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mcdb1b > musculatory system > Flashcards

musculatory system Flashcards

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1
Q

Three types of vertebrae muscle

A

Skeletal muscle

Cardiac

Smooth

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2
Q

Skeletal muscle - basic function

A

Voluntary movement
Most are connected to bones by tendons

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3
Q

Cardiac muscle - basic function

A

Heart muscles

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4
Q

Smooth muscles - basic function

A

Involuntary muscle
Controls blood flow
Movement of food through digestive tract

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5
Q

Skeletal muscles - detailed function / description

A

Very long muscles
Have multiple nuclei
Shapes and sizes are central to their function
Huge cells develop by the fusion of smaller cells into long fibers

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6
Q

how do skeletal muscle fibers form

A

Myoblasts fuse to form a skeletal muscle fiber

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7
Q

Satellite cells are

A

a type of stem cells that are intermingled into your muscle
If you damage your muscle these will repair it

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8
Q

Going to gym and your muscles get bigger

A

You aren’t getting more muscle cells but you are increasing the diameter of the fibers of the cells you have

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9
Q

How muscles generate force

A

Muscles shorten
musscle cells contract to generate force

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10
Q

Skeletal muscle consists of

A

a bundle of long fibers, each a single cell, running along the length of the muscle (muscle fiber)

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11
Q

A muscle fiber is a bundle of

A

smaller subcellular myofibrils arranged longitudinally
One big membrane around it

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12
Q

One single muscle fiber(in the bundle) will be filled with a subcellular array called

A

myofibers

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13
Q

The myofibrils are

A

bundles of organized contractile protein molecules called sarcomeres

Arrays of protein molecules that generate a contractile force

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14
Q

what interaction in the sarcomeres shorten muscles

A

interaction of myosin and actin

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15
Q

Muscle fiber cell contraction relies on the interaction between

A

thin filaments, composed mainly of the proteins actin, and thick filaments, staggered arrays of myosin

\Bundles of Myosin interact with bundles of actin

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16
Q

Force is generated when the sarcomeres

A

contract

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17
Q

Actin filaments(thin) are anchored to ___

A

Z-line\
and myosin tug on these thin filaments moving the Z-disks closer

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18
Q

How does myosin pull the z-lines together?

A

Each myosin has a long tail region and a globular head region
The head of a myosin molecule binds to an actin filament, forming a cross-bridge and pulling the thin filament toward the center of the sarcomere
The sliding filament model\
One sarcomere will get shorter and since all the saromeres are glued together each sarcomere will pull the fibers together and shorter and force can be generated

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19
Q

Hydrolysis of ATP causes myosin head to go through a configuration change

how does this happen

A

Myosin head binds to ATP (low-energy configuration/bent)

When myosin has ATP bound to it it will not associate with actin

Enzymes catalyze the hydrolysis of ATP to ADP +Pi (high-energy configuration)

Hydrolysis of ATP causes change in myosin configuration

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20
Q

Atp hydrolysis allows what two thngs to bind

A

myosin bind to actin and form a cross-bridge

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21
Q

Binding of myosin release

A

ADP + Pi

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22
Q

what movement officially causes our muscle to contract

A

While myosin is bound to actin, it moves back into original configuration causing our muscles to contract

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23
Q

After ADP + Pi is released and myosin is still attached to actin, what occurs

A

a new ATP can bind to the myosin and it releases the myosin from the actin (small nudge/movement)
Many cycles required to contract muscle

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24
Q

what determines the strength of contraction of a muscle

A

There are millions of myosin molecules in each muscle fiber
Many or all of the myosin molecules work together to generate force when needed
The number of myosin molecules activated determines the strength of the contraction

