Title: .Biology Semester 2 / Muscles
Tags: Muscles definition

Q: Describe the structure of a single collagen molecule
A: > A fibrous protein with a quaternary structure
> Each collagen molecule contains 3 helical polypeptide chains arranged in a triple helix held together with hydrogen bonds
> Packed closely because every third amino acid in the polypeptide chain is glycine which is the smallest amino acid; R group made of a single hydrogen atom

Q: Describe the composition of a collagen fibre and explain why it is strong.
A: > Collagen fibrils are composed of covalently bonded, parallel collagen molecules.
> The covalent bonds are staggered which increases tensile strength of the fibril
> Fibrils are arranged together into fibres, which further increases strength

Q: Muscles are attached to bone by [...]
A: tendons

Q: Tendons are made of [...]
A: tough, inelastic collagen

Original: [[oc5::Elbow]] joint = [[oc1::synovial joint]]
This allows [[oc2::large degree of movement]]
Inside joint there is [[oc3::synovial fluid]] for [[oc4::lubrication]]
Q: ... joint = [...]
This allows ...
Inside joint there is ... for ...
A: synovial joint
Q: ... joint = synovial joint
This allows [...]
Inside joint there is ... for ...
A: large degree of movement
Q: ... joint = ...
This allows large degree of movement
Inside joint there is [...] for ...
A: synovial fluid
Q: ... joint = ...
This allows ...
Inside joint there is synovial fluid for [...]
A: lubrication
Q: [...] joint = ...
This allows ...
Inside joint there is ... for lubrication
A: Elbow
Elbow joint = synovial joint
This allows large degree of movement
Inside joint there is synovial fluid for lubrication
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Original: Define neuromuscular junction
[[oc1::A specialised synapse]] [[oc2::which occurs at the end of a motor neurone]] [[oc3::where it meets a muscle fibre]].
[[oc4::Release of acetylcholine]] [[oc5::following depolarisation]] [[oc6::stimulates contraction]].
Remarks: A specialised synapse which occurs at the end of a motor neurone where it meets a muscle fibre.
Release of acetylcholine following depolarisation stimulates contraction.
Q: Define neuromuscular junction
[...] ... ....
... ... ....
A: A specialised synapse
Q: Define neuromuscular junction
A specialised synapse [...] ....
... ... ....
A: which occurs at the end of a motor neurone
Q: Define neuromuscular junction
... which occurs at the end of a motor neurone [...].
... ... ....
A: where it meets a muscle fibre
Q: Define neuromuscular junction
... ... where it meets a muscle fibre.
[...] ... ....
A: Release of acetylcholine
Q: Define neuromuscular junction
... ... ....
Release of acetylcholine [...] ....
A: following depolarisation
Q: Define neuromuscular junction
... ... ....
... following depolarisation [...].
A: stimulates contraction
Define neuromuscular junction
A specialised synapse which occurs at the end of a motor neurone where it meets a muscle fibre.
Release of acetylcholine following depolarisation stimulates contraction.
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Original: Define summation
The [[oc1::additive]] effect of [[oc2::several electrical impulses]] on a [[oc3::neuromuscular junction]].
[[oc6::Individually]] the stimuli [[oc4::cannot evoke a response]], but [[oc7::collectively]] they [[oc5::can generate a response]].
Q: Define summation
The [...] effect of several electrical impulses on a neuromuscular junction.
Individually the stimuli cannot evoke a response, but collectively they can generate a response.
A: additive
Q: Define summation
The additive effect of [...] on a neuromuscular junction.
Individually the stimuli cannot evoke a response, but collectively they can generate a response.
A: several electrical impulses
Q: Define summation
The additive effect of several electrical impulses on a [...].
Individually the stimuli cannot evoke a response, but collectively they can generate a response.
A: neuromuscular junction
Q: Define summation
The additive effect of several electrical impulses on a neuromuscular junction.
Individually the stimuli [...], but collectively they can generate a response.
A: cannot evoke a response
Q: Define summation
The additive effect of several electrical impulses on a neuromuscular junction.
