ToB Flashcards
Define histology
The study of tissue using special stains and electron/light microscopy
Define tissue
A collection of cells specialised to perform a function
Why is histology important clinically?
Histology and biopsy are often needed for definitive proof of a diagnosis such as Crohn’s or cancer
Define biopsy
The removal of a piece of tissue for study under a microscope
What is a smear biopsy and what is it used for?
Collect cells by exfoliation and smear on slide. Used for cervix or buccal cavity
What is curettage and what is it used for?
Scrape cells. Endometrial lining of the uterus
What is a needle biopsy and what is it used for?
Inserting a needle into the tissue to remove the cells. Brain, breast, kidney, liver and muscle.
What is direct incision and what is it used for?
Cut directly in and remove tissue. Skin, larynx, mouth
What is endoscopic biopsy and what is it used for?
Removal of tissues using an endoscope. Lung, intestine, bladder
Name 2 commonly used fixatives
Formaldehyde and glutaraldehyde
How can shrinkage artefacts be formed?
During tissue preparation it is dehydrated and rehydrated which can lead to abnormalities
What is stained by Haematoxylin and eosin?
H stains acidic parts blue (nucleus)
Eosin stains basic parts pink (cytoplasmic proteins and extra cellular fibres)
What is stained by periodic acid schiff?
Stains carbohydrates and glycoproteins magenta (mucous goblet cells)
What is phase contrast and the advantage it gives?
Interference of 2 light waves to see an untainted sample
What is dark field and the advantage of it?
Exclude unscattered light/electrons from the image. Can be used on live and untainted samples
What is fluorescence and the advantage of it?
Tag target molecule with fluorescent stain. Can use multiple stains
What is confocal and what is the advantage of it?
Label tissue with fluorescent probes. Can make a 3D image from a series of 2D images. Use on living samples. Removes out of focus flare
Define epithelia
Sheets of contiguous tissue of varied embryonic origin that cover external surfaces and line internal surfaces of the body
What are the different types of epithelia?
Simple/stratified squamous, columnar, cuboidal. Pseudostratified. Transitional
Location and function of simple squamous?
Blood vessels (endometrium), lining body cavities (mesothelium) alveoli, bow and capsule and loop of henle. Lubrication, gas exchange, barrier
Location and function of simple cuboidal
Thyroid follicles, exocrine glands, kidney tubules and ovaries. Absorption, secretion, barrier and synthesis of hormones
Location and function of simple columnar?
Stomach, small intestine, gall bladder, uterus, large exocrine glands. Absorption, secretion, transportation, lubrication. Note - can have micro villi
Location and function of pseudostratified?
Trachea, bronchi, nasal cavity, epididymis. Secretion, absorption, trapping small particles
Location and function of stratified squamous keratinised.
Skin, oral cavity. Protect against water loss, abrasion and microbes
Location and structure of non keratinised stratified squamous
Oesophagus, vagina, anal cavity, cornea, inner eyelid, larynx. Protect against abrasion and water loss
Location and function on transitional epithelium
Ureters, bladder, urethra. Distensibility, protect underlying tissue from toxic substances
What is the position, structure and function of the basement membrane
Layer between epithelium and connective tissue. Consists of basal lamina and collagen. Serves as filter and strong layer for epithelium to adhere to
Rate of renewal of skin?
28 days
Rate of renewal of small intestine epithelia
4-6 days
Define glands
An epithelial cell or collection of cells specialised for secretion
How can you classify glands by destination of secretion?
Endocrine (directly into the blood) and exocrine (into ducts)
How can you classify glands by their structure?
The secretory part can be unicellular or multicellular. They can also be coiled or branched. If multicellular gland branches it is complex, if it doesn’t branch it is simple.
How can you classify glands by nature of secretion?
Either serous (watery secretion) or mucous.
How can you classify glands by the method of secretion?
Holocene, apocrine or merocrine
What is merocrine secretion and give an example of glands that do it?
Exocytosis - vesicles containing the substance fuses to the membrane and releases its contents. Plasma membrane becomes slightly larger
E.g. Salivary glands and pancreas
What is apocrine secretion and what glands use it?
The substance is draped in cytoplasm and surrounded by the cell membrane before pinching off. Membrane becomes slightly smaller
E.g. Mammary gland
What is holocrine secretion and name a gland that does it?
Cell disintegrates releasing contents
E.g. Sebaceous gland
Describe endocytosis and how, when combined with exocytosis, it gives transepithelial transport
Opposite of exocytosis, material is engulfed by the cell. Then moves the length of the cell before being released by exocytosis
Where and why does glycosylation occur?
N linked in ER. O linked in Golgi. Makes a cell more specifi
What do mucous membranes consist of and where are they found?
Mucus secreting cells, epithelium, lamina propria (CT) and in alimentary track smooth muscle (muscularis mucosae). Found in alimentary, respiratory and urinary tract.
What do serous membranes consist of and where are they found?
Serous fluid secreting cells, simple squamous epithelium (mesothelium) and connective tissue. Found in peritoneum (abdomen) pleural sacs (lungs) and pericardial sac (heart)
Define the limit of solution
Minimum distance two objects can be distinguished at
