Muscle Flashcards
muscle contraction goes from __ to ___ to ___ through the 3 sheath layers
epimysium
perimysium
endomysium
Identify tissue type.
skeletal muscle.
Identify structures.
intercalated discs
condition caused by leaky cell membranes that allow Ca out into cytoplasm and formation of actin-myosin cross bridge, but no ATP is present to release the contraction
rigor mortis
muscle under involuntary control, weak & slow contractions, nonstriated, uninucleated/fusiform cells
smooth muscle
Identify the tissue type in cross section here.
cardiac muscle
runs from 1 Z disc to the next
sarcomere
links actin filaments in an intercalated disc
fascia adherens
final trigger for muscle contraction
Ca ions
what type of channels open to generate an action potential down T tubules
voltage-gated Na channels (Na comes back in)
a nerve cell and all of the muscle cells that it innervates make up a ___
motor unit
functional unit of muscle
sarcomere
bundle of contractile, regulatory proteins organized into a regular pattern
myofibril
Identify layers 1-2.
- outer longitudinal layer
- inner circular layer
(smooth muscle- ileum here)
indentations of plasma membrane in skeletal muscle where action potential is transmitted
(near where A band and I band come together)
T tubules
allow intracellular communication/ion flow in intercalated discs
gap junctions
band where only actin is found
I band
Identify 1-8.
- Z disc
- myosin
- actin
- M line
- 1/2 I band
- A band
- sarcomere
- H band
what happens to thin and thick filament size with contraction?
stays the same size
Identify 1-3.
- gap junction
- desmosome
- fascia adherens
what does all-or-none contraction mean?
if a signal comes down motor neuron, either all muscle cells attached to that neuron contract or none of them will.
ability of muscle cell to respond to stimuli by producing electrical signals, conduct action potential
excitability
Identify 1-5.
- Z disc
- H zone
- I band
- A band
- M line
thick myofilament that occupies entire length of A band
myosin
ability of muscle cell to return to original length after being shortened or stretched
elasticity
these fibers have many mitochondria, lots of myoglobin & glycogen, use both oxidative metabolism & anaerobic glycolysis for E, adapted for rapid contractions and short bursts of activity
Type 2a- fast, intermediate oxidative-glycolytic
how is cross-bridge released?
ATP comes in and binds myosin
according to this, contraction occurs because globular heads on myosin attach to actin and slowly walk along actin fibers to produce tension. Actin is pulled to center of sarcomere and shortening of muscle occurs.
Sliding Filament Hypothesis
cardiac muscle diad is composed of…
a T tubule & 1 terminal cisterna
type of muscle under involuntary control, striated uninucleated cells with a centrally located nucleus- elongated and branches cells with intercalated discs
cardiac muscle
at the H zone, only ___ of myofilaments are found, no ___.
tails, no globular heads
Identify tissue type.
skeletal muscle
what happens to the following when contraction occurs?
A band
I band
H zone
Z discs
A band- stays same size
I band- gets smaller, disappears
H zone- gets smaller, disappears
Z discs- pulled closer together
smooth ER in muscle cell
sarcoplasmic reticulum
plasma membrane in muscle cell
sarcolemma
Identify tissue type.
skeletal muscle
what causes release of Ca ions from sarcoplasmic reticulum?
action potential across sarcolemma
thin myofilament that has 1 end attached to Z disc, and other end extending into A band. It is the only filament present in the I band.
actin
a triad is composed of…
1 T tubule and 2 terminal cisterna
Identify.
Triad (1 T tubule & 2 terminal cisternae)
bisects the I band
Z disc
actin & myosin criss cross to form a latice in these cells
smooth muscle
Identify 1-2.
- terminal cisternae
- T tubule
why is smooth muscle non-striated?
actin/myosin line up differently
Identify the tissue type.
smooth muscle
these fibers have many mitochondria, lots of myoglobin, derive E primarily from aerobic oxidative phosphorylation of fatty acids, adapted for slow, continuous contractions
Type 1- slow, red oxidative
Identify the tissue type in cross-section here.
skeletal muscle
type of junctions found at intercalated discs?
gap junctions & adhesions junctions
in smooth muscle, outer layer is ___ & inner layer is ___
longitudinal
circular
how does muscle contraction occur once Ca ions flood the cell?
Ca ions bind troponin (at TNC subunit). troponin changes shape so actin binding sites are exposed.
myosin/actin form cross bridge and contraction happens
these fibers have fewer mitochondria and myoglobin but lots of glycogen, derive E from anaerobic glycolysis, adapted for rapid contractions but fatigue fast
type 2b- fast, white glycolytic
where is binding site for myosin located?
on each G actin
enlarged sarcoplasm at A band/I band junction
terminal cisternae
shape of smooth muscle cell?
tapers at both ends
sarcomere is composed of…
1/2 I band, all of A band, 1/2 of another I band
portion of A band where only myosin is present
H zone
in skeletal muscle contraction, Ca acts as intracellular messenger and causes synaptic vesicles of ___ to be released
acetylcholine
Identify the tissue type.
smooth muscle
ability of muscle cell to generate force/tension when adequately stimulated
contractility
Identify tissue type.
cardiac muscle.
where is nucleus found in skeletal muscle cell?
right underneath the plasma membrane
links intermediate filaments in an intercalated disc
desmosome
Because more Na ions are let out than K ions come in, ___ occurs to create end plate potential
slight depolarization
Identify 1-5.
- I band (actin only)
- H zone (myosin only)
- M line
- A band
- Z disc
ability of muscle cell to be stretched without damage
extensibility
dark bands on a muscle cell are the ___
light bands on a muscle cell are the ___
A bands
I bands
what happens as ATP is split into ADP and P during muscle contraction?
cocking of the myosin head into high E configuration (waiting for actin to bind)
Because actin from either side may actually overlap with each other when contraction occurs, the ___ disappears.
H zone
what are the 3 subunits of troponin and what do they bind?
TNT- tropomyosin
TNC- Ca
TNI- inhibits actin/myosin interaction
thin filaments = ___ actin
polymerized thin filaments form __ actin
G
F
binding of acetylcholine to neuromuscular junction causes ___ ions to flow out and ___ ions to flow in
K
Na
Identify 1-3.
- Epimysium
- Endomysium
- Perimysium
cytoplasm in muscle cell
sarcoplasm
Identify tissue type.
smooth muscle
muscle cell
myofiber
when the myosin head pivots and bends as it pulls on the actin filament, sliding it toward the M line
working stroke
3 types of skeletal muscle fibers in humans?
Type 1- slow, red oxidative
Type 2a- fast, intermediate oxidative-glycolytic
Type 2b- fast, white glycolytic
Identify the tissue type in cross-section here.
skeletal muscle
shape of contracted smooth muscle cell
corkscrew
3 types of muscle tissue
skeletal cardiac smooth
long, thin regulatory protein that twists around between the 2 twisted strands of G actin
tropomyosin
Identify the tissue type
cardiac muscle
type of muscle that is under voluntary control, is striated, and has large elongated multinucleated cells with oval nuclei
skeletal muscle
regulatory complex of 3 subunits that is located at regular intervals along each tropomyosin molecule
troponin
bisects middle of H zone, binds 1 myofilament to next one
M line
After action potential ends, what happens to Ca ions?
they are removed by active transport back into the sarcoplasmic reticulum
how many T tubules are present in each sarcomere?
2
Identify tissue type.
cardiac muscle
3 layers of connective tissue sheath associated with skeletal muscle?
endomysium (around each myofiber)
perimysium (makes fasicles)
epimusium (around fasicles)
