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KPE 260 Human physiology > Skeletal Muscle L12 > Flashcards

Skeletal Muscle L12 Flashcards

(58 cards)

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1
Q

what are the connective tissue components of skeletal muscles:
surrounded by: __________ _________
____________ subdivides the muscle into fascicles
each fascicle is subdivided into muscle fibres(myofibers) surrounded by _______

A
  • fibrous epimysium
  • perimysium
    -endomysium
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2
Q

when muscles contract, do tendons absorb some of the tension?

A

YES!

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3
Q

what parts of the muscle and tendons must be pulled tight when muscles contract?

A

the non contractile parts:
Ligaments, joint capsules, and fascia are noncontractile components of muscle composed of collagen and elastin fibres.

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4
Q

muscle fibres have plasma membranes called:

A

sarcolemma

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5
Q

muscles fibres are _____________ and form a ________

A

multinucleated
syncytium: a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei.

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6
Q

muscle fibres are striated:
1. I band
2. A band
3. Z lines

A
  1. I bands: light bands
  2. A bands: dArk bands
  3. Z-lines(discs): dark lines in the middle of the I bands
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7
Q

each muscle fibre has densely packed units called _______ that run along length
they are composed of ______ and _________ myofilaments
stacked so ________ and _________ bands align

A

myofibrils
thick and thin
dark and light

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8
Q

striations are produced by:

A

thick and thin filaments

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9
Q

In striations, I bands contain ONLY ______________ filaments, primarily of the protein ______

A

thin
actin

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10
Q

in striations, A bands contain ALL ___________ filament with SOME _________ filament overlap.
the thick filament is the protein ________

A

thick
myosin

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11
Q

in striations, H bands are the _________ of the A band with No ________ filament overlap

A

center
thin

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12
Q

in striations, Z discs(lines) are found in the ___________ of each _______ band

A

center
I band

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13
Q

the functional unit of muscle

A

sarcomere

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14
Q

the sarcomere is 1 ____________ to the next

A

z-disc

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14
Q

the sarcomere is 1 ____________ to the next

A

z-disc

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15
Q

titin:
runs from __________ to ______________
allows___________

A

largest protein in body
protein that runs from Z disc to M line and allows elastic recoil

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16
Q

what protein in sarcomere allows elastic recoil?

A

titin

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17
Q

what is found in the center of each A band and helps hold down thick filaments

A

M lines

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18
Q

Sliding filament theory:
when a muscle contracts, sarcomeres _________

A

SHORTEN

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19
Q

in sliding filament theory when a muscle contracts:

what happens to A bands?

A

DO NOT shorten, but move closer together

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20
Q

in sliding filament theory when a muscle contracts:
I bands:

A

SHORTEN, but thin filaments DO NOT ( thin filaments slide toward H bond)

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21
Q

in sliding filament theory when a muscle contracts:
H band:

A

shortens or disappears
thin filaments slide toward H bond

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22
Q

what are the 3 subunits of troponin? (ICT)

A

I: inihibory part blocks myosin head binding to actin
C: binds to calcium linking it to the nerve (calcium released from sarcoplasmic reticulum)
T: binds to tropomyosin

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23
Q

thick filaments(myosin)

Study These Flashcards
A

Each protein has two globular heads with
actin-binding sites and ATP-binding sites

