ch 4 vocab - tissue level of organization: epithelium + connective Flashcards
two major categories of epithelial tissue
epithelia and glands
epithelia
covers surfaces and lines body cavities
epithelial tissue 4 essential functions
- physical protection
- controls permeability
- provide sensation
- produce specialized secretions
epithelia structure
- apical (free) surface: allows for absorption and secretion
- basolateral surface
glands
cells that secrete substances
characteristics of epithelial tissue
- polarity
- high cellularity, tightly bound by cell junctions
- attachment - base of epithelium bound to noncellular basement membrane
- avascularity
2 major types of glands
endo and exocrine
endocrine glands
releases hormones into bloodstream
- no ducts
exocrine glands
secretes products via DUCTS onto epithelial surfaces
characteristics of epithelial cells
- closlely packed cells
- avascular
-arranged in single (secretes/absorbs) or multiple layers (protective)
cell adhesion molecules (CAMS)
group of transmembrane proteins that allow cells to adhere to each other
cell junctions
specialized areas of the plasma membrane that attach a cell to another cell or extracellular materials
type of cell junctions (3)
- gap
- tight
- desmosomes
gap junctions
cell to cell communication, allows the passage of small molecules and ions between cells
tight junctions
- form a band around cells whose membranes join together to form a virtually impermeable barrier to fluid
- found in bladder
desmosomes
CAMs and proteoglycans link opposing plasma membranes
2 types of desmosomes
spot and hemidesmosomes
spot desmosomes
small discs that stabilize the shape of the cell
hemidesmosomes
looks like 1/2 of a spot desmosomes and anchor cells to the basement membrane
layers of the basement membrane
- basal lamina: layer closer to the epithelium, functions as a selective
- reticular lamina: deeper portion of the basement membrane that consists of reticular fibers and ground substance
tendon vs ligaments
-tendon: cords of dense regular connective tissue that connects MUSCLE to BONE
-ligament: bundles of elastic and collagen fibers that connects BONE to BONE
shapes of epithelium cells
squamos - flat
cuboidal - square
columnar - rectangle
simple squamos epithelium function
reduces friction, controls vessel permeability, performs absorption and secretion
simple squamos epithelium location
lining of ventral body cavities
- heart, lungs
– forms serous membranes
transitional epithelium
epithelium that stretches and relaxes
goblet cells
secrete mucin/mucus
simple columnar epithelium lines the ____ and its function is ______
lines the stomach and other digestive organs
function is protection, absorption, secretion
simple cuboidal epithelium occurs as _______ and its function is _____
occurs as tubules in the kidney
function: limited protection, secretion, absorption
endothelium
epithelium that lines internal surface of heart and blood vessels
STRATIFIED squamos epithelium is found _____ and its function is to ________
- found in top layer/surface (epidermal) of skin
- to provide physical protection
this category of epithelia is found in areas exposed to abrasion and friction
STRATIFIED squamous epithelia
able to transport mucus across its surface
pseudostratified ciliated columnar epithelium