INTRO TO HISTOLOGY Flashcards
Define a tissue
Group of cells working together to carry out a common function
Define an organ
Group of tissues of a different nature in a morphologically recognisable structure
what are the four types of tissue?
Epithelial
Connective
Muscle
Nerve
Describe the relationship between epithelial and connective tissue
Epithelial tissue provides protection to the connective tissue from infection and dehydration. Connective tissue supports and provides nutrition (vascularises) epithelial tissue.
Name and describe the 4 components of the most common staining process
Fixation: stops histological processes from happening
Embedding: placing specimen in a paraffin wax block to sustain it whilst cutting
Sectioning: Thinly slicing the specimen (thinner = higher resolution)
Staining: the specimen with Haemotoxylin-Eosin (HE) stain (MOST COMMON STAIN)
what part of the Haemotoxylin-Eosin stain is acidic/basic and what colour is each part/
Haemotoxylin = Basic = Blue Eosin = Acidic = Red
Give an example of when a basic stain would be needed
Nuclei contain acid, making them basophilic so they would need an acidic dye.
What does the PAS stain stand for wand what is it used for?
Period Acid Schiff
Used for staining carbohydrates/sugars
What are the 2 ways of fixing a specimen?
Chemically: aldehyde based (most common)
Freezing: dry ice or liquid nitrogen
What are the 3 types of simple epithelium, describe them and give one example for each?
Squamous: thin flattened cells e.g. in lung alveoli where quick diffusion is required.
Cuboidal: found in ducts e.g. renal tubules, small excretory ducts
Columnar: involved in secretion of digestive enzymes and absorption of digested food. e.g. digestive tract (stomach, intestine)
What are the two types of stratified squamous epithelium?
Keratinised: found in skin
Non-keratinised: flat cells but thick epithelium for high mechanical resistance/protection. e.g. found in oesophagus and palate of mouth
What is pseudostratified epithelium?
Epithelium that has uneven rows of nuclei which makes it look like many layers but isn’t
What are the two types of pseudostratified epithelium? Give examples
Ciliated: e.g. in trachea where there are cilia hairs present
With stereo cilia (non-motile cilia-like structure) e.g. in the epididymis (duct behind testes)
Describe and give an example of transitional epithelium
Can transition between thick and thin epithelium e.g. urothelium in urinary bladder - when bladder is full, epithelium is thin and when badder is empty, epithelium is thick.
