Histology Flashcards
histology
the study of the microscopic structures of biological tissues
cell theory
1- all living things are composed of 1 or more cells
2- a cell is the basic unit of life
3- new cells arise from pre-existing cells
prokaryotes
no nucleus
eukaryotes
nucleus + cytoplasm present
cytoplasm
cytosol = intracellular fluid
cytoskeleton = network protein filaments maintaining structure
tissues (2)
parenchyma = working tissue
stroma = scaffold + nutrition (blood vessels/nerves)
types of tissue (4)
connective = (space filling) protects + supports
epithelial = covers/lines body surfaces
muscle = contract to generate force
nervous = generate electrical signals (surrounded by the ECM)
carcinoma
the most common type of epithelial cancer (85%)
developing process - dedifferentiation; proliferate; invade CT + organs; enter blood vessels; metastasis
four steps of staining
fixation -> embedding -> sectioning -> staining
staining: fixation
PURPOSE: preservation
freezing (-80 d.c.) aldehyde based
staining: embedding
frozen samples are dehydrated and embedded in paraffin wax for support
staining: sectioning
microtome is used to cut thin sections
the thinner the section, the higher the resolution
staining: staining
non-specific: often need to be rehydrated
specific
haematoxylin + eosin
basic + acid respectively
H is basophilic (stains acidic)
E is acidophilic (stains basic)
PAS (periodic-acid/ Schiff)
stains carbohydrates + glycogen
magenta = positive
lipids are dissolves so appear empty
epithelium: basic knowledge
avascular - nourished by CT
are polar (base different charge to apex)
sit on a basement membrane
covers + protects
forms glandular structure + can combine with nervous tissue to make special senses (e.g. olfactory tissue in the nose)
covering epithelia
cover all body surfaces
glandular epithelia
secretory + arranged into glands
are invaginated/ glandular organs
exocrine glands
retain continuity w/ surface - secrete via ducts
endocrine glands
lose contact with the surface - secrete directly into bloodstream (thyroid gland)
simple structure
single layer/ secretion + absorption/ fragile
stratified
2 or more layers/ protection
pseudostratified
1 layer/ mix of all shapes
looks like stratified as nuclei at different levels + not all cells reach surface BUT all cells touch the basement membrane
squamous
flat shaped
