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endomysium
- wraps a muscle fiber,
- areolar ct
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perimysium
- wrapped fascicles
- collagen sheath
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epimysium
- wraps entire muscle
- dense fibrous ct
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excitability
able to receive and respond to stimuli
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contractility
shorten when a stimulus is adequate
-
extensibility
ability to be stretched
-
elasticity
return to original length
-
functions of muscle
- motion
- positive maintenance
- joint stabilizatin
- heat production
-
indirect attachment to bones
- tendon- extension of fascia
- aponeurosis- flat sheet like
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sarcolema
plasma membrane
-
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sarcoplasmic reticulum
true smooth er
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myoglobin
o2 storage pigment in muscle
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myofibrils
make up muscle fibers, run lenth of cell parallel
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myofilaments
make up myofibrils do not run length of cell. myosin or actin- compartments are called sarcomeres
-
sarcomere
functional unit of contraction
-
thick filamen
- bundles of myosin molecules
- has actin binding sites of its globular head
- has atp binding site
-
thin filament
- actin molecules
- has myosin binding sites
- associated with two regulatory proteins
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tropomyosin
- spirals around the actin filament, covering & blocking myosin binding sites
- preventing contraction
-
troponin
- holds tropomyosin in place around actin;
- has Ca binding sites
-
a band
length of thick filaments
-
H zone
central narrow area of thick filaments
-
M line
fine threads in the H-zone; connects adjacent thick filaments
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I band
light appearing area on either side of the A band; mostly thin myofilaments
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pre stimulus
resting, negatively charged, polarized
-
neuromuscular action
- ach released
- binds to receptors is sarcolemma
- ach causes Ca open
- Ca rushes into sarcoplasm
- Ca binding exposes actin
- power stroke
-
energy for working stroke
atp attached to myosin is split by ATPase
-
acetylcholinesterase
enzyme that stops nerve impulse
-
events at muscular junction
- action potential arrives
- Ca channels in neuron open
- ACH is released from neuron by exocytosis
- ACH binds to receptors, opens channels
- ACHE terminates activity
-
motor unit
single motor neuron and number of musclefibers stimulated by it
-
small motor unit
- 1 neuron 2-10 muscle fibers
- precise muscle movements
-
large motor unit
- 1 neuron + 500 - 2000 muscle fibers
- gross motor movements like leg
-
average motor unit
150 muscle fibers and neuron
-
basic fuel for muscle
- atp
- comes from phosphocreatine stored in muscle tissue
-
atp used rapidly
phosphocreatine 15-30 sec
glycogen (several min)
fats long time
-
threshold strength
weakest stimulus to elicit contraction
-
all or none principal
each fiber will be contracted or not
-
muscle twitch
rapid jerky response to stimulus
-
refractory period
time during contraction when muscle fiber is not able to be further stimulated
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tetanus
complete muscle contraction
-
lock jaw
caused by clostridium tetani
-
treppe
- stimulation/contraction/relaxation
- 2nd stimulus will result in stronger contraction
-
isotoni
equal movement muscle
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isometric
muscle lenght is constant but tension increases
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