Muscle continued Flashcards
What are thick myosin filaments?
head has: actin, atp, and light chain binding regions
two pairs of light chains : (cant bind to Ca), essential, regulatory
What is F actin?
Polymer of G actin
Each actin filament consists of two polymers wound in an alpha helix
plus end inserts on Z disk
What are three molecules in troponin?
Troponin I : inhibits binding b.w actin and myosin
Troponin C: binds calcium
Troponin T: binds Tropomyosin
What is alpha-beta crystalin?
heat shock protein that protects desmin from mechanical stress
What is Dystrophin?
Links alpha actinin/Desmin complex to cytoplasmic side of sarcolemma
Anchors actin to sarcolemma
reinforces sarcolemma during muscle contraction
What is the dystrophin complex?
links dystrophin (intercellular) to Laminin 2 (extracellular)
What is alpha actinin?
Attaches filaments to the Z line
What is Nebulin?
Extends Z disc to end of actin filament
serves as template to regulates length of actin filament
What is Titin?
Large fibrous protein
Extends from Z-disk to middle of H band ad connects ends pf thick filaments to Z-line
Provides myosin with elasticity
centers thick filaments in sarcomere
What is plectin?
Binds to desmin filaments
What is desmin intermediate filaments
framework of desmin filaments which surrounds Z line and extends into each sarcomere
Links myofibrils laterally and to the sarcolemma
What are satillite cells
attached to myotubes before basal lamina is laid down
generally quiescent function as stem cells
Become mitotic in times of stress
C met receptor
hepatic growth factor (HGF)
Gives rise t myogenic precursor cells
replaces damaged muscle by proliferating, fusing, and differentiating into skeletal muscle fibers
What is neuromuscular spin?
Extrafusal fibers (outside spindle)
Intrafusal fibers (inside Spindle)
Contains:
Nuclear bag region, bag fibers, and chain fibers
Alpha motor neurons to extrafusal fibers
Gamma motor fibers to intrafusal fibers
Primary and secondary afferent fibers
WHAT IS CARDIAC MUSCLE TISSUE?
Single mono nucleated cells centrally positioned nuclei sarcomeric arrangement cells communicate via gap junctions (intercalated discs) Cells not directly innervated
What is the T tuble system?.
Not as extensive as in skeletal muscle and each tuble interacts with one cisternae rather than two as in skeletal
Forms diads located at the level of Z lines
What is compostition of intercalated disks
Macula adherentes (desmosomes) join cardiac muscle cells
Fascia adherentes anchor actin filaments of sarcomeres
Gap junctions communication
What is ANP?
Atrial Natriuretic Peptides
secreted by cardiac cells in atria
relax vascular smooth muscle
stored as prohormone in secretory vesicles
stimulated by atrial stretch (causes cleavage of prohormone
What is smooth muscle?
Single mono nucleated cells with central nuclei
no sarcomeric arrangement
cells innervated via ans or enteric system
do not respond to all or none
connected via gap junction
Actin and myosin bundles are incorporated into a meshwork arrangment (found in cytoplasm except nuclear area
Dependent on Ca for contraction
no T tubule system or extensive Sr
Uses Pinocytotic vesicles to transport Ca
What are dense bodies ?
Anchor actin filaments to each other and cell membrane
Contain alpha actinin
Interconnected by a specific type of desmin
communicate force of contraction to cytoskeleton and cell membrane
found in cytoplasm and CM
What are neurotransmitter receptor of smooth muscle?
adrenergic and muscarininc receptors (linked to G protein
Nicotinic cholinergic receptor is a cation ion
Smooth muscle sheets of most organs are poorly innervated so they use gap junctions to spread excitation
