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65 Cards in this Set

  • Front
  • Back
striations results from
an overlapping of internal contractile proteins
endomysium is connective tissue around
muscle cells(muscle fiber)
perimysium is connective tissue around
muscle fascicles(bulk of muscle fibers)
epimysium is connective tissue around
the entire muscle
myofibrils
long protein bundles that occupy the main portion of the sarcoplasm
myofibrils consisting of what proteins? 2
glycogen
myoglobin
myoglobin
red pigment; stores oxygen needed for muscle activity
myoblasts
stem cells that fuse to make each myofibril

myo (muscle fiber)
blasts (stem cells)
satellite cells
unspecialized myoblast cells remaining btw muscle fiber and endomysium

can regenerate a damaged muscle fiber
calcium reservoir in a myofibril?
sarcoplasmic reticulum

Calcium activates muscle contraction
thick filaments made up of?
hundreds of myosin molecules
Thin filament composed of two ______
fiborus (F) actin beads entwined
G actin
a string of subunits that has an active site that can bind to the head of a myosin
When a muscle fiber is ______, each tropomyosin blocks the active sites of G actins and prevents myosin from binding to them.
relaxed
What stabilizes the thick filament, centers between the thin filaments, prevents over-stretching and contributes to elastic recoil?
elastic filaments!
elastic filaments aka 2
titin
connectin
contractile proteins 2
myosin
actin

-they do the work
regulatory proteins 2
tropomyosin
troponin

-when can a fiber contract or not
True or false

Neither the thick or thin filaments change length during shortening.
True

only the amount of overlap changes
Skeletal muscle never contracts unless
stimulated by a nerve
denervation atrophy
shrinkage of paralyzed muscle when connection not restored.
somatic motor NEURONS
nerve cells in the brainstem and spinal cord that serve skeletal muscles
somatic motor FIBERS
the AXONS that lead to the skeletal muscle
motor unit
one NERVE FIBER and all the MUSCLE FIBERS innervated by it
synaptic knob

contains?
swollen end of nerve fiber

-synaptic vesicles filled with acetycholine (ACh)
schwann cell
envelops and isolates all of the NMJ from the surrounding tissue fluid
How is ACh released into the synaptic cleft?
by exocytosis
Basal lamina that catches the ACh by its receptors contains:
acetylcholinesterse (AChE)

that breaks down ACh after contraction causing RELAXATION
ACh think
contraction
AChE think
relaxation
________ stimulates exocytosis of ACh from synaptic knob.
Calcium
Rigor mortis
hardening of muscles and body beginning 3-4 hours after death and peaks at 12 hours

-muscle relaxation requires ATP
all-or-none law
contracting to its maximum or none at all
recruitment or multiple motor unit (MMU) summation
process of bringing more motor units into play
isometric muscle contraction
muscle develops tension but does not shorten

ex: holding a dumbell without moving it causes internal cellular tension causing it to stay the same length or longer
isotonic muscle contraction
muscles changed in length with no change in tension

ex. muscle begins to shorten and move the load
2 enzyme systems control phosphate transfers in generating ATP in immediate energy:
myokinase
creatinine kinase
ATP and CP=
phosphagen system: short burst of energy
As the phosphagenic system gets exhausted, it shifts to ___________.
anaerobic fermentation

30-40 seconds of max activity
anaerobic fermentation think:
glycolysis

can generate 2 ATP for every glucose molecule consumed
glycolysis converts ______ to ______.
glucose to lactic acid
2 ways beating fatigue
oral creatinine
carbohydrate loading
what part of the body are Slow oxidative, slow twitch, red or type I fibers?
calf and postural muscles of the back

-adapted for aerobic respiration and fatigue resistance
Fast glycotic (FG), fast twitch, white or type II fibers found where?
extrinsic eye muscles, gastrocnemius, biceps brachii

-fibers well adapted for quick response but not for fatigue resistance
muscular strength depends on:
muscle size
fascicle arrangement
size of motor units: the larger the stronger
multiple motor unit summation: recruitment
temporal summation
length-tension relationship
fatigue
____________ allow each myocyte to directly stimulate its neighbors (cardiocyte)
Gap junctions
_________ is capable of mitosis and hyperplasia
smooth muscle
In smooth muscle, Z discs are replaced by ________.
dense bodies

-well ordered array of protein masses in cytoplasm
multiunit smooth muscles occurs where? how?
largest arteries, pulmonary air passages, pilo erector muscle and iris

- each myocyte receives its own nerve supply
single unit smooth muscle where? how?
blood vessels, digestive, respiratory, urinary and repro tracts

-a nerve fiber passes through the tissue without synapsing with any specific myocyte= coupled by GAP junctions

-cells contract as a single unit
visceral muscle, think:
single unit smooth muscle
Layers of the mucosa: 3
epithelium
lamina propria
muscularis mucosa
layers of the muscularis externa:
circular layer
longitudinal layer
pacemaker cells
set off a wave of contractions in the entire layer of muscle

stomach/intestines
varicosities
beadlike swellings each containing synaptic vesicles
In smooth muscles, calcium enters and binds to _______ on thick filaments. Not troponin like skeletal and cardiac muscles
calmodulin
Ca2+ > ?
calmodulin
calmodulin > ?
activtes mysoin light-chain kinase
mysoin light-chain kinase >
adds phosphate to regulatory protein on myosin head
then >
myosin ATPase, hydrolizing ATP enables myosin similar power and recover as skeletal muscle
latch-bridge mechanism
resistant to fatigue

-enables it to remain attached to actin for a prolonged time without consuming more ATP
stress-relaxation response?
helps hollow organ gradually fill (UB)
plasticity
the ability to adjust its tension to the degree of stretch

-UB can stretch without getting flabby
strabismus
inability to fixate on the same point with both eyes
Tx of myasthenia gravis
cholinesterase inhibitors
immunosuppressive agents
thymectomy
plasmapheresis