Muscle

Question 1

What are the layers of CT of Skeletal muscle?

Answer 1

• Epimysium (dense irreg): surrounds entire muscle
• Perimysium (dense irreg): surrounds fasicle
• Endomysium (reticular): surrounds individual fibers

Question 2

What are muscle fibers made up of?

Answer 2

myofibrils- arranged in a parallel pattern that gives striations

Question 3

Skeletal is triad or diad?

Answer 3

Triad: 2 SR+1T-tubule

Question 4

Where is the triad for skeletal mus. located?

Answer 4

located at jxn where A band meets the I band

Question 5

What stores Ca2+ in skeletal muscle

Answer 5

SR

Question 6

What do t tubules initate?

Answer 6

Initiate Ca2+ release from SR into sacromere

Question 7

How is new Skeletal mus. formed?

Answer 7

Satellite cells

only found in skeletal

Question 8

What is the different of red v. white muscle in:
* Vascularization
* contraction
* mitochondria
* myoglobin

Answer 8

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

Question 9

What are sacromeres in Skel M?
Compostion?
fxn?

Answer 9

• they are structural units of myofibrils
• Composed of actin (thin) and mysosin (thick)
• Fxn: contraction of sketeal muscle

Question 10

What is the A band, H band, I band, Z disk?

Answer 10

• 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

Question 11

Sketetal muscle contraction is an _ process

Answer 11

ATP-dependent

Question 12

What is rigor mortis, myasthenia gravis and duchenne’s musclular dystrophy

Answer 12

• Rigor mortis: the contiuned contraction of muscle d/t lack of ATP
• Myasthenia gravis: abs target ACh receptor-> prevents contraction
• DM: dysfunctional dystrophin protein

Question 13

Explain the contraction process of skel. m

Answer 13

• 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

Question 14

What is the function of myosin, myomestin, titin, tropomyosin and troponin in skeletal muscle

Answer 14

• 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

Question 15

What reponses when the muscle shortens or lengthens?

Answer 15

Intrafusal -> follows the extrafusal

Question 16

Muscle cells of cardiac have triads or diads?
Where is it loacted

Answer 16

• diad: 1 SR and 1 T tubule
• z-disk

Question 17

Cardiac muscle has _ amounts of SR so the Ca2+ is stored _

Answer 17

lesser, extracellulary

Question 18

What does t tubules initate in cardiac muscle

Answer 18

initate Ca2+ release from SR into sacromere

Question 19

What is b/n cardiac muscle cells

Answer 19

intercalated disks

Question 20

What are intercalated disk composed of?

Answer 20

composed of jxns= fascia adherens, desosomes, gap jxns

desosomes bind IF, fascia adherends binds actin

Question 21

What is endomysium

Answer 21

reticular CT surround the muscle fibers

Question 22

Is cardiac m contraction the same or different than skeletal m?

Answer 22

SAME

Question 23

What are the layers of tissue in the heart?

Answer 23

• Endocardium: simple squamous epithium lining heart
• Myocardium: cardiac muscle
• Epicardium: specialized CT (adipose)
• Perocardium: dense CT + simple squamous epithelium

Question 24

is Smooth m striated? What does it mean?

Answer 24

NO, no sarcomeres

Question 25

What does smooth muscle cells contain

Answer 25

dense bodies and caveola

Question 26

What does dense bodies contain/do

Answer 26

Dense bodies contain alpha-actinin -> fxns as z-disk * Alpha-actinin = protein that binds actin

Question 27

What does caveola do?

Answer 27

Caveola brings in Ca2+ via pinocytosis to initiate contraction * Ca2+ is store extracellularly (like in cardiac m.)

Question 28

How do smooth muscle cells regenerate?

Answer 28

w/o satellite cells

Question 29

What are the layers of smooth muscle

Answer 29

Muscularis mucosa muscularis externa * outer longitudinal layer * inner circular layer

Question 30

KNOW THIS

Question 31

Calcium control for skeletal muscle? cardiac muscle? smooth muscle?

Answer 31

Skeletal: Calsequestrin in terminal cisternae Cardiac: Ca2+ from EC sources Smooth: Calveolae

Question 32

Calcium binding for skeletal muscle? cardiac muscle? smooth muscle?

Answer 32

Skeletal: Troponin C Cardiac: Troponin C Smooth: Calmodulin