Untitled Flashcards Set

a.    Transitional Epithelia

a.     Modified, Stratified squamous epithelia

b.    able to slide past one another and change shape to stretch

c.     forms lining organs in urinary system (urinary bladder, ureters, part of urethra)

                                                                                  i.     subject to considerable stretching

d.    basal layer cells are cuboidal or columnar

e.    free surface cells vary

f.      When not stretched, membrane is many layered, superficial cells are rounded and domelike

g.     When distended with urine, epithelium thins, surface cells flatten and become squamouslike

b.    Glandular Epithelium

a.     Gland:  one or more cells that make and secrete a product (secretion)

b.    Secretion:  contains protein molecules in solution

                                                                                  i.     Glandular cells obtain materials from blood to make secretion which is discharged back into blood

c.     Two types of glands:

                                                                                 i.     Endocrine glands

1.    Ductless glands:  not connected to surface

2.    Hormones (secretions) diffuse directly into blood vessels surrounding glands

3.    Thyroid, adrenals, pituitary

                                                                               ii.     Exocrine glands

1.    Empty secretions through ducts to the epithelial surface

2.    Sweat, oil, liver, mammary, salivary, pancreas, earwax – both internal and external surfaces

a.     Simple Epithelia:  most concerned with diffusion, osmosis, absorption, secretion and filtration; usually very thin

a.     Simple squamous epithelium

                                                                                  i.     Description:  single layer of thin, flat cells resting on basement membrane, surface view looks like floor tiles

                                                                                ii.     Function:  filtration, diffusion, osmosis and secretion in serous membranes

                                                                              iii.     Location:  in areas of little wear and tear; lines heart, blood vessels, lymphatic vessels, air sacs of lungs, Bowman’s capsules of kidneys

1.    forms serous membranes (serosae):  slick membranes that line and cover organs of ventral body cavity

b.    Simple cuboidal epitheliumn

                                                                                  i.     Description:  One layer of cuboidal cells on a basement membrane

                                                                                ii.     Function:  Secretion and absorption

                                                                              iii.     Location:  Common in glands and their ducts (salivary glands and pancreas), Forms walls of kidney tubules and covers surface of ovaries

c.     Simple columnar epithelium (may be non-ciliated or ciliated)

                                                                                  i.     Description:  Single layer of tall cells, nucleus at base, either have microvilli or cilia

1.    Goblet cells:  produce lubricating mucus, may be found in some locations

                                                                                ii.     Function:  secretion, absorption; moves mucus and other substances by ciliary action

                                                                              iii.     Location:  lines GI tract, ducts of many glands and gallbladder; lines upper respiratory tract, fallopian tubes, uterus, paranasal sinuses, mucosae or mucous membranes

d.    Pseudostratified Columnar Epithelium (may be non-ciliated or ciliated)

                                                                                  i.     Description:  Appears stratified because nuclei of cells are at different levels; all cells attached to basement membrane, but not all reach apical surface

                                                                                ii.     Function:  Secretion and movement of mucus by ciliary action

                                                                              iii.     Location:  lines airways of most upper respiratory tract, non-ciliated lines larger ducts of many glands, epididymis, part of male urethra

b.    Stratified Epithelia:  consist of two or more cell layers; more durable than simple; concerned with protection of underlying tissues where there wear and tear; some produce secretions

§  named for apical cells

a.     Stratified Squamous Epithelium

                                                                                  i.     Description:  Squamous at surface, Cuboidal/columnar near basement membrane. Basal cells continually divide, new cells are pushed toward apical surface, become dehydrated, shrunken and harder, apical cells lose cell junctions and get sloughed off

1.    Keratinized:  tough protein in apical layer and several layers deep, protect skin and underlying tissues from microbes, heat, chemicals

2.    Non-Keratinized:  no keratin deposited, tissue remains moist

                                                                                ii.     Function:  Protection

                                                                              iii.     Location:  Found in sites that undergo a lot of friction:  esophagus, mouth, covers tongue, vagina, outer portion of skin,