Individually the stimuli cannot evoke a response, but collectively they [...].
A: can generate a response
Q: Define summation
The additive effect of several electrical impulses on a neuromuscular junction.
[...] the stimuli cannot evoke a response, but collectively they can generate a response.
A: Individually
Q: Define summation
The additive effect of several electrical impulses on a neuromuscular junction.
Individually the stimuli cannot evoke a response, but [...] they can generate a response.
A: collectively
Define summation
The additive effect of several electrical impulses on a neuromuscular junction.
Individually the stimuli cannot evoke a response, but collectively they can generate a response.
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Original: [[oc1::Sustained muscle contraction]] evoked when [[oc2::motor nerves innervating skeletal muscles]] emit [[oc3::action potentials at a very high rate]]
During this state, [[oc4::motor unit is maximally stimulated]], and [[oc5::muscle remains contracted]]
E.g. [[oc6::holding a heavy object]]
Title: Tetanic contraction
Q: [...] evoked when ... emit ...
During this state, ..., and ...
E.g. ...
A: Sustained muscle contraction
Q: Sustained muscle contraction evoked when [...] emit ...
During this state, ..., and ...
E.g. ...
A: motor nerves innervating skeletal muscles
Q: ... evoked when motor nerves innervating skeletal muscles emit [...]
During this state, ..., and ...
E.g. ...
A: action potentials at a very high rate
Q: ... evoked when ... emit action potentials at a very high rate
During this state, [...], and ...
E.g. ...
A: motor unit is maximally stimulated
Q: ... evoked when ... emit ...
During this state, motor unit is maximally stimulated, and [...]
E.g. ...
A: muscle remains contracted
Q: ... evoked when ... emit ...
During this state, ..., and muscle remains contracted
E.g. [...]
A: holding a heavy object
Sustained muscle contraction evoked when motor nerves innervating skeletal muscles emit action potentials at a very high rate
During this state, motor unit is maximally stimulated, and muscle remains contracted
E.g. holding a heavy object
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Original: [[oc1::Tetanus neurotoxin]] enters inhibitory neurones in the CNS.
Cleaves [[oc2::VAMP]] - vesicle associated membrane protein, which is necessary for [[oc3::neurotransmitter vesicle exocytosis]]
I.E. prevents release of inhibitory neurotransmittors [[oc4::GABA]] and [[oc4::Glycine]] from inhibitory neurones.
Prevents their inhibition of [[oc5::overactive motor neurones]] firing and their role in relaxation.
Causes [[oc6::spastic paralysis]]
Title: Tetanus (disease)
Q: [...] enters inhibitory neurones in the CNS.
Cleaves ... - vesicle associated membrane protein, which is necessary for ...
I.E. prevents release of inhibitory neurotransmittors ... and ... from inhibitory neurones.
Prevents their inhibition of ... firing and their role in relaxation.
Causes ...
A: Tetanus neurotoxin
Q: Tetanus neurotoxin enters inhibitory neurones in the CNS.
Cleaves [...] - vesicle associated membrane protein, which is necessary for ...
I.E. prevents release of inhibitory neurotransmittors ... and ... from inhibitory neurones.
Prevents their inhibition of ... firing and their role in relaxation.
Causes ...
A: VAMP
Q: ... enters inhibitory neurones in the CNS.
Cleaves VAMP - vesicle associated membrane protein, which is necessary for [...]
I.E. prevents release of inhibitory neurotransmittors ... and ... from inhibitory neurones.
Prevents their inhibition of ... firing and their role in relaxation.
Causes ...
A: neurotransmitter vesicle exocytosis
Q: ... enters inhibitory neurones in the CNS.
Cleaves ... - vesicle associated membrane protein, which is necessary for neurotransmitter vesicle exocytosis
I.E. prevents release of inhibitory neurotransmittors [...] and [...] from inhibitory neurones.
Prevents their inhibition of ... firing and their role in relaxation.
Causes ...
A: GABA; Glycine
Q: ... enters inhibitory neurones in the CNS.
Cleaves ... - vesicle associated membrane protein, which is necessary for ...
I.E. prevents release of inhibitory neurotransmittors GABA and Glycine from inhibitory neurones.
