Anatomy Tissues Epithelia and Glands
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Anatomy Tissues Epithelia and Glands
CH 4. Epithelia and Glands
What is a tissue?
composed of a group of cells with similar structure that perform related functions and are surrounded by extracellular material (non-living)
What are the 4 different tissue types?
epithelial for covering
connective for support
muscle for movement
nervous for control
What are Epithelial Tissues for?
What are connective tissues for?
What are muscle tissues for?
What are nervous tissues for?
What are epithelial tissues?
serves as a lining for organs that have an opening to the environment
What are the functions of epithelial tissues?
transport such as secretion & absorption
What are the special characteristics of epithelia?
*Cellularity - dense cell areas, multiple points of connection between cells, few extracellular matrix material
* specialized contacts - multiple cell kjunctions tightly connect neighboring cells
* polarity - each cell has a distinguishable apical (top) and basal (bottom) side
* support by connective tissue - an underlying layer of connective tissue supports epithelial tissue
* avascular but innervated - blood vessels do not cross into epithelial tissue but nerve endings do
* regenetration - epithelial cells line organs that are exposed to many conditions that destroy the cells & have a great ability to regenerate quickly.
What is simple epithelia?
a single layer of epithelia designed to allow molecules to cross the membrane quickly (ex. capillaries & lungs)
What are the 4 types of simple epithelia?
simple squamous epithelia
simple cuboidal epithelia
simple columnar epithelium
pseudostratified columnar epithelium
What is simple squamous epithelia?
a flat layer of cells that makes exchange of materials quick & easy.
What are the 2 types of simple squamous epithelia?
Endothelium & Mesothelium
What is Endothelium?
produces a slick slippery surface
What is Mesothelium?
serves as a middle covering as part of serosa found in body cavities
What is simple cuboidal epithelia?
a layer of cube like cells, their height and width are just about equal. it forms gland ducts & tubules
What is simple columnar epithelium?
a layer of tall cells that line the digestive tract & functions in absorption, secretion, & ion movement.
What is pseudostratified columnar epithelium?
a single layer with cells of different heights appearing as if there are different layers.
What do the short & tall cells in pseudostratified columnar epithelium do?
short cells - undifferentiated & give rise to tall cells
tall cells - function of scretion & absorption
What is stratified epithelia?
two or more layers of cells, cells rise from basal side. main function is protection
What are the 3 stratified epithelia?
stratified squamous epithelium,
stratified cuboidal & columnar epithelium
What is stratified squamous epithelium?
many layers of cuboidal or columnar cells with squamous cells at the surface. It is the best form of protection & lines areas that are often-abraded. This type may be keratinized or not keratinized
What is stratified cuboidal & columnar epithelium?
rare tissue that forms only large ducts of glands
What is transitional epithelium?
lines hollow urinary organs & has the ability to stretch from six to three cells thick
What are the epithelial surface features?
1. apical surface features
: microvilli & cilia
2. lateral surface features
: cell junctions
3. basal surface features
: the basal lamina
What are the epithelial apical surface features?
plasma membrane extensions on apical side
microvilli & cilia:
- microvilli increase the surface area
- cilia move to push substances in a certain direction with protein structures in it.
What are the epithelial lateral surface features?
cell junctions - cells are held together by proteins that attach the different cell surfaces
What are the epithelial basal surface features?
the basal lamina: thin non-cellular support sheet made up of proteins, controls what enters epithelium, assist in regeneration
What are Glands?
groups of epithelial cells that make & secrete a substance
What can Glands be?
unicellular or multicellular
What are the 2 type of glands?
Exocrine Glands & Endocrine Glands
What are exocrine glands?
substances like mucus, sweat, & saliva are secreted onto body surfaces or cavities. Has ducts
What are endocrine glands?
have no ducts, secrete hormones into blood stream
What has ducts? endocrine glands or exocrine glands?