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IKK - Anatomy Exam 3 > Histo - Muscle Tissue > Flashcards

Histo - Muscle Tissue Flashcards

1
Q

Muscle tissue develops from ____

A

mesoderm

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2
Q

The cytoplasm in muscle cells is called ___

A

sacroplasm

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3
Q

What is the sarcoplasm?

A

the cytoplasm of muscle cells

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4
Q

The smooth endoplasmic reticulum in muscle cells is called _____

A

sarcoplasmic reticulum

*has new/important role in muscle cells

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5
Q

What is the sarcoplasmic reticulum?

A

the smooth endoplasmic reticulum in muscle cells

*has new/important role in muscle cells

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6
Q

The plasma membrane / plasmalemma of muscle cells is called _____

A

sarcolemma

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7
Q

What is the sarcolemma?

A

The plasma membrane / plasmelemma of muscle cells

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8
Q

What is a muscle cell called?

A

muscle fiber or myofiber

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9
Q

Describe the difference between a muscle fiber and a nervous fiber

A

Nervous fiber is just an axon

Muscle fiber is the entire cell

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10
Q

What are the 3 muscle prefixes

A

sarco-, myo-, mys-

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11
Q

Do muscle organs contain only muscle tissue?

A

no.

by definition, an organ contains two or more primary tissue types, so it must contain other tissue besides muscle tissue

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12
Q

What are the 3 types of muscle tissue based on functional traits?

A

1 skeletal muscle tissue
2 cardiac muscle tissue
3 smooth muscle tissue

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13
Q

Describe the contraction of a skeletal muscle tissue

A

strong, quick, discontinuous, voluntary contraction

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14
Q

Describe the contraction of a cardiac muscle tissue

A

strong, quick, continuous, involuntary contraction

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15
Q

Describe the contraction of a smooth muscle tissue

A

weak, slow, involuntary contraction

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16
Q

What are 4 special characteristics of muscle tissue?

A

1 excitability/irritability
2 contractability
3 extensibility
4 elasticity

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17
Q

Special characteristic of muscle tissue: excitability/irritability.

Describe this.

A

ability to respond to a stimulus via electrical signal (like a neuronal axon)

can produce/conduct action potentials

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18
Q

Special characteristic of muscle tissue: contractability.

Describe this.

A

When tension by a muscle is greater than resistance to a force, the muscle shortens

whether or not muscle shortens, contraction is occurring

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19
Q

Special characteristic of muscle tissue: extensibility.

Describe this.

A

muscle tissue is able to be extended and stressed

*this is a passive process

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20
Q

Special characteristic of muscle tissue: elasticity.

Describe this.

A

muscle tissue’s ability to return to original length after being shortened or lengthened.

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21
Q

What are the 4 functions of muscle tissue?

A

1 produce movement
2 maintain posture
3 stabilize joints
4 generate heat

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22
Q

Describe how muscle tissue produces movement (function)

A

skeletal muscle tissue - moves things from 1 location to another

smooth muscle tissue - moves things within urinary/gi tract through peristalsis

cardiac muscle tissue - move blood throughout cardiac system

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23
Q

Describe how muscle tissue maintains posture (function)

A

*mostly skeletal muscle

muscles are constantly fighting gravity so muscles must contract to maintain posture

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24
Q

Describe why sitting with your back unsupported leads to back pain

A

Skeletal muscles play a large role in maintaining posture

If back is unsupported, muscles maintaining posture must do more work, this leads to back pain

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25
Q

Describe why muscle tissue stabilizes joints (function)

A

*mostly skeletal

because muscles and joints = movement

and muscle tissue plays large role in movement

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26
Q

Describe why muscle tissues generate heat (function)

A

thermogenesis

muscle cells and tissues are generating ATP to generate a force. this is exothermic

think: shivering at bus stop.

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27
Q

Skeletal muscle: striated/nonstriated? Why?

A

striated.

because of arrangement of actin and myosin

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28
Q

Describe the cell shape of skeletal muscle cells

A 
large, elongated, cylindrical cells
structural syncitiated (multinucleated) cells

elongated because muscle cells run the entire length of the muscle

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29
Q

How long are skeletal muscles?

A

skeletal muscle cells are elongated.

they run the length of the muscle

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30
Q

Describe nucleus placement of skeletal muscle cells

A

nuclei are at the periphery just beneath the sarcolemma

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31
Q

Describe why skeletal muscle cells are a structural syncytium

A

skeletal cells are a fusion of embryonic myoblasts, leading to them being multinucleated

this means that skeletal muscle cells are a STRUCTURAL syncitium

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32
Q

Skeletal muscle cells are a fusion of embryonic _____. This means that they are what?

A

myoblasts

this means that they are multinucleated aka structural syncitium.

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33
Q

Cardiac muscle cells are a strong, quick contraction followed by _____

A

quick relaxation period

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34
Q

Describe the cell shape of cardiac muscle cells

A

elongated, branched cells joined by intercalated discs

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35
Q

Are cardiac muscle cells multinucleated or uninucleated?

A

uninucleated

occasionally you will see a slide with 2 nuclei in 1 cell, this is rare.

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36
Q

What are intercalated discs? Which muscle cell type are they in?

A

cardiac muscle

they are eosinophilic lines that connect cardiac muscle cells to each other to keep cells together physically

gap junctions in intercalated discs allow cells to become a FUNCTIONAL syncitium.

this allows cardiac muscle cells to be “interwoven”

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37
Q

Which muscle cell type is a structural syncitium? which is a functional syncitium?

A

structural syncitium = skeletal muscle cells due to embryonic fusion of myoblasts

functional syncitium = cardiac muscle cells due to intercalated disc’s gap junctions connecting them to each other

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38
Q

Are cardiac muscle cells striated or nonstriated?

A

striated (seen in longitudinal cross section)

but striation is broken apart by cardiac muscle cell’s branching. so it appears different than skeletal striation

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39
Q

Compare/contrast the striation patterns of skeletal and cardiac muscle cells

A

Skeletal muscle cells = uninterrupted striated pattern

Cardiac muscle cells = interrupted striated pattern due to branching (mostly) and intercalated discs

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40
Q

Where is the nucleus located in cardiac muscle cells?

A

Nucleus is centered inside the cardiac muscle cell

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41
Q

Are smooth muscle cells striated or non striated?

A

Non striated

Their actin and myosin are arranged in a completely different orientation than skeletal/cardiac muscle cells

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42
Q

Are smooth muscle cells uninucleated or multinucleated?

A

uninucleated.

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43
Q

Describe the cell shape of smooth muscle cells

A

fusiform (wide centered, tapered on edges)

nucleus is located in the widest part of the fusiform cell

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44
Q

Where are smooth muscle cells found?

A

in walls of hollow organs needed to proper things forward

gi, urinary, reproductive, respiratory, iris of eye, blood vessels

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45
Q

What is the average length of a smooth muscle cell?

A

HIGHLY variable

think: can be in blood vessel or in pregnant uterus

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46
Q

How are smooth muscle cells usually oriented with each other?

A

smooth muscle is usually laid down in “sheets” in same direction with alternating pattern

this is helpful for propelling substances forward throughout a tract

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47
Q

What are the 3 classifications of skeletal muscle in humans?

What are they classified based on?

A

classified based on physiology, biochemistry, histochemistry

type 1: slow, red oxidative fibers
type 2a: fast, intermediate oxidative-glytolytic fibers
type 2b: fast, white glycolytic fibers

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48
Q

Type 1: slow, red oxidative fibers (skeletal muscle)

describe the amount of myoglobin, mitochondria and glycogen.

A

many mitochondria and myoglobin present (this is why it is red in color)

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49
Q

What is myoglobin?

A

oxygen-binding protein

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50
Q

Type 1: slow, red oxidative fibers (skeletal muscle)

Why is it red?

A

because so much oxygen due to the high levels of myoglobin (oxygen binding protein) and mitochondria

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51
Q

Type 1: slow, red oxidative fibers (skeletal muscle)

derives energy primarily from ____

A

aerobic oxidative phosphorylation of fatty acids

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52
Q

Type 1: slow, red oxidative fibers (skeletal muscle)

Describe the diameter relative to the other types of fibers

A

relatively small diameter relative to type IIa and type IIb of skeletal muscles

small = least powerful

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53
Q

Type 1: slow, red oxidative fibers (skeletal muscle)

Adapted for what type of contractions? What’s an example of this?

A

slow, continuous contractions over long periods of time

example: muscles to maintain posture

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54
Q

Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)

describe the amount of myoglobin, mitochondria and glycogen.

A

many mitochondria, lots of myoglobin AND glycogen (because it is intermediate)

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55
Q

Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)

Describe the diameter relative to the other 2 fibers

A

Diameter size is intermediate between type I and type IIb skeletal muscle fibers

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56
Q

Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)

derives energy primarily from ___

A

oxidative metabolism and anaerobic glycolysis

intermediate

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57
Q

Type 2a: fast, intermediate oxidative-glycolytic fibers (skeletal muscle)

Adapted for what type of contractions?

A

Rapid contractions and short bursts of activity

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58
Q

Type 2b: fast, white glycolytic fibers (skeletal muscle)

describe the amount of myoglobin, mitochondria and glycogen.

A

Fewer mitochondria and myoglobin

LOTS of glycogen (which makes it pale or white looking)

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59
Q

Type 2b: fast, white glycolytic fibers (skeletal muscle)

Why is it white?

A

because of the glycogen present

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60
Q

Type 2b: fast, white glycolytic fibers (skeletal muscle)

Energy is derived primarily from _____

A

anaerobic glycolysis

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61
Q

Type 2b: fast, white glycolytic fibers (skeletal muscle)

Adapted for what type of contraction/ What is an example of this?

A

Rapid contractions (that fatigue easily)

Example: weight lifting, throwing baseballs, etc.

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62
Q

Most muscles contain which type of muscle fiber?

A

most muscles are a combination of muscle fiber types

may have more of one type depending on it’s function and/or genetics

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63
Q

Myofibrils take up ___% of cytoplasm?

A

80

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64
Q

Describe myofibrils physically

A

long, cylindrical rods runnung parallel to long axis of the cell

~2um in diameter

65
Q

The myofibril pattern is made up because of what?

A

sarcomere

66
Q

What is the smallest unit of contraction?

A

sarcomere

67
Q

A sarcomere is made up of?

It extends from what to what?

A

extends from z disc to z disc

is 1/2 i band, entire a band, 1/2 i band

68
Q

How do sarcomeres line up to create a striated pattern?

A

sarcomeres of 1 myofibril line up laterally with those on the next and the next and the next…

69
Q

What is the area called where you see thick filament?

A

a band

70
Q

Thick filament aka ____

A

myosin filament

71
Q

What is the area called where you see thin filament only?

A

i band

72
Q

Thin filament aka ____

A

actin filament

73
Q

Which is dark/light on a histo slide?

A

A band is dArk

I band is lIght

74
Q

Describe what is found in both a band and i band

A

a band is where any thick filament (myosin) is found

i band is where thin filament (actin) ONLY is found

75
Q

What is the area of thick filament only called?

A

H zone

NO THIN FILAMENT (ACTIN) HERE

76
Q

Where is the h zone? What is found there?

A

the h zone is the center of the a band / center of the sarcomere

this is where thick filament (myosin) only is found.

no thin filament (actin) is found here

77
Q

What is the center of the h zone?

A

the m line

78
Q

What is the m line?

What is found there?

A

the center of the h zone

contains proteins that connect myosin together to maintain the structure of sarcomeres

79
Q

What is the normal length of a sarcomere?

A

~2.5um

the distance changes when it contracts/relaxes

80
Q

When is the h zone present?

A

in a relaxed muscle

(think: if contracted, myosin bind to actin and pulls it inward. therefore there is no area with “thick filament only” since the thin filament is overlying the thick. therefore the h zone disappears)

81
Q

What is the sliding filament hypothesis?

A

the theory that myosin pulls actin towards center of the sarcomere as a means of contraction

82
Q

Does contraction = shortening

A

no.

but if the force is greater than the resistance, then shortening will occur

83
Q

As myosin pulls actin towards the center, what happens to the h zone?

A

h zone gets smaller and ultimately disappears

84
Q

As myosin pulls actin towards the center, what happens to the i band?

A

the i band gets smaller and ultimately disappears

85
Q

As myosin pulls actin towards the center, what happens to the a band?

A

the a band remains the same length

86
Q

As myosin pulls actin towards the center, what happens to the z discs?

A

z discs are pulled together in this processes.

this means that the sarcomere shrinks, the myofibril shrinks and the cell overall gets shorter

87
Q

As myosin pulls actin towards the center, what happens to the length of myosin/actin?

A

they remain the same length

the way that they are overlapping is what changes.

88
Q

Thick filament (myosin) is made up of ____

A

2 heavy interwoven polypeptide chains

has 2 globular heads at either end

89
Q

What is located at the globular head ends of myosin?

A

actin binding sites, atp binding sites and atpase activity

90
Q

How many myosin molecules compose 1 thick myofilament?

A

several hundred

91
Q

Thin filament (actin) is made up of ____

A

globular subunits (g actin)

2 strands of g actin twisting together, each has a myosin binding site that is blocked by tropomyosin

92
Q

What is g actin?

A

the globular subunit of actin

2 g actins twisting together = actin

93
Q

The myosin binding site on g actin is blocked by ____

A

tropomyosin

94
Q

What is tropomyosin?

A

long, thin molecules twist around actin filaments

blocks myosin binding site n g actin (globular subunit of actin)

95
Q

What is troponin and it’s subunits?

A

TNT: attaches troponin to tropomyosin

TNC: binds calcium ions (important because calcium is the final signal for contraction)

TNI: inhibitor of actin/myosin interaction

96
Q

What is the TNT subunit of troponin responsible for?

A

attaching troponin to tropomyosin

97
Q

What is the TNC subunit of troponin responsible for?

A

binding calcium

calcium is the final stage for muscle contraction

98
Q

What is the TNI subunit of troponin responsible for?

A

inhibiting actin/myosin interactions

99
Q

What are t tubules?

A

extensions of the sarcolema (plasma membrane)

100
Q

Extensions of the sarcolema are called ___

A

t tubules

101
Q

What is the enlarged part of the sarcoplasmic reticulum called? Why is it enlarged?

A

terminal cisterna

it is storing calcium ions

102
Q

What is the part of the sarcoplasmic reticulum called that stores calcium ions?

A

terminal cisterna

this is the enlarged part of the sarcoplasmic reticulum

103
Q

What is a skeletal muscle triad made up of?

A

1 t tubule

2 terminal cisterna

104
Q

1 t tubule and 2 terminal cisterna come together to make up a ____

Where is this found?

A

skeletal muscle triad

this is present 2x in a sarcomere (at each i band/a band junction)

105
Q

What is found at the I band A band junction?

A

a skeletal muscle triad

this is found twice per sarcomere (because there are 2 a band/i band junctions in a sarcomere)

106
Q

What connects the t tubules and the terminal cisterna?

A

voltage-gated regulatory proteins

107
Q

When an action potential comes down from the t tubules towards the terminal cisterna, it first hits the ____

A

voltage-gated regulatory proteins

108
Q

What happens with the action potential hits the voltage-gated regulatory proteins in between the t tubules and the terminal cisterna?

A

these regulatory proteins undergo a conformational change which causes the release of Ca from the terminal cisterna

109
Q

Ca from the terminal cisterna is due to what?

