FHMP 017 + 018 Tissues and Organs histology Flashcards
what is histology?
microscopic study of tissues
What is histopathology?
microscopic examination of tissues for signs of disease
describe light microscopy
- fresh tissue is soft so needs to be fixed to hard structure (fix to aldehyde)
- dehydrate in acetone and embed in wax
- cut into thin slices and place on glass slide
- use dyes to see better (coloured)
- can be alive or dead
- low resolution (200nm)
describe electron microscopy
- Uses electron beams
- more dangerous
- resolution 0.2 nm
- black and white images
- cells are fixed
- transmission and scanning
- free electrons travel in waves, like light
- resolving power is greater because the wavelength of the electron beams are smaller
- fix in aldehyde and place in electron stain OsO4
- dehydrate in acetone and embed in plastic and cut thin slices then place on copper grid
what is H + E stain?
- Haematoxylin dye + eosin dye
- haematoxylin = dyes nuclei dark purple
- eosin = dyes cytoplasm pink/red
what are the 5 primary tissues?
- connective
- epithelial
- muscle
- nerve
- blood
what are the different types of connective tissue?
- connective tissue proper = loose (areolar, reticular), dense (regular -tendons-, irregular - dermis
- specialised connective tissue = adipose, blood, lymphoid
- supporting connective tissue = cartilage, bone
what are the different types of epithelia?
- simple (1 layer)
- stratified (more than 1 layer)
- squamous ( flat)
- cuboidal (cuboid shape)
- columnar (tall)
- pseudostratified (1 layer but looks like multiple due to long cells with nuclei at different levels)
- transitional (changes shape with environment)
Where are simple squamous cells found?
lines air sacs of lungs, inner lining of heart and blood vessels, serous membranes, inner ear drum
Where are stratified squamous cells found?
Epidermis of skin (keratinised), lining of mouth, tongue, throat, larynx, oesophagus, canal vagina (nonkeratinised)
Where are simple columnar cells found?
lines gastrointestinal tract from stomach to anus, uterus, uterine tubes
Where are stratified columnar cells found?
male urethra, mammary gland duct
Where are simple cuboidal cells found?
lines surface of ovary, kidney tubules, kidney, thyroid, mammmary glands, salivary glands, small ducts
Where are stratified cuboidal cells found?
larger ducts in sweat glands and salivary glands
Where is pseudostratified epithelium found?
trachea, respiratory tract
Where is transitional epithelium found?
urinary bladder, renal pelvis, ureters
what are the different types of muscle tissue?
skeletal, cardiac, smooth
What is nervous tissue?
a tissue consisting of neurons and the cells that support them
what is blood tissue?
Connective tissue with a liquid extracellular matrix called blood plasma
what are some problems with multicellularity?
- cells need to communicate (need to use nerves, hormones, local signals, gap junctions)
- cells must adhere to one another (meshwork of large extracellular molecules such as collagen, extracellular matrix and specialised adherens/anchoring junctions between plasma membranes)
What is the extracellular matrix?
- nonliving material found between cells in connective tissue
- synthesised by fibroblasts
- contains collagen, elastin and proteoglycans
- cells are anchored to the ECM and cytoskeleton through receptors in their surface
What are anchoring junctions?
- They attach cells to other cells or basement membrane and they transmit stresses via the cytoskeleton. -They are made up of actin filaments and intermediate filaments
- desmosomes = between adjacent cells
- hemidesmosomes = between cell and extracellular matrix
What are the layers above and below the epidermis?
- keratin on top
- then epidermis with desmosomes between cells
- then ECM receptors attach the desmosomes to connective tissue (always below epithelia)
what happens if cellular adhesion is disturbed?
- Pemphigus / blistering disease, where skin epithelial cells split apart and form blisters
- Cancer - without cell adhesions easier for cancer to metastasize
what colour is cartilage dyed?
blue
what does adipose tissue look like under a microscope?
white round circles alone or in a group
what do blood vessels look like under a microscope?
round red circles ( look at the layers in the wall )
large + thin walls = vein
large and thick walls = artery
very small and thin walls = capillary
what does smooth muscle look like?
Fiber thickest in middle, tapered at each end, with one centrally positioned nucleus; not striated
what does skeletal muscle look like?
striated, multi-nucleated (eccentric), fibers parallel