Prevents their inhibition of [...] firing and their role in relaxation.
Causes ...
A: overactive motor neurones
Q: ... enters inhibitory neurones in the CNS.
Cleaves ... - vesicle associated membrane protein, which is necessary for ...
I.E. prevents release of inhibitory neurotransmittors ... and ... from inhibitory neurones.
Prevents their inhibition of overactive motor neurones firing and their role in relaxation.
Causes [...]
A: spastic paralysis
Tetanus neurotoxin enters inhibitory neurones in the CNS.
Cleaves VAMP - vesicle associated membrane protein, which is necessary for neurotransmitter vesicle exocytosis
I.E. prevents release of inhibitory neurotransmittors GABA and Glycine from inhibitory neurones.
Prevents their inhibition of overactive motor neurones firing and their role in relaxation.
Causes spastic paralysis
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Original: Structure of muscles
Composed of cells that are [[oc1::elongated]] to form fibres
Contain filaments made of proteins [[oc2::actin]] and [[oc3::myosin]]
Q: Structure of muscles
Composed of cells that are [...] to form fibres
Contain filaments made of proteins ... and ...
A: elongated
Q: Structure of muscles
Composed of cells that are elongated to form fibres
Contain filaments made of proteins [...] and ...
A: actin
Q: Structure of muscles
Composed of cells that are ... to form fibres
Contain filaments made of proteins actin and [...]
A: myosin
Q: Structure of muscles
Composed of cells that are [...] to form fibres
Contain filaments made of proteins [...] and [...]
A: elongated; actin; myosin
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Original: 1. [[oc3::Smooth]]
[[oc1::Inv]]oluntary, controlled by [[oc2::autonomic NS]]
2. Skeletal
[[oc5::Striated]] muscle tissue, [[oc4::v]]oluntary,  controlled by [[oc6::somatic NS]]
3. Cardiac
Controlled by [[oc7::autonomic NS]]
Title: Types of Muscle!
Q: 1. ...
[...]oluntary, controlled by ...
2. Skeletal
... muscle tissue, ...oluntary,  controlled by ...
3. Cardiac
Controlled by ...
A: Inv
Q: 1. ...
Involuntary, controlled by [...]
2. Skeletal
... muscle tissue, ...oluntary,  controlled by ...
3. Cardiac
Controlled by ...
A: autonomic NS
Q: 1. [...]
...oluntary, controlled by autonomic NS
2. Skeletal
... muscle tissue, ...oluntary,  controlled by ...
3. Cardiac
Controlled by ...
A: Smooth
Q: 1. Smooth
...oluntary, controlled by ...
2. Skeletal
... muscle tissue, [...]oluntary,  controlled by ...
3. Cardiac
Controlled by ...
A: v
Q: 1. ...
...oluntary, controlled by ...
2. Skeletal
[...] muscle tissue, voluntary,  controlled by ...
3. Cardiac
Controlled by ...
A: Striated
Q: 1. ...
...oluntary, controlled by ...
2. Skeletal
Striated muscle tissue, ...oluntary,  controlled by [...]
3. Cardiac
Controlled by ...
A: somatic NS
Q: 1. ...
...oluntary, controlled by ...
2. Skeletal
... muscle tissue, ...oluntary,  controlled by somatic NS
3. Cardiac
Controlled by [...]
A: autonomic NS
1. Smooth
Involuntary, controlled by autonomic NS
2. Skeletal
Striated muscle tissue, voluntary,  controlled by somatic NS
3. Cardiac
Controlled by autonomic NS
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Original: Two layers
1. [[oc1::Circular layer]]
Runs [[oc2::around intestine]]
Causes [[oc3::segmentation]]
2. [[oc1::Longitudinal]] layer
Runs [[oc4::along intestine tube]]
Causes [[oc5::wave-like contractions]]
Title: Smooth muscle in the intestine
Q: Two layers
1. [...]
Runs ...
Causes ...
2. [...] layer
Runs ...
Causes ...
A: Circular layer; Longitudinal
Q: Two layers
1. Circular layer
Runs [...]
Causes ...
2. Longitudinal layer
Runs ...
Causes ...
A: around intestine
Q: Two layers
1. ...
Runs around intestine
Causes [...]
2. ... layer
Runs ...
Causes ...
A: segmentation
Q: Two layers
1. ...
Runs ...
Causes segmentation
2. ... layer
Runs [...]
Causes ...
A: along intestine tube
Q: Two layers
1. ...
Runs ...
Causes ...
2. ... layer
Runs along intestine tube
Causes [...]
A: wave-like contractions
Two layers
1. Circular layer
Runs around intestine
Causes segmentation
2. Longitudinal layer
Runs along intestine tube
Causes wave-like contractions
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Q: Name four places smooth muscle is found
A: Intestine walls
Iris of eye
Artery walls
Wall of cervix

