muscle Flashcards
excitability
responsiveness to stimuli
contractilitt
stimulation of muscle, tension
elasticity
muscle recoils to resting length
extensibility
extend in length
skm tissue
striated, elongated with perioherally located nuclei
fxns of skm tissue
movement, posture, temp, storage and movement of materials, support
epimysium
made of dense irregular ct
covers muscle
perimysium
made of dense irregular ct
covers fascicle
endomysium
made of areolar ct
covers muscle fiber
sarcolemma
covers myofibril
neurovascular bundle
artery, vein, nerve
tendon
ct layers merge into a thick cord to attach muscles to bone
deep fascia
ensheathes wrapped muscle, separates individual muscles, binds them together into functional groups, fills spaces bw muscles
thick filaments are made of…
myosin
thin filaments are made of…
actin
aponeurosis
tendon in the form of a thin flattened sheet
shock absorption, distribute and support weight
blood vessels and nerves extend through…
epimysium and perimysium
fxn of blood vessels
deliver nutrients and remove waste
vessels and nerves are controlled by…
somatic NS (voluntary)
motor neurons
neurons that stimulate muscle contractions via axon
neuromuscular jxn
jxn between axon and muscle fiber
skm cells are multinucleate due to …
myoblasts fusing during embryonic development
some myoblasts dont fuse, and remain in adult skm as …
satellite cells
satellite cells
can be initiated to differentiate to assist in repair/regeneration of injured skm
sarcoplasmic reticulum stores…
calcium
calcium initiates…
contraction
transverse tubules
deep invagination of sarcolemma that extend into sarcoplasm, form narrow network of membranous tubules, help move muscle impulse
triad
communication link consisting of 2 terminal cisternae and 1 t-tubule
regulatory proteins
tropomyosin and troponin
tropomyosin
covers myosin binding site on actin
troponin
attaches actin to tropomyosin, has a binding site for calcium
nebulin
actin-binding protein, responsible for thin filament length during sarcomere assembly, determines length of thin filaments
striations in skm tissue due to
variations in thickness of thick and thin filaments
sarcomere
functional contractile unit of skm fiber, between z lines
A band
entire thick filament, some thin
I band
thin filament only
H zone
central region of A band, only thick filament
M line
thin filament
attachment site for thick filament, keeps alignment during contraction
Z line
thin filament
attachment site for thin filament
sliding filament theory
as muscle contracts, thin filaments slide past thick filaments, and sarcomere shortens
during contraction:
A band remains constant
H zone disappears
I band narrows
Z lines move closer
muscle contraction begins eith
nerve impulse stimulating muscle fiber at neuromuscular jxn
acetylcholine
neurotransmitter that initiates changes in motor end plate, start contraction
acetylcholinesterase
enzyme that breaks down ACh to stop contraction
muscle contraction steps
- nerve impulse to NMJ
- ACh binds
- calcium released
- ca binds to troponin to reveal binding site
- myosin binds to actin, shortening sarcomere
- ca goes to SR and tropomyosin covers binding site, relaxing muscle
excitation-contraction coupling
stimulation of a muscle fiber by a nerve impulse results in a series of events that leads to muscle contraction
motor unit
several muscle fibers controlled by a single motor neuron
smaller motor units are involved in…
finer movements
isometric contraction
activated but not shortened, just tension, no movement
isotonic contraction
muscle activated, shortens/lengthens, moves load
concentric isotonic
shortening
eccentric isotonic
lengthening
slow oxidative fibers
slow, prolonged contractions, red muscle, darkest fiber color
fast oxidative fibers
intermediate, medium darkness
fast glycolytic fibers
fast, rapid intense movements, white muscle, lightest fiber
all muscle fibers associated with a particular motor unit
same type of fiber
circular organization
concentric, close passageway or opening
parallel organization
fascicles parallel to long axis of muscle, not very strong, high endurance
ex: abs
convergent organization
triangular muscle with common attachment site, can change direction of pull
ex: pecs
pennate organization
one or more tendons, greatest force
skm contraction is
voluntary
joints are … bones are … muscle contraction is … and whatever you are trying to move is …
fulcrums, levers, effort, load
first class lever
resistance and applied force on opposite sides of fulcrum
ex: nodding head
second class lever
resistance between fulcrum and applied force
balance larger weight but slower and shorter distance
ex: calf raises
third class lever
applied force between fulcrum and resistance
greater speed and distance but less force
ex: bicep curl
actions
prime movers/agonists, antagonists, synergists
prime movers/agonists
muscles provide major force
antagonists
oppose or reverse particular movement
synergists
aid agonists
cardiac muscle arrangement
thick bundles of cells, striated, shorter, 1-2 nuclei, many mitochondria
why does cardiac muscle have more mitochondria
aerobic respiration
shape of cardiac muscle
Y-shaped branches, join muscle fibers via intercalated discs
autorhythmic cardiac muscle cells
make the muscle involuntary
intercalated discs have…
desmosomes and gap jxns
smooth muscle organization
short, uninucleate, nonstriated, thin filaments attached to dense bodies, few SR, no t tubules or z discs
smooth muscle contains … for communication
gap jxns
smooth muscle is
involuntary, modulated by nervous system, autorhythmic cells
smooth muscle contraction
slow, sustained
