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Quiz 2 > CTO Quiz 2: Muscle Tissue > Flashcards

CTO Quiz 2: Muscle Tissue Flashcards

1
Q

Types of Muscle

A

1) skeletal- fast contracting, powerful, voluntary control, discontinuous activity
2) cardiac- fast contracting, powerful, involuntary, continuous activity
3) smooth- slow contracting, weak, involuntary control, discontinuous activity

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2
Q

Excitability

A

respond to neurotransmitters or hormones

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3
Q

Conductivity

A

ability to propagate electrical signals

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4
Q

Contractility

A

ability to shorten and generate force

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5
Q

Extensibility

A

ability to stretch without damaging tissue

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6
Q

Elasticity

A

ability to return to original shape after stretch

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7
Q

Skeletal Muscle (general properties)

A

striated, voluntary
multinucleated syncytium (peripheral nuclei)
no mitosis
hypertrophy in response to demand

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8
Q

Muscle fiber

A

skeletal muscle cell

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9
Q

Epimysium

A

surrounds entire muscle (just beneath deep fascia)

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10
Q

Perimysium

A

separates muscles into fasicles

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11
Q

Fasicles

A

bundles of muscle fibers

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12
Q

Endomysium

A

separates individual fibers

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13
Q

Organization of Muscle (large to small)

A

muscle–> fasicle–> fiber–> fibril–> myofilaments (thick and thin)

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14
Q

Skeletal Muscle Development

A

myoblasts fuse together during fetal development
mature muscle cells do not divide
muscle growth result of cellular hypertrophy
satellite cells retain ability to regenerate new cells

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15
Q

I Band

A

zone of just thin actin filaments (no overlap)
isotropic- stain lightly
cross section- actin + actin assoc proteins

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16
Q

Z Disc

A 
border between adjacent sarcomeres
stain very dark
point of attachment for actin fillaments
limits contraction (maximal overlap)
cross section- anchor where + ends of actin meet
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17
Q

A Band

A

length of myosin (does not change with contraction)
anisotropic- stains darkly
comprised of myosin heavy fillament
in middle of contractile unit
cross section (A band overlap)- myosin and myosin with actin

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18
Q

M Line

A

attachment of adjacent myosin molecules
in the middle of H Zone
cross section-where myosin tails meet + myosin structural proteins

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19
Q

H Zone

A

zone of just myosin
distance between actin filaments
in very center of sarcomere
cross section- myosin only, no actin overlap, part of A band

20
Q

Thin Filament Actin-Associated Proteins

A 
tropomyosin (covers myosin binding site)
troponin C (binds calcium), T (binds tropomyosin), and I (inhibits myosin binding)
21
Q

Muscle Contractile Protein (Myosin II)

A

2 heavy chains (bind to thin filament)
2 light chains
2 regulatory chins
actin binding protein- binds actin to form cross-bridges
mechanoenzyme- ATPase- hydrolyzes ATP- uses energy to detach crossbridges

22
Q

Muscle Structure Proteins

A

provide proper alignment, elasticity and extensibility
titin, myomesin, nebulin, alpha actin, dystrophin (protein wrong in MS)
3 classes of intermediate filaments- desmin, vimentin and synemin (btw myofibrils)
cap z- caps ends of a ctin filaments (adjacent to Z disc)
actinin- anchors a-actin at Z disc
titin- starts at z line and binds to thick filament- acts as spring
myomesin- attaches myosin thick filaments at M line

23
Q

Muscle Contraction (zones)

A

Z disc moves toward A band
H band and I band decrease in width as a result of increased myosin/actin cross bridges
A band remains same width

24
Q

Power Stroke

A

binding of myosin to actin- releases ADP- pulls actin towards - end, + end anchored to Z disc
brings Z discs closer- shortens sarcomere
NO ENERGY EXPENDED

25
Q

Releasing Actin

A

myosin head binds to ATP to release actin (ATP not hydrolyzed)

26
Q

Re-cocking Mysoin Head

A

hydolysis of ATP recocks myson head

ADP still remains attached until myosin binds with actin again

27
Q

Location of Sarcoplasmic Reticulum

A

junction between A and I bands of sarcomere

28
Q

Neuromuscular Junction

A

synaptic connection between neurons and muscle
one neuromuscular junction per skeletal muscle fiber regardless of fiber length
one nerve fiber can innervate multiple muscle fibers
all muscle fibers innervated by one nerve fiber are called a motor unit

29
Q

Acetylcholine

A

neurotrasmitter involved in contraction
end synaptic bulbs contain synaptic vesicles with ACh
motor end plate membrane contains receptors
when ACh binds, opens ligand-gated Na channels in the cell membrane. Na ions then enter the muscle cell, initiating depolarization that results Ca release into the sarcoplasm and muscle contraction