Q: What regulates the rate of contraction of the SA node in the heart?
A: Autonomic NS

Original: Muscle contains basic units called [[oc1::fibres]]
Each [[oc1::fibre]] is a [[oc2::large cell containing many nuclei]]
Muscle cell ([[oc3::myocyte]]) cytoplasm is called [[oc4::sarcoplasm]], cell membrane is called [[oc4::sarcolemma]], ER called [[oc4::sarcoplasmic]] reticulum
Contain large quantities of [[oc5::mitochondria]] and [[oc5::glycogen]]
In each fibre there are a number of [[oc6::myofibrils]] containing [[oc6::contractile units]] called [[oc6::sarcomeres]]
Within myofibrils there are [[oc7::protein myofilaments]] made of [[oc7::actin]] and [[oc7::myosin]]
Title: Structure of striated muscles
Q: Muscle contains basic units called [...]
Each [...] is a ...
Muscle cell (...) cytoplasm is called ..., cell membrane is called ..., ER called ... reticulum
Contain large quantities of ... and ...
In each fibre there are a number of ... containing ... called ...
Within myofibrils there are ... made of ... and ...
A: fibres; fibre
Q: Muscle contains basic units called fibres
Each fibre is a [...]
Muscle cell (...) cytoplasm is called ..., cell membrane is called ..., ER called ... reticulum
Contain large quantities of ... and ...
In each fibre there are a number of ... containing ... called ...
Within myofibrils there are ... made of ... and ...
A: large cell containing many nuclei
Q: Muscle contains basic units called ...
Each ... is a large cell containing many nuclei
Muscle cell ([...]) cytoplasm is called ..., cell membrane is called ..., ER called ... reticulum
Contain large quantities of ... and ...
In each fibre there are a number of ... containing ... called ...
Within myofibrils there are ... made of ... and ...
A: myocyte
Q: Muscle contains basic units called ...
Each ... is a ...
Muscle cell (myocyte) cytoplasm is called [...], cell membrane is called [...], ER called [...] reticulum
Contain large quantities of ... and ...
In each fibre there are a number of ... containing ... called ...
Within myofibrils there are ... made of ... and ...
A: sarcoplasm; sarcolemma; sarcoplasmic
Q: Muscle contains basic units called ...
Each ... is a ...
Muscle cell (...) cytoplasm is called sarcoplasm, cell membrane is called sarcolemma, ER called sarcoplasmic reticulum
Contain large quantities of [...] and [...]
In each fibre there are a number of ... containing ... called ...
Within myofibrils there are ... made of ... and ...
A: mitochondria; glycogen
Q: Muscle contains basic units called ...
Each ... is a ...
Muscle cell (...) cytoplasm is called ..., cell membrane is called ..., ER called ... reticulum
Contain large quantities of mitochondria and glycogen
In each fibre there are a number of [...] containing [...] called [...]
Within myofibrils there are ... made of ... and ...
A: myofibrils; contractile units; sarcomeres
Q: Muscle contains basic units called ...
Each ... is a ...
Muscle cell (...) cytoplasm is called ..., cell membrane is called ..., ER called ... reticulum
Contain large quantities of ... and ...
In each fibre there are a number of myofibrils containing contractile units called sarcomeres
Within myofibrils there are [...] made of [...] and [...]
A: protein myofilaments; actin; myosin
Muscle contains basic units called fibres
Each fibre is a large cell containing many nuclei
Muscle cell (myocyte) cytoplasm is called sarcoplasm, cell membrane is called sarcolemma, ER called sarcoplasmic reticulum
Contain large quantities of mitochondria and glycogen
In each fibre there are a number of myofibrils containing contractile units called sarcomeres
Within myofibrils there are protein myofilaments made of actin and myosin
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Q: Whole muscle
↓
[...]
↓
[...]
↓
[...]
A: Muscle fibre (myocyte); Myofibril; Sarcomere

