Principles and techniques of pathology Flashcards
(61 cards)
1
Q
What is general pathology?
A
- reactions of cells and tissues to abnormal stimuli and inherited defects
2
Q
What is systemic pathology?
A
- specific disease processes as they affect organs and systems
3
Q
What are the 4 components of pathology?
A
- aetiology
- pathogenesis
- molecular and morphological changes
- functional derangements and clinical manifestations
4
Q
What is the definition of aetiology?
A
- the cause of a disease
5
Q
What are the two classes of aetiology?
A
- genetic
- acquired
- may be a combination
6
Q
What is genetic aetiology?
A
- inherited mutations, disease associated gene variants
7
Q
What is acquired aetiology?
A
- infectious, nutritional, chemical and physical
8
Q
What is pathogenesis?
A
- the sequence of events in the response of cells and tissues to the aetiologic agent
- from initial stimulus to the ultimate expression of the disease
9
Q
What do therapeutic interventions often focus on?
A
- focus on specific pathways within the pathogenesis of a disease
10
Q
What is pathophysiology?
A
- the specific changes in physiology
11
Q
What are molecular changes?
A
- changes in the molecular and or immunological expression in diseases states
12
Q
What are morphological changes?
A
- structural changes in cells, tissues or organs
- may be characteristic of a disease or diagnostic
13
Q
INFO CARD:
A
- in recent years additional attention had been given to microbiological changes in disease states - microbiome
14
Q
What are functional derangements?
A
- end result of genetic, biochemical and structural changes in cells and tissues
15
Q
What is clinical manifestations (signs) and disease progress?
A
- the result of functional abnormalities
16
Q
INFO CARD:
A
- Rudolf Virchow proposed that disease starts with the alteration of cells, which we now recognise to be structural and/or functional alteration
17
Q
What does cell injury disrupt?
A
- disrupts homeostasis
18
Q
The aetiologies of cell injury are numerous but they lead to 4 basic mechanisms - what are these?
A
- ATP depletion (disrupts processes that require energy)
- cell membranes of increased permeability
- disruption of biochemical pathways
- DNA damage (so cant coordinate things)
- there may be one or a combination of these
19
Q
The injured cell can react in a limited number of ways - what are these?
A
- adaptation
- degeneration
- death
- may do all of these sequentially
20
Q
What is often the ultimate cause of cell injury?
A
- oxygen deficiency
21
Q
What are the mechanisms that can lead to oxygen deficiency and ultimately cell injury?
A
- inadequate oxygen of blood e.g., cardiac or respiratory failure
- reduced vascular perfusion (ischaemia)
- reduced oxygen transport e.g., anaemia and CO exposure
- inhibition of respiratory enzymes in the cell e.g., cyanide
22
Q
What are the physical agents that can cause cell injury?
A
- trauma
- temperature extremes
- ionising radiation
- electric shock
23
Q
What are the infectious agents that can cause cell injury?
A
- prions
- viruses
- bacteria
- fungi
- parasites
24
Q
What nutritional imbalances can cause cell injury?
A
- dietary deficiencies
- long term starvation
- caloric excess
- dietary toxicities
25
What are the genetic or developmental derangements that can cause cell injury?
- inherited diseases
- metabolic diseases
- neoplasia
- autoimmune diseases
- susceptibility to infection
- congenital abnormalities
26
Workload imbalance can cause cell injury - what happens if there is increased workload?
- respond by hypertrophy or hyperplasia (cell dependent)
- if excessive = leads to cell degeneration and death
27
Workload imbalance can cause cell injury - what happens if there is reduced workload?
- loss of innervation, hormones or growth factors
- leads to atrophy
- excessive cells can be removed by apoptosis
28
Chemicals, drugs and toxins can also cause cell injury - what can these compounds do?
- alter homeostasis
29
What does toxicity depend on in cells?
- depends on cell tolerance to the effect of the compound
30
What does a cells susceptibility to chemicals, drugs and toxins depend on?
- miotic rate
31
What is miotic rate?
* The ability to:
- take-up
- bind
- Concentrate
- Metabolise
32
Cell injury can also be caused by immunological dysfunction - what are examples of this?
