2 - Introduction to Histology and BLood Flashcards
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
Adult female erythrocyte count
3.8-5.8 x 10^12/L
Adult male erythrocyte count
4.5-6.5 x 101^2/L
Normal neutrophil count (adult)
2.0-7.5 x 10^9/L
Normal eosinophil count (adult)
0.04-0.4 x 10^9/L
Normal basophil count
<0.1 x 10^9/L
Normal lymphocyte count
1.5-4 x 10^9/L
Normal monocyte count
0.2-0.8 x 109/L
Normal platelet count
150-400 x 10^9/L
Haematocrit
Proportion of blood that is red blood cells
Normal haematocrit
~45%
Average erythrocyte diameter
7.2 micrometers
Average erythrocyte lifespan
120 days in blood
Reticulocytes
Immature form of red blood cells that are released into the blood
Make up less than 1% of circulating red blood cells
Morphological features of reticulocytes
No nucleus
Still some organelles and RNA in cytoplasm
When do reticulocyte numbers increase in the blood?
After haemorrhage or haemolysis
Name for form in which RBC is first released into blood
Reticulocyte
Name for immature, nucleated RBC
Normoblast
Average diameter of platelets
2-4 micrometers
Life span of platelets
8-10 days
Important morphological difference between granulocytes and mononuclear leukocytes
Granulocytes have multi-lobated nucleus, mononuclear leukocytes have unlobated nucleus
Examples of factors contained in neutrophil granules
1)
2)
3)
1) Myeloperoxidase
2) Lysozyme
3) Collagenase
Average lifespan of neutrophils
A few days
Shape of eosinophil nucleus
Bilobated
Shape of basophil nucleus
Bilobated
Largest leukocyte
Monocyte
Shape of monocyte nucleus
Monolobated, eccentric (on edge of cell), bean-shaped
Factors controlling haematopoiesis
Colony-stimulating factors
Examples of blood examination techniques 1) 2) 3) 4)
1) Full blood examination/complete blood examination
2) Bone marrow biopsy
3) Blood films stained
4) Haemostasis tests
