Muscle Flashcards
What are the layers of CT of Skeletal muscle?
- Epimysium (dense irreg): surrounds entire muscle
- Perimysium (dense irreg): surrounds fasicle
- Endomysium (reticular): surrounds individual fibers
What are muscle fibers made up of?
myofibrils- arranged in a parallel pattern that gives striations
Skeletal is triad or diad?
Triad: 2 SR+1T-tubule
Where is the triad for skeletal mus. located?
located at jxn where A band meets the I band
What stores Ca2+ in skeletal muscle
SR
What do t tubules initate?
Initiate Ca2+ release from SR into sacromere
How is new Skeletal mus. formed?
Satellite cells
only found in skeletal
What is the different of red v. white muscle in:
* Vascularization
* contraction
* mitochondria
* myoglobin
Red
* Rich vascular supply
* contract:Slow but repetitive; not easily fatigued; weaker contraction
* mito:numerous
* myo: rich
White
* poorer vascular supply
* contract:fast but easily fatigued; stronger contraction
* mito: few
* Myo: poor
What are sacromeres in Skel M?
Compostion?
fxn?
- they are structural units of myofibrils
- Composed of actin (thin) and mysosin (thick)
- Fxn: contraction of sketeal muscle
What is the A band, H band, I band, Z disk?
- A: actin+ myosin-> SAME length during contraction
- H: only myosin-> SHORTENS during contraction
- I: only actin-> SHORTENS during contraction
- Z: located on both sides of the sacromere to serve as boundries
Sketetal muscle contraction is an _ process
ATP-dependent
What is rigor mortis, myasthenia gravis and duchenne’s musclular dystrophy
- Rigor mortis: the contiuned contraction of muscle d/t lack of ATP
- Myasthenia gravis: abs target ACh receptor-> prevents contraction
- DM: dysfunctional dystrophin protein
Explain the contraction process of skel. m
- NMJ secretes ACh to stimulate T-tubules à Ca2+ release from SR
- Ca2+ binds troponin C (TnC) + allows myosin to bind actin
- ATP(onmyosin)gets hydrolyzed into ADP+Pi which binds to actin
- Pi gets released to create a tighter bond b/n actin+myosin
- Power stroke-> a conformational change leads to the release of ADP § A new molecule of ATP binds and muscle relaxes
What is the function of myosin, myomestin, titin, tropomyosin and troponin in skeletal muscle
- Myosin: major protein of thick filaments, binds actin to then hydrolyzes ATP to produce a contraction
- Myomesin: cross links thic filaments what are next to each other at M line
- Titin: forms an elastic lattice that anchors thick filaments at z line
- Tropomyson and tropinin: complex what works to make a contraction
What reponses when the muscle shortens or lengthens?
Intrafusal -> follows the extrafusal
Muscle cells of cardiac have triads or diads?
Where is it loacted
- diad: 1 SR and 1 T tubule
- z-disk
Cardiac muscle has _ amounts of SR so the Ca2+ is stored _
lesser, extracellulary
What does t tubules initate in cardiac muscle
initate Ca2+ release from SR into sacromere
What is b/n cardiac muscle cells
intercalated disks
What are intercalated disk composed of?
composed of jxns= fascia adherens, desosomes, gap jxns
desosomes bind IF, fascia adherends binds actin
What is endomysium
reticular CT surround the muscle fibers
Is cardiac m contraction the same or different than skeletal m?
SAME
What are the layers of tissue in the heart?
- Endocardium: simple squamous epithium lining heart
- Myocardium: cardiac muscle
- Epicardium: specialized CT (adipose)
- Perocardium: dense CT + simple squamous epithelium
is Smooth m striated? What does it mean?
NO, no sarcomeres
What does smooth muscle cells contain
dense bodies and caveola
What does dense bodies contain/do
Dense bodies contain alpha-actinin -> fxns as z-disk
* Alpha-actinin = protein that binds actin
What does caveola do?
Caveola brings in Ca2+ via pinocytosis to initiate contraction
* Ca2+ is store extracellularly (like in cardiac m.)
How do smooth muscle cells regenerate?
w/o satellite cells
What are the layers of smooth muscle
Muscularis mucosa
muscularis externa
* outer longitudinal layer
* inner circular layer
KNOW THIS
Calcium control for
skeletal muscle?
cardiac muscle?
smooth muscle?
Skeletal: Calsequestrin in terminal cisternae
Cardiac: Ca2+ from EC sources
Smooth: Calveolae
Calcium binding for
skeletal muscle?
cardiac muscle?
smooth muscle?
Skeletal: Troponin C
Cardiac: Troponin C
Smooth: Calmodulin