Term
| skeletal muscle converts __ energy to ___ energy to ___ energy. |
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Definition
| electrical energy> chemical energy> mechanical energy |
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Term
| what is the largest tissue in body? |
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Definition
|
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Term
|
Definition
-attached to bone
-striated
-voluntary
-neural control
-high power
-normally
relaxed |
|
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Term
|
Definition
-heart
-striated; involuntary
-intrinsic activity
-neural-humoral control
-high power
pump (repetitive) |
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Term
|
Definition
-hollow organs
-non-striated;smooth
appearance
-intrinsic activity
-involuntary
-neural-humoral control
-low power
-normally contracting
(variable) |
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Term
| functional characteristics of skeletal muscle: |
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Definition
Excitability / Irritability
Contractility
Extensibility
Elasticity |
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Term
| a muscle fasiculus is a bundle of muscle ___. |
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Definition
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Term
| a muscle fiber is made of many ___. |
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Definition
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Term
| fasiculus> fiber> myofibril |
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Definition
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Term
| connective tissue around the entire muscle is the ____. The wrapping around each fasicle is the ___. The wrapping around each fiber is the ____. |
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Definition
- epimysium
- perimysium
- endomysium |
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Term
| the cell membrane of a muscle cell is called: |
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Definition
|
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Term
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Definition
| - oxygen binding protein in cytoplasm of muscle cells |
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Term
| Each skeletal muscle cell is ___ innervated. |
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Definition
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Term
| Does red slow twitch or white fast twitch have more myoglobin? |
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Definition
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|
Term
|
Definition
- functional unit in skeletal muscle
- goes from one z line to the next |
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Term
| the H zone of the sarcomere is where ___ ____ are lacking. |
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Definition
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Term
| ___ protein is the largest protein in the body. |
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Definition
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Term
| functional role of Titin protein: |
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Definition
- looks like a spring/slinky
- connects the thick myofilament to the Z line
- so when you stretch your muscles you are stretching titan protein |
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Term
| When you overstretch your muscles, what has happened? |
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Definition
| - stretched out titan too much to the point that it can't recoil back |
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Term
| the thick myofilament in the sarcomere is ___. the think myofilament in the sarcomere is ___. |
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Definition
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Term
| In the H zone, myosin is arranged in ___ to ___. Outside of the H zone, myosin is arranged __ to __. |
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Definition
- tail to tail
- head to tail |
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Term
|
Definition
- long, straight, tail portion of myosin
- helps control ATPase activity so helps control movement of the myosin heads |
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Term
|
Definition
| - myosin protein chain terminating in globular head portion- cross bridging |
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Term
| Each of the myosin heads has what 2 binding sites? |
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Definition
- actin binding site
- ATP binding site |
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Term
| what determines the rate of muscle contraction when the muscle is stretched? |
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Definition
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Term
| will fast twitch muscle have slow or fast myosin atpase? |
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Definition
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Term
| How does fast myosin atpase correspond to a fast contraction? |
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Definition
| - fast myosin atpase hydrolyzes ATP more quickly |
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Term
| what determines if a muscle will be fast twitch or slow twitch? |
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Definition
- the nerve that innervates it
the nerve determines the characteristics of the muscle |
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Term
| ___ is responsible for 50% of muscle tension during resting state. |
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Definition
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Term
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Definition
| large elastic protein extending from myosin to Z-disk; holds thick filament in lace along with M-line proteins; responsible for most of passive tension |
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Term
| ___ ___ and ___ determine the passive force of a muscle. The more you stretch a muscle the greater its ___ ___ will be without nerve stimulation. |
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Definition
- connective tissue
- titin
- passive force |
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Term
| each molecule of actin has a __ binding site that is blocked by ___ in the relaxed state. |
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Definition
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Term
| 1 tropomyosin protein covers ___ actin molecules. |
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Definition
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Term
| 3 binding sites of troponin: |
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Definition
C site: binds calcium
T site: binds tropomyosin
I site: inhibitory subunit, binds actin |
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Term
| what occurs so that actin and myosin can bind? |
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Definition
| - calcium increases> calcium binds C site on troponin, troponin changes confirmations and binds tropomyosin causing tropomyosin to dissocaite from actin> actin and myosin bind |
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Term
|
Definition
| - protein that runs along actin (thin filament) for support |
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Term
| during a muscle contraction, what changes occur in the sarcomere? |
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Definition
- distance between Z lines gets shorter
- A band stays the same width
- I band gets much shorter, or disappears with a big contraction
- H zone disappears b/c thin filaments overlap |
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Term
| invaginations in the sarcolemma are called what and occur where? |
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Definition