24
thin filaments(actin)
Have proteins called tropomyosin and troponin that prevent myosin binding at rest
25
action of sliding in sliding filament theory
Sliding is produced by several cross bridges that form between myosin and actin. a) The myosin head serves as a myosin ATPase enzyme, splitting ATP into ADP + Pi. b) This allows the head to bind to actin when the muscle is stimulated.
26
Release of Pi upon binding cocks the myosin head, producing a__________ _________ that pulls the thin filament toward the center
power stroke
27
After the power stroke, _______ is released and a new ATP binds.
ADP -This makes myosin release actin. -ATP is split. The myosin head straightens out and rebinds to actin farther back. Continues until the sarcomere has shortened
28
what does Regulation of Contraction
F-actin(fibrous actin) is made of 300-400 G-actin subunits, arranged in a double row and twisted to form a helix
29
F-actin(fibrous actin) is made of 300-400 G-actin subunits, arranged in a double row and twisted to form a helix
cross bridges
30
Troponin complex 1. Troponin I inhibits binding of 2. Troponin T binds to 3. Troponin C binds to
1. Troponin I inhibits binding of myosin. 2. Troponin T binds to tropomyosin. 3. Troponin C binds to calcium.
31
When muscle cells are stimulated, Ca2+ is released where?? some attaches to Troponin C, causing a _________ Myosin is allowed access to form cross bridges with______
inside the muscle fiber. conformational change in troponin and tropomyosin. ACTIN
32
sarcoplasmic reticulum is a modified Er that stores Ca when most SR is stored in: _______
-muscle is at rest -terminal cisternae
33
When a muscle fiber is stimulated, Ca2+ diffuses out of
calcium release channels (ryanodine receptors).
34
At the end of a contraction, Ca2+ is actively pumped back into the
SR
35
role of SR
role of SR
36
transverse tubules are: NT: open to the : able to conduct: closely situated next to:
-Narrow membranous tunnels formed from the sarcolemma -acetylcholine -extracellular environment -action potentials -terminal cisternae
37
to stimulate a muscle fiber: _____________ is released from motor neuron conducted along__________ calcium is released)SR) and can bind to:
acetylcholine -the sarcolemma(Na) -troponin C
38
can get graded muscle contraction but not fiber..HOW?
recruitment more motor units
39
Axon terminal of motor neuron forms neuromuscular junction with _______
a single muscle fibre
40
Signals are passed between nerve terminal and muscle fiber by means of neurotransmitter ___________ Released ACh binds to receptor sites on motor end plate of _________________ Binding triggers ____________ of specific channels in motor end plate Ion movements _________ motor end plate, producing end-plate potential
-Acetylcholine -muscle cell membrane -opening -depolarize
41
in muscle relaxation: Action potentials ________ Calcium release channels ___________ Ca2+-ATPase pumps move Ca2+ ___________________________ No more Ca2+ is available to bind to Tropomyosin moves to block the myosin heads from
-cease -close -back into SR (active transport). -troponin C -binding to actin
42
ACH Agonists: drugs that can stimulate a receptor: (2)
1. nicotine 2. muscarine
43
ACH antagonists: drugs that inhibit a receptor
1. curare 2. atrophine
44
1. curare 2. atrophine
1 motor neuron all the muscle fibres it innervates
45
1 motor neuron all the muscle fibres it innervates
NO
46
1 motor neuron all the muscle fibres it innervates
site where a motor neuron stimulates a muscle fiber
47
site where a motor neuron stimulates a muscle fiber
area of the muscle fiber sarcolemma where a motor neuron stimulates it using the neurotransmitter, acetylcholine
48
TYPE I Muscle fibres are: slow twitch fibers
slow oxidative contract relatively slowly and use aerobic respiration (oxygen and glucose) to produce ATP. They produce low power contractions over long periods and are slow to fatigue. slower contraction speed; can sustain contraction for long periods without fatigue; rich capillary supply; more mitochondria; more respiratory enzymes; more myoglobin a. Tend to have high oxidative capacity, so are called (slow) oxidative fibers b. Due to high myoglobin content (which has a red pigment), these are also called red fibers c. Found in postural muscles
49
Type IIA fibers fast oxidative
fast twitch, have high oxidative and glycolytic capacity, and are relatively resistant to fatigue fast-twitch but with high oxidative capacity; called fast oxidative fibers
50
Type IIB fibers (IIX) fast-glycolytic (myosin heavy chain, ATPase)
fast twitch, have low oxidative and high glycolytic capacity, and fatigue rapidly faster contraction speed, fatigue fast, fewer capillaries, mitochondria, respiratory enzymes, and less myoglobin a. Also called white fibers b. Have more glycogen stores and are called fast glycolytic fibers c. Found in stronger muscles
51
endurance running recruits:
type I and IIa
52
at rest utilizes:
at rest utilizes:
53
each muscle fibre is activated thru impulses delivered via
motor end plate
54
motor end plate
when a muscle quickly contracts and relaxes after a single electrical shock of sufficient voltage (AP). -Increasing the voltage increases the strength of the twitch up to a maximum. -When a second shock is applied immediately after the first, a second twitch will partially piggyback the first. This is called summation
55
summation:
two successive action potentials (AP), if the twitch tension resulting from the first AP does not decline to zero before asecond twitch arrives, the twitch forces summate.
56
tetanus:
frequency of APs(action potentials)-a rise in the contractile force of a single muscle (fibre) until force reaches a plateau called the tetanic tension. This is the maximum tension that can be produced by a fibre. if a muscle fibre is stimulated so rapidly that it doesnt have an opportunity to relax at all between stimuli, a maximal sistained contraction known as tetanus occurs a. Increasing the frequency of electrical shocks decreases the relaxation time between twitches. This is called incomplete tetanus. b. At a certain frequency, there will be no relaxation. This is called complete tetanus, a smooth, sustained contraction.
57
Latent period
time between the stimulus and the contraction (excitation-contraction coupling to the attachment of myosin cross bridges to actin)

KPE 260 Human physiology (4 decks)

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