Q: Define Sarcomere
A: Smallest contractile unit of muscle

Q: What is the thin filament within the sarcomere?
A: Actin

Q: What is the thick filament within the sarcomere?
A: MYOSIN
myosin
Myosin

Q: Describe the structure of a myosin molecule
A: Has heads that stick out, can bind to myosin binding sites on actin filaments

Q: When a sarcomere contracts, which bands change and which remain the same length?
A: The light (I) bands get shorter
The dark (A) bands stay the same length

Original: The [[oc1::sliding filament theory]]
When muscles contract, [[oc2::sarcomeres become smaller]]
However [[oc3::the filaments, actin and myosin,]] [[oc4::do not change length]]
Instead [[oc5::they slide past each other]]
When contraction occurs, [[oc6::the overlap (A band) enlargens]] and [[oc7::the I band and H zone become narrower]]
Q: The [...]
When muscles contract, ...
However ... ...
Instead ...
When contraction occurs, ... and ...
A: sliding filament theory
Q: The sliding filament theory
When muscles contract, [...]
However ... ...
Instead ...
When contraction occurs, ... and ...
A: sarcomeres become smaller
Q: The ...
When muscles contract, sarcomeres become smaller
However [...] ...
Instead ...
When contraction occurs, ... and ...
A: the filaments, actin and myosin,
Q: The ...
When muscles contract, ...
However the filaments, actin and myosin, [...]
Instead ...
When contraction occurs, ... and ...
A: do not change length
Q: The ...
When muscles contract, ...
However ... do not change length
Instead [...]
When contraction occurs, ... and ...
A: they slide past each other
Q: The ...
When muscles contract, ...
However ... ...
Instead they slide past each other
When contraction occurs, [...] and ...
A: the overlap (A band) enlargens
Q: The ...
When muscles contract, ...
However ... ...
Instead ...
When contraction occurs, the overlap (A band) enlargens and [...]
A: the I band and H zone become narrower
The sliding filament theory
When muscles contract, sarcomeres become smaller
However the filaments, actin and myosin, do not change length
Instead they slide past each other
When contraction occurs, the overlap (A band) enlargens and the I band and H zone become narrower
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Original: How to tell a [[oc4::CONTRACTED]] sarcomere
1. Narrow [[oc1::H zone]]
2. Narrow [[oc1::I band]]
3. Large [[oc2::overlap of filaments]]
4. [[oc3::Lenth of the sarcomere]] is shorter
Q: How to tell a ... sarcomere
1. Narrow [...]
2. Narrow [...]
3. Large ...
4. ... is shorter
A: H zone; I band
Q: How to tell a ... sarcomere
1. Narrow H zone
2. Narrow I band
3. Large [...]
4. ... is shorter
A: overlap of filaments
Q: How to tell a ... sarcomere
1. Narrow ...
2. Narrow ...
3. Large overlap of filaments
4. [...] is shorter
A: Lenth of the sarcomere
Q: How to tell a [...] sarcomere
1. Narrow ...
2. Narrow ...
