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Histology > Muscle > Flashcards

Muscle Flashcards

0
Q

Esophageus 3 different portion. Skeletal is…

A

First portion

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1
Q

Can you detect striations in skeletal muscle cross section?

A

No

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2
Q

Skeletal muscle…nuclei?

A

Multi nucleated. Syncytial - beneath plasmolemma

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3
Q

Origin of skeletal muscle?

A

Myoblasts - mononuclear, undifferentiated, no myofibrils

Form myotubes - differentiate - organelles expressed

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4
Q

Satellite cells in muscle fibres?

And in cardiac muscle

A

Surround muscle fibre. Quiescent myoblasts - fuse - myoblasts - myotubes - replace lesions
No satellite cells - not repair after dmg

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5
Q

What surrounds groups of muscle fibres?

A

CT

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6
Q

Sarcomere proteins?

A

Titin - thick fil correct arrangement at m line
Nebulin - maintain correct length of actin
Actinin - attach actin fil to z line

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7
Q

G actin to f actin

A

Req atp and mg2+ and k+

Polymerisation

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8
Q

Troponin tic

A

T - bind to torpomyosin
I - bind to actin
C - bind to calcium

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9
Q

Myosin head(2)

A

2 peptides

Active site - attach to actin filament

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10
Q

Desmin, plectin, ab crystallin, a-actinin

A

Desmin - int filament inserted into costameres
Plectin - connect adjacent desmin
Ab-crystallin - heat shock protein - protect desmin from stress related damage
A-actinin - anchor actin to z-disk

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11
Q

Dystrophin and mutation

A

Linked sarcolemma to actin
Mutation - muscular dystrophy
Vital in cell stability

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12
Q

M line protein function and names? And em line?

A

Maintain correct arrangement of myosin filament
Myomesin, m protein, schlemin
Electron dense line

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13
Q

Sliding filament mech

A

Atp bind to myosin head, break cross bridge.
Atp hydrolysis myosin head 90
Myosin bind to actin. Release adp + pi 45* angle

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14
Q

Rigor mortis?

And why?

A

Stiffening muscle after death.
24/48 hr muscle after muscle proteins broekn down. Allows muscle to relax.

No oxy, no atp. Atp not bind to myosin head

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15
Q

Smooth muscle contains specifically different from skeletal and cardiac muscle?

A

Dense bodies.
Greater elasticity.
Larger tension curve

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16
Q

Sarcoplasmic reticulum. Triad? And where is central portion of triad?
Where located?

A

2 terminal cisternae of sarcoplasmic reticulum 1 t tubule
H band central portions between 2 triads
Triad located at a-i junction

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17
Q

Depolarisation of pm of t tubule pm

A

Ca2+ channels move. Calcium released. High to low conc gradient. Ca bind to TnC. Cause tropomyosin to move. Expose myosin head binding sites

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18
Q

Nmj and toxins(4)

A

Neuron + muscle cell - synapse.
Large no of infoldings on post synaptic membrane
Toxins (4)-botulinum - block rel of ach
Curare - ach receptor block
Neostigmine - prevent removal of ach - used against curare
Neurotoxins - ach receptor block

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19
Q

Disease of nmj?

A

Myasthenia gravis - autoimmune attack ach receptors - lost

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20
Q

Different types of skeletal muscle fibres?

A

Red slow twitch - type one
Intermediate - pink type 2a
White - type 2 b fast twitch

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21
Q

Which stain to differentiate between skeletal muscle fibres?

A

Succinate dehydrogenase. Stains mito. Slow twitch - greater amount of mito

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22
Q

Red slow twitch muscle fibres

A

High no of mito. Low glycogen store - completely borken down due to aerobic. Large no of capp. Myoglobin. Resistance to fatigue. Slow sustained contractions.

Found in postural and axial muscle of skeleton

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23
Q

Pale fast twitch muscle fibres?

A

Low myoglobin. Low mito. Low capp. High glycogen. Easy fatigue due to lactic acid production. Upper limps, digit muscle, extrinsic ocular muscles.
Fastest level of myosin head hydrolysis

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24
Q

Intermediate

A

Lower limbs. Contract similar to fast twitch. High no. Mito, myoglobin. Store glycogen and anaerobic respiration

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25
Q

Hypertrophy and stimulated by(3)

A

Increase in muscle size. Increase in no of filaments.

Resistance training. Testosterone. Anabolic steroids

26
Q

Atrophy and how occur!

A

Muscle cells smaller - reduction in muscle size

Pathology - removal of nerve, immobility, lack of use

27
Q

Cardiac muscle tissue. Innervation? What cells and what Connect by?

A

Autonomic nervous system
Myocardium - heart contraction (cardiomyocytes) - joined by junctions (intercalated disks)

Numerous cylindrical cells arranged from end to end

28
Q

Heart layers?

A

Pericardium - serosa cavity - epitcardium - myocardium - endocardium

29
Q

Nuclei of cardiac?

A

Central, maube multiple

30
Q

Cross section of cardiac muscle

A

Some nucleus seen
Striated
Granules
Presence of myofibrils

31
Q

Cardiac cells, biconical juxtanuclear region contains

A

Mito, lipofuscins, golgi, glycogen, grangles

32
Q

Cardiac muscle granules contain?

