8 Skeletal Muscle as an Effector Organ Flashcards Preview

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Flashcards in 8 Skeletal Muscle as an Effector Organ Deck (61):
1

skeletal mm def

usu attached to the skeleton; used for locomotion and maintaining body posture

2

visceral mm

mm that lines the walls of internal organs and blood vessels (vascular)

3

cardiac mm

heart mm

4

striated mm

skeletal and cardiac

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smooth mm

lack striations - vascular and visceral mm

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voluntary mm

receive signals from CNS - most skeletal mm

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involuntary mm

mostly receives signals from ANS - visceral and cardiac mm

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tendon

attaches mm to bone

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origin

proximal attachment of mm

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insertion

distal end of mm attachment

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muscle fibers

skeletal mm cells

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endomysium

connective tissue surrounding individual mm fibers

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perimysium

connective tissue surrounding bundles of muscle fibers (fasciculi)

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epimysium

connective tissue surrounding the ENTIRE muscle

15

muscle fibers is composed of smaller fibrous structures called _____

myofibrils

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myofibril is divided into ___ and ____ filaments

thick and thin

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think filaments are ___ bands

A bands

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thin filaments are ___ bands

i bands (think of "i" as a thin letter)

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the M line runs down the center of the

A band

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___ runs across the center of the I band

Z line/Z disk

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sarcomere is defined as the space from ___ to ____

Z disk to Z disk

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when mm contracts, this appears shorter (but not really, it just overlaps more)

I band

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thin filaments are composed of

actin, tropomyosin, troponin
7:1:1

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thin filaments are the main site of

calcium regulation

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two states of actin molecule

G actin - monomeric
F actin - polymer of G actins

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tropomyosin is composed of

a-helical chains

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troponin has these 3 proteins

Troponin-T
Troponin-C
Troponin-I

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Troponin-C

calcium sensor in skeletal and cardiac mm

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Troponin-I

"glue" that holds troponin-tropomyosin-actin together

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these two components are involved in tension generation

actin
myoson

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these two components are regulatory proteins

troponin
tropomyosin

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thick filaments are made primarily of

myosin, a dimer with two globular heads, plus a rod-like area

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attached to each globular head portion of myosin are

two essential light chains and two regulatory light chains

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myosin thick filament consists of

two chain coiled structure with amino-terminal regions (S1 regions)

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___ region of myosin binds ATP and actin

head region

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sarcolemma

outer membrane surrounding each muscle fiber
consists of plasma membrane (plasmalemma) and basement membrane

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plasma membrane of skeletal mm fiber contains no ___ like cardiac mm

gap junctions/tight junctions

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T-tubules

tubular extensions of the sarcolemma that extend deep into the fiber from the surface

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Sarcoplasmic reticulum (SR)

muscle's ER, adapted for uptake, storage, and release of Ca2+ ions; a tubular network

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terminal cisternae

enlarged portion of SR containing T-tubules
***Ca2+ stored here***

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triad

group of 1 T-tubule and 2 terminal cisternae

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H zone

composed of thick filament only, in the center of the diagram (M line runs right through it)

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The A band technically consists of

both thick and thin filaments

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excitation-contraction coupling

depolarization of the sarcolemma, calcium released into cytoplasm, binding of calcium to regulatory sites to initiate crossbridge cycling

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Ca2+ binding to ___ removes blocking action of ____

1/ troponin
2/ tropomyosin

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the ____ AP causes release of Ca2+ from terminal cisternae of SR

T-tubule

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Ca2+ ions bind to _____ to initiate contraction

Troponin-C

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calsequestrin

a protein in the SR that binds Ca2+

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in the resting state, _____ interferes with interaction between actin and myosin

tropomyosin

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Calcium binding to troponin-C causes tropomyosin to conformationally change, exposing _____

myosin-binding sites on actin filaments

51

the active site is on the ____

thin filaments

52

each tropomyosin molecule exerts control over ___ actin monomers

7

53

the crossbridge can get ready for a new cycle once

ATP binds to myosin

54

in the absence of ____, myosin molecules become permanently attached to actin filaments to form actomyosin complex, causing _______

ATP, rigor mortis

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muscle contraction occurs as long as ___ and ___ are present

ATP, Ca2+

56

this structure stores calcium ions

sarcoplasmic reticulum

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cardiac mm AP is activated by

cells in the muscle itself, which spreads from cell to cell

58

intercalated disc

connects cardiac cells and allow them to function as one

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desmosome/tight junction

mechanical connection between cells

60

gap junction

electrical connection between cells

61

cardiac muscle metabolism is mostly ____

aerobic