L1 The Covering Of The Epthelium Flashcards
What are the 2 forme of epithelial tissues
▪️Sheets of contiguous cells that cover the body on its external surface and line the hollow organs on the internal surface
▪️glands which originate from invaginated epithelial cells for secretions
What are the functions of epithelial tissues
▪️Protection of underlying tissues of body from abrasion and injury
▪️transcellular transport of molecules across epithelial layers
▪️secretion of mucus,hormones,enzymes and so forth from various glands
▪️absorption of material from a lumen
▪️control of movement of materials between body compartments via selective permeability of intercellular junctions between epithelial cells
▪️detection of sensations via taste buds,retina of eye and specialized hair cells in ear
What are the general features of epithelium
▪️formed of closely packed cells with limited intercellular space
▪️cells are related by intercellular junctions
▪️separated from the underlying connective tissue by the basal lamina
▪️high regenerative capacity through stem cell division as epithelium possess a unipotent stem cell that is capable of division and differentiation in to one type of epithelium only
▪️non vascular tissue but richly innervated
What are the types of simple epithelium
1-squamous
2-cuboidal
3-columnar
4-pseudocoddstratified columnar
Describe the simple squamous epithelium in terms of shape,site & function
Shape:flat cells forming thin sheets
Site:lining~ pulmonary alveoli, parietal layer of bowman’s capsule,blood and lymphatic vessels
Function:limiting membrane,fluid transport and gaseous exchange
Describe simple cuboidal epithelium in terms of shape, site and function
Shape:cuboidal
Site: thyroid gland follicles,covering of ovary,kidney tubules
Function: secretion, absorption and protection
Describe simple Columnar epithelium in terms of shape,site and function
Shape:columnar
Site: lining~ oviducts,uterus, much of digestive tract
Function: transportation,absorption,secretion and protection
Describe simple pseudostratified columnar epithelium in terms of shape site and function
Shape: all cells rest on basal lamina but not all reach epithelial surface(surface cells are columnar)
Site:lining~most of trachea and primary bronchi
Function: secretion, absorption, lubrication, protection and transportation
What are the types of stratified epithelium
1-non keratinized squamous 2-keratinized squamous 3-cuboidal 4-columnar 5-transitional
Describe stratified non keratinized squamous in terms of shape site and function
Shape: flat cells forming the most superficial cell layer
Site: lining~ oral cavity, oesophagus and vagina
Function: form a physical barrier for protection
Describe stratified keratinized squamous in terms in shape site and function
Shape:flat cells form the most superficial cell layer and covered by keratin
Site:skin
Function: protection
Describe stratified cuboidal epithelium in terms of shape site and function
Shape: cuboidal cells form the most superficial layer of cell layer
Site: ducts of sweat glands
Function: protection and secretion
Describe stratified columnar epithelium in terms of shape site and function
Shape:columnar
Site:conjunctiva of eye
Function: secretion and protection
Describe stratified transitional epithelium in terms of shape site and function
Shape:dome shaped
Site:lining ofurinary bladder and uterus
Function: protection and distensible
What is transitional epithelium and how is it adapted to its function
Its structurally adapted to volume changes
▪️has wide intercellular spaces allowing cells to glide and reduce number of layers in response to pressure
▪️The dome shaped cells form a barrier between urine and blood vessels in underlying tissue
