anatomy > muscles > Flashcards

muscles Flashcards

(74 cards)

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1
Q
A
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2
Q

what does the letter A represent

A

actin only

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3
Q

what does the letters A+M represent

A

actin and myosin with actin overlapping

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4
Q

what does the letter M represent

A

myosin only

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5
Q

what does the M line represent, and why is it darker than the rest of the H zone

A

it is the centre of the sarcomere
anchors myosin
darker as it contains other proteins

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6
Q

what is the A band

A

spans from the Z line to the M line
appears dark under the microscope (anisotropic)
doesn’t shorten during contraction

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7
Q

what is the H zone

A

only myosin, lighter, no actin overlapping

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8
Q

what is the I band

A

isotropic - spans from one Z line to another
shortens under contraction

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9
Q

what is the Z line and why is it so dark

A

defines the sarcomere unit
anchors myosin
contains other proteins making it darker

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10
Q

locate a fascicle

A
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11
Q

locate the epimysium

A
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12
Q

locate the perimysium

A
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13
Q

where is the endomysium connective tissue

A
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14
Q

what is contained in the endomysium connective tissue

A

comprehensive vascular system so it can deliver O2 for muscle contraction/protein synthesis

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15
Q

a myofibril containing all the conventional structures like sarcomere, SER, sarcoplasm, sarcolemma etc is common to which muscle types

A

only the striated - so skeletal and cardiac
- and thus a myofibril is completely different within smooth muscle

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16
Q

a single myosin molecule consists of:

A
  • 2x heavy chains - long tail rod and head region
  • 4x light cahins - which wrap around the neck
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17
Q

actin and myosin arrangement in striated vs smooth

A

striated: parallel and most organised in skeletal
smooth: diagonal, criscrossing

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18
Q

actin and myosin consume ATP in the presence of what to give rise to what

A

Ca2+
- muscle contraction

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19
Q

actin subunits _________ to form ________

A

polymerise to form chains

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20
Q

by implementing what two things in smooth muscle, allow smooth muscle cells to contract uniformly?

A

adherens junction
or connexins

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21
Q

cardiac muscle contain ___________, specialised ________ which together allow what…..

