BL S5 - Epithelial TIssue And Exocrine Glands Flashcards
What does a mucous membrane do?
Give examples of where mucous membranes are found.
Lines internal tubes which open to the exterior of the body.
The respiratory, urinary and alimentary tract.
What does a mucous membrane consist of?
Epithelium lining a lumen
Adjacent layers of CT called lamina propria.
Muscularis mucosae - smooth muscle - alimentary tract.
What is a serous membrane and where are they found?
Thin 2 part membranes which line internal closed body cavities - enveloping viscera.
Peritoneum - enveloped abdominal organs
Pleural sacs - envelop lungs
Pericardial sacs - envelops heart
What does a serous membrane consist of?
Mesothelium - secretes the lubricating fluid
Thin layer of connective tissue attached the epithelium to adjacent tissues.
What is epithelium tissue?
Where us is found?
Sheets of contiguous cells, of varied embryonic origin that cover the external surface of the body and line the internal surfaces.
Skin
GI tract, respiratory, genitourinary tract. - open to exterior
Pericardium, peritoneum, pleural sacs, blood and lymphatic vessels - don’t open to exterior.
What is the function of simple squamous epithelium?
Lubrication
Gas exchange - short diff distance
Physical barrier
Active transport via pinocytosis
Where is simple squamous found?
Bowmans capsule
Lung alveoli
Endothelium
Mesothelium
What happens if excessive secretion of fluid occurs from squamous cells?
Hydroceles around testes
Serous fluid between visceral andparietal layers of the tunica vaginalis
Describe simple cuboidal epithelium.
Single layer of polygonal cells where their height is the same as their width.
What are the functions of simple cuboidal and where are they found associated with the function?
Absorption / conduit - exocrine glands
Absorption and secretion - kidney tubules
Barrier - ovary
Hormone synthesis, storage and mobilisation - thyroid
Describe simple columnar epithelium.
Single layer of cells with heights greater than their wights.
What are the functions of simple columnar and where are the Found associated with these functions?
Absorption - small intestine, colon and gall bladder.
Secretion - stomach lining, small intestine and colon
Lubrication - small intestine and colon
Transport - oviduct.
Describe psuedostratified epithelium.
All cells make contact with the basement membrane but not all reach surface - nuclei at varying levels. Often ciliated.
What are the functions of pseudostratified epithelium and where are they found?
Secretion and conduit - respiratory tract, vas deferens
Mucous secretion - respiratory tract
Particle trapping and removal - respiratory tract
Describe stratified squamous epithelium.
Multiple layers with the outermost being squamous cells.
Where is non-keratinised stratified squamous epithelium found?
Anal canal Cornea Oral cavity Oesophagus Valine Inner surface of the eye
What is the fucntion of non-keratinised epithelium?
Protect against abrasion
Reduce water loss but remain moist
What are the functions of keratinised epithelium?
Reduces water loss and ingress Prevents toxin ingress Protects against abrasion Acidic pH - reduces microbial colonisation Shielding against UV damage.
Where is keratinised epithelium mainly Found?
Skin epidermis
Describe transitional epithelium.
Surface cells vary in shape from columnar to cuboidal depending on where the tissue is stretch or relaxed.
Where is transitional epithelium aka urothelium found?
Urinary tract Renal calyces Ureter Bladder Urethra
What are the functions of transitional epithelium?
Distensibility
Protection of underlying tissue from toxic chemicals
What percentage of the epidermis is keratinocytes?
90%
What are the 4 layers of the epidermis?
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
