Unit 1 Epithelium Flashcards
4 basic tissue types
epithelial
connective
muscle
nervous
nervous tissue characteristics
- intertwining elongated processes
- no ECM
- transmission of nervous impulses
epithelial characteristics
- aggregated polyhedral cells
- small amt ECM
- lining, surface, secretion
muscle characteristics
- elongated contractile cells
- moderate amt ECM
- movement
connective characteristics
- fixed/wandering cells
- abundant ECM
- support/protection
epithelial tissue
sheet of cells that covers surfaces/cavities
2 forms of epithelia
covering/lining
glandular
functions of epithelia
protection, absorption, filtration, excretion, secretion, sensory reception
epithelia origins
all 3 embryonic germ layers
Where is epithelia from the ectoderm found?
skin. lining of mouth, nose, anus
Where is epithelia from the endoderm found?
respiratory/digestive tract
Where is epithelia from the mesoderm found?
CV system, mesenteries, kidney tubules, reproductive tract
5 general characteristics of epithelium
avascular (innervated) contiguous polarized regenerative basal lamina
functions of epithelium
protection/selectively permeable barrier secretion absorption transcellular transport sensation
classification of epithelia
layers: simple v. stratified
shape: squamous v. cuboidal v. columnar
stratified epithelia exception
shape can vary in each layer, thus it is named for the apical surface
simple epithelia characteristics
single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm
endothelium
simple squamous epithelium found in lymph vessels, blood vessels, heart
mesothelium
simple squamous epithelium found in mesenteries, ventral body cavity
simple epithelia function
allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae
simple epithelia location
kidney glomeruli, air sacs of lungs, lining of heart, blood vessels, and lymphatic vessels; lining of ventral cavity
simple cuboidal epithelia
single layer of tubelike cells with large spherical central nuclei
simple cuboidal function
secretion, absorption
simple cuboidal location
kidney tubules; ducts/secretory portions of small glands; ovary surface
simple columnar epithelia
single layer of tall cells with round to oval nuclei; some cells have cilia; may contain mucus secreting unicellular glands (goblet cells)
simple columnar function
absorption, secretions of mucus, enzymes, etc.; ciliated type propels mucus (or reproductive cells) by ciliary action
simple columnar location
conciliated lines most of digestive tract, gallbladder, excretory ducts of some glands; ciliated varieties lines small bronchi, uterine tubes, and some regions of the uterus
pseudostratified columnar epithelia
single layer of cells of differing heights, some not reading the free surface; nuclei seen at different level; may contain goblet cells and cilia
pseudostratified columnar function
secrete substances (mucus); propulsion of mucus by ciliary action
pseudostratified columnar location
conciliated type in sperm-carrying ducts, ducts of large glands; ciliated lines trachea, most of UR tract
stratified squamous epithelia
thick membrane composed of several layers; keratinized or non-keratinized
stratified squamous function
protects underlying tissues in areas subject to abrasion
stratified squamous location
nonkeratinized: moist linings of mouth, esophagus, vagina
keratinized: epidermis of skin
stratified cuboidal epithelia
rare; only 2 layers thick
found in sweat/mammary glands
stratified columnar epithelia
rare; only apical layer is columnar; occurs in tradition areas between 2 types of epithelia
pharynx, male urethra, some glandular ducts, conjunctiva
transitional epithelia
surface cells are dome shaped or squamouslike; resembles both squamous and cuboidal
transitional function
stretches readily, permits stored urine to distend bladder
transitional location
ureters, bladder, part of urethra
gland
one or more cells that make/secrete aqueous fluid
glandular classification
product release
number of cells
endocrine
internally secreting (ductless)
exocrine
externally secreting (ducts)
hormones
messenger chemicals that travel through lymph/blood to specific organs
simple exocrine
unbranched
compound exocrine
branched
tubular
secretory cells from ducts
alveolar (acinar)
secretary cells from sacs
tubuloalveolar
both types
types of secretion glands
serous acinus
mucous acinus
mixed acinus
serous acinus
thin, watery secretion w/protein
pyramidal cells w/basal nuclei
secretory granules in apical cytoplasm
small central lumen
mucous acinus
more viscous secretion, high carbs
pyramidal cell with basal nuclei (frequently flattened)
clear cytoplasm
large central lumen
mixed acinus
mucous acinus with serous demilune
intracellular channels deliver serous secretions to lumen
mode of secretion
merocrine
holocrine
apocrine
merocrine
aka eccrine
exocytosis
sweat, pancreas
holocrine
rupture
sebaceous glands
apocrine
only apex ruptures
mammary glands?