage and signaling mechanisms.
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Muscle Fiber
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each fiber contains hundreds or even thousands of myofibrils. Each individual fiber consists of a membrane (sarcolemma) and can be further broken down into myofibrils.
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Fasciculus
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Muscle fibers are grouped into bundles of up to 150 fibers called fasciculus.
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Muscle
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Contains smaller wrapped packages known as fasciculus. Each muscle belly is made up of muscle cells or fibers.
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Belly Muscle
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a term used to describe the large mass of muscle that powers movement.
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Contractile property of Muscle Tissue
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allows it to become short and thick in response to nerve impulse and then to relax once impulse removed
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Muscle Cells Elongated
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resemble fibers such as those in rope
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Muscle tissue
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constructed of bundles of these fibers, each approximately the diameter of a human hair
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3 basic muscle types
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Skeletal, cardiac, smooth
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microfilaments |
Narrow, tube like cell structure composed of a protein similar to actin, occurring singly and in bundles, involved in cytoplasmic movement & changes in cell shape. Movement that causes muscles to contract and shorten. |
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Smooth (Visceral) Muscle
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not striated, spindle-shaped cells, single nucleus, involuntary, found within certain hallow organs, blood vessels, respiratory airways, Ability to expand and contract essential to internal processes of body (digestion/regulation of blood pressure)
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Cardiac Muscles
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striated, usually has a single nucleus, branching cells, joined to another muscle cell at an intercalated disc, involuntary, found only in the walls of the heart, Contraction of cardiac muscle squeezes blood out of chambers of the heart, causing blood to circulate through the body, Fibers shorter; receive richer supply of blood than any other muscle in body, Does not regenerate; damage often leads to tissue death
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Skeletal muscles
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mostly attached by tendons to bones. Some muscles attach directly to bone or soft tissue without tendon, using a broad sheet of connective tissue called an aponeurosis. Cells are multinucleate and striated (visible banding), called voluntary bc movement is controlled by conscious thought. Long & cylindrical. muscle is striated, voluntary muscle that allows movement, stabilizes joints, and helps maintain body temperature
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Rules for naming muscles
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muscles can be named based on the location, shape, direction of fibers or a combination.
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orbicularis oculi
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location: encircles eyemuscle origin: frontal, maxilla, & orbitmuscle insertion: eyelidmuscle action: closes eyelid
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biceps brachii
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location: upper armmuscle origin: scapulamuscle insertion: radiusmuscle action: flexes arm at elbow
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triceps brachii
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location: posterior upper armmuscle origin: proximal humerus & scapulamuscle insertion: posterior ulnamuscle action: extends arm at elbow
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Masseter
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location: jaw or mandiblemuscle origin: zygomatic archmuscle insertion: mandiblemuscle action: closes jaw
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sternocleidomastoid
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location: anterolateral neckmuscle origin: sternum & claviclemuscle insertion: mastoid processmuscle action: flexes and rotates head
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Aponeurosis
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a broad sheet of connective tissue
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Contraction
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shortening of a muscle, When muscle stimulated, calcium released from sarcoplasmic reticulum (SR) and allows actin, myosin, & ATP to interact, which causes the contraction
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agonist
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primary mover; chief muscle causing movement; as muscle contracts bones will move
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Point of origin
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muscle end attached to stationary bone
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Point of insertion
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muscle end attached to moving bone
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Synergistic
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muscles that assists primary movers
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Antagonist
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muscles cause movement in opposite direction of agonist
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All movement
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result of contraction of primary movers and relaxation of opposing muscles
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Diaphragm
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Dome-shaped muscle, primary muscle of breathing, separates abdominal cavity and thoracic cavity, Responsible for performing major work of bringing atmospheric air into lungs, Muscle under both voluntary and involuntary control
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rotation
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circular movement that occurs around an axis
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abduction
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to move away from midline of body
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adduction
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movement toward midline of body
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extension
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increasing angle between two bones connected at a joint
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extensor muscle
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Muscle that straightens the joint is
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Flexion
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opposite of extension, decreasing angle between two bones
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flexor
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Muscle that bends the joint
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epimysium
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Typical muscle surrounded by connective tissue, continuous with tendon
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fascicles
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bundles of muscle fibers inside muscles
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perimysium
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surrounds fascicles
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myofibrils
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long organelles inside of muscle cells, made of protein threads arranged in contractile units with two types of protein threads: myosin and actin
