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a&p chap 7 muscles

QuestionAnswer
Contraction moves the body and body parts
Three types of muscle structure and function skeletal muscle, smooth muscle, and cardiac muscle
Structure of skeletal Muscle Muscle fibers = muscle cellsSkeletal muscles is composed of mainly muscle fibersMuscle fibers extend length of muscleMuscle fibers are arranged in fascicles
Dense connective tissue surrounds each fiber, fascicle, and muscle Establishes tendons to attach muscle to boneEstablishes aponeuroses to attach muscle to other muscles and connective tissues
Skeletal muscle fibers Are multinucleated, long, thin cylinders with rounded ends that extend the length of the muscle
Sarcolemma (skeletal muscle fibers) is the plasma membrane
Sarcoplasm (skeletal muscle fibers) is the cytoplasm
Contain myofibrils (skeletal muscle fibers) the contractile elements - contain thin actin filaments and thick myosin
Each myofibril consists of repeating contractile units called sarcomeres
Neuromuscular interaction A motor neuron sends impulses to a muscle fiber, which produces an actionEach muscle fiber is innervated and controlled by a motor neuronWithout nervous stimulation, a muscle fiber cannot contract
Motor units Consists of a motor neuron and all the muscle fibers it contactsPrecise control: motor unit with very few muscle fibersNo precise control: motor units contain 100s of muscle fibers
Neuromuscular junction Connection between axon of motor neuron and sarcolemma of muscle fiberSpace between axon and sarcolemma is synaptic cleftAxon tip has vesicles with neurotransmitter acetylcholine (ACh)
Physiology of Muscle Contraction Contraction involves a number of rapid structural and chemical changes within a muscle fiberExplained by the Sliding Filament Model
Energy for contraction Energy comes from ATPDue to small amount of ATP in cells, more ATP must be formed to support contractionsUses 2 pathways for making energyCreatine phosphateCellular respiration
Creatine phosphate Storage form of readily available energyStores energy from excess ATP Energy is transferred back to ADP when ATP levels decreaseDepleted quickly in rapidly contracting muscle
Cellular respiration is a 2 step process Anaerobic phaseAerobic phaseRequires oxygen to operate and produce ATP
Oxygen for aerobic phase comes from Hemoglobin in red blood cellsMyoglobin in muscle cells
Sufficient oxygen levels allow for aerobic respiration to occur and Pyruvic acid from anaerobic phase is broken down completely in the mitochondrion during aerobic respiration to CO2 and H2O
Insufficient oxygen with strenuous exercise prevents aerobic respiration so, Pyruvic acid from anaerobic phase gets converted to lactic acid instead of being broken down in to CO2 and H2O
Lactic acid build up causes discomfort and rapid deep breathing.
To remove lactic acid, it must be Broken down by aerobic respiration orConverted back into glucoseBoth processes require oxygen
Oxygen debt amount of oxygen required to metabolize lactic acid and restore normal ATP and creatine phosphate levels
Endurance training increases efficiency of aerobic cellular respiration by increasing Number of mitochondria per muscle fiberEfficiency of obtaining oxygen from blood by increasing area of contact between blood vessels and muscle fibersConcentration of myoglobin
Heat production Heat from muscle contraction is used to maintain normal body temperatureDecrease in body temperature results in shiveringHeat is a by-product of cellular respiration and other metabolic processes happening inside the muscle cell.
Muscle interactions Muscles function in groupsGroups arranged to provide opposing movementsAgonists produce an actionAntagonists produce the opposite actionAgonists and antagonists contract alternatelySynergists are sometimes involved to assist the agonist.
Naming of Muscles Terms used in muscle naming provide information about the muscleExamples of naming criteria areFunctionShapeRelative positionLocation Site of attachmentOrigin and insertionSizeOrientation of fibers
Major Skeletal Muscles There are over 600 muscles in the human bodyAll muscles have anOrigin is the immovable muscle attachmentInsertion is the movable muscle attachmentAction refers to what movement is accomplished when the muscle is contracted
Muscles of breathing Primary breathing muscle is the diaphragm, separating the thoracic and abdominal cavitiesMuscles of the ribs (intercostals) also assist in breathing
Foot movements include DorsiflexionPlantar flexionInversion – sole faces midlineEversion – sole faces away from midline
Created by: Nikia Farmer Nikia Farmer on 2010-07-21




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