Muscle Flashcards
7 functions of muscle tissue
movement, heat, speaking, breathing, posture/body support, protect organs, regulating elimination of materials
Muscle cell =
muscle fiber = myocyte
glucogen storage organelle
glycosomes
O2 storage organelle
myoglobin
Skeletal muscle function
motility and heat
What muscles make up the heart
smooth and cardiac
Cardiac is controlled by what
neural and hormonal (endocrine) control
What is automaticity
create own AP
Which muscles have gap junctions
cardiac and smooth
which muscle doesn’t have gap junctions?
skeletal
Which muscles make up the heart
cardiac and smooth
What are satellite cells, what do they do, and located
A type of stem cell
for healing damage
between sarcolemma and endomysium
Name the skeletal musccle discrete organs
Muscle tissue
blood vessels
nerve fibers
connective tissues
What are the skeletal muscle layers outer to inner
Epimysium
Perimysium
Endomysium
What does the epimysium surround
skeletal muscle
what does the perimysium surround
fascicle
what does the endomysium surround
muscle fiber (cell)
what is the rodlike contractile unit of a skeletal muscle called
myofibrils or fibrils
Sarcomere definition
segment of myofibrils, from Z disc to Z disc
skeletal muscle motor end plate contains which type of receptors
ACh nicotinic receptors
extensor vs flexor
extensor: incr angle at joint
flexor: decr
abductor vs adductor
abductor: move limb AWAY form midline of the body
adductor: TOWARD
Levator vs depressor
Levator: moves insertion UPWARD
depressor: Downwards
Rotator vs Sphincter
Rotator: rotates a bone along its axis
Sphincter: constricts an opening
Dark band =
A band and thick filaments
Light band
I band and thin filaments
What is the smallest contractile unit
sarcomere
Which parts shorten when muscle contract
H band, I band, z disc, the sarcomere as a whole
which zone stays the same length during contraction
A band
What is cross bridge
During contraction when head licks the thick and thin filaments together forming a cross bridge
what is the thick and thin filaments made of
thick/ dark / A band: myosin
thin/ light/ I band: actin
2 regulatory proteins in thin filament
Troponin and tropomyosin
TnI, TnT, TnC do what
TnI = bind to actin
TnT = bind to tropomyosin
TnC= bind to Ca2+
What causes the movement of tropomyosin
when Ca2+ bind to TnC and changes the shape of troponin
What is the myosin head considered
ATPase bc break ATP into ADP and Pi
What is the sliding filament theory
Pi is release bc binding cocks the myosin head creates a power stroke that pulls the thin filament to toward the center
What happens after power stroke (shortening movement)
ADP is release (during power stroke), myosin and actin separate when a new ATP bind, ATP splits into ATP and Pi by myosin ATPase and binds to another actin
Dystrophin
links thin filaments to proteins of sarcolemma (cell membrane)
Nebulin, myomesin, C protein
bind filament or sarcomeres together, maintain sarcomere alignment
titin
hold thick filament in place, help recoil after stretch, resist excessive stretch
Sarcoplasmic Reticulum (SR)
stores and regulates intracellular Ca2+, main storage is in terminal cisterna
t-tubules
- penetrate deep into the cell’s interior to conduct impulse,
- help open Ca2+ channels from the SR known as ryanodine receptors to release Ca2+ into cytoplasm to bind to troponin
linking electrical signal to contraction is called
excitation-contraction coupling
which cells use Na+ to depolarize
muscle and contractile cells
which cells use Ca2+ to depolarize?
pacemaker cells
2 types of muscle contractions
Isometric contraction: incr muscle tension, size stay the same, has MAX
Isotonic contraction: muscle shorten
More precise movements mean
motor unit w/ decr muscle fibers = incr control
What are the steps of muscle cell AP?
- ACh released binds to nicotinic ACh receptors opening ligans gated channels
- Na+ go in and depolarize
- AP produced/starts in sarcolemma (cell membrane)
- AP travel down T tubule
- open Ca2+ Channels called ryanodine receptors in the SR
terminal cisternae
-Ca2+ released into sarcoplasm - in myofibrils Ca2+ binds to troponin
Twitch
- Latent period
- Period of contraction
- Period of relaxation
muscle responses are graded by
frequency and strength
motor unit
an alpha motor neuron and all the muscle fibers it supplies
wave summation
2 stimuli close together
Tetnus
smooth sustained contraction, no relaxation
twitch summation (or wave)
incr frequency and incr contractile force
Treppe effect
good to warm up
Contractions incr bc:
- incr in Ca2+ sarcoplasm
- incr heat generated = incr effiency enzymes
myostatin
paracrine regulator that inhibits satellite cells
Most efficient muscle stretch
80-120%
Smooth muscle layers:
- longitudinal layer: dilates and contracts
- Circular layer: organ elongates + lumen narrows (closer to lumen)
Calmodulin
regulatory molecule for smooth muscle
What does smooth muscles have instead of neuromuscular junctions
axon terminal swellings called varicosities, they release NT into synaptic cleft called diffuse junction
Which muscle uses neuromuscular junctions
skeletal muscle
Where does smooth muscles get Ca2+
Ca2+ come from outside the cell, caveoli contain Ca2+ pumps
what do skeletal muscles have that smooth muscles don’t
Skeletal muscles have:
- Z discs, sarcomeres
- troponin complex
- striations
- t-tubules
- neuromuscular junctions
how does albuterol work on the lungs
albuterol acts on beta 2 receptors on the smooth muscles on the lungs.
It causes an incr in cAMP which inhibits MLCK
inhibition causes smooth muscle cell relaxation
eventually bronchodilation
Does smooth muscle or skeletal muscle take longer to contract
Smooth, 30X longer
Stress relaxation response
smooth muscle:
- responds to stretch and them adapts to new length but can still contract
- (reason stomach and bladder can temporarily store content)
Single Unit Smooth muscle characteristics:
- gap junctions
- spontaneous AP
- contract rhythmically as a unit
- arranged in opposing sheets and have stress-relaxation response
Multiunit smooth muscle characteristics
- rare gap junctions
- infrequent spontaneous AP
structurally indep muscle fibers - lor of nerve supply, like to receive info rather than make AP
- graded contraction