- failure to respond (immunodeficiency)
- overreaction (allergic/hypersensitivity reaction)
- reaction to self (autoimmunity)
33
Aging an cause cell injury through accumulated damage to cells through what?
- proteins
- lipids
- nucleic acids
- depends on the ability of different cells to replicate or repair
34
What are the categories of aetiology?
* think VITAMINCDE
V- Vascular
I - inflammatory/infectious
T- trauma/toxicity
A - autoimmune
M - metabolic
I - iatrogenic/idiopathic
N - nutritional/neoplastic
C- congenital
D - degenerative
E - endocrine
35
What is ante mortem sampling?
- samples from the living
35
What do clinical pathologists use for ante mortem sampling?
- biochemistry
- cytology
- haematology
- analysis of other body fluids (urinalysis and CSF analysis)
36
What do anatomical pathologists do?
- use surgical biopsies for histopathology
37
What is histopathology and what does it identify?
- the microscopic examination of tissues
- identification of morphological changes in anatomy
38
What is the advantage of histopathology over cytology?
- interpretation of changes in tissue architecture and relationship between cells and tissues
39
What does histopathology require?
- requires fixed ( most often 10% neutral buffered formalin) tissue
40
What stain is routinely used in histopathology?
- uses haematoxylin and eosin staining
41
Many histochemical stains exist to do what?
- characterise features seen (pigments, microorganism)
- reveal features not visible on H&E
- differentiate structures and tissue components
- react with chemical components of tissues
42
Formalin fixed paraffin embedded tissue blocks can be archived and used for comparison later - such as?
- samples from the same animal (clinical progression)
- control tissues (for special stains)
- research
43
What is immunohistochemistry?
- an antibody labelling technique, made visible using a chromogen or fluorescent reporter
44
Immunohistochemistry relies on epitopes - what are these?
- areas of proteins in the target to bind specific antibodies
45
What can immunohistochemistry be used to identify?
- cell types
- tissue/protein components
- microorganisms
46
What are the antibodies like in immunohistochemistry?
- specific to the target (e.g., an antibody raised against a specific microorganism or unique feature of a cell type/tissue component)
- identify of the target is based in the combination of antibodies that can or cannot label it
47
What techniques can be used for assessing samples obtained from clinical cases/and or PME?
- Histopathology
- Immunohistochemistry
- Microbiology / parasitology
- Molecular techniques
- Ultrastructural pathology (less common
48
What samples can be analysed for microbiologists and parasitologists?
- Samples (e.g. swabs, faeces) taken in clinical practice, or at post mortem examination
49
What information can be provided from samples sent to microbiologists and parasitologists?
- Provides specialist information about presence of organisms
- Can provide additional information for treatment (e.g. antibiotic sensitivity)
50
What does ultrastructural pathology use?
- Uses electron microscopy to examine cellular and subcellular morphological changes
51
Why is untrastrucural pathology limited?
- due to cost, specialist sample processing and availability of facilities with EM expertise and infrastructure
52
The target area for ultrastructural pathology is very small so how should it be used?
- needs to be used carefully and with other information about the
disease process
53
Where is ultrastructural pathology used?
- in research more than clinical settings
54
Where may ultrastructural pathology be used in a clinical setting?
- Specialist renal pathology
55
What are molecular techniques for PME?
- ELISA
- PCR
56
What is ELISA?
- Another immunological technique used on fluid samples (e.g. plasma, serum, urine)
57
What can ELISA be used to quantify?
- Can be used to quantify levels of a protein in a sample (e.g. inflammatory mediators, protein
component of a microorganism)
58
What is ISH?
- In situ hybridization
59
What targets are used in ISH?
- Whilst IHC needs a protein target, ISH techniques have a nucleic acid
target (mRNA)
60
How is ISH performed?
1. A probe (a complimentary strand of DNA or RNA) is used to bind to the
target
2. An antibody, bound to an enzyme, is used to label the sites of probe
binding
3. A substrate is added, and reacts at the site of the enzyme, to produce a
product which can be visualised
4. Fluorescent and chromogens are used
5. Allows assessment of expression of genes, or microbial genetic material
(e.g. locating viral material)
