Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cells & Tissues > Introduction to Histology > Flashcards

Introduction to Histology Flashcards

1
Q

What is histology?

A

The study of cells and tissues by microscopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is histopathology?

A

The study of diseased tissue by microscopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the ABCDE for determining whether a mole is normal or cancerous?

A

Asymmetry

Border

Colour

Diameter

Evolving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is meant by asymmetry?

A

If you draw a line through the middle of the mole, the halves of a melanoma will not match in size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is meant by border?

A

The edges of a melanoma tend to be uneven, crusty or notched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant by colour?

A

Healthy moles are uniform in colour

A variety of colours, especially white and/or blue is bad

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is meant by diameter?

A

Melanomas are usually larger in diameter than a pencil eraser

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is meant by evolving?

A

When a mole changes in size, shape or colour or begins to bleed or scab, this is dangerous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the extent of the spread of a tumour called?

A

Staging

Determining how far a tumour has spread

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 4 stages in the clinical applications of histology?

A
  1. make a diagnosis
  2. determine prognosis
  3. plan and confirm treatment
  4. predict/confirm response to drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is histology important?

A

It allows ‘normal’ to be defined

This allows comparisons and abnormal characteristics to be identified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the first stage in histological preparation?

A

Tissue sampling

This involves taking a tissue sample by surgical excision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the second stage in histological preparation?

Why is it needed?

A

Fixation

The tissue is fixed by placing it in a chemical to preserve it

The tissue will begin to degrade if it doesn’t have a blood supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In which 3 ways does fixation preserve tissues?

A
  1. stopping intrinsic autolytic enzyme action (autolysis) which involves the tissue breaking itself down
  2. prevention of bacterial contamination (putrefaction)
  3. increasing mechanical strength to preserve structure and morphology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do fixatives work?

A

They link molecules together so that they no longer function

They also kill any bacterial contaminants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What types of bonds are formed by aldehyde and alcohol fixatives?

A

Aldehyde fixatives form protein covalent cross-links

Alcohol fixatives denature proteins and cause aggregation/fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What types of bond are formed by oxidising fixatives?

A

Protein covalent cross-links via oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is freezing not often used as a method of fixation?

A

It is a quick solution but results in poor morphology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does formalin (formaldehyde solution) work?

A

It forms protein covalent cross-links

Joining together complex molecules within the tissue means they no longer function and the tissue becomes rigid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the pros of using formalin?

A
  1. it has good penetration and mechanical strength

2. good tissue morphology preservation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the cons of using formalin?

A
  1. it is poor at preserving DNA and RNA

2. it needs to be quite warm in order to work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does glutaraldehyde work?

A

It is similar to formalin but is a larger molecule so forms protein covalent cross-links

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the pros of using glutaraldehyde?

A
  1. it works well at low temperatures

2. it is used for electron microscopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the cons of using glutaraldehyde?

A
  1. it only works on smaller tissue samples
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does ethanol work as a fixative?

A

It fixes by precipitation

It reduces protein solubility so that they form precipitates

26
Q

When is ethanol used as a fixative and why?

A
  1. cytology smears
  2. nucleic acid research

It doesn’t cross-link so it doesn’t damage DNA or RNA

27
Q

What is the third stage in histological preparation?

A

Block selection

This involves slicing the sample and placing areas of interest in a plastic cassette

28
Q

What is the fourth stage in histological preparation?

A

Tissue processing

This involves slicing the tissue thinly, placing it on a slide and staining it to look under a microscope

29
Q

What must the properties of the tissue be like to allow it to be sliced thinly?

How is this overcome?

A

It must be stiff and resistant to mechanical trauma

It is placed in wax to allow thin sections to be cut

30
Q

What are the 4 stages involved in placing a tissue in wax?

A
  1. dehydration - removing water from the tissues using alcohol
  2. clearing - replacing alcohol with xylene
  3. wax infiltration - replacing xylene with paraffin wax
  4. embedding - orientate the tissue to form a paraffin block
31
Q

Why must water be removed from the tissues before they are placed in wax?

A

Wax is hydrophobic

32
Q

What is the fifth stage in histological preparation?

A

Section cutting and mounting

33
Q

What are the stages involved in section cutting and mounting?

