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73 Cards in this Set
- Front
- Back
Three types of muscle found in the body
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skeletal, cardiac, smooth
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prefixes that refer to muscles
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myo & mys
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what determines the concentration of muscles?
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the movement of microfilaments
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Skeletal muscle characteristics
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1. attached by tendons to bones
2. cells are multinucleated 3. Striated 4. voluntary |
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What do muscle fibers look like?
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long cylinders
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Another name for muscle fibers
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muscle cells
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muscle cells are surrounded by what?
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connective tissue
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Endomysium
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encloses a single muscle fiber
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Perimysium
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Wraps around a fasicle of muscle fibers
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Epimysium
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covers the entire skeletal muscle
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Fascia
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On the outside of of the epimysium, continuous with hypodermis and epimysium
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Tendons
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cord-like structures composed of collagen fibers, often cross a joint due to toughness and small size
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Aponeuroses
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Sheet-like structures, attach muscles to other muscles or skin. Indirectly attach muscles to bones
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Aponeuroses is similar to what?
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A tendon but in sheet form
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Sites of muscle attatchment
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Bones, Cartilages, Connective tissue coverings
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Smooth muscle characteristics
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1. Lacks striations
2. Spindle-shaped cells 3. Single nucleus 4. Involuntary muscle control |
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Cardiac muscle characteristics
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1. Striations
2. Single nucleus 3. Branching cells 4. Involuntary 5. Joined to other muscle cells at intercalated disks |
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Skeletal muscle functions
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1. Produce movement
2. Maintain posture 3. Stabilize joints 4. Generate heat |
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Do skeletal muscles push or pull to do work?
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They pull and shorten
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Microscopic anatomy: Sarcolemma
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specialized plasma membrane outside of muscle fiber
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Microscopic anatomy: Myofibrils
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Long organelles inside muscle cells, fill most of interior space of muscle fibers
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Microscopic anatomy: Sarcoplasmic reticulum
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specialized smooth endoplasmic reticulum
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Endoplasmic reticulum
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wrapped around myofibrils
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L band
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"Light band" contains only thin filaments
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A band
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"dark band" contain the entire length of the thick filaments
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Microscopic anatomy: Sarcomere
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contractile unit of a muscle fiber (functional unit of muscle fibers, repeating units like links on a chain)
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Myofilaments
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thin filament= actin filaments
thick filament= myosin filaments |
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Myosin Filaments characteristics
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Thick filaments, composed of the protein myosin, has ATPase enzymes, myosin filaments have heads
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Actin Filaments characteristics
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Thin filaments, composed of the protein actin, anchored to the z-disc
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ATPase enzyme
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can break ATP to release energy to do work
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Z-disc
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Proteins that connect sarcomeres to other sarcomeres
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Sarcoplasmic reticulum
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stores and releases calcium, surrounds the myofibrils
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Excitability
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ability to receive and respond to a stimulus
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Contractility
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ability to shorten when an adequate stimulus is received
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Extensibility
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ability of muscle cells to be stretched
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Elasticity
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ability to recoil and resume resting length after stretching
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What stimulates a muscle to contract?
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motor neuron (nerve cell)
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Motor unit
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one motor neuron and all the skeletal muscle cells stimulated by that neuron
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Relationship between motor units and motor neurons
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Motor neurons are branching to a motor unit
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Neuromuscular junction
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Association site of axon terminal of the motor neuron and muscle, location where an axon terminal of a neuron interacts with the sarcolemma of a muscle fiber
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Axons
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long extensions that carry signals
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Action Potential
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special kind of electrical signal (can be carried by neurons and muscle cells)
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Axon terminals
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Ends of axons
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Synaptic Gap
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Gap between nerve and muscle (THEY DO NOT MAKE CONTACT) The area between is filled with interstitial fluid
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How many fibers are stimulated during a muscle contraction?
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It depends based on how much force is put into the contraction
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Graded response
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different degrees of muscle shortening
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How are graded responses produced?
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By changing:
1.The frequency of muscle stimulation 2. The number of muscle cells being stimulated at one time |
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Use one or fewer motor units
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Very small, very fine, precise movements (only in muscles of eyes)
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Use many motor units and larger motor units
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Large, powerful, less precise movements (ie hamstrings)
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Types of graded responses
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Twitch, Tetanus, Unfused tetanus, Fused tetanus
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Twitch
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Single, brief contraction, not a normal muscle function
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Tetanus
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One contraction is immediately followed by another, the muscle does not completely return to a resting state
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Fused (complete) Tetanus
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Sustained, continuous contraction
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First source of energy to muscles
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Stored ATP, only 4-6 seconds of energy provided, ATP bonds are broken to release energy
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Unfused (incomplete) Tetanus
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Some relaxation occurs between contractions
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Second source of energy to muscles
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Direct phosphorylation of ADP by creatine phosphate
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Third source of energy to muscles
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Aerobic respiration or Anaerobic glycolysis
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How does Aerobic respiration give the muscles energy?
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Glucose is broken down to carbon dioxide and water, releasing ATP
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Characteristics of aerobic respiration
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Requires Oxygen, Very efficient with high ATP output
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How does anaerobic glycolysis provide muscles with energy?
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Glucose is broken down to pyruvic acid to produce some ATP
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Anaerobic glycolysis characteristics
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Does not require oxygen, does require large amounts of glucose. Not efficient but is fast
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What type of exercise requires anaerobic glycolysis?
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powerful explosive exercise, does not last long so it is reserved for intense short exercise
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What type of exercise requires aerobic respiration?
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Endurance exercise, ie running and cycling
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What happens when a muscle is fatigued?
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It can no longer contract even with stimulus
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Cause of fatigue
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Oxygen deficit
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How is muscle fatigue cured?
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oxygen must be repaid to get rid of accumulated lactic acid
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Types of muscle contractions
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Isotonic, Isometric, Eccentric
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Isotonic Contractions
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The muscle shortens and movement occurs (visible movement), myofilaments are able to slide past each other during contractions
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Isometric contraction
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Tension in the muscle increases, the muscle is unable to shorten or produce movement, movement will not occur
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Eccentric Contraction
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Muscle breaking, stopping the muscle from going as fast as it usually would
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Muscle tone
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Some fibers are always contracted, different muscle fibers at different times, involutary
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Sarcoplasmic Reticulum
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Looks like a crocheted sweater surrounding myofibrils, they store calcium
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Acetylcholine
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neurotransmitter in neuromuscular junctions, stimulate muscle cells
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