TOB L1.2 EPITHELIAL TISSUES Flashcards by Matt Quinn

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

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Simple Squamous Epithelia
Functions
(LGBaT)

Lubrication (pericardium, pleua, peritoneum/viscera)
Gas exchange (alveoli)
Barrier (bowmans capsule)
Active transport via pinocytosis (meso/endothelium)

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Simple Cuboidal Epithelia

Locations (four)

Thyroid follicles
Small ducts of many exocrine glands
Kidney tubules
Surface of the ovary (germial epithelium

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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)

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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

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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)

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(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

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(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)

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Stratified Squamous Non-Keratinised Epithelia

Locations (seven)

Oral cavity
Oesophagus
Larynx
Vagina
Part of anal canal
Surface of cornea
inner surface of eyelid

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Stratified Squamous Non-Keratinised Epithelia

Functions (two)

Protections against abrasion

- Reduces water loss whilst remaining moist

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Stratified Squamous Keratinised Epithelia

Locations (two)

Surface of skin

- Limited distribution in oral cavity

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Stratified Squamous Keratinised Epithelia

Functions (four)

Protection against abrasion
Prevents water loss
Prevents ingress of microbes
Shields against UV light damage

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Stratified Transitional (urinary) Epithelia
Locations (four)

Renal calyces
Ureters
Bladder
Urethera

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Stratified Transitional (urinary) Epithelia
Functions (two)

distensibility

- protection of underlying tissue from toxic chemicals

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Basement membrane

Position + Description

Thin, flexible, acellular layer which lies between epithelial cells and subtending connecting tissue

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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

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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

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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.