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Body logistics > L2- Examining Cells and Tissue > Flashcards

L2- Examining Cells and Tissue Flashcards

1
Q

standard measurement of cell size

A

um

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2
Q

what is used for sizing of cells under microscope

A

graticule

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3
Q

enlarged red bloods cells

A

indication for some forms of vasculitis

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4
Q

resolution definition

A

The smallest distance by which two objects can be separated and still be distinguishable as two separate objects.

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5
Q

the higher the resolving power

A

the more easily two objects can be distinguished

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6
Q

lens of eye has

A

low resolution

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7
Q

resolving power increase with

A

increasing magnifying class

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8
Q

smallest human cell seen by naked eye

A

Oocyte

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9
Q

name 2 main types of microscopy

A

light and electron

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10
Q

smallest organelle seen with light microscopy

A

mitochondria

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11
Q

smallest organelle seen with electron microscopy

A

ribosome

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12
Q

light microscopy uses

A

a visible light source and glass lenses to look at specimens up to 1500X magnification and 0.2um resolving power

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13
Q

electron microscopy uses

A

a beam of charged electrons and electromagnetic lenses to look at specimens at up to 500,000X magnification and 0.5nm resolution.

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14
Q

when is electron microscopy used

A

technique for obtaining high resolution of biological specimens. Used to investigate detailed structure of tissues, cells, organelles and macromolecular complexes.
- High resolution= due to use of electrons

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15
Q

why does electron microscopy give higher resolution

A

uses lectern beam- shorter wavelength than light

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16
Q

advantages of light microscpy

A
  • can view images in natural colours
  • large field of view
  • cheap and easy prep
  • can view living and moving objects
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17
Q

disadvantages of light microscope

A 
lower magnification (x600)
Lower resolution 0.25um
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18
Q

advantages of electron microscopy

A
  • higher magnification (x500,000)

- higher resolution (0.25nm)

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19
Q

disadvantages of electron microscopy

A
  • can only view dead objects
  • difficult and epxsneiv to prep
  • limited field of view
  • only monochrome images can be seen
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20
Q

types of light microscopy

A

1) Phase contrast
2) Dark field
3) Confocal microscopy

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21
Q

phase contrast

A

combines interference of 2 light waves

- enhances images of use unstained cells

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22
Q

dark field

A
  • Very specialised technique used with living cells
  • Illuminates the sample with light that will not be collected by the objective lens and thus will not form part of the image
  • This produces the classic appearance of a dark, almost black background with bright objects on it
  • Can be used in EM images
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23
Q

confocal microscopy

A

captures multiple 2D images at different depths to reconstruct 3D structures
- use with Immunofluorescence

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24
Q

type sof elektron microscopy

A

Tranmission

Scanning

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25
Q

TEM

A

o Used to view thin specimens through which electrons can pass through (same principles as a light microscope)
o 2 dimensional
o Used to image the interior of cells, structure of protein molecules and organisation of molecules in viruses and cytoskeletal filaments etc.
o Small amount of sample can be analysed at a time

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26
Q

SEM

A

o Depends on the emission of secondary electrons from the surface of a specimen
–> sample can be thick
o Provides detailed images of the surfaces of cells and whole organisms not possible by TEM
o 3-dimensional
o Large amount of sample can be analysed at a time
o Images can be colourised

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27
Q

how many micrometers (um) in a millimetre

A

1000

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28
Q

how many micrometers in a nanometer (nm)

A

1000

29
Q

histology is important in order to

A

visualise content and architecture of the cells

to distinguish between certain pathologies e..g benign or maligant

30
Q

Sample preparation steps

A

1) Tissue procurement
2) Tissue fixation
3) Embedding
4) Staining

31
Q

procurement means

A

biopsy- removal of a small piece of tissue from an organ or tissue for microscopic examination

