Print Muscle Tissue and the Neuromuscular Junction flashcards

front 1 muscle tissue types	back 1 skeletal, smooth, cardiac
front 2 properties of muscle tissue	back 2 excitable conductive contractile elasticity extensibility
front 3 excitable	back 3 Responsive to a stimulus
front 4 conductive	back 4 transfers stimulus along the cell membrane

front 5 contractile	back 5 shorten their length to create tension
front 6 elasticity	back 6 return to rest after shortening or lengthening
front 7 extensibility	back 7 stretch beyond their resting length
front 8 primary function od muscle tissue	back 8 movement support posture temperature regulations communications

front 9 epimysium	back 9 surrounds entire muscle DICT
front 10 perimysium	back 10 surrounds fascicles DICT with BV and nerves
front 11 endomysium	back 11 surrounds and electrically insulates each muscle fiber ARC with reticular fibers
front 12 deep fisca	back 12 large sheet external to epimysium

front 13 superficial fascia	back 13 separate muscle from skin ARADCT
front 14 tendon	back 14 attaches a muscle to bone skin or other muscles
front 15 aponeurosis	back 15 this flattened connective tissue
front 16 sacrolemma	back 16 plasma membrane

front 17 sarcoplasm	back 17 cytoplasm
front 18 sarcoplasmic reticulum	back 18 smooth ER
front 19 Myofibrils	back 19 muscle fiber running the entire length contraction = shorten contain myofilaments
front 20 thick filaments	back 20 myosin tail

front 21 thin filaments	back 21 • Actin • Tropomyosin • Troponin
front 22 sacromere	back 22 functional unit of muscle smallest piece functions as a muscle
front 23 I band	back 23 contains thin filaments not thick
front 24 A band	back 24 contains thick filament are dark

front 25 H zone	back 25 center of A band contains thick filaments not thin
front 26 M line	back 26 protein in center of H zone that attaches thick filaments
front 27 contraction of skeletal muscle	back 27 • Contracting muscles pull on tendons to produce movement. • To pull, muscles develop tensions as their sarcomeres shorten. • For sarcomeres to shorten, thick filaments attach to thin filaments and pull them toward the centers of the sarcomeres • The sliding filament theory explains muscle contraction
front 28 sliding filaments theory	back 28 Calcium ions bind to troponin on actin’s active site Myosin binds actin to form a cross-bridge (“cocked” formation) Phosphate is released, the myosin head moves into low-energy conformation and actin slides towards the M line (“powerstroke”) A new molecule of ATP replaces ADP (cross-bridge detachment) Cross-bridges break and the cycle repeats

front 29 NMJ	back 29 where the axon terminal of an alpha motor neuron and the membrane of a muscle fiber meet
front 30 Stimulation causes build-up of	back 30 intracellular Na+, exit of intracellular K
front 31 Graded potentials lead to	back 31 action potentials and Ca2+ release
front 32 Stimulation ends when	back 32 acetylcholinesterase degrades Ach in synaptic cleft

front 33 synaptic knob	back 33 expanded tip of neuron axon
front 34 synaptic vesicles	back 34 Membrane sacs in synaptic knob, filled with acetylcholine (ACh)
front 35 synaptic cleft	back 35 Narrow space separating synaptic knob and motor end plate
front 36 motor end plate	back 36 Region of sarcolemma with many folds (increased surface area) under the synaptic knob

front 37 ACh receptors:	back 37 Proteins that bind Ach on the motor end plate
front 38 Acetylcholinesterase (AChE)	back 38 Enzyme in synaptic cleft that breaks down Ach (prevents continuous stimulation of muscle)
front 39 motor unit	back 39 a single motor neuron and the muscle fiber it controls
front 40 Muscle tension is ideal at a specific muscle length	back 40 This is due to optimal placement of actin and myosin for cross-bridge formation

front 41 Muscle Atrophy	back 41 A wasting of muscle that reduces fiber size Reduced stimulation results in reduced muscle size, tone, and power
front 42 Muscle hypertrophy	back 42 An increase in fast muscle fiber SIZE (not cells!) Building muscle increases fiber size not number of fibers Number of myofibrils per fiber increases More mitochondria and more glycogen stored in the cells Results from repetitive, exhaustive stimulation of muscle
front 43 Resting Muscle	back 43 • More ATP is produced than needed • ATP transfers the energy to create ADP ATP + creatine → creatine phosphate + ADP
front 44 contracting muscle	back 44 The reverse reaction generates ATP from creatine phosphate Creatine phosphate + ADP → ATP + creatine • ATP is continuously generated at the same rate it is used

front 45 Fatigue-inducing situations	back 45 • Lactic acid build-up after high-intensity exercise • Glycogen depletion after medium-intensity exercise over long periods of time
front 46 muscle fatigue	back 46 Muscle cannot continue contractions even under nervous stimulation
front 47 smooth muscles	back 47 • Smaller than skeletal muscle cells • Spindle-shaped • Have centrally-located nucleus • No T-tubules or visible sarcomeres • Do not fuse during development • Connected by junctions • Have membrane invaginations called caveolae
front 48 main function of smooth muscle	back 48 line walls of hollow organs responsible for involuntary movements contraction of organs

front 49

Excitation-Contraction Coupling
in Smooth Muscle Tissue

back 49

1. Ca2+ enters sarcoplasm; interacts with calmodulin
2. Myosin light chain kinase (MLCK)
phosphorylates myosin

3. Myosin-actin cross-bridges form

4. Cross-bridges develop muscle tension
5. Relaxation: removal of Ca2+ and
myosin dephosphorylation

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