Skeletal Muscle Flashcards Preview

Musculoskeletal > Skeletal Muscle > Flashcards

Flashcards in Skeletal Muscle Deck (33):
1

What innervates skeletal muscle?

motor neurons in the ventral horn of the spinal cord
-they disperse to provide innervation to multiple muscles, but each fiber is only innervated by 1 neuron

2

Motor Unit

Motor neuron + muscle fibers that it innervates

3

Small Motor Neuron Body

-innervate few muscle fibers
-relatively small cross-sectional diameters
-"slow" motor unit (b/c mechanical characteristics)

4

Large Motor Neuron Body

-innervate large # of muscle fibers
-large cross-sectional diameters
-"fast" motor unit (b/c mechanical characteristics)

5

What happens when action reaches nerve terminal?

-ACh is released from synaptic vesicles in to the synaptic cleft from Ca2+ channels
-nicotinic channels are targets for ACh (ion channels)

6

How is ACh removed from motor end plate?

-acetylcolenesterase

7

T-tubules

bring musclee cell membrane close to sarcoplasmic reticulum

8

Sacrcoplasmic Reticulum

endoplasmic reticulum that stores Ca2+ at high conc. in cell

9

Triad

1) T-tubule
2) SR
3) intervening structure

10

Depolarization of T-tubule membrane does?

confermation change of dihydropyrodine receptor
-activated Ca2+ channel (riadanine receptor)
-passive eflux of Ca that increase Ca conc.
-then channel close, and active transport puts Ca back in SR
-Ca2+ acts as secondary messanger for action potential causing intracellular space to have Ca in response to action potential

11

Sarcomeres

striations of light and dark bands (under polarized light), myofibril proteins

12

I band

has Z line, light bands, think filamentous proteins

13

Unit from 1 Z line to the next?

sarcomere

14

A band

dark bands, thick filamentous proteins

15

Sliding filament theory?

force is generated as thin and thick filaments slide over one another

16

Thick filaments

myosin

16

Thick filaments

myosin

17

Thin filaments

actin
troponins (C, T, I)
tropomyosins

17

Thin filaments

actin
troponins (C, T, I)
tropomyosins

18

Actin monomers

form fibrous helical chains, high affinity binding side for myosin heads

18

Actin monomers

form fibrous helical chains, high affinity binding side for myosin heads

19

Myosin

large protein with filamentous tail and globular head (2 light chains per head)

19

Myosin

large protein with filamentous tail and globular head (2 light chains per head)

20

Tropomyosins

fibrous proteins that extend on the length of the thin filament
-can cover myosin binding sites

20

Tropomyosins

fibrous proteins that extend on the length of the thin filament
-can cover myosin binding sites

21

Troponins

form ternary complex of C, I, and T (binding complex)

21

Troponins

form ternary complex of C, I, and T (binding complex)

22

Tropomosin at Rest

prevents actin and myosin interaction

22

Tropomosin at Rest

prevents actin and myosin interaction

23

Tropomosin Action Potential

Ca+2 moves tropomosin and lets actin and myosin bind

23

Tropomosin Action Potential

Ca+2 moves tropomosin and lets actin and myosin bind

24

What happens when actin and myosin bind?

conformational change, pulls thick filament toward Z-line
Power stroke (pulls Z-lines toward each other)
-muscle fiber contraction

24

What happens when actin and myosin bind?

conformational change, pulls thick filament toward Z-line
Power stroke (pulls Z-lines toward each other)
-muscle fiber contraction