CHAPTER 3 Flashcards
EPITHELIAL TISSUE
epithelium sheet of cells that covers a body surface or lines a body cavity
General forms
covering lining
General functions
outer layer of skin lines open cavities of eurogenital, digestive, and respiratory. covers organ walls of closed cavities
Special characteristics
glandular- secretory tissue
Polarity
2 surfaces. smooth and slick
Protection
underlying tissue from mechanical injury
Absorption
lining small intestine
Filtration
kidney
Excretion
sweat glands
Secretion
glands secrete enzymes, hormones, lubricating fluids
Sensory reception
specialized cells detect stimuli
Apical Surface
upper- free exposed to body exterior or to cavity of internal organ
Microvilli
fingerlike extensions of plasma membrane increase surface area, intestines/ kidney tubules; fuzzy brush border
Cilia
lining of trachea tiny hair like projections that propel substances along free surfaces
Basal surface
lower-attached, glycoprotein and collagen fibers lies adjacent to basal surface
Basal lamina
noncellular thin supporting sheet adhesive selective filter
Specialized contacts
tight junctions, desmosomes found between adjacent cells lateral
Supported by connective tissue
epithelial rests upon
Reticular lamina
layer of extracellular material containing a fine network of collagen fibers that belong to connective tissue
Basement membrane
formed from 2 laminae basal and reticular help resist stretching and tearing defines boundary
Avascular but innervated
no blood vessels must be nourished by diffusion from underlying connective tissue supplied by nerve fibers
Regeneration
high capacity
Classification
all have 2 names, 1st indicate number of cell layers, 2nd indicates shape of cells
Simple epithelia
single layer of cells found where absorption, secretion, or filtration occurs
Stratified epithelia
two or more layers of cells where cells stacked on top of each other. high abrasion where protection is important. mouth/ skin surface. shape can change with more layers.
Squamos cells
flattened scale like cells
Cuboidal cells
box like cells
columnar cells
tall and column shaped
simple sqaumous epithelium
single layer of flattened cells with disc shaped central nuclei and sparce cytoplasm the simplest of epthelia
simple squamous epithelium- function
allows passage of materials by diffusion and filtration in sites where protection is not important, secretes lubricating substances in serosae
simple squamous epithelium- location
kidney glomeruli, air sacs of lungs, lining of heart, blood and lymphatic vessels, lining of ventral body cavity (serosae)
Endothelium
specific name. lining lymphatic, blood, and heart vessels
Mesothelium
serous membranes that are lining ventral body and covering its organs
simple cuboidal epithelium
single layer of cube-like cells with large spherical central nuclei
simple cuboidal epithelium- functions
secretion and absorption
simple cuboidal epithelium- location
kidney tubules, ducts and secretory portions of small glands, ovary surface
simple columnar epithelium
single layer of tall cells with round to oval nuclei, some cells bear cilia, layer may contain mucus secreting unicellar glands (goblet cells)
simple columnar epithelium- function
absorption, secretion of mucus, enzymes, and other substances, ciliated type propels mucus(or reproductive cells) by ciliary action
simple columnar epithelium- location
non-ciliated type lines most of the digestive tract (stomach to anal canal), gallbladder and excretory ducts of some glands, ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus
Pseudostratified columnar epithelium
single layer of cells differing heights, some not reaching free surface, nuclei seen at different levels, may contain mucus secreting cells and bear cilia
Psueudostratified columnar epithelium- function
secretion, particularly of mucus, propulsion of mucus by ciliary action
Pseudostratified columnar epthelium- location
nonciliated type in males sperm carrying ducts and ducts of large glands, ciliated variety lines the trachea, most of the upper respiratory tract
Stratified squamos epithelium
thick membrane composed of several cell layers, basal cells are cuboidal or columnar and metabolically active, surface cells are flattened (squamos) In the keratinized type, the surface cells are full of keratin and dead, basal cells are active in mitosis and produce the cells of the more superficial layers
Stratified squamos epithelium- function
protects underlying tissues in areas subject to abrasion
Stratified squamos epithelium- location
non keratinized type forms the moist linings of the esophogus, mouth, and vagina
stratified squamos epithelium- location
forms the epidermis of skin, a dry membrane, nuclei/ living
Stratified cuboidal epithelium (rare)
sweat, mammary glands
Stratified columnar epithelium
limited distribution throughout body
Transitional epithelium
resembles stratified squamos and stratified cuboidal basal cells. cuboidal or columnar surface cells dome shaped or squamos like, depending on degree of origin stretch
Transitional epithelium- function
stretches readily and permits distension of urinary organ by contained urine
Transitional epithelium- location
lines the ureters, urinary bladder, and part of the urethra
Glandular epithelia
consist of one or more cells that make and secrete a secretion of water based fluid that usually contains proteins, lipids, or steroids
Glandular epithelia- classification
according to traits, location, and number of cells
location of glandular secretion
internally secreting (interstitial fluid or blood)
endocrine
gland secretes hormone into blood externally onto surface or into cavity
exocrine
uses duct to secrete to body surface or cavity