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Sarcomeres
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unit contains two threadlike contractile proteins: myosin and actin, makes up myofibril
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myosin
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Thick myofilaments made up of protein
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actin
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THIN ones made up of protein
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contraction of muscles
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causes the two types of myofilaments to slide toward each other and shorten each sarcomere, and therefore entire muscle. requires temporary connections, or cross-bridges, formed between myosin heads and actin
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ATP (adenosine triphosphate)
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provides energy to help myosin heads form and break crossbridges with actin
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calcium
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causes muscles to contract. stored away from actin and myosin in sarcoplasmic reticulum (SR)when muscle is relaxed. When calcium returns to SR, cross-bridges are broken, and the muscle relaxes
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sodium ion channels
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opens when nervous system tells muscle to contract, signal caused by muscle fiber membrane
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sodium ions
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flow into muscle fiber, exciting it
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Neuromuscular junction
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Association site of axon terminal of the motor neuron and muscle
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Synaptic cleft
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Gap between nerve and muscleNerve and muscle do not make contactArea between nerve and muscle is filled with interstitial fluid
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calcium ion
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entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by exocytosis
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Neurotransmitter
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chemical released by nerve upon arrival of nerve impulse in the axon terminal -for skeletal muscle it is ACh
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Muscular Fuel
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needs fuel in the form of nutrients and oxygen to survive and function, Body stores glycogen in the muscle, where it waits to be converted to useable energy source, When needed, glycogen converted to glucose which releases energy, Muscles with very high demands store fat and use it as energy, Energy release causes heat production; this is why strenuous/prolonged exercises can overheat our bodies, Higher demand muscles have richer blood supply to carry oxygen to muscles giving those muscles a darker color
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Vasodilation
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enlarging diameter of blood vessel, can lead to decreases in blood pressure due to smooth muscle relaxation in blood vessel
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Vasoconstriction
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decreasing diameter of blood vessel, Increases blood pressure
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sphincter
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Special type of smooth muscle found throughout digestive system.muscles act to let materials in and out by contracting and relaxing
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Involuntary muscles
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do not contract as rapidly as skeletal muscles Receives only moderate blood supply, resulting in poor repair of injured tissue
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Myopathy
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muscle disease or disorder, Causes include: injury, genetics, nervous system disorders, medication, and cellular abnormalitiesTreatment depends on the cause
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Tendinitis/Tendinosis |
Degenerative disease leading to breakdown and scarring of tendons
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shin splints
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Common inflammatory injury of lower leg extensor muscles and surrounding tissues
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strains and tears
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caused by overstretching tendons or muscles Injuries range from slight overstretch to complete muscle tear or tendon rupture Injuries acute, resulting from trauma, or chronic, resulting from overuse or disease
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signs/symptoms of strains and tears
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vary on severity of injuryMild strain (no tear of muscle or tendon fibers)Moderate strain (some tearing of muscle or tendon fibers)Severe strain (complete tear of muscle or tendon)
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Myalgia
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pain or tenderness in muscle
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Fibromyalgia Syndrome
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Fibromyalgia syndrome (FMS): chronic pain syndrome The cause is unknown and there is no definitive treatment; presently treat with symptom management
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Duchenne Muscular Dystrophy
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Genetic, incurable myopathy All types of muscle affected (smooth, cardiac, and skeletal)Carried on X chromosome, seen more often in boysDisease courseProgressive disease usually diagnosed around age fourBy age ten, child usually wheelchair-bound; Average life span is 17 yearsDeath usually due to respiratory or cardiac failure, no effective treatment
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Myasthenia Gravis
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Autoimmune disorder where immune system attacks and destroys large number of acetylcholine receptors at the neuromuscular junctionSigns and symptoms When motor neurons release acetylcholine, muscle cell cannot respondMuscle weakness fluctuates, worsening with activity and improving with rest
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Tetanus
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Also known as “lockjaw;” caused by untreated bacterial wound infectionBacteria responsible is Clostridium tetani, which lives in soilBacteria release toxin that keeps muscle constantly contracted (“locked”)Prevention possible through vaccinationInitial tetanus series given in childhoodBooster shots given every ten years to adults
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Nonsteroidal anti-inflammatory drugs (NSAIDs)
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Relieve inflammation, but do not have negative side effects of steroidsExamples: ibuprofen (Advil™), naproxen (Aleve™)
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Pain medications
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Aspirin and Acetaminophen (Tylenol)
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Muscle relaxants
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Help muscles rest in order to heal themselvesHelp to relieve musculoskeletal pain or spasmExamples: Flexeril™, Parafon Forte™
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Paralytic medications
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Clinically induce paralysis (like during surgery)Cut off communications between brain and musclesVery precise science; an overdose of these medications can stop heart or breathingExamples: succinylcholine (Anectine™), pancuronium (Pauvulon™)
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interrelation between the nervous and muscular systems
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motor neuron of nervous system initiates activity of muscle contraction through release of neurotransmitter called acetylcholine (ACh)
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