2 - Introduction to Histology and BLood Flashcards
(52 cards)
How is tissue prepared for viewing under a light microscope? 1) 2) 3) 4)
1) Fix sample
2) Embed in paraffin
3) Sectioning of sample
4) Stain material
How is a sample fixed?
Expose sample to formaldehyde
Effects of fixing sample
Crosslinks molecules in sample, preventing degradation of sample (EG: from bacterial decomposition, autolysis).
Stiffens sample, making it easier to make thin slices.
Formaldehyde is a powerful antibacterial
Paraffin embedding process
1)
2)
3)
1) Fixed samples dehydrated in alcohol
2) Alcohol replaced with xylene
3) Add molten paraffin
Why do samples need to be dehydrated before embedding in paraffin?
Sample is mostly water, paraffin isn’t water-based. Need to remove water.
Thickness of sectioned samples
5-15 micrometers
Most common histological dye
Haemotoxylin and eosin (H and E)
Haemotoxylin stain colour
Blue/purple
Eosin stain colour
Pink
What does haemotoxylin bind to?
Acidic or negatively-charged compounds.
Examples of things that haemotoxylin binds to
1)
2)
1) Phosphate groups of nucleic acids
2) Some acid mucins, proteoglycans
What does eosin bind to?
Positively-charged compounds
Amphophilic
Binds to both eosin and haemotoxylin
Example of an amphophilic cell
Plasma cell.
Cytoplasm stains pink with eosin, a lot of protein and rER binds haemotoxylin
Four basic tissue types
1) Connective tissue
2) Epithelia
3) Muscle
4) Neural tissue
Parenchyma
Funcitonal cells
Stroma
Support tissue
Types of connective tissue
1)
2) a, b
3)
1) Embryonic
2) Connective tissue proper
a) Loose
b) Dense (regular or irregular)
3) Specialised connective tissue
Examples of specialised connective tissue 1) 2) 3) 4) 5) 6)
1) Cartilage
2) Bone
3) Adipose tissue
4) Blood
5) Haemopoietic tissue
6) Lymphatic tissue
Amount of blood in an average 70kg person
~5L
Blood functions
1)
2)
3
1) Transport: O2, CO2, nutrients, waste, hormones, heat, cells 2) Defence (immune system) 3) Haemostasis
Components of plasma 1) 2) 3) 4) 5)
1) Water
2) Proteins
3) Salts
4) Lipids
5) Sugars
Tonicity of plasma
Isotonic, except for proteins, which can’t extravasate
Three main groups of proteins in blood
1) Those involved in coagulation
2) Albumins
3) Globular proteins
