Test Three Flashcards
titin
attaches myosin to the Z disc, stabilizes myosin from flipping
What is number 11?
I band
excitability
the ability of a muscle to be electrically stimulated
What is number 9?
H zone
Which band stays unchanged during muscle contraction?
A band
autorhythmic
“any cell that can open its own first sodium ion channel and start its own action potential”
What is the all-or-none principle?
“when a muscle is stimulated it will contract completely or not at all”
isotonic contraction
muscle shortens, (picking up a glass of TONIC water)
What are myoblasts?
Immature muscle cells
What is the main neurotransmitter?
acetylcholine
sarcolemma
muscle cell membrane
sarcoplasm
cytoplasm of muscle cell
What are the 8 steps to a muscle contraction?
- electrical stimulus must travel down the neuron
- this causes the synaptic vesicles to line up and release acetylcholine (into the synaptic cleft)
- acetylcholine opens a sodium ion channel on the motor end plate of the muscle cell
- sodium ions fly into the cell, starting an action potential
- the action potential causes the sarcoplasmic reticulum to release calcium ions
- calcium ions pull off troponin and roll back the tropomyosin. this opens up the myosin head binding sites
- ATP is broken down on the myosin head, this energy is put into the myosin head, popping it into the binding site(on both sides of the M-line)
- both energized heads engage and power stroke (rotate) pulling the Z-discs closer together
extensibility
muscle can be stretched without damaging the muscle
What is attached to the dense bodies?
intermediate filaments
What are the 5 sarcomere bands/lines/zones?
- H zone- center of any sarcomere -A band-center part of a sarcomere that contains the whole myosin filament (and parts of actin filaments) -I band- only contains actin -Z disc- ends of the sarcomere -M line- middle thick bit, stops actin from contracting too far (think of it as a parking block)
What is complete tentanus and what is the contraction rate?
no relaxtion period between contractions, EMERGENCY ONLY; 80-100 times a second
tropomyosin
“wraps around thin filaments (actin) in relaxed muscle”
What is the contraction phase?
cell depolarizes, making charges equal on both sides
Is myosin thick or thin and does it slide or rotate?
thick, rotate
What organs do skeletal muscles make up and what does this muscle look like?
voluntary muscles; long fibers, striated
creatine kinase
shuttles phosphate from creatine to ADP for use when extra energy is needed fast
What is the refractory phase?
the cell is COMPLETELY depolarized, “at this refractory phase the cell has lost its membrane potential and can’t respond to a stimulus from another neuron”
motor unit
“a single motor neuron and all the muscle cells it associates with”
Who are the contractile proteins?
actin and myosin
What controls cardiac muscles?
autorhythmic
dendrites
carry signal to a cell body in a neuron
What are the 4 qualities of cardiac muscle?
-involuntary -highly elongated -intercalated discs -autorhythmic
What is number 2?
actin
axon
carries signal away from the cell body in a neuron
What is the perimysium and what type of tissue is it made of?
wraps around FASICICLES (bundles of 10-100 muscle cells) (dense irregular CT)
What controls smooth multi unit muscles?
nerves
What occurs during membrane potential? (contraction or relaxation)
Relaxation
What organs do smooth visceral muscles make up and what does this muscle look like?
walls of blood vessels & hollow organs such as the bladder and stomach, pointy ends, involuntary
What are numbers 1 & 6?
Z discs
synapse
“communication between a neuron and another cell”
What is number 2?
perimysium
What is number 7?
sarcomere
elasticity
ability of a stretched muscle to come back to its original shape
Who inhibits contraction?
tropomyosin
What is number 3?
endomysium
What is incomplete tetanus and what is the contraction rate?
has relaxation periods between contractions, everyday contraction; 20-30 times a second
Is actin thick or thin and does it slide or rotate?
thin; slides
T-tubules
invaginations of cell membrane
sarcoplasmic reticulum
tube that wraps around myofibril and contains many calcium ions
What is endomysium and what type of tissue is it made of?
wraps around each INDIVIDUAL MUSCLE CELL (areolar CT)
What is the latent phase?
waiting for calcium ions to enter the channel
What controls skeletal muscles?
nerves
What is number 1?
epimysium
isometric contraction
muscle tenses but doesn’t shorten (trying to pick up a METRIC ton)
What are the 4 functions of ATP with muscle cells?
-repolarize cell (pump sodium back out) -pump calcium ions back into sarcoplasmic reticulum -activate myosin heads -flight, flight or freeze response
contractibility
“a muscle cell will contract forcefully in response to an action potential”
What is number 3?
myosin
Why are intercalated discs with their gap junctions so important?
“gap junctions in the intercalated discs allow electrical signals from the SA node to pass through the discs smoothly, keeping the heart chambers beating in rhythm”
What are dense bodies?
structures to which intermediate filaments attach in smooth muscles to move
What is the epimysium and what type of tissue is it?
wraps around ENTIRE muscles (dense irregular CT)
What occurs during action potential? (contraction or relaxation)
contraction
What are the 4 phases for a twitch contraction?
- latent phase- waiting for calcium ions to enter channel
- contraction phase- cell depolarizes, making charges equal on both sides
- ***refractory phase***- cell is completely depolarized, “at the refractory phase the cell has lost its membrane potential and can’t respond to a stimulus from another neuron”
- repolarization (relaxation) phase- ATP pumps sodium out of the cell, restoring the membrane potential
What do myosin heads rotate towards during a power stroke?
the M line
motor end plate
muscle cell receptor site directly opposite of the synaptic vesicles, this opens sodiem ion channels
What are the 2 ways muscle contraction is controlled?
-the number and size of motor units recruited -the frequency of stimulation
What organ does cardiac muscles make up and what does this muscle look like?
cardiac; involuntary, highly elongated & branched cells, intercalated discs
What disappears during muscle contraction
- I bands
- H zone
action potential
the rolling open of sodium ion channels around the cell membrane (depolarized)
calsequestrin
protein that neatly organizes calcium in the sarcoplasmic reticulum
What is the repolarization (relaxation) phase?
ATP pumps sodium out of the cell, restoring the membrane potential
What is number 4?
M line
What are fascicles?
bundles of 10-100 muscle cells
What is number 5?
titin
What controls smooth visceral muscles?
autorhythmic or hormones
troponin
“holds troposyosin onto thin filaments (actin), blocking binding sites”
myomesin
protein that makes up the M line
What is the mesoderm?
where skeletal muscles come from, it differentiates into myoblasts
What enzyme stores phosphate and when is this used?
creatine kinase; used when extra energy is needed fast
membrane potential
“whenever a cell has a difference in charge across its membrane” (polarized)
myoglobin
special protein that stores oxygen in muscle cells (leaks into blood when a muscle is damaged)
What’s the difference between a myofibril and a sarcomere?
a myofibril is a bunch of sarcomeres connected together at their Z discs (makes muscle stringy)
What organs do smooth multi unit muscles make up and what does this muscle look like?
arrector pili & iris, pointy ends, involuntary
synaptic cleft
space between axon of one neuron and the dendrite of another
What is number 10?
A band
