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Body Logistics > 2. Histology > Flashcards

2. Histology Flashcards

1
Q

Define a tissue

A

a collection of integrated cells which work together to carry out a specific function(s)

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2
Q

Define histology

A

the microscopic study of body tissues

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3
Q

How can you obtain a tissue sample?

A

Surgery e.g. tumour resection
Scraping methods e.g. scalpel, scrapes
Aspiration with needle e.g. synovial fluid, bone marrow
Venepuncture e.g. blood smears

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4
Q

Describe the preparation for a slide for light microscopy

A

Preserve the tissue within formalin
Harden the tissue with paraffin wax
Cut the sample into very thin slices with a microtome
Stain - commonly with haematoxylin and eosin

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5
Q

What is H&E and what does it stain?

A

Haematoxylin and Eosin
Haematoxylin stains DNA/RNA blue - acidic
Eosin stains cytoplasm and ECM pink - proteins

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6
Q

What is immunofluorescence?

A

Antibody labelled with a fluorescent marker

Fluorophore emits visible fluorescent light

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7
Q

What is immunohistochemistry?

A

Antibody tagged with an enzyme

Colourless substrate added - enzyme converts substrate into a coloured product e.g. peroxidases

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8
Q

What is phase contrast?

A

Converts phase shifts in light into brighntess changes which are visible, and no staining is required

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9
Q

How does confocal microscopy work?

A

A laser excites a fluorescent molecules and electrons in the dye are excited to a higher level.
As they relax a light with higher wavelength is emitted.
Emitted light sent through mirrors and a pinhole screen to a detector.

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10
Q

Define resolution

A

The smallest distance by which two objects can be separated and still be distinguishable as two separate objects.
Mathematically expressed as d = gamma/2 NA
- d = limit of resolution
- gamma = wavelength
- NA = numerical aperture

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11
Q

What are the resolving powers of microscopes?

A
  • Compound light microscope up to 200nm - cells
  • SEM up to 0.4nm
  • TEM up to 0.078 nm
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12
Q

Outline light microscopy vs electron

A

Light: Can view images in natural colours
Cheap easy preparation
Can view living and moving objects

Electron: Only monochrome
Difficult, expensive preparation
Dead material

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13
Q

Transmission vs Scanning

A

Both fixed with glutaraldehyde, fix with epoxy resin

Transmission allows for thin cuts, scanning - surface

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14
Q

Explain the process of freeze fracture electron microscopy

A

The tissue is frozen at -160 and fractured by hitting with a knife edge. The fracture line passes through the plasma membrane exposing interior.

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15
Q

What are some requirement to image tissues using light microscopy?

A

Need to preserve to prevent from rotting (formalin)
Need to embed to be sliced thinly (paraffin wax)
Need to stain so we can see cell compartments (H&E)

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16
Q

Give examples of tissue procurement using an endometrial sample.

A

Endometrial Biopsy - suction small part of wall.
Curettage - scrape endometrium.
Pipelle - place into endometrium, twist and pull.
Hysterectomy - full removal to take a look at.

17
Q

Why must fixation solutions be buffered?

A

Otherwise water causes swelling within the sample and artefacts.

18
Q

Name some routine staining methods

A

Haematoxylin and eosin, masson’s trichrome (different colours) periodic acid-schiff stain

19
Q

Describe the process of obtaining a frozen section

A

Specimen placed on metal disc frozen rapidly to -30. Cryosection - microtome within cold environment cuts the specimen then stained with H&E.

20
Q

Paraffin wax formalin fixed vs frozen section

A

Paraffin:
fixed tissues, takes 24 hours, permanent, used in pathological diagnosis, long time but more permanent.

Frozen section:
fresh tissues, 10-20 mins, lasts only a few months but can be used during operations.

21
Q

Describe the process to culture cells

A

Harvest cells
Isolate cells using appropriate enzymes, use of collagenase and DNAase as otherwise DNA from broken nucleus infects sample.
Centrifugation, place into appropriate growth medium.

22
Q

What are some advantages of having access to cells within culture?

A

Allows manipulation of the cells and experiments to determine cells and thus tissue function.
Homogeneity of sample, less need for animal models.

23
Q

What are some disadvantages of cell culture?

A

Hard to maintain, only grow small amount of tissue at high cost, cells can change phenotype, influence of other cells and tissues not maintained.

24
Q

What is dark field?

A

A very specialised technique using living cells, illuminates the sample with light not collected by the objective lens. Produces appearance of dark background.

25
Q

What are the four broad tissue classifications?

A

Epithelial, connective, muscle and nerve

26
Q

What are the characteristics of epithelial tissue?

A

Often on edge of other tissues, surrounds others.
Polarised when at surfaces.
Always have a basement membrane.
Sometimes in clusters. Held together by strong proteins.
Often secrete something from apical surfaces.
Communicate through junctions in lateral and basal surfaces.

27
Q

What are the main cells in connective tissue?

A

Fibroblasts, chrondrocytes, osteocytes and stem cells.

28
Q

What are some examples of connective tissue?

A

Loose connective tissue, fibrous connective tissue, adipose tissue, cartilage, blood and bone.

29
Q

What are the main products of connective tissue?

A

Fibres, ground substance, and wax and gel like materials.

30
Q

Describe the main characteristics of nerve tissue?

A

Consist of the electricity condution nerve cells - neurons and several support cells. Main fast communication systems in the body.

31
Q

What are the three main types of muscle?
Which ones are voluntary/involuntary?
Which ones are striated?

A

Skeletal, cardiac and smooth.
Skeletal is voluntary.
Skeletal and cardiac are striated.

32
Q

What are some functions of the plasma membrane?

A 
Intercellular adhesion and recognition
Signal transduction
Compartmentalisation
Selective permeability
Transport of materials, exo/endocytosis
33
Q

What is the function of the nucleus, nucleolus and nuclear envelope?

A

The nucleus contains DNA, nucleoproteins and RNA.
The nucleolus is the site of ribosomal RNA synthesis for ribosomal assembly.
The nuclear envelope is a double layer of membranes bouding the nucleus, it is a type of specialised ER.

34
Q

What is the function of the ER?

A

Rough endoplasmic reticulum - ribosomes are attached allowing protein synthesis.
Smooth endoplasmic reticulum - lipid biosynthesis.

35
Q

What is the function of the golgi apparatus?

A

Sort, concentrate, package and modify proteins.

36
Q

What is the function of lysosymes?

A

Degradation and process of cellular material.

37
Q

What is the function of peroxisomes?

A

Modify toxic molecules before they re-enter the bloodstream and in neutrophils where the peroxide is used to kill bacteria.

38
Q

What is the function of the mitochondria?

A

Generation of energy rich ATP molecules by oxidative phosphorylation.

39
Q

What is the function of the cytoskeleton?

What is it comprised of?

A

Provides structural support for the plasma membrane and cell organelles, allows movement.
Comprised of microfilaments, intermediate filaments and microtubules.

Body Logistics (9 decks)

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