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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
TEM
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
26
SEM
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
27
how many micrometers (um) in a millimetre
1000
28
how many micrometers in a nanometer (nm)
1000
29
histology is important in order to
visualise content and architecture of the cells to distinguish between certain pathologies e..g benign or maligant
30
Sample preparation steps
1) Tissue procurement 2) Tissue fixation 3) Embedding 4) Staining
31
procurement means
biopsy- removal of a small piece of tissue from an organ or tissue for microscopic examination
32
examples of tissue procurement methods
- Curettage (endometrium) - Transvascular - Needle aspiration
33
Curettage
scraping method for uterine tissue
34
Needle aspiration
bone marrow, synovial fluid, thyroid tissue
35
transvascular
venepuncture e.g. ABG analyst
36
two ways of tissue fixing
1) Paraffin- embedded tissue section | 2) Frozen section
37
Paraffin- embedded tissue section
*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
Frozen section
- surgical specimens frozen to -20 and -30 - cryostat- slice tissue - staining: H&E
39
paraffin wax formalin and frozen section are methods which
samples stay true to their original form | - preservation of biological tissue from decay due to autolysis and putrefaction
40
paraffin wax formalin fixed sample stay true to their original form due to
cross bridges formign the sample
41
paraffin wax embedding method (after fixation)
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
both paraffin embedded and frozen section samples can be stained with
Haematoxylin and Eosin
43
Haematoxylin and Eosin
principle tissue stain in medical diagnosis
44
haemtoxylin stains
nucleic acid- (acid- negative) blue
45
Eosin stains
proteins in the cytoplasm and extracellular - pink
46
name two other routine staining methods
massons trichome | periodic acid-schiff stain
47
In massons trichome what colour does keratin and muscle fibre go
red
48
In massons trichome what colour does collagen dn bone go
blue or green
49
In massons trichome what colour does cytoplasm go
red or pink
50
In massons trichome what colour does nuclei go
dark brown to black
51
period acid-schiff stains
anything with a sugar attached
52
embedding the tissue
allows the sample to be sliced very thinly e.g. melted paraffin wxx sets hard when cooled
53
what is used to fix/ preserve a sample
formalin
54
why do we stain a tissue
to see cell components
55
what is quicker to do paraffin-embedded tissue section or frozen section
paraffin-embedded tissue section: 24-48h frozen section: 10 -20 mins
56
morphology of paraffin-embedded tissue section and frozen section under a microscope
paraffin-embedded tissue section- clarity frozen section- opaque
57
application of paraffin-embedded tissue section
pathological diagnosis
58
application of frozen section
intraoperative
59
how long can a paraffin-embedded tissue section be kept
permanant
60
how long can a frozen section be kept
months
61
RBC and H&E
pink and white int he middle- no DNA or protein where the nuclei is meant to be
62
fat and H&E
cannot be visualised
63
preparation of live cells
``` - ‘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
what needs to be maintained constant in the internal environment when preparing live cells
 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
cells in culture allow
experiments to determine cells and thus tissue function e.g. endothelial cells induced to die through programmed cell death
66
advantage of cell culture
- Absolute control over the physical environment - Homogeneity of sample - Less need for animal models
67
disadvantage of cell culture
- 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
immunohistochemsitry
antibody labelled with enzyme
69
immunofluorescence
antibody labelled with fluorescent markers - antibody bind to antigen - fluorophore emits visible light

Body logistics (39 decks)

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