Microscopy and Epithelia Flashcards by Alex Brown

What constitutes an organ?

Aggregations of tissues

How well did you know this?

Not at all

Perfectly

What is histology?

The study of the structure of tissues by means of special staining techniques combined with light and electron microscopy

How well did you know this?

Not at all

Perfectly

What diseases would a doctor not give a diagnosis until the histologists have given one?

Cancers, crohns

How well did you know this?

Not at all

Perfectly

How many nanometers in a millimeter?

1 million

How well did you know this?

Not at all

Perfectly

How many micrometers in a milimeter?

1000

How well did you know this?

Not at all

Perfectly

What is the size of most cells?

10-20 micrometers

How well did you know this?

Not at all

Perfectly

What is a biopsy?

The removal of a small piece of tissue from an organ or part of the body for microscopic examination.

How well did you know this?

Not at all

Perfectly

What are the 6 types of biopsy, what are they and what tissues are they for?

Smear- collect cells by spontaneous or mechanical exfoliation, smear on slide. For cervix, buccal cavity.
Currettage- remove tissue by scooping/scraping. For endometrial lining of uterus.
Needle- put needle into tissue to gather cells. For brain, breast, kidney, liver, muscle.
Direct incision- cut directly into tissue of interest and remove tissue. For skin, mouth, larynx.
Endoscopic- removal of tissue via instruments through an endoscope. For lung, intestine, colon, bladder.
Transvascular- for heart, liver

How well did you know this?

Not at all

Perfectly

Why may biopsy’s need to be fixed and what would they be fixed with?

To preserve the cellular structure, no autolysis or putrefacation.
Commonly used fixatives include formaldehyde and glutaraldehyde.

How well did you know this?

Not at all

Perfectly

What can tissue processing lead to and how?

Shrinkage artefacts. During prep of slide tissue is dehydrated and rehydrated

How well did you know this?

Not at all

Perfectly

What are two common stains?

Haemotoxylin and eosin

Periodic Adic-Schiff (PAS)

How well did you know this?

Not at all

Perfectly

What do each of H&E stain?

Haemotoxylin stains the acidic components of the cell, eg nucleolus (RNA), chromatin (DNA), purple/blue.
Eosin stains the basic components of the cell, eg most cytoplasmic proteins and extracellular fibres, pink

How well did you know this?

Not at all

Perfectly

What does PAS stain?

Carbohydrates and glycoproteins magenta

How well did you know this?

Not at all

Perfectly

What stains elastic fibres?

Silver stain

How well did you know this?

Not at all

Perfectly

What is phase contrast and what are the advantages?

Uses interference effects of two combining light waves. Enhancing the image of unstained cells

How well did you know this?

Not at all

Perfectly

What is dark field and what are the advantages?

Exclude unscattered beam (electron/light) from the image. Live and unstained samples.

How well did you know this?

Not at all

Perfectly

What is fluorescence and what are the advantages?

Target molecule of interest with fluorescent Ab. Use multiple fluorescent stains on one specimen.

What is confocal and what are the advantages?

Tissue labelled with one or more fluorescent probes. Eliminated out of focus flare. 3D from a series of 2d images, imaging of living specimens.

What are the surfaces with epithelial linings with examples

Exterior surfaces (skin)
Interior surfaces opening to the exterior (GI tract, respiratory tract, genitourinary tract)
Interior surfaces not opening to the exterior (pericardial sac, pleural sac, peritoneum, blood vessels, lymphatic vessels)

Where is simple squamous epithelium found and what are its functions?

Lining of blood vessels (endothelium), lining of body cavities (pericardium, pleura, peritenium ‘mesothelium’), alveoli, bowmans capsule
Lubrication (pericardium, pleura, peritoneum/vicera), gas exchange (alveoli)

Where is simple cuboidal epithelium found and what are its functions?

Small ducts of many exocrine glands, thyroid follicles, kidney tubules
Absorption and conduit (glands)
Absorption and MOSTLY secretion (kidney)
Hormone synthesis, storage and mobilisation (thyroid)

Where is simple columnar epithelium found and what are its functions?

Stomach lining, SI and colon, ductili efferents of testis, large ducts of come exocrine glands.
MOSTLY Absorption (SI and colon), secretion (stomach, SI and colon), lubrication (SI and colon)

What do simple columnar with microvilli allow for?

Bind adjacent plasma membranes tightly together in the apical portions of some epithelia. Membrane proteins cant bypass this zonula occludens so the cell is able to restrict certain proteins to its apical surface and segregate others to its lateral and basal surfaces

Where is simple pseudostratified epithelia found and what are its functions?

Lining of nasal cavity, trachea and bronchi (upper respiratory tract), epididymis
Secretion and conduit (URT), absorption (epididymis), mucus secretion (URT), particle trapping and removal (URT).

Where is stratified squamous non-keratinised epithelium found and what are its functions?

Oesophagus, oral cavity, larynx, vagina, surface of cornea. | Protection against abrasion, reduces water loss whilst maintaining moist.

Where is stratified squamous keratinised epithelium found and what are its functions?

Surface of skin Protection against abrasion and physical trauma, prevents water loss, prevents ingress of microbes, protects against UV damage.

Where is stratified transitional epithelium found and what are its functions?

Bladder, urethra, ureters | Distensibility and flexibility, protection of underlying tissue from toxic chemicals

What is the position of the basement membrane?

Thin, flexible, acellular layer which lies between epithelial cells and the subtending connective tissue.

What is the structure of the basement membrane?

Consists of basal lamina which is laid down by the epithelia and therefore lies closest to them. Thickness cam be increased by a variably thick layer of reticular fibres elaborated by the subtending connective tissue

What is the function of the basement membrane?

Strong, flexible layer to which the epithelial cells adhere. Also serves as a cellular and molecular filter. The degree to which malignant cells penetrate the basement membrane is highly relevant to prognosis.

What does turnover rate of epithelia depend on?

Cell function and location

What rate does the epithelia turnover occur?

At a constant rate unless there is acceleration due to injury.

What is the time for the epidermis to go fro, cell division in the basal layer (through differentiation, migration to the exterior, keratinisation and death) to being sloughed off?

28 days

What happens if the epithelia arent normally renewed?

Proliferation can be triggered to replace damaged/lost cells

What are microvilli?

Apical extensions that greatly increase the SA for selective absorption of intestinal contents.

What are sterocillia?

Very long microvilli, extend from the surface of the ductus deferens and the epididymis. They may have absorptive function.

What are cillia?

Extensions from cells that beat in coordinated waves. Found in the lining of the trachea where they sweep mucus and dirt out of the lungs. Also found in the fallopian tubes where they move the ovum from the ovary to the uterus.

What kind of configuration do cillia have?

9+2

What is metaplasia?

The epithelias capacity to change from one type to another, eg in smokers the psuedostratified epithelium of URT may become stratified squamous.

What is neoplasia?

When in disease changes may occur in the epithelia giving rise to a neoplasm (tumour) which is termed a carcinoma.

What are epithelia?

Sheets of contiguous cells of varied embryonic origin that cover the external surface of the body and line the internal surfaces

Define a tissue

A collection of cells specialised for a particular function