Histology: Epithelium Flashcards
why would a tissue stain on a slide be blue?
Haematoxylin- natural dye
combines with nucleic acids in the nucleus and stains them blue–> thus a blue nucleus
RER has ribosomes–> stained blue
Cells that have alot of RER give the cytoplasm a bluish appearance which is said to be basophilic (love the base)
why would a tissue stain on a slide be pink?
Eosin- combines with basic components of cytoplasm (usually proteins) and stains pink.
–> intra/extra cellular strucutres that stain pink are said to be acidophilic or eosinophilic (loves the eosin or acid)
Epithelium
covers all external and internal surfaces of the body and forms the bulk of some organs, including liver, kidney and glandular tissue.
Ectoderm
forms the skin and associated glands which lines oral, nasal and anal passages.
Mesoderm
- epithelial linings of cardiovascular system (endothelium)
- mesothelium lining thoracic and abdominal cavities
- tubules, ducts and accessory glands of urogenital system
Endoderm
- epithelia of the gut, respiratory tract, urinary bladder, liver, gall bladder, pancreas
- epithelial glands of the gut
Simple squamous epithelium:
- CELL SHAPE
- FUNCTION
- LOCATION
- flattened
- frictionless surface
- selective fluid and gaseous exchange
- lining blood and lymphatic vessels, alveoli, pleural and peritoneal cavities
Simple cuboidal:
- CELL SHAPE
- FUNCTION
- LOCATION
- cube and deep with round nucleus
- secretion, absorption, acting as a conduit, protection
- renal convoluted tubules and ducts
- gland ducts and secretory portions
- ovarian surface epithelium
- capsule of the lens
Simple columnar:
- CELL SHAPE
- FUNCTION
- LOCATION
- usually same height and arranged in columns
- nuclei generally at same level
- absorption, secretion, protection and transportation
- lining the GIT system, larger calibre ducts draining exocrine glands, uterine tubes, endometrium
Pseudostratified columnar:
- CELL SHAPE
- FUNCTION
- LOCATION
- appears multi- layered but every cell has an attachment to basement membrane
- however, not every cell reaches the free surface
- nuclei appear at different levels
- protection and movement of substances
- cells lining upper respiratory tract, excretory passages of male reproductive tract
Stratified squamous
- CELL SHAPE
- FUNCTION
- LOCATION
- can be keratinised or non- keratinised
- to provide resistance to wear and tear and form a physical barrier to protect underlying tissues
- skin, oral cavity, oesophagus, part of anal canal, vagina, lining parts of the GIT
Transitional
- CELL SHAPE
- FUNCTION
- LOCATION
- multilayered (represents a transition from stratified squamous to stratified columnar)
- protection and capable of distension
- only really found in renal system: cells lining renal calyces, ureters, bladder and portion of ureter
Keratin
- non- living protein formed by the death of older cells
- anchored to the newer cells below
- acts a strong waterproof barrier that protects underlying tissue/ cells
Microvilli
- project from the surface of the cells
- are found mainly in absorptive cells
- increase the surface area of a cell for absorption
Cilia
- have an internal structure of microtubules
- use energy to sway with a metachronal rhythm
- move substances over the surface of cells
- are located mainly in the upper respiratory tract
