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Microanatomy > Exam 2: Muscle > Flashcards

Exam 2: Muscle Flashcards

1
Q

Myocyte

A

muscle cell = myofiber = muscle fiber

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2
Q

Myofilaments

A

filaments in muscle cells

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3
Q

Sarcoplasm

A

cytoplasm of muscle cells

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4
Q

What are muscle cells specialized for?

A

forceful contraction

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5
Q

What is muscle derived from? (embryonic tissue)

A

mesoderm

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6
Q

3 types of muscle

A

smooth
skeletal
cardiac

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7
Q

Which type of muscle is not striated?

A

smooth

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8
Q

Smooth muscle characteristics

A

central nuclei
long/tapered ends (for contraction)
innervated by ANS (involuntary contraction)

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9
Q

What kind of tissue is smooth muscle surrounded by?

A

Reticular fibers in loose connective tissue w/ myelinated axons (to transmit contractions)

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10
Q

Fusiform / Dense Bodies

A

attachment points for actin in smooth muscle
coil/contract cells

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11
Q

What structures allow the contraction mechanism of muscle?

A

actin & myosin

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12
Q

What shape does smooth muscle cell nuclei take during contraction?

A

elongated –> spiral/coil

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13
Q

Caveolae

A

invaginations of plasma membrane in smooth muscle

involved in Ca2+ entry/exit during contraction

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14
Q

Smooth muscle contraction

A

Ca2+ binds to calmodulin
Activates MLCK –> phosphorylates myosin –> cleave ATP = contraction
not rapid | sustained, tonic contraction of organs

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15
Q

Two types of smooth muscle contraction

A

unitary/visceral
multiunit

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16
Q

Unitary/visceral contraction

A

smooth muscle contraction
peristaltic waves trigger other cells via gap junctions

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17
Q

Multiunit contraction

A

fine control (ex. iris)
sheets of cells contract at same time because all innervated individually (not gap junctions)

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18
Q

Skeletal muscle characteristics

A

striated
multi-nuclei at periphery
reticular fibers important for contraction

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19
Q

Cardiac muscle characteristics

A

striated
1 nuclei per cell at center | rectangular nuclei
branches | intercalated disks
HIGHLY vascular

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20
Q

Myofibrils

A

columns of sarcomeres

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21
Q

Explain the mechanical disadvantage of contraction in skeletal muscle

A

power traded for leverage & speed

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22
Q

Desmin

A

intermediate filament of skeletal muscle
keeps sarcomeres in register & maintain structural integrity of myofibrils

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23
Q

alpha-actinin

A

anchors actin filaments at Z-line in skeletal muscle & dense bodies of smooth

24
Q

Titin

A

protein that anchors and keeps sarcomere from over-extending (elastic!)

25
Q

Desminopathies

A

mutated desmin breaks up sarcomeres which leads to separation
cardiomyopathy is one result of desminopathy

26
Q

I band

A

actin filaments not yet overlapping with myosin
transected by Z line

27
Q

T tubule

A

invaginations of muscle cell which increases contraction/Ca2+ sequestering

28
Q

Triad in skeletal muscle

A

T tubule + SR on both sides
allows for more efficient contraction

29
Q

Contraction of Skeletal Muscle

A

Ca2+ binds to troponin (conform change) | moves tropomyosin so myosin can bind to actin |
myosin flexes & actin moves along it as long as ATP / Ca2+ bound

30
Q

Smooth muscle contraction controlled by activation of…

A

myosin

31
Q

Striated muscle contraction controlled by access to…

A

actin

32
Q

Type I skeletal muscle fiber

A

Slow, oxidative
Long, sustained contraction

33
Q

Type IIa skeletal muscle fiber type

A

oxidative phosphorylation for relatively fast contraction

34
Q

Type IIb skeletal muscle fiber type

A

Rapid contraction, susceptible to fatigue

35
Q

Epimysium

A

DICCT sheath around whole muscle

36
Q

Perimysium

A

loose CT around fascicles

37
Q

Endomysium

A

connective tissue of reticular fibers around each myocyte
highly vascular

38
Q

Intercalated Disks

A

cardiac muscle only
junctions that transmit force of contraction between cells

39
Q

Parts of Intercalated disks

A

transverse portion
lateral portion

40
Q

Transverse portion of intercalated disk

A

transmits force of contraction from one cardiac cell to another

41
Q

Lateral portion of intercalated disk

A

communicating junctions from one cell to another (gap junctions) to transmit trigger for contraction

42
Q

What structures are within intercalated disk?

A

Fascia adherens
Macula adherens (desmosomes)
Gap Junctions

43
Q

Fascia adherens

A

anchors actin filaments in intercalated disk

44
Q

Diad

A

structure in cardiac muscle
made of T tubule, SR on one side
Z line around it

45
Q

How does smooth muscle grow in response to physiological demand?

A

Hypertrophy AND hyperplasia

46
Q

Hypertrophy

A

individual cells get larger

47
Q

Hyperplasia

A

division of cells / increase in reproduction rate

48
Q

How does smooth muscle repair after injury?

A

cell replacement by connective tissue/scar tissue (DICCT)
some new myocytes from pericytes

49
Q

How does skeletal muscle grow in response to physiological demand?

A

Hypertrophy only

50
Q

How does skeletal mucsle repair after injury?

A

substantial cell replacement
new myofibers from satellite cells

51
Q

How does cardiac muscle grow in response to physiological demand?

A

Hypertrophy only

52
Q

I band

A

light band made of actin filaments

in skeletal muscle

53
Q

A band

A

dark band containing myosin filaments

in skeletal muscle

54
Q

Z disk/line

A

within I band where actin filaments attach

in skeletal muscle

55
Q

H band

A

light zone at center of A band, gap between actin filaments

in skeletal muscle

56
Q

M line

A

fine threads connecting central part of myosin filaments

in skeletal muscle

Microanatomy (21 decks)

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