BMSC 207 Final Exam Questions With
Correct Answers
Muscle |Primary |Function
Generate |force |and/or |movement |in |response |to |a |physiological |stimulus.
For |body |movement, |maintenance |of |posture, |respiration, |production |of |heat, |communication,
|constriction |of |organs |and |vessels, |and |heart |beat. |In |all |muscle |types |the |generation |of |force |
depends |on |the |conversion |of |chemical |energy |(ATP).
Skeletal |Muscles
Primarily |voluntary |by |somatic |motor |neurons |(some |reflexes |are |involuntary). |They |are |
striated |and |multinucleated. |Usually |attached |to |bones |by |tendons. |The |origin |of |the |muscle |is
|considered |to |be |closest |to |the |trunk |or |to |more |stationary |bone. |The |insertion |point |is |the |
more |distal |or |more |mobile |attachment. |Antagonistic |muscle |groups |are |flexor-extensor |pairs. |
The |flexor |brings |bones |together |while |the |extensor |moves |bones |away. |Skeletal |muscle |
makes |up |40% |or |total |body |weight |and |consumes |15-60% |of |daily |energy |expenditure.
Cardiac |Muscle
Mostly |involuntary: |spontaneous |electrical |activity |and |can |be |altered |by |autonomic |NS, |and |
hormones. |Striated |and |uninucleate. |Much |more |branched. |It |is |made |up |of |cardiac |myocytes |
which |are |shorter, |branched |cells |that |usually |contain |a |single |nucleus. |Interconnected |by |
intercalated |disks: |desmosomes |link |mechanically |and |gap |junctions |link |them |electrically. |Like
|skeletal |muscle |it |is |striated |and |has |sarcomeres |containing |a |similar |pattern |of |thick |and |thin |
filaments.
Less |T-tubules |but |larger |compared |to |skeletal. |Less |SR |as |it |requires |the |entry |of |extracellular |
Ca++. |A |large |abundance |of |mitochondria |for |oxidative |metabolism |for |ATP |production. |Cells |
may |contract |over |3 |billion |times |without |resting.
Smooth |Muscle
Primarily |involuntary: |autonomic |control, |spontaneous, |hormones, |paracrines |or |autocrines, |
non-striated |and |uninulceate. |They |provide |mechanical |control |of |the |digestive |tract, |urinary |
tract, |reproductive |tract, |blood |vessels, |and |airways. |This |type |of |muscles |is |the |most |
complicated |and |the |cells |are |long |and |spindle |shaped.
Muscle |Terminology
,Cell=fiber
Cell |Membrane=sarcolemma
Cytoplasm=sarcoplasm
Modified |endoplasm |reticulum=sarcoplasmic |reticulum
Skeletal |muscle |structure
Whole |muscle-multiple |fascicles-bundles |of |muscle |fibers. |Single |muscle |fibers |often |extend |
the |entire |length |of |a |muscle.
Myofibril
A |long, |filamentous |organelle |found |within |muscle |cells |that |has |a |banded |appearance.
Muscle |Striations
Correspond |to |ordered |arrays |of |thick |and |thin |filaments |within |the |myofibrils- |one |muscle |
fibre=1000+ |myofibrils
Thin |Filaments
F-actin: |the |backbone |of |these |filaments, |double |stranded |alpha |helical |polymer |of |G-actin |
molecules. |Contains |binding |site |for |thick |filaments |(myosin). |Tropomyosin: |two |identical |alpha
|helices |that |coil |around |each |other |and |sit |in |the |two |grooves |formed |by |actin |strands, |
regulate |the |binding |of |myosin |to |actin. |Responsible |to |covering |the |binding |site.
Troponin |complex: |a |heterotrimer |consisting |of |1) |troponin |T |(TnT) |which |binds |to |a |single |
molecule |of |tropomyosin. |2) |troponin |C |(Tnc): |Ca2+ |binding |site |3) |troponin |I |(TnI): |under |
resting |conditions |is |bound |to |actin |inhibiting |contraction. |Every |7 |actin |molecules.