30
Q

Binding Myosin to Actin

A

Ca binding to troponin C moves complex off myosin binding site- allows myosin head to bind to actin

31
Q

Cardiac Muscle (general properties/ differences from skeletal muscle)

A

striated, involuntary, self propagating, regulated by autonomic nervous system
nuclei are centrally located
individual muscle cells are separated by thick black lines called intercalated discs with gap junctions (fascia adherens on transverse, macula adherenes desmosomes on verticle)- allow for direct communication of ions b/t adjacent cells
cells branch
no mitosis
hypertrophy in response to demand
T tubules exist at Z lines, in apposition to only one cisterna
more mitochondria

32
Q

Smooth Muscle (general properties/ differences from skeletal muscle)

A

single fusiform cells
central nucleus
no striations
no clear indication of communication
appear in layers surrounding lumen
dense plaques contain contractile proteins and intermediate filaments
invagination like caveolae instead of T-tubles
hyperplasia and hyepertrophy in response to demand
mitosis and regeneration occur
surrounded by reticular fibers (type III collagen)
pinocytotic vesicles
low in SR

33
Q

Dense Bodies

A

sites of attachment of smooth muscle contractile fibers (actin and myosin)with each other and with the basement membrane
contain alpha actinin +
allow for cork skrew contraction

34
Q

Smooth Muscle Contraction

A

intracellular Ca enters cytoplasm from extracellular environment or from voltage gated channels activated by depolarization or can be released by SR via various hormones and transmitters (2nd messenger systems)
Ca binds to calmodulin, which binds to myosin light chain kinase
complex uses energy to phosphorylate myosin light chains, which liberates actin binding sites on myosin
contraction terminated by phosphatases
nervous control by autonomics (hormones can lead to contraction- ex oxycytosin leads to uterine contraction)
intermediate filaments are required

35
Q

Axon Terminals for Smooth Muscle

A

varicosities with vesicles of neurotransmitter exists at various points along axon terminal
released neurotransmitter has an influence on smooth muscle cells in the area

36
Q

Visceral Type Smooth Muscle

A

sheets of smooth muscle working in coordination
peristalsis
gut, uterus
sparse innervation
extensive gap junctions
waves of contraction propagate through muscle
nerves influence, but role of nerves modest

37
Q

Multiunit Type Smooth Muscle

A

precise and rapid contraction
smooth muscle of eye, arrector pili
heavily innervated

38
Q

Myoepithelial Cells

A

derived from epithelium
near glands, help with movement of secretions
reside in basement membrane of epithelium
have actin, myosin, are contractile

39
Q

Organization of Connective Tissue (large to small)

A

epimysium (muscle)–> perimysium (fasicle) –> endomysium (fiber)

40
Q

Muscle Regulatory Proteins

A

turn on and off contraction
troponin complex, tropomyosin, myosin light chain kinase (smooth muscle only)
troponin I binds to actin and inhibits myosin binding protein
troponin C- binds to calcium
troponin T- binds to tropomyosin

41
Q

Muscle Contraction Order of Events

A

Ca in cytoplasm binds to troponin C–> pulls tropomyosin away exposing the myosin binding site–> myosin binds to actin causes release of ADP from the head of the myosin molecule–> conformational change (stroke) to M line (minus side) (plus end anchored to z disk- pulls 2 z disks together)
Note- no energy used for the process yet
new ATP comes onto myosin–> myosin head released–> hydrolysis of ATP to ADP (energy used BUT phosphorus remains attached until myosin head binds with actin again–> recocking of myosin head (backwards towards + end/z disc) –> kicks back, cycle can begin again

42
Q

Rigor Mortis

A

no ATP present
begins 3-4 hrs after death
all ATP used up and sarcoplasmic reticulum stars leaking Ca
lasts 2-3 days until proteins break down

43
Q

Motor Unit

A

group of muscle fibers innervated by one nerve fiber

44
Q

Motor Plate

A

specialization of sarcolemma in contact with axon terminal (highly folded)

45
Q

Intercallated discs

A

thick black lines separating muscle cells (zig zag)
transverse portions have fascia adherence (broad desmosomes)
vertical portions have true desposomes and gap junctions–>communication of ions between adjacent cells–>electrical behavior like syncytium (connected cells of skeletal muscle

46
Q

Duchene’s Muscular Dystrophy

A

X linked

actin binding protein (dystrophin) missing –> muscles fall apart due to decreased binding

47
Q

Mysthenia Gravis

A

condition of neuromuscular junction

attacks acetylcholine receptor

Quiz 2 (6 decks)

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