Muscles Flashcards

(38 cards)

1
Q

sarcolemma

A

cytosol of a muscle cell

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2
Q

sacroplasm

A

cytoplasm of a muscle cell

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3
Q

sarcomere

A

gives striation to the muscle cell
made up of thick and thin filaments
fundamental to muscle contraction

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4
Q

motor unit

A

= 1 motor neuron + all the muscle fibers the neuron innervates
those with fewer muscle fibers are better for precise movement

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5
Q

characteristics of muscle fibers

A

excitability
contractibility
extendability
elasticity

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6
Q

parts of a sarcomere

A
A-band 
I-band 
H-zone 
M-line
Z-line
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7
Q

A-band

A

myosin filaments

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8
Q

I-band

A

actin filaments and Z-line

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9
Q

H-zone

A

area of myosin that DOESN’T overlap

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10
Q

M-line

A

middle of myosin filament

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11
Q

Z-line

A

anchored actin filament

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12
Q

what changes in the sarcomere when a muscle contracts?

A

z-lines move closer together
I-band shortens
H-zone disappears

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13
Q

what are thin filaments mostly made of?

A

actin filaments

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14
Q

what are thick filaments mostly made of?

A

myosin

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15
Q

anatomy of myosin

A

head: binds actin

neck and tail: have variable lengths

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16
Q

which myosin type is present in muscles?

17
Q

myosin II

A

aka muscle myosin

has very long tail region that gives the structure of thick filaments

18
Q

myosin I

A

acts as an anchor between the cell membrane and the cytoskeleton

19
Q

myosin V

A

transports various cargo molecules

one of the main transport molecules

20
Q

proteins involved in regulating access to myosin binding sites

A

troponin

tropomyosin

21
Q

tropomyosin

A

binds and obscures myosin binding sites

22
Q

troponin

A

respond to calcium ions

23
Q

troponin subunits

A

TnC: binds to calcium ions
TnI: interacts with actin and obscures the binding site
TnT: interacts with tropomyosin

24
Q

proteins responsible for changes in intracellular calcium ion concentration

A
ATPase 
SERCA
sodium/calcium reversible exchanger
L-type calcium channel
RyR
25
ATPase
actively transports calcium ions outside the cell
26
SERCA
actively transports calcium ions from the sarcoplasm into the sarcoplasmic reticulum (SR)
27
sodium/calcium reversible exchanger
moves sodium and calcium either inside or outside the cell
28
L-type calcium channel
first responder to voltage changes across the sarcolemma
29
RyR
calcium channel that allows calcium to rapidly exit the SR | is where most of the intracellular calcium comes from
30
factors that determine the force of muscle action
the length of the muscle fiber before stimulation the number of recruited motor units the frequency of neuronal stimulation
31
summation
stimuli of increasing frequency that result in combining individual twitches
32
which type of muscle is NOT striated?
smooth (visceral) muscle
33
fast twitch muscle
reaches depolarization faster because of the number and the properties of the present sodium and calcium channels
34
slow twitch muscle
has slower depolarization and a longer contraction cycle
35
cardiac muscle
contraction is similar to slow twitch muscles, but differs in repolarization
36
what stimulates contraction of cardiac muscle?
pacemaker cells
37
what forms connections between the cytoplasms of two cardiac muscle cells?
desmosomes | gap junctions
38
which type of muscle has NO organized sarcomeres?
smooth (visceral muscle)