Pathology - Intro Flashcards
Define Pathology, Histology and Histopathology
Pathology - study of disease
Histology - study of cells and tissues by microscopy
Histopathology - study of diseased cells and tissues by microscopy
Define Epidemiology and Aetiology
epidemiology - population distribution of disease
aetiology - cause of the disease
Define Pathogenesis?
how the disease develops
define prognosis
the anticipated course of the disease
4 Steps of Treatment from the start
make diagnosis
determine prognosis
plan treatment
confirm response to treatment
10 Steps of Histological Process Examination
- tissue
- fixation
- cut up the section
- process the tissue
- cutting and mounting
- staining
- scanning
- microscopy
- diagnosis
- prognosis prediction
What is tissue fixation?
preservation of tissues
2 ways in which tissues decay
- autolysis - intrinsic autolytic enzyme action
- putrefaction - bact. contamination
4 Different Fixatives, how do they work?
Aldehyde - form protein covalent cross-links
Alcohol - denature proteins = aggregation
Oxidising = protein cross links
Freezing
2 Aldehyde Fixatives.
Formalin
Glutaraldehyde
Which is the most common Fixative?
Formalin - formaldehyde solution
why is formalin the most common fixative? (3)
- protein covalent cross links
- good penetration and mech. strength
- good tissue morphology preservation
one negative of formalin
poor nucleic acid preservation (DNARNA)
how long is formalin effective for?
24-48 hrs
how do you cut thin sections of tissue in tissue processing?
place it in wax
what 2 properties must the tissue have when it is cut thin?
stiff and resistant to tearing
why cant tissue just be dropped into water?
wax = hydrophobic
water = hydrophilic
how do you remove water from the tissue and embed into wax? (3)
dehydration by alcohol
replace alcohol with xylene - cleans
replace xylene with paraffin wax
what does FFPE stand for?
formalin fixed paraffin embedded tissue
What is the most common stain?
Haematoxylin and Eosin Stain
Describe Haematoxylin and Eosin Stain.
haemotoxylin
- basic dye
- stains acid structure purple
- DNA = purple
Eosin
- acidic dye
- stains basic structures pink
- proteins = pink
is H&E stain specific?
no
-only specific to acid and base structures
what is immunohistochemistry?
the process of identifying specific antigens by using the principles of antibody binding
define metaplasia
a change in which one differentiated cell type is replaced by another cell type
define pathogenesis
the exact mechanism that causes the disease
define infarction
tissue necrosis as a consequence of ischaemia
