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37 Cards in this Set
- Front
- Back
General Roles of Muscle Tissue
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-Motion
-Stabilize body positions & regulate organ volume -thermogenesis |
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Functional Properties of Muscle Tissue
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Excitability
Contractility Extensibility Elasticity |
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Structural Statements to Skeletal Muscles
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cylindrical (multinucleate)
striated |
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Structural Statements to Cardiac Muscles
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branching (single cell)
intercalated discks striations |
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Structural Statements to Smooth Muscles
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2 types: Single & Multi unit
Spindle Shaped, no striations, no neuromuscular juncion, no T Tubule, no troponin, uses calmodulin |
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Myofiber
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muscle fiber
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Myofibril
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rodlike bundle of contractile filaments found in muscle fibers
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Triad
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successive groupings of the 3 membranous structures: terminal cisterna, T tubule, and terminal cisterna
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Sarcomere
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Piece of Myofibril
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How to Z discs, I bands, and A bands of myofibril change with contraction
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--I bands shorten
--Distances between successive Z discs is reduced --H zones disappear --Contiguous A bands move closer together but don't change in length |
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4 steps of cross bridge cycling
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Binding
Bending Unbinding Straightening |
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Binding stage of cross bridge cycle
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Ca2+ required
activated myosin heads are strongly attracted to exposed binding sites on actin and cross bridges are formed cross |
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Bending stage of cross bridge cycle
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ADP released
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Unbinding stage of cross bridge cycle
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As a new ATP molecule binds to the myosin head, myosin's hold on actin loosens and the cross bridges detach from actin
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Straightening stage of cross bridge cycle
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ATP hydrolosis energy to "cock" cross bridges
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3 parts of neuromuscular junction
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axon end( neuromuscular junction)
Neuromuscular Gap Motor End Plate |
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What are the events that occur at the Neuromuscular junction?
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When a nerve impulse reaches the end of an axon, the voltage gated calcium channels in its membrane open, allowing calcium to flow in from the ECF. Prescence of Calcium inside axon terminal cause some of synaptic vesicles to fuse w/axonal membrane and release ACh into synaptic cleft by exocytosis. ACh diffuses across the cleft and ataches to Ach receptors on sarcolemma. Then, the Ach is quickly broken down to its building blocks, acetic acid and choline by acetycholinesterase.
This destruction of Ach prevents continued muscle fiber contraction. |
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What is meant by excitation-contraction coupling?
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It is the sequence of events by which transmission of an action potention along the sarcolemma leads to the sliding of myofilaments
Calcium binds to troponin Troponin then pulls on tropomyosin Open binding sites on actin |
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Botulinis toxin
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Blocks exocytosis, Ach can't be released.
Individual dies of suffocation, diaphram can't contract (flaccid paralysis) |
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Curare
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ACh mimicer
Doesn't open channels Contractions are prevented (flaccid paralysis) |
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AchE
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an Ach antagonist
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Motor Unit
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a motor neuron and all the muscle cells it stimulates
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All or None Law
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A motor neuron delivers a threshold stimulus to all of the cells of the motor unit and each cell contracts fully and completely. There is no partial contraction of the motor unit. The muscle either contracts or it doesn't
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How are graded contractions achieved? What four factors effect the amount of force (tension) a muscle can generate?
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1. Frequency of stimulatino of muscle fiber by motor neurons
2. Length of muscle fibers before they begin to contact 3. The # of muscle fibers contracting at any one given time (# of activated motor units) 4. Structural compnents of the muscle itself |
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Twitch
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response of a motor unit to a single actino potential of its motor neuron
3 phases: latent, contraction, relaxation |
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Tetanus
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state of sustained contraction of a muscle during which the muscle does not relax to its initial length or tension, induced by a rapid succession of stimuli
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Summation
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Process by qhich multiple or reeated stimuli can produced a response in a nerve muscle or other part that one stimulus cannot produce
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Tone
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sustained, small contractions of motor units give skeletal muscles a firmness without producing movement. This is essential for maintaining posture
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Isometric contraction
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occur when muscle does not or cannot shorten, but tension within it greatly increases.
No length change, 0% efficient, all energy lost as heat ex- holding a book in a steady position |
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isotonic contraction
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occur when you move a constant load through the range of motions possible at a joint. In this type of contraction, the tension within the muscle stays the same during contraction, while the length of the fibers shortens (Most movements in body)
Length changes 25% efficient |
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Concentric and eccentric contraction fall under what type of contraction?
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Isotonic
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Concentric
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muscl eshortens and soes work, like picking up a book or kicking a ball
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Eccentric
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muscle generates force as it lengthens
Ex- calf muscle as you walk up a hill |
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_____ contractions put the body in position to contract _______.
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Eccentric, concentrically
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Treppe
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Muscle begins to contract after a long period of rest, its initial contractions to the stimuli get stronger and stronger. Even thought the stimuli are of same intensity & speed, the 1st few contractions produce a staircase effect. No summation- warm up period for athletes
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Oxygen Debt
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extra amount of oxygen body must take in for restorative processes
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Why does oxygen debt occur?
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For a muscle to return to its resting state, its oxygen reserves must be replenished, the accumulated lactic acid must be reconverted to pyruvic acid, glycogen stores must be replenished, glycogen stores must be replaced, ATP and creating phosphate reserves must be resynthesized. Also, the liver must convert any lactic acid persisting in the blood to glucose or glycogen. Oxygen debt represents the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used
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