32
Q

examples of tissue procurement methods

A
  • Curettage (endometrium)
  • Transvascular
  • Needle aspiration
33
Q

Curettage

A

scraping method for uterine tissue

34
Q

Needle aspiration

A

bone marrow, synovial fluid, thyroid tissue

35
Q

transvascular

A

venepuncture e.g. ABG analyst

36
Q

two ways of tissue fixing

A

1) Paraffin- embedded tissue section

2) Frozen section

37
Q

Paraffin- embedded tissue section

A

also involves embedding

  • formalin used to kill sample and prevent putrefaction
  • melted paraffin wax- to embed tissue for slicing
  • microtome- slice tissue into v thin slice
  • staining: H&E
38
Q

Frozen section

A
  • surgical specimens frozen to -20 and -30
  • cryostat- slice tissue
  • staining: H&E
39
Q

paraffin wax formalin and frozen section are methods which

A

samples stay true to their original form

- preservation of biological tissue from decay due to autolysis and putrefaction

40
Q

paraffin wax formalin fixed sample stay true to their original form due to

A

cross bridges formign the sample

41
Q

paraffin wax embedding method (after fixation)

A
  1. Dehydrated in different concentrations of alcohols
  2. Immersed in dissolved paraffin wax (hot) overnight
  3. Tissue orientated in a mould and more wax added
  4. Allowed to cool to room temperature
  5. Gently eased out of mould
42
Q

both paraffin embedded and frozen section samples can be stained with

A

Haematoxylin and Eosin

43
Q

Haematoxylin and Eosin

A

principle tissue stain in medical diagnosis

44
Q

haemtoxylin stains

A

nucleic acid- (acid- negative) blue

45
Q

Eosin stains

A

proteins in the cytoplasm and extracellular - pink

46
Q

name two other routine staining methods

A

massons trichome

periodic acid-schiff stain

47
Q

In massons trichome what colour does keratin and muscle fibre go

A

red

48
Q

In massons trichome what colour does collagen dn bone go

A

blue or green

49
Q

In massons trichome what colour does cytoplasm go

A

red or pink

50
Q

In massons trichome what colour does nuclei go

A

dark brown to black

51
Q

period acid-schiff stains

A

anything with a sugar attached

52
Q

embedding the tissue

A

allows the sample to be sliced very thinly e.g. melted paraffin wxx sets hard when cooled

53
Q

what is used to fix/ preserve a sample

A

formalin

54
Q

why do we stain a tissue

A

to see cell components

55
Q

what is quicker to do paraffin-embedded tissue section or frozen section

A

paraffin-embedded tissue section: 24-48h

frozen section: 10 -20 mins

56
Q

morphology of paraffin-embedded tissue section and frozen section under a microscope

A

paraffin-embedded tissue section- clarity

frozen section- opaque

57
Q

application of paraffin-embedded tissue section

A

pathological diagnosis

58
Q

application of frozen section

A

intraoperative

59
Q

how long can a paraffin-embedded tissue section be kept

A

permanant

60
Q

how long can a frozen section be kept

A

months

61
Q

RBC and H&E

A

pink and white int he middle- no DNA or protein where the nuclei is meant to be

62
Q

fat and H&E

A

cannot be visualised

63
Q

preparation of live cells

A 
-	‘cutting and ‘dicing’
o	collagenase and DNAse
	centrifugation steps on basis of cell density
o	Put cells in appropriate growth medium
o	Culture enzymes
	View under phase contrast microscope
64
Q

what needs to be maintained constant in the internal environment when preparing live cells

A

 Conc of oxygen, CO2, salt and other electrolytes
 Conc of nutrients and waste products
 pH
 Temp
 Volume and pressure of fluid and cell compartments equalised

65
Q

cells in culture allow

A

experiments to determine cells and thus tissue function e.g. endothelial cells induced to die through programmed cell death

66
Q

advantage of cell culture

A
  • Absolute control over the physical environment
  • Homogeneity of sample
  • Less need for animal models
67
Q

disadvantage of cell culture

A
  • Hard to maintain
  • Only grow small amount of tissue at high cost
  • Dedifferentiation
  • Instability, aneuploidy
  • 3 dimension architecture lost
  • influence of other cells/ tissue not maintained.
68
Q

immunohistochemsitry

A

antibody labelled with enzyme

69
Q

immunofluorescence

A

antibody labelled with fluorescent markers

  • antibody bind to antigen
  • fluorophore emits visible light

Body logistics (39 decks)

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