A
  1. making a thin slice of tissue from the wax block
  2. place the block in a slicer to shave off bits of tissue
  3. ribbon of paraffin placed in water
  4. ribbon of paraffin picked up by slide
34
Q

What is the sixth stage in histological preparation?

Why is it needed?

A

Section staining

An unstained tissue section is translucent to light, so dyes are added to make it visible

35
Q

What is the purple component of haemotoxylin and eosin stain?

What does this stain and why?

A

Haemotoxylin is purple

It is a basic dye that is attracted to acidic structures

The nuclei (DNA) are stained purple

36
Q

What is the pink component of haemotoxylin and eosin stain?

What does this stain and why?

A

Eosin is pink

It is an acidic dye that will stain basic structures pink

Proteins in the cytoplasm are dyed pink

37
Q

What is periodic acid schiff (PAS) stain used to detect?

A
  1. mucin and mucopolysaccharides
  2. fungal organisms
  3. visualisation of basement membranes
38
Q

What is a mucin?

A

A high molecular weight, heavily glycosylated protein produced by epithelial tissues

39
Q

What is the drawback of using PAS stain?

A

Glycogen is PAS positive

Glycogen will stain a deep magenta colour

40
Q

What is DPAS and what is it used for?

A

PAS is combined with diastase

Diastase in an enzyme which removes glycogen and helps to distinguish it from other PAS positive elements

41
Q

What is Gram stain used for?

A

To identify bacteria based on the constituents of their cell walls

42
Q

How are Gram positive and Gram negative bacteria distinguished from each other?

A

Gram positive stain blue

Gram negative stain red

43
Q

What is Giesma stain used for detecting?

A

H. pylori bacteria in the stomach which are involved with inflammation

44
Q

What colour will Giesma stain colour the bacteria and human cells?

A

Human cells are purple

Bacterial cells are pink

45
Q

What is Grocott’s methenamine silver stain (GMS) used for?

A

Detecting fungi

It shows fungal cell walls as black

46
Q

What is Oil red O stain used to detect?

A

It is used to stain fat

47
Q

Why can Oil red O only be used on frozen tissue and not processed tissue?

A

Xylene removes all the oil from the tissues

This means there are no fats in processed tissue

48
Q

What is Orcein stain used to detect?

A
  1. copper-associated proteins
  2. elastic fibres
  3. hepatitis B sAg
49
Q

What disease results in abnormal retention of copper?

Which stain can be used to detect this?

A

Wilkinson’s disease leads to an abnormal retention of copper

Orcein stain

50
Q

Which organ is Orcein stain most commonly used in?

A

Liver

51
Q

What is Perl’s stain used for?

A

It is used in lung tissue to look for asbestos bodies

52
Q

What colour will Perl’s stain dye components?

A

it dyes iron blue

It also dyes ferruginous (asbestos) bodies

53
Q

What is Ziehl Neelsen stain used for?

A

Identifying mycobacterium

They contain mycolic acid and large amounts of fatty acids, waxes and complex lipids

54
Q

What is the downside of using tinctorial stains, like H&E?

A

They are not specific

55
Q

What is immunohistochemistry?

A

Using antibodies against a specific protein target

It is not a stain, but a way of locating a specific molecule

56
Q

What is the first stage in immunohistochemistry?

A

A solution containing primary antibody is added to formalin-fixed paraffin embedded tissue

The primary antibody is allowed some time to find the target complementary antigen

57
Q

What happens after the primary antibody is added in immunohistochemistry?

A

Unbound and surplus antibodies are washed away and a secondary antibody is added

58
Q

What happens once the secondary antibody is added in immunohistochemistry?

What is special about the secondary antibody?

A

The secondary antibody is given time to bind to the primary antibody

The secondary antibody carries a linker molecule with HRP enzymes

59
Q

What is added after the secondary antibody in immunohistochemistry and why?

A

DAB is added

HRP enzymes transform DAB into a coloured precipitate

This gives a visual representation of where the primary antibody first bound to its target

60
Q

What is the major benefit of using immunohistochemistry?

A

The antibody stain allows you to see if a specific protein is present in the tissue

This allows it to be used in diagnosis

61
Q

How can immunohistochemistry be used in prognosis?

A

Through mismatch repair

If a tumour has lost expression of its mismatch repair protein, it will no longer be brown

Cells & Tissues (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions