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Epimysium
- in sk. m
- CT encapsulates major bv's and nerves
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Perimysium
- in sk. m
- CT encapsulates small bv's and nerves
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Endomysium
- in sk. m
- CT encapsulates capillaries & nerve endings
- NO bv's or nerves
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Basal vs. external lamina
- Basal lamina- for epithelial cells
- external lamina- other? Schwann, muscles
- External lamina- between sarcolemma & endomysium
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Muscle organization
Muscle->fasicle (group)->myofiber (cell)->myofibril->myofilaments (thin/thick)
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M line
where thick anchors
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Nebulin
- determines thin filament length
- part of think filament: actin, tropomyosin, troponin, nebulin
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Desmin
links Z line to organelles and sacrolemma
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Titin
- stretch M to Z "tit"ens
- prevet overextetion during relaxation
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Strength of muscle contraction determined by:
- 1.size of motor unit
- 2. # motor units activated
- 3. # myofibrils in each muscle fiber (inc byt exercise/hypertrophy)
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Myotendinous junctions
Very long I bands interact will collegen fibrils of tendon
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Golgi Tendon Organ
pinches sensory nerve endings and provides energy of how much force muscle is producing
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muscle spindle
- intrafusal muscle fiber- encapsulated in fluid filled capsule
- 1. nuclear chain & nuclear bag 2. annulospiral ending: provides info on RATE of extenision; flower spray: EXTENT
- extrafusal- outside spindle
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dystrophin
elastic linkage between peripheral actin and dystroglycan, which bind to external lamina
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Nemaline Myopathies
thin filament defect
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Desmin-related Myopathies (DRM)
defect in desmin
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Amylotrophic Lateral Sclerosis
Loss of upper and lower motor neuron
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Progressive Muscular Atrophy (PMA)
Loss of lower motor neurons
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Multiple sclerosis (MS)
Loss of upper motor neurons
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Myasthenia Gravis
Autoimmune, disrupts ACh signaling at NMJ
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Mitochondrial Myopathies
muscle wkness, exercise intolerance
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MD: Duchenne MD, Myotonic MD
- progressive wkness, muscle fiber necrosis
- Duchenne MD- defects in dystrophin gene, common early onset
- Myotonic MD- slow relaxation, late onset MD
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Pericardium
2 layers mesothelium: parietal, visceral
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Endocardium
layer of enothelial & subendothelial (sm. m, collegen, fibroblast) cells
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Intercalated disks
- link sarcomeres
- transverse, longitud
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fascia adherens
- thin filaments insert into fascia adherens
- like "a Z line"
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Desmosomes
- link intermedaite fil
- tranverse and long
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Gap junction
- electrical signals portals
- ONLY long
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ANP
- lowers bp by inhibiting renal Na reabsorption & secretion of vasocontrictors.
- directly promotes relaxation of sm m
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