Thick |Filaments
Myosin |head |contains |a |region |for |binding |actin |as |well |as |a |site |for |binding |and |hydrolyzing |
ATP. |One |on |each |head. |Regulatory |light |chain |regulates |ATPase |activity |of |myosin. |Essential |
light |chain |stabilizes |myosin |head. |It |consists |of |a |bundle |of |myosin |molecules |(~250). |Each |
one |of |these |has |two |light |chains.
Titin
A |very |large |protein |extending |from |the |M |line |to |Z |line, |appears |to |be |involved |in |
stabilization |and |the |elastic |recoil |behavior |muscle.
Nebulin
a |large |protein |that |interacts |with |the |thin |filaments, |believed |to |regulate |the |length |of |the |
thin |filaments |and |contribute |to |the |structural |integrity |of |myofibrils.
,Sarcomere
Z-disk- |zigzag |protein |structure |that |is |the |attachment |site |for |the |thin |filaments.
I |bands- |lightest |band |of |sarcomere, |region |occupied |only |by |thin |filaments
A |band- |darkest |band |of |sarcomere, |encompasses |entire |length |of |the |thick |filament, |including
|very |dark |area |where |thin |and |thick |filaments |overlap.
H |zone- |central |region |of |A |band, |consists |only |of |thick |filaments.
M |line- |proteins |form |the |attachment |site |for |the |thick |filaments, |equivalent |to |z-disk |for |thin |
filaments.
Important |muscle |structures
-sarcoplasmic |reticulum: |modified |endoplasmic |reticulum |that |wraps |around |each |myofibril.
-Terminal |Cisternae: |The |ends |of |sarcoplasmic |reticulum |that |abut |the |t-tubules. |Used |for |
calcium |storage.
-Transverse |Tubules: |Invaginations |of |the |muscle |fiber |membrane, |associated |with |the |
sarcoplasmic |reticulum.
-Triad: |T-tubule+2 |terminal |cisternae.
-Mitochondrion: |Organelles |that |generate |ATP |through |oxidative |phosphorylation.
Glucose |is |stored |as |glycogen |within |the |sarcoplasm.
Know |the |flow |chart |on |pg. |378-379, |381
Sliding |filament |model
The |theory |explaining |how |muscle |contracts, |based |on |change |within |a |sarcomere, |the |basic |
unit |of |muscle |organization, |stating |that |thin |(actin) |filaments |slide |across |thick |(myosin) |
filaments, |shortening |the |sarcomere; |the |shortening |of |all |sarcomeres |in |a |myofibril |shortens |
the |entire |myofibril. |The |force |generated |by |a |contracting |skeletal |muscle |is |called |tension |and
|on |an |attachment |point |it |is |called |load.
Skeletal |muscle |contraction
The |areas |of |the |brain |responsible |for |voluntary |movement |and |the |descending |tracts |in |the |
spinal |cord. |Brain |regions |involved |include:
-primary |motor |cortex: |output |to |the |brain |stem |(face) |or |spinal |cord |(all |others).
-Basal |ganglia-initiate |and |terminate
-premotor |cortex |(motor |association)-input
-Midbrain
-cerebellum
Neuromuscular |junction
point |of |synaptic |contact |between |somatic |motor |neuron |and |individual |muscle |fiber.
, excitation-contraction |coupling
an |action |potential |initiated |in |the |skeletal |muscle |fiber |results |in |an |in |an |increase |in |
intracellular |(sarcoplasmic) |Ca2+. |Action |potentials |propagate |from |the |sarcolemma |to |the |
interior |of |muscle |fibers |along |the |transverse |tubule |network. |Sarcolemma |penetrates |into |the
|muscle |fibre |in |the |form |of |T-tubules |and |wraps |around |each |myofibril |in |specific |regions. |
Specialized |Ca++ |storage |organelles |called |the |sarcoplasmic |reticulum |are |strategically |
organized |with |the |T-tubules. |The |ultimate |intracellular |signal |that |triggers |contraction |in |all |
muscle |types |is |a |rise |in |intracellular |calcium. |Depending |on |the |muscle |type |Ca |can |enter |the |
sarcoplasm |from |the |extracellular |space |via |voltage-gated |Ca |channels |or |can |be |released |into |
the |sarcoplasm |from |the |intracellular |Ca |storage |reservoir |of |the |sarcoplasmic |reticulum. |The |
process |by |which |electrical |excitation |of |the |surface |membrane |triggers |and |increase |of |Ca |in |
muscle |is |this |process.
corticospinal |tract
descending |tract |(ventral |and |interior |lateral |white |matter) |The |upper |motor |neuron |is |brain |
to |spinal |cord |while |the |alpha |(lower) |motor |neuron |is |spinal |cord |to |muscle.
Alpha |motor |neuron
spinal |cord |to |muscle. |A |single |motor |neuron |and |all |the |muscle |fibers |it |innervates |is |known |
as |a |motor |unit. |The |area |where |the |motor |neuron |makes |synaptic |contact |with |the |muscle |
fiber |is |known |as |the |neuromuscular |junction. |These |are |large, |myelinated |axons |that |
branches |and |each |branch |can |innervate |several |muscle |fibers, |all |muscle |fibers |respond |
simultaneous. |The |number |of |fibers |per |motor |unit |is |different |usually |<10 |for |fine |
movements |and |>100's |for |less |concise |movements.
amyotrophic |lateral |sclerosis |(ALS)
neurodegenerative |motor |neuron |disease |in |which |either |the |lower |or |upper |motor |neurons |
degenerate |leading |to |muscle |atrophy |and |weakness |form |disuse. |10% |of |cases |are |genetically
|inherited |1/4 |of |which |are |due |to |a |mutation |in |genes |producing |superoxide |dismutase |which
|destroys |oxygen |free |radicals. |It |will |cause |eventual |respiratory |failure.
Neuromusclular |junction |(NMJ)
The |synapse |of |a |lower |motor |neuron |to |a |muscle |fiber |is |this. |The |region |of |sarcolemma |at |
the |NMJ |is |known |as |the |motor |end |plate. |Junctional |folds |on |the |sarcolemma |increase |
surface |area, |motor |neuron |vesicles |contain |acetylcholine, |muscle |sarcolemma |contains |
nicotinic |acetylcholine |receptors |that |are |only |excitatory! |There |are |3 |main |parts:
1) |Presynaptic |motor |neuron |filled |with |synaptic |vesicles
2) |The |synaptic |cleft
Correct Answers
Muscle |Primary |Function
Generate |force |and/or |movement |in |response |to |a |physiological |stimulus.
For |body |movement, |maintenance |of |posture, |respiration, |production |of |heat, |communication,
|constriction |of |organs |and |vessels, |and |heart |beat. |In |all |muscle |types |the |generation |of |force |
depends |on |the |conversion |of |chemical |energy |(ATP).
Skeletal |Muscles
Primarily |voluntary |by |somatic |motor |neurons |(some |reflexes |are |involuntary). |They |are |
striated |and |multinucleated. |Usually |attached |to |bones |by |tendons. |The |origin |of |the |muscle |is
|considered |to |be |closest |to |the |trunk |or |to |more |stationary |bone. |The |insertion |point |is |the |
more |distal |or |more |mobile |attachment. |Antagonistic |muscle |groups |are |flexor-extensor |pairs. |
The |flexor |brings |bones |together |while |the |extensor |moves |bones |away. |Skeletal |muscle |
makes |up |40% |or |total |body |weight |and |consumes |15-60% |of |daily |energy |expenditure.
Cardiac |Muscle
Mostly |involuntary: |spontaneous |electrical |activity |and |can |be |altered |by |autonomic |NS, |and |
hormones. |Striated |and |uninucleate. |Much |more |branched. |It |is |made |up |of |cardiac |myocytes |
which |are |shorter, |branched |cells |that |usually |contain |a |single |nucleus. |Interconnected |by |
intercalated |disks: |desmosomes |link |mechanically |and |gap |junctions |link |them |electrically. |Like
|skeletal |muscle |it |is |striated |and |has |sarcomeres |containing |a |similar |pattern |of |thick |and |thin |
filaments.
Less |T-tubules |but |larger |compared |to |skeletal. |Less |SR |as |it |requires |the |entry |of |extracellular |
Ca++. |A |large |abundance |of |mitochondria |for |oxidative |metabolism |for |ATP |production. |Cells |
may |contract |over |3 |billion |times |without |resting.
Smooth |Muscle
Primarily |involuntary: |autonomic |control, |spontaneous, |hormones, |paracrines |or |autocrines, |
non-striated |and |uninulceate. |They |provide |mechanical |control |of |the |digestive |tract, |urinary |
tract, |reproductive |tract, |blood |vessels, |and |airways. |This |type |of |muscles |is |the |most |
complicated |and |the |cells |are |long |and |spindle |shaped.
Muscle |Terminology
,Cell=fiber
Cell |Membrane=sarcolemma
Cytoplasm=sarcoplasm
Modified |endoplasm |reticulum=sarcoplasmic |reticulum
Skeletal |muscle |structure
Whole |muscle-multiple |fascicles-bundles |of |muscle |fibers. |Single |muscle |fibers |often |extend |
the |entire |length |of |a |muscle.
Myofibril
A |long, |filamentous |organelle |found |within |muscle |cells |that |has |a |banded |appearance.
Muscle |Striations
Correspond |to |ordered |arrays |of |thick |and |thin |filaments |within |the |myofibrils- |one |muscle |
fibre=1000+ |myofibrils
Thin |Filaments
F-actin: |the |backbone |of |these |filaments, |double |stranded |alpha |helical |polymer |of |G-actin |
molecules. |Contains |binding |site |for |thick |filaments |(myosin). |Tropomyosin: |two |identical |alpha
|helices |that |coil |around |each |other |and |sit |in |the |two |grooves |formed |by |actin |strands, |
regulate |the |binding |of |myosin |to |actin. |Responsible |to |covering |the |binding |site.
Troponin |complex: |a |heterotrimer |consisting |of |1) |troponin |T |(TnT) |which |binds |to |a |single |
molecule |of |tropomyosin. |2) |troponin |C |(Tnc): |Ca2+ |binding |site |3) |troponin |I |(TnI): |under |
resting |conditions |is |bound |to |actin |inhibiting |contraction. |Every |7 |actin |molecules.
Thick |Filaments
Myosin |head |contains |a |region |for |binding |actin |as |well |as |a |site |for |binding |and |hydrolyzing |
ATP. |One |on |each |head. |Regulatory |light |chain |regulates |ATPase |activity |of |myosin. |Essential |
light |chain |stabilizes |myosin |head. |It |consists |of |a |bundle |of |myosin |molecules |(~250). |Each |
one |of |these |has |two |light |chains.
Titin
A |very |large |protein |extending |from |the |M |line |to |Z |line, |appears |to |be |involved |in |
stabilization |and |the |elastic |recoil |behavior |muscle.
Nebulin
a |large |protein |that |interacts |with |the |thin |filaments, |believed |to |regulate |the |length |of |the |
thin |filaments |and |contribute |to |the |structural |integrity |of |myofibrils.
,Sarcomere
Z-disk- |zigzag |protein |structure |that |is |the |attachment |site |for |the |thin |filaments.
I |bands- |lightest |band |of |sarcomere, |region |occupied |only |by |thin |filaments
A |band- |darkest |band |of |sarcomere, |encompasses |entire |length |of |the |thick |filament, |including
|very |dark |area |where |thin |and |thick |filaments |overlap.
H |zone- |central |region |of |A |band, |consists |only |of |thick |filaments.
M |line- |proteins |form |the |attachment |site |for |the |thick |filaments, |equivalent |to |z-disk |for |thin |
filaments.
Important |muscle |structures
-sarcoplasmic |reticulum: |modified |endoplasmic |reticulum |that |wraps |around |each |myofibril.
-Terminal |Cisternae: |The |ends |of |sarcoplasmic |reticulum |that |abut |the |t-tubules. |Used |for |
calcium |storage.
-Transverse |Tubules: |Invaginations |of |the |muscle |fiber |membrane, |associated |with |the |
sarcoplasmic |reticulum.
-Triad: |T-tubule+2 |terminal |cisternae.
-Mitochondrion: |Organelles |that |generate |ATP |through |oxidative |phosphorylation.
Glucose |is |stored |as |glycogen |within |the |sarcoplasm.