3. Large ...
4. Lenth of the sarcomere is shorter
A: CONTRACTED
How to tell a CONTRACTED sarcomere
1. Narrow H zone
2. Narrow I band
3. Large overlap of filaments
4. Lenth of the sarcomere is shorter
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Original: The [[oc1::POWER STROKE]]
1. [[oc2::Myosin head attaches to binding site on an actin filament]] forming a [[oc3::cross bridge]]
2. [[oc4::Myosin head bends]], [[oc4::thin filament is pulled along]], [[oc5::overlap increases]]; [[oc6::ADP and Pi released]]
3. [[oc7::Cross bridge is broken]] as [[oc8::new ATP attaches to myosin head]]
4. [[oc9::Myosin head moves to original position]] as [[oc10::the ATP is hydrolised to ADP and Pi]]
[[oc11::New cross bridge can then form]]
Q: The [...]
1. ... forming a ...
2. ..., ..., ...; ...
3. ... as ...
4. ... as ...
...
A: POWER STROKE
Q: The POWER STROKE
1. [...] forming a ...
2. ..., ..., ...; ...
3. ... as ...
4. ... as ...
...
A: Myosin head attaches to binding site on an actin filament
Q: The ...
1. Myosin head attaches to binding site on an actin filament forming a [...]
2. ..., ..., ...; ...
3. ... as ...
4. ... as ...
...
A: cross bridge
Q: The ...
1. ... forming a cross bridge
2. [...], [...], ...; ...
3. ... as ...
4. ... as ...
...
A: Myosin head bends; thin filament is pulled along
Q: The ...
1. ... forming a ...
2. Myosin head bends, thin filament is pulled along, [...]; ...
3. ... as ...
4. ... as ...
...
A: overlap increases
Q: The ...
1. ... forming a ...
2. ..., ..., overlap increases; [...]
3. ... as ...
4. ... as ...
...
A: ADP and Pi released
Q: The ...
1. ... forming a ...
2. ..., ..., ...; ADP and Pi released
3. [...] as ...
4. ... as ...
...
A: Cross bridge is broken
Q: The ...
1. ... forming a ...
2. ..., ..., ...; ...
3. Cross bridge is broken as [...]
4. ... as ...
...
A: new ATP attaches to myosin head
Q: The ...
1. ... forming a ...
2. ..., ..., ...; ...
3. ... as new ATP attaches to myosin head
4. [...] as ...
...
A: Myosin head moves to original position
Q: The ...
1. ... forming a ...
2. ..., ..., ...; ...
3. ... as ...
4. Myosin head moves to original position as [...]
...
A: the ATP is hydrolised to ADP and Pi
Q: The ...
1. ... forming a ...
2. ..., ..., ...; ...
3. ... as ...
4. ... as the ATP is hydrolised to ADP and Pi
[...]
A: New cross bridge can then form
The POWER STROKE
1. Myosin head attaches to binding site on an actin filament forming a cross bridge
2. Myosin head bends, thin filament is pulled along, overlap increases; ADP and Pi released
3. Cross bridge is broken as new ATP attaches to myosin head
4. Myosin head moves to original position as the ATP is hydrolised to ADP and Pi
New cross bridge can then form
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Q: Describe the role of ATP in the myosin power stroke
A: Energy from ATP needed to break the cross bridge and reset the myosin head