- T-tubules
- intersection of A and I bands |
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Term
| what is the T tubule filled with? |
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Definition
|
|
Term
| what surrounds each myofibril? |
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Definition
|
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Term
| sarcomplasmic reticulum function: |
|
Definition
- storage and release of calcium
- calcium ATPase
- calsequestrin (calcium binding protein) |
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Term
| a t- tubule with SR on either side is called? |
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Definition
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Term
| SR has ___ proteins that are receptors that regulate the ___ release from the the SR ____. |
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Definition
- foot
- calcium
- cisternae |
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Term
| T- tubule proteins act as ___ centers. |
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Definition
| voltage, they are dihydropyradine receptors |
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Term
| The SR is an ___ network, while the T tubules are in contact with the____ fluid. |
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Definition
- intracellular
- extracellular |
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Term
| the portion of the SR nearest the t tubule is called the ___ ___. This is where calcium is released from. |
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Definition
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Term
| proteins on the t-tubules detect a change in ___ ___ in the SR, which causes a conformational change in the calcium channel so that calcium is released. Increased calcium in SR> muscle contraction. |
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Definition
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Term
| The internal zipper of the T tubule and SR junction refers to: |
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Definition
| - external 4 integral foot proteins on SR binding with internal integral transmembrane proteins on internal face of T tubule |
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Term
| So on the SR t tubule junction, the SR foot proteins bind to the transmembrane proteins of the t tubule. this allows the DHP receptor voltage center of the t-tubule to sense a change in membrane potential of the sarcolemma, which in turn causes a conformational change in the SR's ryanodine calcium channels so that calcium is released into the SR and the muscle contracts. |
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Definition
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Term
| describe process of EC coupling: |
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Definition
| - action potential travels down sarcolemma to t-tuble> voltage channels on t-tubule get excited> ryanodine calcium channels on SR open up> calcium increases inside cell> actin and myosin interact > contraction |
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Term
| A somatic nerve can innervate ___ muscle fibers, but each skeletal muscle fiber is only innervated by ___ nerve. |
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Definition
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Term
| The nerve that innervates more muscle fibers will generate more __. |
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Definition
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Term
| once calcium has rushed into cell in response to an action potential, what happens next in skeletal muscle? |
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Definition
| - calcium signals vesicles of acetylcholine to fuse with the cell membrane and release acetylcholine into the synaptic cleft> acetylcholine binds to specific receptors in post synaptic membrane> binding causes opening (sometimes closing) of ion channels in the post synaptic membrane> change in membrane potential of postsynaptic membrane> altered excitability of cell |
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Term
| with an electrical synapse there is direct communication between the ___ of the two cells. This is not the case with chemical synapses. |
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Definition
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Term
| in the synaptic cleft, acetylcholine gets degraded by: |
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Definition
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Term
| the neuromuscular junction is formed by: |
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Definition
- axonal endings with synaptic vesicles of neurotransmitter
- motor end plate of a muscle= part of the sarcolemma that contains acetylcholine receptors |
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Term
| axonal ends and muscle fibers are always separted by a space called the: |
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Definition
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Term
| When a nerve impulse reaches the end of an axon at the neuromuscular junction |
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Definition
Voltage-regulated calcium channels open and allow Ca2+ to enter the axon
Ca2+ inside the axon terminal causes axonal vesicles to fuse with the axonal membrane
This fusion releases ACh into the synaptic cleft via exocytosis
ACh diffuses across the synaptic cleft to ACh receptors on the sarcolemma
Binding of ACh to its receptors initiates an action potential in the muscle |
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Term
| ACh bound to ACh receptors is quickly destroyed by ___ ____. This destruction prevents continued muscle contraction in the absense of a stimulus. |
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Definition
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Term
| An action potential is a transient ___ event that includes ____ reversal of a ____ or nerve cell membrane and the propogation of the action potential along the membrane. |
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Definition
- depolarization
- polarity
- sarcolemma |
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Term
| ACh receptors are on the ___ ___ ___. |
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Definition
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Term
| when acetylcholine binds its receptors on the motor end plate, ____ ____ open allowing __ and ___ to diffuse out so that the interior of the sarcolemma becomes less negative. This is called ____. |
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Definition
chemically/ligand gated channels
- sodium
- potassium
- depolarization |
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Term
| Initially depolarization is a local electric event called an __ __ ___. Later, it ignites an ___ ___-that spreads in all directions across the sarcolemma. |
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Definition
- end plate potential
- action potential |
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Term
| There is more sodium and chloride ___ the cell than ___ the cell. |
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Definition
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Term
| There is more potassium ___ the cell than ___ the cell. |
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Definition
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Term
| The inside of the cell is ___ compared to the outside of the cell. The ___ ___ pump helps maintain this by pumping out __ ___ and bringing in ___ ___. |
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Definition
- negative
- out 3 sodiums
- in 2 potassiums |
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Term
| the resting membrane is 75x more permeable to potassium and chloride than to sodium. can leak out of channels that are always open. |
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Definition
