Flashcards in Chapter 10- Muscles Deck (66)
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1
Myology
scientific study of muscles
2
how much mass do muscles account for
~45%
3
functions of muscles
maintain posture and body position
movement
heat production
guard orifices
support visceral organs
4
properties of muscle tissue
Excitability
-the ability to receive and respond to electrical or chemical stimuli
Contractility
-the ability to shorten forcibly when stimulated
Extensibility
-ability to be stretched without damaging the tissue
Elasticity
-ability to return to original shape after being stretched
5
composition of mucles
-muscles are organs
-consist of many tissue types
-connective tissue
-arteries/veins
-nerves
-lymphatics
-contractile muscle cells
6
skeletal muscle characteristics
-attaches to bone, skin, or fascia
-striated with light and dark bands
-voluntary control
-long, thin and multi-nucleated fibers
-arranged into packages that attach to and cover the bony skeleton
-contracts rapidly, but tire easily
-may exert great force
-fiber=1 muscle cells
7
muscle structure
-belly: main portion of a muscle (thick part)
-belly is attached to tendons
-tendons are attached to bone
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fascia
-deep fascia
--dense irregular CT around muscle
--holds it in place and separates it form other muscles
-subcutaneous fascia
--loose CT beneath skin, surrounds several muscles
9
skeletal muscle organization
-many muscle fibers are bundled together into groups called fascicles
-10-100 muscle cells
-several fascicles make up a muscle (so several hundred fibers(cells))
10
skeletal muscle CT
-epimysium
-perimysium
-endomysium
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epimysium
surrounds the whole muscle
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perimysium
surrounds fascicles
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endomysium
separates individual muscle fibers
14
tendon formed from what
all connective tissue extended beyond the muscle belly
15
aponeuroses
tendons that form thick flattened sheets
16
myoblasts
embryonic cells that fuse to form muscle fibers
-causes the length and multinucleation
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myosatellite cells
myoblasts that do not fuse
-assist in repair of damaged cells
18
fiber structure
-sarcoplasm: fiber cytoplasm
-sarcolemma: plasma membrane of a fiber
-transverse (T) tubule: extensions of the sarcolemma into the sarcoplasm
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myofibrils
contractile organelles
-extend the length of fiber
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sarcoplasmic reticulum
surrounds the myofibrils
-similar to ER
-contains calcium ions which tell muscle to contract
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sarcomere
functional unit of the myofibril
-made of thick and thin filaments
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thick filaments
myosin
-twisted protein with globular heads
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thin filament
actin
-structural protein
-coiled "beads"
regulatory proteins
-allow/prohibit attachment between actin and myosin
-tropomyosin
-troponin
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sarcomere bands
cause the striated appearance
bands
-A band: entire thick filament range
-I band: only thin filaments
-H band: only thick filaments
- Zone of overlap: both filaments
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Sarcomere lines
divide and flank the sarcomere
-Z line:
--end of sarcomere
--made of actin protein
--anchor thin filaments
-M line:
--middle of the sarcomere
--stabilize thick filaments
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structural proteins
titin: anchors a thick filament to a Z line
-accounts for elasticity and extensibility
nebulin: holds F actin together on thin filaments (runs through center)
actinin: makes up Z line
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sliding filament theory
actin slides over myosin
-zone of overlap enlarges
-h band shrinks
-I band shrinks
- A band remains the same
- Z line moves closer to A band
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Neuromuscular junction is made up of
-motor unit
-neuromuscular junction
-synaptic termical
-motor end plate
-synaptic cleft
-neurotransmitter
29
motor unit
neuron and all the muscle cells stimulated by the neuron
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