Original: Muscle contraction initiation
Involes [[oc1::troponin]]: guards keeping doors shut
[[oc2::Tropomyosin]]: Doors
[[oc3::Calcium ions]]: donut
[[oc4::Actin filament binding sites]]: gold coins
Q: Muscle contraction initiation
Involes [...]: guards keeping doors shut
...: Doors
...: donut
...: gold coins
A: troponin
Q: Muscle contraction initiation
Involes troponin: guards keeping doors shut
[...]: Doors
...: donut
...: gold coins
A: Tropomyosin
Q: Muscle contraction initiation
Involes ...: guards keeping doors shut
Tropomyosin: Doors
[...]: donut
...: gold coins
A: Calcium ions
Q: Muscle contraction initiation
Involes ...: guards keeping doors shut
...: Doors
Calcium ions: donut
[...]: gold coins
A: Actin filament binding sites
Muscle contraction initiation
Involes troponin: guards keeping doors shut
Tropomyosin: Doors
Calcium ions: donut
Actin filament binding sites: gold coins
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Original: Muscle contraction initiation
Relaxed state: [[oc1::tropomyosin blocks access to actin binding sites]]
Action potential: [[oc2::causes influx of Ca^2+ which bind to troponin]]
Troponin [[oc3::changes shape]], [[oc4::displacing tropomyosin, exposing binding sites]]
Allows [[oc5::myosin heads to bind to actin]]
When [[oc6::stimulation ends]], [[oc7::Ca^2+ actively transported back to sarcoplasmic reticulum]]
And relax.
Q: Muscle contraction initiation
Relaxed state: [...]
Action potential: ...
Troponin ..., ...
Allows ...
When ..., ...
And relax.
A: tropomyosin blocks access to actin binding sites
Q: Muscle contraction initiation
Relaxed state: tropomyosin blocks access to actin binding sites
Action potential: [...]
Troponin ..., ...
Allows ...
When ..., ...
And relax.
A: causes influx of Ca^2+ which bind to troponin
Q: Muscle contraction initiation
Relaxed state: ...
Action potential: causes influx of Ca^2+ which bind to troponin
Troponin [...], ...
Allows ...
When ..., ...
And relax.
A: changes shape
Q: Muscle contraction initiation
Relaxed state: ...
Action potential: ...
Troponin changes shape, [...]
Allows ...
When ..., ...
And relax.
A: displacing tropomyosin, exposing binding sites
Q: Muscle contraction initiation
Relaxed state: ...
Action potential: ...
Troponin ..., displacing tropomyosin, exposing binding sites
Allows [...]
When ..., ...
And relax.
A: myosin heads to bind to actin
Q: Muscle contraction initiation
Relaxed state: ...
Action potential: ...
Troponin ..., ...
Allows myosin heads to bind to actin
When [...], ...
And relax.
A: stimulation ends
Q: Muscle contraction initiation
Relaxed state: ...
Action potential: ...
Troponin ..., ...
Allows ...
When stimulation ends, [...]
And relax.
A: Ca^2+ actively transported back to sarcoplasmic reticulum
Muscle contraction initiation
Relaxed state: tropomyosin blocks access to actin binding sites
Action potential: causes influx of Ca^2+ which bind to troponin
Troponin changes shape, displacing tropomyosin, exposing binding sites
Allows myosin heads to bind to actin
When stimulation ends, Ca^2+ actively transported back to sarcoplasmic reticulum
And relax.
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Q: Explain why mitochondria are essential for muscular contraction
A: Mitochondria produce ATP, which is used in:
Repolarisation of sarcolemma via Na/K pumps (active transport)
Attaches to myosin head allowing detachment from actin binding site
Hydrolysed by ATPase to ADP + Pi for the tilting of myosin head (increasing overlap)
Calcium ion pumps in the sarcoplasmic reticulum allowing relaxation
Synthesis of protein for growth and repair