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25
what regulatoru components allow you to control your muscle
Troponin and tropomyosin
26
do troponin and tropomyosin generate any force
no
27
What prevents actin and myosin from interacting
tropomyosin When u aren't using the muscle the tropomyosin sits where myosin wants to bind
28
troponin is regulated by Ca2+ in what way
Ca2+ binds to troponin Causing the tropomyosin to move out Exposes myosin binding sites
29
Calcium binding allows interaction of myosin and actin A low concentration of Ca2+ means that o
only some of the troponin will have bound Ca2+ Generate a weak contractile force
30
A higher concentration of Ca2+ means that
more of the troponin will have bound Ca2+ Generate a stronger contractile force
31
the degree of contraction is changed by
Adjusting the amount of calcium
32
Motor neuron talks to a muscle at
the neuromuscular junction
33
Where does Ca2+ come from?
Sarcoplasmic reticulum is a series of internal sacss within the muscle fiber Muscle cells store calcium in these sacs An internal membrane enclosed compartment Calcium can be selectively released from the SR into the cytoplasm where it will bind to troponin
34
what does action potentials propogating through muscle fibers result in
muscle contraction
35
describe the general steps of the beginning of muscle contraction via action potentials what sets off the action potential
1. Starts with arrival of the action potential at the motor nerve terminus 2. All of our motor neurons release acetylcholine when an action potential arrives → when brain tells muscle to contract Acetylcholines allow sodium into the cell, depolarizes it, set off action potential → action potential move through surface of cell
36
Muscle fibers are big and have only one neuromuscular junction per fiber, per cell, the goal is to activate contraction throughout fiber. To accomplish this the action potential
spreads in the fiber membrane
37
One action potential down a motor neuron will always set off an action potential in the muscle cell why
Already made decision to contract muscle so it will happen
38
Transverse tubules
extensions of the plasma membrane that extend into the cell The action potential moves down the T tubules
39
what happens once action potential reaches the T tubules
since the T tubules are close to the SR, the Arrival of the action potential in the T tubules is sensed by the sarcoplasmic reticulum and Ca2+ channels are opened Ca2+ rushes out of the SR into the cytoplasm where it binds to troponin and moves tropomyosin out of the way which initiates contraction
40
Contraction must also be turned off how is this done
ATP uses the Ca2+ pump and activates it and causes it to pump Ca2+ against its concentration gradient back into the SR As the Ca2+ moves back into the SR, the tropomyosin now blocks myosin binding site on actin again and the muscle fiber relaxes
41
Which is true? As cytoplasmic (myoplasmic) Ca2+ increases, more actin binding sites are blocked by tropomyosin Ca2+ and ATP both bind actin The ATPase activity of myosin means that it makes ATP Myofibrils are found inside the sarcoplasmic reticulum ADP is released from myosin when it binds actin
: (e) ADP is released from myosin when it binds actin
42
How we control strength of muscle contraction → muscle tension Two mechanisms by which the nervous system produces graded contractions
Not all fibers within a muscle are activated for a contraction It depends upon the desired strength of the contraction Individual fibers can also adjust their strength too, to be activated to varying degrees by varying the amount of Ca2+ released
43
Motor unit
Each motor neuron makes contact with multiple muscle fibers Each muscle fiber has only one neuromuscular junction but one motor neuron makes muscle neuromuscular junctions with multiple fibers Motor neuron and all the muscle fibers it controls
44
How do differing motor units determine strength of contraction
Our muscles contain a mix of large and small motor units Muscles that do large strenuous tasks like those in our legs and back have mostly large motor units Fine motor control like in our fingers requires many small motor units Depending on task, the big vs small motor units that are used are different
45
This process of which motor units get activated is called
recruitment or recruited
46
Motor unit recruitment
Recruitment is the process by which more and more motor neurons are activated in order to meet the required task As recruitment proceeds and large motor units are activated, the force developed by a muscle increases Start with little motor units → activate larger and more if we aren’t accomplishing task and so on and so forth → get more contraction and strength
47
A single motor unit... Consists of many motor neurons but only a single muscle fiber Are all of the same size When faced with a task you always recruit the largest motor units first The cell bodies of motor neurons are in the muscles they control None of these is correct
(E) none of these is correct (d) the cell bodies of motor neurons are in your spinal cord and it sends an axon out to the muscle and you have one motor neuron controlling multiple muscle fibers
48
Second way that you regulate strength
within a motor unit control how strongly we tell each fiber to contract (turn on motor unit high or low)
49
A twitch Results from
a single action potential in a motor neuron In a twitch only a few troponin bind Ca2+ Only some of the actin and myosin go through cross-bridging cycles Only a small amount of tension is generated in the muscle
50
Change how much cross-bridging occurs by changing
amount of Ca2+ is in the area
51
52
Tension increases as
