8 Skeletal Muscle as an Effector Organ

Question 1

skeletal mm def

Answer 1

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

Question 2

visceral mm

Answer 2

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

Question 3

cardiac mm

Answer 3

heart mm

Question 4

striated mm

Answer 4

skeletal and cardiac

Question 5

smooth mm

Answer 5

lack striations - vascular and visceral mm

Question 6

voluntary mm

Answer 6

receive signals from CNS - most skeletal mm

Question 7

involuntary mm

Answer 7

mostly receives signals from ANS - visceral and cardiac mm

Question 8

tendon

Answer 8

attaches mm to bone

Question 9

origin

Answer 9

proximal attachment of mm

Question 10

insertion

Answer 10

distal end of mm attachment

Question 11

muscle fibers

Answer 11

skeletal mm cells

Question 12

endomysium

Answer 12

connective tissue surrounding individual mm fibers

Question 13

perimysium

Answer 13

connective tissue surrounding bundles of muscle fibers (fasciculi)

Question 14

epimysium

Answer 14

connective tissue surrounding the ENTIRE muscle

Question 15

muscle fibers is composed of smaller fibrous structures called _____

Answer 15

myofibrils

Question 16

myofibril is divided into ___ and ____ filaments

Answer 16

thick and thin

Question 17

think filaments are ___ bands

Answer 17

A bands

Question 18

thin filaments are ___ bands

Answer 18

i bands (think of “i” as a thin letter)

Question 19

the M line runs down the center of the

Answer 19

A band

Question 20

___ runs across the center of the I band

Answer 20

Z line/Z disk

Question 21

sarcomere is defined as the space from ___ to ____

Answer 21

Z disk to Z disk

Question 22

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

Answer 22

I band

Question 23

thin filaments are composed of

Answer 23

actin, tropomyosin, troponin

7:1:1

Question 24

thin filaments are the main site of

Answer 24

calcium regulation

Question 25

two states of actin molecule

Answer 25

G actin - monomeric

F actin - polymer of G actins

Question 26

tropomyosin is composed of

Answer 26

a-helical chains

Question 27

troponin has these 3 proteins

Answer 27

Troponin-T
Troponin-C
Troponin-I

Question 28

Troponin-C

Answer 28

calcium sensor in skeletal and cardiac mm

Question 29

Troponin-I

Answer 29

“glue” that holds troponin-tropomyosin-actin together

Question 30

these two components are involved in tension generation

Answer 30

actin

myoson

Question 31

these two components are regulatory proteins

Answer 31

troponin

tropomyosin

Question 32

thick filaments are made primarily of

Answer 32

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

Question 33

attached to each globular head portion of myosin are

Answer 33

two essential light chains and two regulatory light chains

Question 34

myosin thick filament consists of

Answer 34

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

Question 35

___ region of myosin binds ATP and actin

Answer 35

head region

Question 36

sarcolemma

Answer 36

outer membrane surrounding each muscle fiber

consists of plasma membrane (plasmalemma) and basement membrane

Question 37

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

Answer 37

gap junctions/tight junctions

Question 38

T-tubules

Answer 38

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

Question 39

Sarcoplasmic reticulum (SR)

Answer 39

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

Question 40

terminal cisternae

Answer 40

enlarged portion of SR containing T-tubules

Ca2+ stored here

Question 41

triad

Answer 41

group of 1 T-tubule and 2 terminal cisternae

Question 42

H zone

Answer 42

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

Question 43

The A band technically consists of

Answer 43

both thick and thin filaments

Question 44

excitation-contraction coupling

Answer 44

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

Question 45

Ca2+ binding to ___ removes blocking action of ____

Answer 45

1/ troponin

2/ tropomyosin

Question 46

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

Answer 46

T-tubule

Question 47

Ca2+ ions bind to _____ to initiate contraction

Answer 47

Troponin-C

Question 48

calsequestrin

Answer 48

a protein in the SR that binds Ca2+

Question 49

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

Answer 49

tropomyosin

Question 50

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

Answer 50

myosin-binding sites on actin filaments

Question 51

the active site is on the ____

Answer 51

thin filaments

Question 52

each tropomyosin molecule exerts control over ___ actin monomers

Answer 52

7

Question 53

the crossbridge can get ready for a new cycle once

Answer 53

ATP binds to myosin

Question 54

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

Answer 54

ATP, rigor mortis

Question 55

muscle contraction occurs as long as ___ and ___ are present

Answer 55

ATP, Ca2+

Question 56

this structure stores calcium ions

Answer 56

sarcoplasmic reticulum

Question 57

cardiac mm AP is activated by

Answer 57

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

Question 58

intercalated disc

Answer 58

connects cardiac cells and allow them to function as one

Question 59

desmosome/tight junction

Answer 59

mechanical connection between cells

Question 60

gap junction

Answer 60

electrical connection between cells

Question 61

cardiac muscle metabolism is mostly ____

Answer 61

aerobic