Know |the |flow |chart |on |pg. |378-379, |381
Sliding |filament |model
The |theory |explaining |how |muscle |contracts, |based |on |change |within |a |sarcomere, |the |basic |
unit |of |muscle |organization, |stating |that |thin |(actin) |filaments |slide |across |thick |(myosin) |
filaments, |shortening |the |sarcomere; |the |shortening |of |all |sarcomeres |in |a |myofibril |shortens |
the |entire |myofibril. |The |force |generated |by |a |contracting |skeletal |muscle |is |called |tension |and
|on |an |attachment |point |it |is |called |load.
Skeletal |muscle |contraction
The |areas |of |the |brain |responsible |for |voluntary |movement |and |the |descending |tracts |in |the |
spinal |cord. |Brain |regions |involved |include:
-primary |motor |cortex: |output |to |the |brain |stem |(face) |or |spinal |cord |(all |others).
-Basal |ganglia-initiate |and |terminate
-premotor |cortex |(motor |association)-input
-Midbrain
-cerebellum
Neuromuscular |junction
point |of |synaptic |contact |between |somatic |motor |neuron |and |individual |muscle |fiber.
, excitation-contraction |coupling
an |action |potential |initiated |in |the |skeletal |muscle |fiber |results |in |an |in |an |increase |in |
intracellular |(sarcoplasmic) |Ca2+. |Action |potentials |propagate |from |the |sarcolemma |to |the |
interior |of |muscle |fibers |along |the |transverse |tubule |network. |Sarcolemma |penetrates |into |the
|muscle |fibre |in |the |form |of |T-tubules |and |wraps |around |each |myofibril |in |specific |regions. |
Specialized |Ca++ |storage |organelles |called |the |sarcoplasmic |reticulum |are |strategically |
organized |with |the |T-tubules. |The |ultimate |intracellular |signal |that |triggers |contraction |in |all |
muscle |types |is |a |rise |in |intracellular |calcium. |Depending |on |the |muscle |type |Ca |can |enter |the |
sarcoplasm |from |the |extracellular |space |via |voltage-gated |Ca |channels |or |can |be |released |into |
the |sarcoplasm |from |the |intracellular |Ca |storage |reservoir |of |the |sarcoplasmic |reticulum. |The |
process |by |which |electrical |excitation |of |the |surface |membrane |triggers |and |increase |of |Ca |in |
muscle |is |this |process.
corticospinal |tract
descending |tract |(ventral |and |interior |lateral |white |matter) |The |upper |motor |neuron |is |brain |
to |spinal |cord |while |the |alpha |(lower) |motor |neuron |is |spinal |cord |to |muscle.
Alpha |motor |neuron
spinal |cord |to |muscle. |A |single |motor |neuron |and |all |the |muscle |fibers |it |innervates |is |known |
as |a |motor |unit. |The |area |where |the |motor |neuron |makes |synaptic |contact |with |the |muscle |
fiber |is |known |as |the |neuromuscular |junction. |These |are |large, |myelinated |axons |that |
branches |and |each |branch |can |innervate |several |muscle |fibers, |all |muscle |fibers |respond |
simultaneous. |The |number |of |fibers |per |motor |unit |is |different |usually |<10 |for |fine |
movements |and |>100's |for |less |concise |movements.
amyotrophic |lateral |sclerosis |(ALS)
neurodegenerative |motor |neuron |disease |in |which |either |the |lower |or |upper |motor |neurons |
degenerate |leading |to |muscle |atrophy |and |weakness |form |disuse. |10% |of |cases |are |genetically
|inherited |1/4 |of |which |are |due |to |a |mutation |in |genes |producing |superoxide |dismutase |which
|destroys |oxygen |free |radicals. |It |will |cause |eventual |respiratory |failure.
Neuromusclular |junction |(NMJ)
The |synapse |of |a |lower |motor |neuron |to |a |muscle |fiber |is |this. |The |region |of |sarcolemma |at |
the |NMJ |is |known |as |the |motor |end |plate. |Junctional |folds |on |the |sarcolemma |increase |
surface |area, |motor |neuron |vesicles |contain |acetylcholine, |muscle |sarcolemma |contains |
nicotinic |acetylcholine |receptors |that |are |only |excitatory! |There |are |3 |main |parts:
1) |Presynaptic |motor |neuron |filled |with |synaptic |vesicles
2) |The |synaptic |cleft