the series of action potentials(frequency) increases
53
The nervous system dictates that strength of contraction in each fiber Via
frequency of action potentials it sends down the motor neuron One action potential gives us a little contraction The amount of calcium released into the cytoplasm is not enough for every troponin to be bound to them → only some possible cross-bridges take place If action potentials are closer together in time the twitches sum up and the tension increases
54
One action potential occurs and calcium is pumped out of SR while atpase is also working to put calcium back into SR If second action potential occurs before calcium pump can pump all the calcium back to SR what can occur
the calcium concentration adds up and more can bind to troponin Occurs because Ca2+ pumps cannot pump the released Ca2+ pumps cant pump the released Ca2+ back into the sarcoplasmic reticulum from before the next action potential arrives Increases cross-bridging
55
Tetanus
- A state of smooth and sustained contraction produced when the rate of stimulation is so high that muscle fibers cannot relax between stimuli - Once you have every troponin with a calcium bound to it you won’t be able to get more cross-bridging and tension is at its max
56
If ca2+ is released faster from their channels on the sarcoplasmic reticulum faster then
the ca2+ pump can send it back into the sarcoplasmic reticulum, then the force of contraction will increase
56
When you need more strength: Use
larger motor units but also send more action potentials so that you can contract more strongly
57
Not all skeletal muscle fibers are the same One of the ways they differ is
how they generate ATP
58
How do we get ATP from muscle cells?
Muscles have three systems for obtaining ATP Immediate system Glycolytic system Oxidative system
59
Immediate system for obtaining atp
creating phosphate (anaerobic) Uses creatine-phosphate which can rapidly generate ATP Only enough for a few short bursts of energy
60
Glycolytic system
(anaerobic) Metabolizes carbohydrates to pyruvate and lactic acid Get 2 atp
61
Oxidative system
(aerobic) → require oxygen Metabolizes carbohydrates and fatty acids to H2O and CO2 Get about 26 or 28 atp
62
When you are exercising you can’t deliver enough oxygen to meet the needs of your muscles
Why you can only run at full speed for a short time Limited by lack of oxygen Muscles become fatigued → lactic acid build up
63
solution for muscle fatigue
For short intense contractions muscles use Creatine-P and Glycolysis for ATP synthesis (not enough oxygen for oxidative phosphorylation) The anaerobic or glycolytic ATP generation Anaerobic ATP generation causes lactic acid buildup which fatigues your muscles (glycolysis) → eventually have to stop Pant to get oxygen back → oxidative phosphorylation to catch-up Lactic acid goes back to pyruvate and then goes to oxidative phosphorylation Happens when you exceed limits of circulatory system to deliver oxygen to _
64
slow oxidative muscle fibers (contraction speed, major atp source, rate of fatigue, mitochondria, muoglobin content)
slow contraction speed aerobic respiration slow rate of fatigue many mitochondria high myoglobin content (red muscle)
65
fast oxidative muscle fibers
contraction speed is fast major atp source is aerobic respiration intermediate rate of fatigue many mitochondria high myoglobin content
66
fast glycolytic muscle fibers
fast contraction speed major atp source is glycolysis fast rate of fatigue few mitochondria low myoglobin content (white muscle)
67
Myoglobin draws oxygen to muscle cell from
interstitial fluid
68
In a muscle we will have motor units that are slow twitch and fast twitch what is the difference in structure
Fast twitch motor units are bigger Used for big strenuous actions
69
Fast-twitch vs Slow-twitch fibers
Fast twitch Enable brief, rapid, powerful contractions Fast-twitch fibers can be either glycolytic or oxidative Slow-twitch Contract more slowly but sustain longer contractions Slow fibers have less sarcoplasmic reticulum than fast fibers and pump ca2+ more slowly All slow-twitch fibers are oxidative
70
Q: during an aerobic exercise a.Your muscles fatigue quickly due to lactic acid build up b.Your muscles generate ATP via oxidative phosphorylation c.The use of oxygen by your muscles does not exceed supply d.Your muscles switch from using atp to power cross-bridging to using lactic acid e.More than one of these is correct
(E) b and c are correct
71
Cardiac muscle
Found only in the heart Has sarcomeres Consists of Striated cells that are electrically connected by intercalated disks Only one nucleus per cell Electrically connected via gap junctions Have action potentials that are conducted through gap junctions
72
Cardiac muscle can generate action potential without
neural input smooth muscle
73
Cardiac and smooth muscle cells are arranged in sheets Cells in the sheets are in electrical contact via
gap junctions
74
gap junctions allow for
action potential in one cell can spread to all others in the sheet Synchronize contractions
75
Smooth muscle
Not muscle you think about to move Simplest muscle cells structurally Found mainly in walls of hollow organs such as those of the circulatory, digestive, and reproductive systems Contractions are relatively slow and may be initiated by the muscle themselves Relatively weak Contractions may also be caused by stimulation from neurons in the autonomic nervous system
76
smooth muscles lack striations becausr
the actin and myosin are not regularly arrayed Calcium ions enter the cytosol through the plasma membrane They don't have a sarcoplasmic reticulum Interacting network that contracts the whole cell

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