Original: Action potential travels along [[oc1::motor neurone]]
Releases [[oc1::acetylcholin]]e at [[oc2::neuromuscular junction]] ([[oc2::synaptic cleft]])
Stimulates [[oc3::depolarisation of sarcolemma]] ([[oc4::ACh binds to ligand-gated channels, allows influx of Na^+ and Ca^2+]])
Action potential travels down [[oc5::T-tubule]] into [[oc5::the centre of the muscle cell/fibre]]
Stimulates the [[oc6::sarcoplasmic reticulum]] ([[oc6::reservoire of Ca^2+]]) to [[oc7::increase Ca^2+ permeability]]; [[oc7::outflux of Ca^2+ into myofibrils]]
[[oc8::Ca^2+ bind to myosin heads]] and [[oc9::initiate power strokes for contractions of sarcomeres]]
Title: Neuromuscular junction mechanism
Q: Action potential travels along [...]
Releases [...]e at neuromuscular junction (synaptic cleft)
Stimulates ... (...)
Action potential travels down ... into ...
Stimulates the ... (...) to ...; ...
... and ...
A: motor neurone; acetylcholin
Q: Action potential travels along motor neurone
Releases acetylcholine at [...] ([...])
Stimulates depolarisation of sarcolemma (...)
Action potential travels down ... into ...
Stimulates the ... (...) to ...; ...
... and ...
A: neuromuscular junction; synaptic cleft
Q: Action potential travels along ...
Releases ...e at neuromuscular junction (synaptic cleft)
Stimulates [...] (ACh binds to ligand-gated channels, allows influx of Na^+ and Ca^2+)
Action potential travels down ... into ...
Stimulates the ... (...) to ...; ...
... and ...
A: depolarisation of sarcolemma
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates depolarisation of sarcolemma ([...])
Action potential travels down T-tubule into the centre of the muscle cell/fibre
Stimulates the ... (...) to ...; ...
... and ...
A: ACh binds to ligand-gated channels, allows influx of Na^+ and Ca^2+
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates ... (ACh binds to ligand-gated channels, allows influx of Na^+ and Ca^2+)
Action potential travels down [...] into [...]
Stimulates the sarcoplasmic reticulum (reservoire of Ca^2+) to ...; ...
... and ...
A: T-tubule; the centre of the muscle cell/fibre
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates ... (...)
Action potential travels down T-tubule into the centre of the muscle cell/fibre
Stimulates the [...] ([...]) to increase Ca^2+ permeability; outflux of Ca^2+ into myofibrils
... and ...
A: sarcoplasmic reticulum; reservoire of Ca^2+
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates ... (...)
Action potential travels down ... into ...
Stimulates the sarcoplasmic reticulum (reservoire of Ca^2+) to [...]; [...]
Ca^2+ bind to myosin heads and ...
A: increase Ca^2+ permeability; outflux of Ca^2+ into myofibrils
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates ... (...)
Action potential travels down ... into ...
Stimulates the ... (...) to increase Ca^2+ permeability; outflux of Ca^2+ into myofibrils
[...] and initiate power strokes for contractions of sarcomeres
A: Ca^2+ bind to myosin heads
Q: Action potential travels along ...
Releases ...e at ... (...)
Stimulates ... (...)
Action potential travels down ... into ...
Stimulates the ... (...) to ...; ...
Ca^2+ bind to myosin heads and [...]
A: initiate power strokes for contractions of sarcomeres
Action potential travels along motor neurone
Releases acetylcholine at neuromuscular junction (synaptic cleft)
Stimulates depolarisation of sarcolemma (ACh binds to ligand-gated channels, allows influx of Na^+ and Ca^2+)
Action potential travels down T-tubule into the centre of the muscle cell/fibre
Stimulates the sarcoplasmic reticulum (reservoire of Ca^2+) to increase Ca^2+ permeability; outflux of Ca^2+ into myofibrils
Ca^2+ bind to myosin heads and initiate power strokes for contractions of sarcomeres
Other fields (not shown on cards):
Settings: 1,1,1 | n,n,y,n

T-tubules are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells.