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Anatomy > Primary Tissue 4 : Muscle > Flashcards

Primary Tissue 4 : Muscle Flashcards

1
Q

What is muscle tissue

A

-primary tissue which optimizes universal cell property of contractibility

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2
Q

Which components generate forces for muscle contraction

A

-actin and associated proteins ( Myosin )

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3
Q

Origin of muscle

A

-mesoderm

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4
Q

What are the key differentiations of muscle cells

A
  • elongated cell

- production of abundance of contractile apparatus

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5
Q

Describe myofibril , myofilaments and

A
  • bundles of sarcomeres

- the components of a sacromere ( actin and myosin )

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6
Q

The types of muscles

A

1 skeletal
2 cardiac
3 smooth

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7
Q

Cytoplasm, membrane and sER of muscle cells name !?

A
  • sacrolemma
  • sacroplasm
  • sacroplasmic reticulum
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8
Q

Development of skeletal muscle

A
  • mesenchymal cells of mesoderm called myeoblasts align and fuse into long multinucleated cyclindrical tubes myotube
  • myotubes synthesize myofibrillar proteins and cross striations begin to appear
  • continued synthesis of myofilaments displaces nuclei to peripheral of sacroplasm
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9
Q

What happens to undifferentiated myeoblasts

A

-become satellite cells which serve a regenerative function

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10
Q

How many Layers of CT surround the muscle and name them

A

Three

1 epimysium
2 perimysium
3 endomysium

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11
Q

Location and functions of the 3 layers surrounding skeletal muscle

A

1 epimysium- external dense sheath of CT surrounding entire muscle. Septa extends inwards dividing fascicles and bring large vessels and nerves to perimysium

2 perimysium- thin CT surrounding individual fascicles. Septa provides vessels and nerves to each endomysium

3 endomysium - thin delicate reticular fibers surrounding individual cells. Has blood and nerves to cells

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12
Q

What is a muscle fascicle

A

-a functional unit of bundles of muscle fibers which work together

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13
Q

Fascia and tendon location and function

A
  • overlies endomysium and continuous with tendon

- continuous with tendon and connects muscle to bone or skin

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14
Q

Do individual fibers extend from one end of muscle or not !?

A

Do not

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15
Q

What does collagen of CT do

A

-transit mechanic forces from individual fibers

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16
Q

What are myofibrils and where are they found and what are they made of

A
  • cyclindrical tubes parallel to long axis of cell.
  • collection of myofilaments

-made of myofilaments ( actin and myosin )

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17
Q

Describe myosin 2 and formation, subunits and functions

A
  • has 2 heavy chains which intertwine into tails

- 4 light chains make 2 globular heads with binding sites for myosin and ATP

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18
Q

Describe thick filaments structure

A

-numerous myosin molecules with tails intertwined and heads protruding at either end

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19
Q

Describe proteins attached to actin in muscle and their functions

A

1 tropinin- has three domains

  • TnC binds to Ca2+ found at top
  • TnT binds to tropomyosin found at bottom
  • TnI found at middle and regulates actin and myosin interactions

2 tropomyosin - 40nm coil of 2 peptide chains intertwine in between grooves of actin
-make inaccessible active site of actin from myosin

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20
Q

Bands of myofibrill

A

1 A band - region has thick filaments with overlaying thin filaments

2 I band - region is thin filaments and titin only

3 H zone - region of thick filaments only

4 M line - line which dissects and holds thick filaments. Has m line proteins

5 Z disc - where Titin and actin are held

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21
Q

What is sacromere and where found and function

A
  • region of filaments in between 2 discs

- is functional repetitive unit of myofibrill

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22
Q

What causes striations of muscle cells

A

-lateral arrangement of sacromeres of adjacent myofibrill’s

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23
Q

Describe titin, Z and M line proteins

A
  • largest protein in body with a spring like domain
  • bind thick filaments to Z disc

-has alpha actinini to hold actin filaments

  • has myomesin to hold thick filaments to M line
  • creatine kinase to catalyze transfer of phosphate from phosphocreatine to ADP supplying energy for contraction
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24
Q

Describe Nebulin proteins

A

-accessory proteins which hold actin filaments laterally to each other and anchors them to alpha actinin

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25
Q

What is phosphocreatine

A

-source of high energy phosphate groups

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26
Q

Where sER found in muscle and function

A
  • surround myofibrills

- stores and releases Ca2+ during contraction

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27
Q

What is T-tubule and function

A
  • invaginations in lemma which penetrate into plasma and encircle myofibrils
  • allow for uniform and simultaneous muscle nerve to reach sER
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28
Q

Triad structure and function

A
  • a T-tubule surrounded by 2 terminal Cisternae

- allows for muscle nerve at lemma to trigger sER to release Ca2+ simultaneously and uniformly

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29
Q

Events of contraction describe up to active site being exposed.

A
  • nerve impulse triggers synoptic knob to release synoptic vessels into cleft which bind with Ach receptors on NMJ
  • initiation of muscle impulse which spreads from lemma to triad and stimulates sER to release Ca2+ into plasm
  • Ca2+ binds to TnC changing shape of troponin which moves tropomyosin and active site of actin are exposed
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30
Q

Events of contraction describe after active site exposed.

A
  • myosin heads attach to active site forming crossbridge and using ATP hydrolysis heads pivot
  • pivoting moves actin towards sacromere center
  • another round of ATP causes head to regain pre-pivot state
  • cycle of bind-pivot and pre-pivot continues moving filaments past each other and towards sacromere center
  • sacromere shortens causing muscle to contract.
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31
Q

What keeps contraction cycle going

A

-as long as Ca2+ is bound to tropinin and tropomyosin active site is exposed

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32
Q

What happens to contracts when impulse stops !?

A
  • Ca2+ is actively transported into sER

- tropomyosin hides active site and filaments passive slide back to normal state past each other

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33
Q

What is and causes of rigor mortis at death

A

/stiffening of muscle

-at death no ATP and actin myosin crossbridge is stable and rigid

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34
Q

How are individual muscle fibers innervated

A
  • myelinated axons from perimysium branch out

- each branch has several unemyelinated twigs that pass through epimysium and form NMJ with individual muscle fibers

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35
Q

Describe NMJ structure, functions and adaptations

A
  • synoptic Knob is in depression on lemma surface
  • Schwann cells lemma at NMJ continues with sacrolemma
  • are numerous foldings on sacrolemma to increase # of AcH receptors
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36
Q

Describe what is synoptic cleft and motor end

A
  • space between knob and motor end

- surface on sacrolemma with numerous foldings and in contact with knob

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37
Q

Describe selectivity of Ach receptors and function and mode of action and what it makes

A

-it is non-selective

  • upon binding to Ach its opens cation channels
  • cations influx depolarizing membrane producing muscle impulse
38
Q

How is prolonged contact of neurotransmitter and receptor prevented

A
  • Ach quickly dissociates from receptor

- free Ach molecules removed by extra cellular enzyme acetylcholinesterase

39
Q

How many NMJ can be formed by a single motor axon

A
  • 1 or many
40
Q

How to produce precise muscle control

A

-single muscle fiber innervated by single motor neuron / axon

41
Q

What is a motor unit

A

-single axon and all muscle fibers in contact with its branches

42
Q

How is force of contraction varied

A

-not all fibers in a fascicle contract at the same time

43
Q

How much force will a single motor neuron generate when fired

A

-directly proportional to the number of muscle fibers it innervates

44
Q

List components of mitotic spindle

A
  • intrafusal muscle
  • modified perimysium
  • afferent nerves wrapped around modified muscle
  • interstitial fluid
45
Q

How do intrafusal muscle fibers differ from normal ones

A
  • fewer myofibrills

- nuclei closely aligned ( nuclear chain fiber ) or piled in central dilation ( nuclear bag )

46
Q

Where is mitotic spindle found , function and mechanism of action

A
  • among fascicles
  • provide CNS with info about stretch and tension of musculoskeletal system
  • they detect changes in length of normal fascicles caused by bodily movements and sent to CNS
47
Q

Describe stretch receptor and function

A

/afferent sensory receptors wrapped around intrafusal fibers in mitotic spindle

-ones that sent info to CNS

48
Q

Describe function, structure and mode of action of Golgi body

A
  • smaller structure wrapped around sensory nerves penetrating collagen at myotendinous joints
  • detect tension of tendon during movement

-sent info to CNS
/inhibit motor activity if tension is excessive

49
Q

List the skeletal muscle fiber types and list major criteria and other criteria

A

1 slow oxidative ( red
2 fast glycolytic ( white )
3 fast oxidative glycolysis ( pinkish )

1 ATP synthesis pathway ( oxidative phosphorylation or anaerobic glycolysis )
2 maximal rate Of contraction

1 number of mitochondria
2 number of capillaries
3 glycogen molecules
4 amount of myoglobin

50
Q

What determines slow or fast maximal rate of skeletal muscle

Describe myoglobin Structure and function

A
  • isoforms with diff max rate of ATP hydrolysis

- similar to hemoglobin has Fe bound to it and used for O2 storage In sER

51
Q

Describe red skeletal muscle function, number of mito glycogen myoglobin capillaries , rate of fatigue oxidative phosphorylation and myosin-ATP activity contraction and where found

A
  • slow contractions over time without much fatigue
  • much mito
  • sparse glycogen
  • much capillaries
  • slow to fatigue
  • slow oxidative phosphorylation
  • slow myosin-ATP activity
  • slow speed of contraction

-Postural muscles of back

52
Q

Describe White skeletal muscle function, number of mito glycogen myoglobin capillaries , rate of fatigue oxidative phosphorylation and myosin-ATP activity contraction and where found

A
  • specialized for rapid short term contractions
  • few mito
  • high glycogen
  • sparse myoglobin
  • few capillaries
  • high rate of fatigue
  • relies on anaerobic glycolysis
  • high myosin-ATP activity
  • high rate of contraction

-extra ocular muscles

53
Q

Describe Fast Oxidative-Glycolytic skeletal muscle function, number of mito glycogen myoglobin capillaries , rate of fatigue oxidative phosphorylation and myosin-ATP activity contraction and where found

A
  • intermediate of the red and white
  • numerous mito
  • high myoglobin
  • high capillaries
  • fast contraction
  • high ATP-myosin activity
  • intermediate rate of fatigue
  • major pathway is oxidative phosphorylation

-major muscles of the legs

54
Q

Skeletal muscle characteristics

nuclei , tubule system , organization, location , function and what innervates

A
  • multi nucleated found at peripheral of sacrolemma
  • tubule at center or triad at A-I junctions
  • epimysium,perimysium and endomysium
  • skeletal muscle, tongue, diaphragm , eyes
  • voluntary movements
  • efferent motor innervation
55
Q

Skeletal muscle method of regeneration, where contractions are triggered and special feature and striations

A
  • limited to satellite cells
  • at NMJ
  • very organized SR and transverse tubule system
  • is striated
56
Q

How does the heart muscle form ( development )

A

-during embryonic development cells of primitive heart align as a chain like array and do not fuse

57
Q

Describe cardiac muscle fiber , where and how they join

A

-cells branch and Join other fibers via junctions at intercalated discs

58
Q

How does heart acquire characteristic wave contraction

A

-bundles of cells interweave in spiralling manner

59
Q

Describe the CT layers of heart muscle cells

A
  • endomysium delicate sheath rich in capillaries

- perimysium separates bundles of muscle fibers

60
Q

Describe intercalated discs and their function

A
  • transverse lines that cross fibers where myocardial cells join
  • they interdigitate and have junctions to adhere cells ( desmosomes , gap and fascia adhesions ) and strengthen tissue
61
Q

Nuclei and striations structures of myocardial cells

A

/single nuclei at the center

-has striations

62
Q

Function of gap junctions in myocardial cells

A
  • provide ionic continuity between cells

- serve as electrical synapses promoting rapid impulse conduction

63
Q

Method of contraction of myocardial cells

A

-same as skeletal cells

64
Q

What is major fuel source of myocardial cells and how stored

A

-FA stored as TRIG in small lipid droplets

65
Q

Ventricle thicker than atrium

So !?

A

-pumps blood into circulation system

66
Q

Describe T-tubule and SR of myocardial cells where found and organization

A
  • T tubule well developed with large lumen ( not present at atrium)
  • SR less developed
  • organized as dyads ( 1 T tubule and 1 terminal Cisternae )
67
Q

Where do myocardial impulses originate from

A

-initiated , regulated and propagated by locally by nodes of unique myocardial fibers specialized for impulse generation

68
Q

What innervates the heart

Effect para and sympathetic has !?

A

-autonomic nervous system at nodes

/sympathetic increases
-parasympathetic decreases signal propagation

69
Q

Regulatory function of the atrium and what it does

A

-release the hormone atrial natriuetic factor ( ANF ) that targets kidney affecting Na+ excretion

70
Q

Regenerative capacity and response of myocardial to stimuli

A
  • no regenerative capacity at all

- hypertrophy

71
Q

Smooth muscle function, what innervates and where found

A
  • specialized for steady contractions
  • innervates by ANS
  • at blood vessels , in digestive, urinary,reproductive and respiratory tract and their organs
72
Q

Shape, striations and nuclei of smooth muscle

A
  • tappers at the ends
  • occurs singly and found at center ( widest part )
  • no striations
73
Q

Synonym for smooth muscle

A

-visceral

74
Q

Endomysium of visceral

A

-delicate network of collagen 1 and 3

75
Q

How is visceral cells closely packed and describe the fiber

A
  • narrow parts ends adjacent to wide ends of adjacent cells

- single small closely packed fusiform cells

76
Q

What happened to smooth cells during contraction

A

/become scalloped and nucleus distorted

77
Q

How are visceral cells linked

A

-gap junctions

78
Q

What is on lemma of visceral cells and their Function

A
  • numerous invaginations called caveolae

- function to control release of Ca2+ from rudimentary SR ( no tubule )

79
Q

How are contractile apparatus arranged and what controls contractions in visceral tissue

A
  • crisscrossed sacroplasm obliquely
  • calmodulin ( tropomyosin )
  • myosin light chain kinase MLCK ( tropinin )
80
Q

Describe dense body location and function

A

1 deep in cyto - have alpha actinin to bind to thin filaments

2 near lemma - has attachment sites for intermediate filaments at adhesion junctions

81
Q

Function of myocardial cells

A

-involuntary contraction of the heart to pump blood throughout circulatory system

82
Q

How does visceral function as a unit

A

-arrangement of cytoskeleton and contractile apparatus at dense bodies

83
Q

What is intermediate filament of myocardial and visceral cells made of

A

-desmin

84
Q

Where contractile force transmitted by dense bodies and how do they link adjacent cells

A

/have e-Cadherin proteins to link to intermediate filaments of adjacent cells via desmosomes

-transmit contractile forces throughout cell and tissue

85
Q

Describe contractions of visceral tissue

A

-partial , slow , spontaneous wave like contractions

86
Q

What innervates visceral tissue and how contractions propagated

A

ANS

-distant fibers via gaps junctions stimulate contractions

87
Q

Describe CT organization of visceral, response to stimuli and regenerative capacity

A
  • has delicate endomysium and less organized CT
  • good regenerative capacity involving mitotis
  • hypertrophy and hyperplasia
88
Q

Secondary function of visceral

A
  • supplements fibroblasts

- make collagen, proteoglycans and fibers

89
Q

How do synaptic vesicles reach visceral tissue

A

-axons near smooth muscle has periodic swellings which releases Ach or norepinephrine which binds to receptors

90
Q

Functions of muscle

A

1 produce movement
2 thermogenesis
3 maintain posture

91
Q

Properties of muscle cells

A

1 excitable
2 contractible
3 elasticity
4 extensibility

92
Q

Muscle glycogen and mitochondria

A
  • glycosome

- sarcosome

Anatomy (15 decks)

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