A

conformational change of voltage-gated regulatory proteins causes the release of Ca from termianl cisterna

110
Q

Once Ca is released from terminal cisterna, what is the intracellular calcium level?

A

high

this is the final stage of contraction

111
Q

Neuromuscular junction aka ____

A

motor end plate

112
Q

What is the neuromuscular junction?

A

aka motor end plate

chemical synapse between motor (efferent) neurons and skeletal muscle fibers/cells

113
Q

What is a motor unit?

A

a motor (efferent) neuron and all of the muscle fibers (cells) that it interacts with

114
Q

What happens to muscle fibers if the motor unit is activated?

How many muscle fibers per motor unit?

A

ALL of the skeletal muscle cells contract (can have 1 - 160 muscle fibers per motor unit)

115
Q

How are motor units different in areas of fine motor control?

A

In areas of fine motor control = small motor unit

compared to lower limb = lots of big motor units

116
Q

An action potential comes down a motor neuron and hits the ____

A

neuromuscular junction

117
Q

How does the axon terminal of motor neuron and the plasma membrane of skeletal muscle cell interact during action potential contraction flow?

A

axon terminal of motor neuron gets close (does not touch) skeletal muscle cell plasma membrane

118
Q

Action potential of motor neuron releases calcium, causing ___

A

releases calcium via voltage gated channels

this causes calcium to flood into the axon terminals

causes release of ACh

Causes graded potential of sarcolemma

119
Q

Voltaged gated channels on the plasma membrane of skeleta musclecell create another AP, which travels through ___

A

T Tubules

120
Q

T tubules interact with terminal cisterna at the ____

How does the terminal cisterna release Calcium?

A

triad

conformational change of the terminal cisternae causes releases of calcium

121
Q

What kind of energy state is myosin in?

A

high energy state

myosin is in high energy state waiting for actin to build a cross bridge

122
Q

Do globular heads of myosin pull all at once?

A

no.

if they pulled all at once, they would “snap back” to original orientation. They pull in waves

123
Q

As myosin goes from high energy to low energy, ____ is released

A

ADP and phosphate

124
Q

How does the cross bridge break between myosin and actin?

A

ATP binds to globular head

125
Q

Describe rigor mortis (and timeline) in terms of calcium and ATP

A

When dead, calcium floods into cell, binds to troponin, moves tropomyosin, myosin/actin cross bridge form.

Because dead, no ATP formation. So cross bridge cannot break.

This starts 3-4 hours after death, peaks at 12 hours, and dissipates 48-60 hours because of prolyolytic enzymes from lysosomes which degrade cells

126
Q

Skeletal muscle (the organ) contains what 4 components?

A
  1. skeleta muscle tissue
  2. vessels (arteries, capillaries, veins, lymph nodes)
  3. Nerve fibers
  4. Connective tissue
127
Q

What are the 3 connective tissue sheaths associated with skeletal muscle (the organ)?

A

endomysium
perimysium
epimysium

128
Q

Are the three connective tissue sheaths associated with skeletal muscle (the organ) completely separate or connected?

A

endomysium, perimysium and epimysium are all connected

129
Q

Describe endomysium

A

delicate layer of connective tissue surrounding individual skeletal muscle fibers

130
Q

Describe perimysium

A

many skeletal muscle fibers together are wrapped in perimysium.

perimysium wrapped structures are known as fassicles

131
Q

What is a fassicle?

A

Perimysium wrapped structures are known as fassicles

132
Q

Describe epimysium

A

All fassicles together are wrapped in epimysium

External sheath, dense connective tissue surrounding entire muscle

133
Q

If you were handed a muscle - what connective tissue sheath would you be touching?

A

epimysium

134
Q

Walk through the contraction stages from myofibril contraction to bone.

A

myofibril -> cell -> endomysium -> perimysium -> epimysium -> tendon -> bone

135
Q

The tendon connects what to what?

A

connects epimysium of muscle to periosteum of bone

136
Q

What do sharpey’s fibers connect?