A

intercalated disks and specialised junctions
contraction in unison

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22
Q

cardiac muscle is under _______ control

A

involuntary

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23
Q

each muscle fibre is innervated by how many motor neurons

A

one only

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24
Q

explain this picture

A
  • intermediate and thin filaments formed by actin and myosin chains stretch to dense bodies located on adjacent smooth muscle forming a mesh like network encircling a large n of smooth muscle cells
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24
familial hypertrophic cardiomypothay symptoms are what:
chest pain shortness of breath sensation of fluttering or pounding dizziness fainting
25
how does excitation contraction coupling prepare myofilaments to contract?
1. AP propogates down sarcolemma reaching T/transvere tubules 2. T tubules link Ca2+ channels of terminal cisternae of SR 3. Ca2+ released from SR into sarcoplasm 4. Ca2+ binds to troponin on thin filament which shifts tropomyosin off myosin binding sites 5. enables myosin to bind to actin
26
how is skeletal muscle attached to skeleton
via tendons
27
in diarrhoea, smooth muscle activity ______ in constipation, smooth muscle activity _______
increases decreases
28
in smooth muscle, actin and myosin form what which are anchored where
form continous chains that are anchored at dense bodies
29
is cardiac striated?
yes
30
is skeletal muscle striated?
yes, with visible sarcomeres
31
is smooth muscle striated?
no, no visible sarcomeres
32
junctional folds in sarcolemma contain what _______ and what does it help occur
ACh receptors which bind to ACh to initiate muscle contraction
33
locomotion is a function of skeletal muscle. what does thus mean?
movement from one place to another
34
skeletal muscle is attached to the ____
skeleton
35
skeletal muscle is under ______ control
voluntary
36
smooth muscle is under ________ control
involuntary
37
source of Ca2+ in skeletal muscle vs cardiac muscle vs smooth muscle
skeletal: mainly Sarcolemma reticulum cardiac: SR and extracellular environment (through voltage gated Ca channels) smooth: SR and extracellular (via caveolae)
38
the basic contraction mechanism/gliding (cross bridge cycle) is ______ in skeletal vs cardiac muscle - excitation contraction couplding is ______ in skeletal vs cardiac msucle
similar different
39
thick filaments are composed of _______ what are they shaped like?
myosin like golf clubs
40
tropomyosin is what
a fibrous protein which extends along the grooves of actin polymers - stabilises the polymer
41
we know that smooth muscle myofibrils are completely different to the striated ones. where do the actin filaments attach?
actin filaments attach to dense bodies that are spread throughout the cell
42
what are some metabolic functions of skeletal muscle? (3)
amino acid reserve (muscles atrophy and protein is broken down into AA during starvation) synthesis + storage of glutamine myokine production
43
what are some structural functions of skeletal muscle? (4)
movement balance posture strength
44
what are the 3 components of actin/thin filament
actin troponin complex tropomyosin
45
what are the cell/fibre shapes of skeletal muscle
long and cylindrical
46
what are the cell/fibre shapes of cardiac muscle
branched and short
47
what are the cell/fibre shapes of smooth muscle
spindle shaped
48
what are the regulatory proteins in striated muscle vs smooth muscle
striated: Troponin - tropomysoin smooth: calmodulin - MLCK
49
what are the sarcolemma specialisations in striated vs smooth
T tubules vs Caveolae
50
what are the steps of transmission at a NMJ (neuromuscular junction)
1. nerve signal arrives at axon terminal of NMJ which opens voltage gated Ca2+ channels 2. Ca2+ flood in and stimulate release of ACh from synaptic vesicles which diffuse into synaptic cleft 3. Ach binds to ACH receptors on sarcolemma 4. ligand gated receptors change shape 5. Na+ diffuse in and K+ to diffuse out --> depolarization 6. ACh recycled by acetylcholinesterase
51
what can an AP (action potential) not do when going from nerve fibre down to muscle fibre
cannot 'jump'
52
what does the AP (action potential) travel in sequence
from brain ---> motor (in skeletal) nerve fibre -----> muscle fibre
53
what does the tropomyosin cover
the myosin binding sites
54
what does tropomyosin do in the absence of Ca2+
block the myosin binding site on actin
55
what happens during sliding filament mechanism
1. at rest, ATP molecule binds to myosin head and ATPase enzyme on myosin hydrolyzes ATP 2. reaction releases energy that promotes myosin head into an extended, high energy position 3. extended myosin binds to active site on actin molecule (exposed by E-C coupling process) - called the 'cross bridge' ----> Pi is released from ATP making bond stronger 4. myosin released ADP bending myosin head and tigging actin akong centre of sarcomere --> 'power stroke' 5. a new ATP molecule binds to myosin head to release myosin from actin 6. ATP hydrolysis by ATPase extends the myosin head again 7. steps 3-5 are repeated ('cross-bridge cycling') at a new active actin site further down filament to shorten the sarcomere
55
what in a contractile unit in striated muscle vs smooth muscle
sarcomere (Z disk to Z disc) vs dense bodies + intermediate filaments
56
what is a bundle of muscle cells called? what is the plural term for bundles
fascicle fasciculi
57
what is a sarcomere
- the basic repeating unit of striated muscle which causes it to contract - the area between two Z - discs
57
what is a synapse and in a muscle what is it called specifically
the functional connection between a nerve fibre and a target cell - Neuromuscular junciton (NMJ)
58
what is cardiac muscles primary purpose
pump blood
59
what is smooth muscles primary functions?
move contents through hollow organs (e.g blood vessels, bladder, gut)
60
what is the anaology for the relationship between the SR, sarcoplasm and the sarcolemma
wrapper = sarcolemma chocolate filling = sarcoplasm wafers wrapped in layers = SR
61
what is the anchoring structure (where sacromere is anchored in striated) in striated vs smooth muscle
striated: Z line/Z disc smooth: dense bodies
62
what is the complex of troponin proteins comprised of
Tn-T (tropomyosin binding) Tn-C (calcium binding) Tn-I (inhibitory sub unit)
63
what is the event that links muscle action potential to muscle contraciton and what is its main purpose
excitation-contraction coupling - prepare myofilaments to contract
64
what is the order of heirarchy of size starting from fascile and ending with myofilaments
1. fascile = bundle of muscle cells/fibres 2. muscle fibre (muscle cell) 3. myofibrils --> 100s to 1000s inside one muscle cell 4. myofilaments like actin and myosin are contained within myofibrils
65
what is the sarcolemma
the plasma membrane surrouding a striated msucle fibre
66
what is the sarcoplasm and what is it surrounded within
cytoplasm specific to muscle, and will haveother organelles - surrounded within the sarcoplasmic reticulum
67
what kind (number and location) of nuclei does skeletal, smooth and cardiac muscle have?
skeletal ---> multiple, pheriphery smooth ----> single, central cardiac ----> 1-2, central
68
when comparing a resting sarcomere and a contracting sarcomere, what elements change or stay the same
as actin glides over myosin, A band stays constant but I band shortens by 70%
69
where is cardiac muscle found
in the walls of the heart
70
which muscle types contain actin and myosin
all although arranged differently in striated vs smooth
70
where is smooth muscle found? 2
1. walls of hollow visceral organs 2. and blood vessles
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