Muscle Flashcards
muscle tissue is composed of
- muscle cells (myocytes, myofibers)
- stem cells (satelite cells)
- nerve supply
- somatic motor (voluntary)
- visceral motor (involuntary)
- exciteable plasma membranes
- connective tissue
- blood vessel, lymphatics
non-muscle contractile tissue
- myoepithelial cells (gladular)
- myofibroblasts (wound healing)
skeletal muscle
- striated
- voluntary
- skeletal movement
visceral
- striated
- voluntary visceral muscle
- tongue
cardiac
- striated
- under autonomic control
- sympathetic and parasympathetic
smooth
- nonstriated
- wide distribution
- gut, bronshioles, blood vessels, ureter, gall bladder
- autonomic via parasympathetic and sympathetic NS
myo, sarc, mysium
-having to do with muscle
sarcolemma
-plasma membrane + external lamina
sarcoplasm
-cytoplasm
sarcoplasmic reticulum
-sER
myofiber
-myocyte = muscle cell
skeletal muscle layers
-epimysium, perimysium, endomysium
characteristics of skeletal muscle
striated
- multinucleated
- voluntary
- long unbranched fibers
- continuous external lamina
- no gap junction
- rich CT investment: surrounds entire muscle, surrounds fascicles, surrounds fibers
- multinucleated, a true syncytium
- nuscleus is eccentric
- each cell is full of myofibrils which are full of myofilaments
where are organelles contained in muscle fibers
-in the gaps between myofribrils
I band
- Z line is found in the middle of this
- this is where you only find myosin, no actin
A band
-where myosin and actin overlap
H band
-where you only see actin
M line
-where the actin is anchored
Z line
-where the myosin is anchored
during contraction what happens to the bands
- z lines come together
- a band does not change
- h band narrows
- i band narrows
t tubules
-run transversely through the myofibrils, carrying a membrane potential which triggers the sarcoplasmic reticulum to release calcium
what links contractile proteins to the ECM
- dystrophin
- a mutation in this protein causes muscular dystrophy
red muscle fibers
- many mitochondria, myoglobin dn oxydative enzymes
- aerobic
white muscle fibers
- fewer mitochondria and oxidative enzymes
- anaerobic, quick to fatigue
- strong
sensory perception
-muscle spindle provides proprioception and stretch sensation
golgi tendon organ
-proprioception and inhibition reflew
cardiac muscle
- involuntary
- striated
- long, branched fibers
- discontinuous external lamina
- many gap junctions
- cells often binucleate
- intrinsic capability to beat
fascia adherin
the end to end junction of cardiac muscle
-desmosomes
cardiac t tubule
- less efficient than skeletal muscle but cell-autonomous contractility and a functional syncitium compensate
- does not completely surround the miofibril
endocrine myocardial cells
- release ANF, a vasodilator
- released in response to high BP, high NA+, and angiotensin 2
- predominantly in the aorta
purkinje fibers
- specialized conducting cells
- rich in glycogen
- conduct impulses
excitation contraction coupling of smooth muscle
- electrical via Ca gated channels, slow excitation, NT released through varicosities. also done via caveolae which is a faster process
- mechanical via stretching simulating mechanosensitive ion channels (myogenic)
- hormonal - oxytocin stimulating uterine contraction
leiomyomas
- uterine fibroids
- bundles of smooth muscle
repairing skeletal
- satellite cell activation
- disease or trauma
cardiac repair
- some satellite cell activation but not much
- limited mitosis is possible
- most repair though is fibrotic
smooth repair
-actively proliferates in response to damage and physiological need