A

periosteum of bone to bone tissue

137
Q

What connects the periosteum of bone to the bone tissue?

A

sharpey’s fibers

138
Q

Compare cardiac m and skeletal m:

Striation?

A

Skeletal m: striated

Cardiac m: striated, but less so because of branching

139
Q

Compare cardiac m and skeletal m:

cell shape/nucleus

A

Skeletal: long, cyllindrical, multinucleated, nuclei located under sarcolemma

Cardiac: short, fat, branched, 1 nucleus in center

140
Q

Compare cardiac m and skeletal m:

contraction

A

both operate under sliding filament mechanism.

141
Q

Compare cardiac m and skeletal m:

Mitochondria in cell volume

A

Skeletal m: mitochondria are 2% cell volume

Cardiac m: large mitochondria are 25-40% of cell volume

142
Q

Compare cardiac m and skeletal m:

Sarcomeres

A

both have z discs, a band, i band

143
Q

Compare cardiac m and skeletal m:

T tubules. How many and where are they?

A

Skeletal m: 2 t tubules per sarcomere @ a-i junction

Cardiac m: 1 t tubule per sarcomere @ z line

144
Q

Compare cardiac m and skeletal m:

diad/triad
sarcoplasmic reticulum complex or simple? big/small terminal cisterna?

A

Skeletal m: triad
- complex sarcoplasmic reticulum with large terminal cisterna and 2 t tubules

cardiac m: diad
- simple sarcoplasmic reticulum with small terminal cisterna and 1 t tubule

145
Q

What are the 2 jobs of intercalated discs in cardiac muscle cells?

A
  1. make sure cells dont let go of each other

2. make sure cells communicate and work as 1 (functional syncitium)

146
Q

How do intercalated discs of cardiac muscle cells stain histologically?

A

dark lines that traverse the slide

147
Q

What are the 3 components of intercalated discs of cardiac muscle cells?

A
  1. fascia adherens
  2. desmosomes (macula adherens)
  3. gap junction
148
Q

Fascia adherens of intercalated discs in cardiac muscle cells

Describe what they do/what they connect

A

Connect actin of 1 cell to actin of another cell (they function like z discs)

they form an anchoring junction

149
Q

Desmosomes of intercalated discs in cardiac muscle cells

Describe what they do/what they connect

Desmosomes aka ____

A

desmosomes aka macula adherens

connect intermediate filaments of 1 cell to intermediate filaments of another cell

they form an anchoring junction

150
Q

Gap junctions of intercalated discs in cardiac muscle cells

What do they do?

A

These serve for intracellular communication

They form a communication junction

So if 1 cell gets the signal to contract, they all get the signal to contract. This is how cardiac muscles function as functional syncitium

151
Q

How are cardiac muscle cells able to function as a functional syncitium?

A

gap junctions of intercalated discs of cardiac muscle cells serve as intracellular communication junctions.

this is how they operate as a functional syncitium

152
Q

What connective tissue sheath is present in the smooth muscle cells

A

endomysium

153
Q

What produces endomysium in smooth muscle cells?

Why is this different than normal?

A

endomysium is produced by smooth muscle cells

usually, fibroblasts produce connective tissue, this is different here.

154
Q

Do smooth muscle cells have a sarcoplasmic reticulum?

A

Yes. It is rudimentary.

It is present for calcium contraction

155
Q

Do smooth muscle cells have t tubules?

A

No t tubules because actin and myosin line up differently here

156
Q

How do actin and mysoin line up in smooth muscle cells?

A

in a lattice network

they cross obliquely across the cell, this is why smooth muscle isn’t striated

157
Q

Describe the contraction of a smooth muscle cell

A

Corkscrew twist, brings nucleus down with it.

Still contracts based on the sliding filament mechanism

158
Q

Actin filaments of smooth muscle are tied into ____ (which are located ___)

A

dense bodies

these are located inside the cell at the surface

IKK - Anatomy Exam 3 (11 decks)

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