TOB L1.2 EPITHELIAL TISSUES Flashcards
Simple Squamous Epithelia
Locations (6 points)
- Lining of blood vessels “endothelium”
- Lining of body cavities - pericardium, pleura, pertoneum ‘mesothelium’
- Respiratory epithelium (pulmonary alveoli)
- Bowman’s capsule (kidney)
- Loop of Henle (kidney)
- Inner and middle ear
Simple Squamous Epithelia
Functions
(LGBaT)
- Lubrication (pericardium, pleua, peritoneum/viscera)
- Gas exchange (alveoli)
- Barrier (bowmans capsule)
- Active transport via pinocytosis (meso/endothelium)
Simple Cuboidal Epithelia
Locations (four)
- Thyroid follicles
- Small ducts of many exocrine glands
- Kidney tubules
- Surface of the ovary (germial epithelium
Simple Cuboidal Epithelia - It’s glandular!
Functions (four)
Baah(riatric)
- Barrier/covering (ovary)
- Absorption & Conduit (exocrine glands)
- Absorption & Secretion (kidney tubules)
- Hormone synthesis, storage and metabolism (thyroid)
Simple Columnar Epithelia
Locations (seven)
- Stomach lining & gastric pits
- Small intestine &olon
- Gall bladder
- Large ducts of some exocrine glands
- Uterus
- Oviducts
- Ductuli efferents of testis
Simple Columnar Epithelia
Functions (four)
LAST
- Lubrication (small intestine & colon)
- Absorption (small intestine, colon & gall bladder)
- Secretion (stomach lining & gastric pits, small intestine & colon)
- Transport (oviduct)
(simple) Pseudostratified Epithelia
Locations (five)
- Lining of nasal cavity, trachea and bronchi
- Epididymis and ductus deferens
- Auditory tube and part of typanic cavity
- Lacrimal sac
- Large excretory ducts
(simple) Pseudostratified Epithelia
Functions (four)
MAPS
- Mucus secretion (Nasal Cavity, trachea and bronchi (URT) )
- Absorption (Epdidiymis)
- Particle trapping and removal (URT)
- Secretion and conduit (URT, ductus deferens)
Stratified Squamous Non-Keratinised Epithelia
Locations (seven)
- Oral cavity
- Oesophagus
- Larynx
- Vagina
- Part of anal canal
- Surface of cornea
- inner surface of eyelid
Stratified Squamous Non-Keratinised Epithelia
Functions (two)
- Protections against abrasion
- Reduces water loss whilst remaining moist
Stratified Squamous Keratinised Epithelia
Locations (two)
- Surface of skin
- Limited distribution in oral cavity
Stratified Squamous Keratinised Epithelia
Functions (four)
- Protection against abrasion
- Prevents water loss
- Prevents ingress of microbes
- Shields against UV light damage
Stratified Transitional (urinary) Epithelia Locations (four)
- Renal calyces
- Ureters
- Bladder
- Urethera
Stratified Transitional (urinary) Epithelia Functions (two)
- distensibility
- protection of underlying tissue from toxic chemicals
Basement membrane
Position + Description
Thin, flexible, acellular layer which lies between epithelial cells and subtending connecting tissue
Basement membrane
Structure
- Basal lamia, laid down by epithelial cells
- Thickness increased by a variably thick layer of reticular fibrils (type 3 collagen), elaborated by subtrending connective tissue
Basement Membrane
Function (three)
- Strong, flexible layer to which epithelial cells adhere
- Serves as cellular and molecular filter
- Degree to which malignant cells penetrate basmenent membrane highly relevant to prognosis
Defintion of Epithelial tissue
Sheets of contiguous cells, of varied embryonic origin, that cover the external and internal surfaces of the body
Describe rate of renewal in epithelial tissue
- High rate of renewal
- Differs depending on type and function
- Constant rate unless accelerated by damage
- In skin, time from differentiation, migratiion to exterior, keritnization and death 28 days.
State the meaning of the term tissue
A collection of cells specialised to perform a particular function. Aggregation of tissues constitutes organs.
Define histology
The study of the structure of tissues by means of special staining techniques combined with light and electron microscopy
Why is histology important to doctors?
Many diseases, such as chron’s or cancer, doctors will not give a treatment until histopathologists have given a diagnosis.
How big are most cells?
10-20 micrometers
What is a smear and what tissues can it be used on?
Collect cells by spontaneous/mechanical exfoliation and smeared on slide.
Cervix or the buccal cavity
What is a curettage and what tissues can it be used on?
Remove tissue by scooping/scraping
Endometrial lining of uterus
What is a needle biopsy and what tissues can it be used on?
Put into tissues to gather cells
Brain, breast, liver, kidney, muscle
What is a direct incision and what tissues can it be used on?
Cut directly into tissues of interest and remove tissue
Skin, mouth, larynx
What is endoscopy and what tissues can it be used on?
Removal of tissues via intruments through an endoscope
Lung, intestine, bladder
What is transvascular and what tissues can it be used on?
Tissue taken from blood vessels
Heart, liver
Give two fixatives
Glutaraldehyde and formaldehyde
What do fixatives do on a cellular level?
Form covalent bonds between free amino groups of proteins, cross lining adjacent proteins. This arrests biological activity, preventing autolysis and putrefaction and makes cells more ammenable to staining and rendering them more stable.
What is a shrinkage artifact and how can it be caused?
Abnormalities in slide, caused by tissue dehydration and re-hydration in slide preparation process.
What does Haematoxylin stain, and what colour? Is haemotoxylin basic or acidic?
Acidic components of cell, such as Nucelolus (RNA), Chromatin (DNA). Stains them purple/blue. Haemotoxylin is basic.
What does Eosin stain, and what colour? Is Eosin basic or acidic?
Stains basic components of cells, such as cytoplasmic proteins and extracellular fibres. Stains them pink. Eosin is acidic.
What is PAS?
Period Acid-Schiff
Stains carbohydrates and glycoproteins magenta.
What is Phase contrast microscopy, and what are its advantages?
Uses interference effects of two comibining light waves
Enhances the image of unstained cells
What is dark field microscopy, and what are its advantages?
Exclude unscattered beam (light/electron) from the image.
Good with live and unstained samples
What is fluorescent microscopy, and what what are its advantages?
Target molecule of interest with fluorescent antibodies
Use multiple different fluorescent stains on one specimen
What is confocal microscopy, and what are its advantages?
Tissue labelled with one or more fluorescent probes
Eliminates “out of focus flare”,
Allows 3d imaging from a series of 2D images
Allows imaging of living specimens.
Define epithelial cells
Sheets of contiguous cells, of caried embryonic origin that cover the external surface of the body and line internal surfaces
What is the function of microvilli occludin?
Bind adjacent plasma membranes tight together in the apical portions of some epithelia.
This means membrane proteins cannot bypass zonula occluden, so cell is able to restrict certain proteins to its apical surface and segregate other to its lateral basal surfaces.
Define microvili
Apical extensions that greatly increase the surface area for selective absoption of intestinal contenes
Define stereocillia
Very long microvili extrend from surface of ductus deferens and the epididymis. May have an absorptive function.
Define cillia
Extensions from cells which beat in coordinated waves. Found in the lining of trachea where they sweep mucus and dirt out of liungs. Also found in fallopian tubes, where they move the ovum from the ovary.