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Term
| what maintains electrochemical gradient? |
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Definition
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|
Term
| cell membrane is impermeable to : |
|
Definition
| organic ions in the cytoplasm |
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Term
| the sarcolemma is relatively impermeable to sodium and potassium |
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Definition
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Term
| At the beginning of the generation of an action potential, an axonal terminal of a ___ neuron releases ACh and causes a patch of the ___ to be permeable to sodium (sodium channels open). When sodium enters the cell, the resting potential is ___, meaning ___ occurs. If the stimulus is strong enough, an action potential occurs. |
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Definition
- motor
- sarcolemma
- decreased
- depolarization |
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Term
| if the motor end plate depolarization is strong enough from acetyl choline, then ___ ___ ___ channels will open up causing the big depolarization that initiates the action potential. an action potential is __ or __. |
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Definition
- voltage gated sodium
- all or nothing |
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Term
| an action potential cannot occur in skeletal muscle unless the ___ ___ ___ channels are open |
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Definition
| - voltage gated sodium channels |
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Term
| How is an action potential propagated? |
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Definition
| - polarity reversal of the initial patch of the sarcolemma changes the permeability of the adjacent patch> voltage gated sodium channels in adjacent patch open up> depolarization> once initiated the ap is unstoppable and ends in contraction of muscle |
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Term
| Repolarization= immediately after wave of depolarization, permeability of sarcolemma changes. explain. |
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Definition
- Na+ channels close
- K+ channels open
- K+ diffuses out of the cell, restoring electrical polarity of the sarcolemma |
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Term
| Repolarization occurs in same direction as depolarization and must occur before muscle can contract again (___ __) |
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Definition
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Term
| the ionic concentration of the resting state is restroed by what pump at the end of repolariztion? |
|
Definition
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|
Term
|
Definition
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|
Term
| in rigor mortis all the myosin is bound to actin b/c there is no ___ and so much ___. |
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Definition
- no ATP
- so much calcium |
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|
Term
Steps in muscle relaxation:
1. Calcium is pumped back into the ___. Calcium binds ___ in the SR. Calcium binds ___ in the cytoplasm.
2. Calcium is released from ___.
3. ___ blocks actin active site.
4. Cessation of interaction between ___ and ___. |
|
Definition
1. SR, calsequestrin in SR, calmodulin in cytoplasm
2. calcium is released from troponin
3. tropomyosin blocks the active site on actin
4. actin and myosin |
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Term
| If a muscle generates enough force to balance the load, then the muscle is ___. |
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Definition
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Term
| Events at the Neuromuscular Junction |
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Definition
Nerve impulse reaches the end of an axon at the neuromuscular junction
↓
Voltage-regulated Ca2+ channels open and allow Ca2+ to enter the axon terminal
↓
Fusion of axonal vesicles containing ACh with the axonal membrane
↓
Release of ACh into the synaptic cleft via exocytosis
↓
ACh diffuses across the synaptic cleft
↓
ACh binds to chemically (ligand) gated channels (nicotinic ACh receptors) on muscle sarcolemma
↓
Na+ diffuses into cell and K+ diffuses out causing depolarization (initially, this is a local electrical event called an end plate potential)
↓
Ignites (via opening of voltage gated Na+ channels) an action potential that spreads in all directions across the sarcolemma
↓
Formation of cross-bridges between actin and myosin and sliding of thin on thick filaments
↓
Myosin cross bridges alternately attach and detach
↓
Thin filaments move toward the center of the sarcomere
↓
Generation of tension and/or shortening
(Hydrolysis of ATP powers this cycling process)
↓
CBC continues as long as Ca2+ levels elevated and ATP available |
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Term
| ____ refers to the activation of ___ cross bridges (force-generating sites). |
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Definition
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Term
| ___ occurs when the ____ generated by the cross bridge extends forces opposing ___. |
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Definition
- shortening
- tension
- shortening |
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Term
| ___ ends when cross bridges become inactive, the ___ generated declines, and ___ is induced. |
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Definition
- contraction
- tension
- relaxation |
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Term
| two types of skeletal muscle contraction are: |
|
Definition
- isometric contraction
- isotonic contraction |
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Term
| during isometric contraction, ___ increases, but ____ does not occur. |
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Definition
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|
Term
| during isotonic contraction, the muscle does ___. |
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Definition
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|
Term
| during what kind of contraction does the muscle shorten? |
|
Definition
|
|
Term
|
Definition
- alpha motor neuron and all the muscle fibers it supplies
- then number of muscle fibers per motor unit can vary from 4 to several hundred |
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Term
| muscles that control fine movements have ___ motor units. |
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Definition
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Term
| muscle fibers from a motor unit are spread throughout the muscle, therefore contraction of a ___ ___ ___ causes contraction of the ___ __. |
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Definition
- single motor unit
- entire muscle |
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|
Term
| summation of motor neurons: |
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Definition
| As level of excitation of motor neurons increases, more neurons fire, more motor units activated, increased tension development |
|
|
Term
| recruitment size principle: |
|
Definition
Smaller motor units activated first (Type I) – fine control: slow, oxidative, red fibers (endurance)
As load increases, more T required, larger & larger motor units gradually activated (Type II) – power – fast, glycolytic, white fibers
Order of recruitment: S/I → FR/IIA → FF/IIb units |
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|
Term
| describe red muscle fibers: |
|
Definition
red fibers:
- slow
- oxidative
- type I
- endurance |
|
|
Term
|
Definition
white fibers:
- fast
- glycolytic
- power
- type II |
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|
Term
| the more weight you are lifting, the more and larger ___ ___ are recruited. |
|
Definition
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