OS 203 2.2 Muscle Tissue - Sheet1 Flashcards
A band - “A,” means?
anisotropic - birefringent in polarized light
what’s in the A band
thick and thin filaments except at H band (thick only)
I band - “I,” meaning?
isotropic - does not alter polarized light
bisects the I band, name means?
Z line, Zwischesheibe - between discs
light area bisecting the A band, name means? contains what?
H band, Heller (light), thick filament only
bisects H band, proteins? (3)
M line; myomesin, a-actinin, titin
attaches thick filaments at the center of the M line
myomesin
attaches thin filaments to the Z line
a-actinin
extends from M line to Z line; maintains central location of A band; prevents over-stretching. appearance?
titin; coiled appearance at the attached portion in the I band
inner surface of sarcolemma is coated with what? function?
dystrophin - protects muscle from stress during contraction
x-linked autosomal recessive mutation affecting the expression of dystrophin (unable to walk by puberty)
duchenne muscular dystrophy
sarcoplasm contains
glycogen (for anaerobic glycolysis) and myoglobin
continuation of SR with gated calcium release channels; reservoir of?
terminal cisternae; calcium ions and calsequestrin
continuation of sarcolemma; location in skeletal muscle; fxn
T tubule; A-I jxn; interiorization of action potential
myosin components
2 chains heavy meromyosin (HMM) with heads at A band, ATP-binding site; light meromyosin (LMM) with tail at H band
thin filament components (3)
F-actin, troponin, tropomyosin
F-actin is made of
2 strands G-actin (with myosin binding sites) wound around e/o
troponin portions (3)
TnC (binds Ca), TnI (inhibit actin-myosin, binds to actin), TnT (binds to tropomyosin)
remove this to expose the binding site
troponin-tropomyosin complex
remains unchanged during contraction
A band
motor neuron and all muscle fibers it innervates
motor unit / neuromotor unit
branches in the terminal ends of nerve axon attached to the myofiber
terminal bouton
large motor unit: how many innervated? examples?
~100 muscle fibers; back, biceps
small motor unit: how many innervated? examples?
~3-5 muscle fibers; eye, hand
motor end plate / myoneural jxn: neurotransmitter
acetylcholine
primary vs secondary synaptic cleft
primary: between axon and sarcolemma; secondary (subneural cleft?): deep folds in the sarcolemma
postsynaptic membrane contains
nicotinic acetylcholine receptors (ligand-gated Na+ channels)