A

Atrial natriuretic factor
Brain natriuretic factor

Effect sodium secretion in kidney. Response to high blood bp.
Inhibit renin by kidney and Aldesterone by adrenal cortex
Inhibit sm contraction

33
Q

What happens during heart failure of levels of BNP

A

Increase

34
Q

Cardiomyocytes 2 features?

A 
Elongated (100um)
Rounded nucleus (maybe multiple)
35
Q

What tissue surrounds cells and contains?

A

Connective tossue.

Bv provide vascularisation to avascular cardiac bundle

36
Q

Transverse and lateral portion of intercalated disks?

A

Transverse - mascula adherens(desmosomes), fascia adherens (cadherin and catenins) strong adhesion
Longi - gap junction - ca2+ movement
Intercalated disks connect cells mechanically, electrically, chemically - contracts cell like single mass

37
Q

Cardiac muscle - what does adherens junction do?

A

Bind actin at z lines

38
Q

Cardiac muscle - endomysium?

A

Rich capl network - ct bv cardiomyocytes

39
Q

How to differentiate between sm and cardiac muscle in cross section?

A

Different morphology of cytoplasm.
Sm cyto - homogenous
Cardiac - granules/myofibrils

40
Q

Cardiac and skeletal muscle nucleus?

A

Skeletal periphery

Cardiac at nucleus

41
Q

Diads in cardiac muscle?

A

1 t tubule 1 sr larger than in skeletal muscle

At z lines and no AI junctuon

42
Q

Heart contraction?

A

Purkije fibres - modified muscle cells (less abundant contractile myofibre) not specialised for contraction. SAN AVN VENTRICLES

43
Q

Between myofibrils?

A

Inaddition to juxtanuclear mito, large mito between myofibrils and glycogen granules

44
Q

Diads less numerous in?

A

Cardiac atrial muscle

45
Q

Cardiac muscle cells injury and repair

A

Injury to cardiac muscle. Loss of cells - replaced by fibrous ct - cardaic function lost at injury - myocardial infarction

46
Q

Cardiac cells divide?

A

0.1% of cardiac cells are able to divide

47
Q

Smooth muscle thin filaments

A

Actin, troponin, calponin, caldesmon

48
Q

Sm thick filaments

A

Myosin.
Side polar thick filament.
No central bare zone.
Bare zone at ends form tapered ends.

49
Q

Calponin and caldesmon are?

A

Actin binding proteins (ABP)

Block myosin binding site

50
Q

Sm. Innervation. Shape of cells. Any striations, why? When do actin and myosin interact?

A

Autonomic nervous system
Elongated and fusiform
No transverse striations - fewer myofibril
Actin and myosin only interact when contract

51
Q

Sm cells surrounded by?

A

Basal lamina and supported by ct

52
Q

Relation of sm cells?

A

Thinner aspect of one cells with thicker aspect of another cell

53
Q

Cross section of sm cells?

A

Depending on where cut.
Centre -> able to see nucleus.
Where diameter largest

54
Q

Where sm found?

A

Muscularis externa of Hollow organs.
Ovary medulla. Gi tract. Cillary process of eye. Wall of arteries and veins. Pre-capp sphincters, iris of eye.

Si, li - innner circ outer longi
Urinary tract - inner longi outer circ.
Urinary bladderr, ureter 3 layers - inner longi, middle circ, outer longi

55
Q

Dense bodies are located?

A

Sm. Below sarcolemma, a-actinin binds actin and tropomyosin

No troponin.

Dense bodies act as sm z-lines

56
Q

Sm int. Filaments

A

Vimentin and desmin
Help with contraction
Pulling cell ends
Shortening cell

57
Q

Sm has no?

However does have? And where found? And what function?

A

No myofibrils, no striations,

However many infoldings of sarcolemma - caveolae -> in cardiac and sm.
Act as t tubules.

58
Q

Sm - calveolae (5)

A 
Integral membrane proteins.
Sm cardiac muscle membrane - caveolin 3
Non receptor endocytosis
Closely associated with ser
Regulation of contraction and ca
59
Q

In terms of innervation.

2 types of sm

A

Single unit - one axon innervates all sm in area. Therefore spread via gap junctions
Multiple unit - group of sm cells - innervated by many axons.

60
Q

Autonomic neuron varicosity?

A

Contains NET

61
Q

Sm contraction steps?

A

Ca released. Bind to calmodulin. Activates myosin light chain kinase. Phosphorylation of light chain on myosin head. Expose heavy bind - therefore exposed actin filament binding site

Actin myosin form crosslink-> contraction -> shortening of cell

62
Q

Sm Descrease in ca

A

Ca not bind to calmodulin. MLCK deactivated. Myosin phosphatase activates. Dephosphorylation of myosin light chain. Covers myosin head. Therefore actin unable to bind.

63
Q

Skeletal muscle cells - morphology in cross section and lngi section?

A

Polygonal cells
Peripheral nucleus

Z lines - h band - a i bands - nucleus at periphery

Histology (17 decks)

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