Anatomy Tissues Epithelia and Glands

composed of a group of cells with similar structure that perform related functions and are surrounded by extracellular material (non-living)

• epithelial for covering
• connective for support
• muscle for movement
• nervous for control

covering

support

movement

control

serves as a lining for organs that have an opening to the environment

• boundary layer
• interface layer
• protection
• transport such as secretion & absorption

• *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.

a single layer of epithelia designed to allow molecules to cross the membrane quickly (ex. capillaries & lungs)

• simple squamous epithelia
• simple cuboidal epithelia
• simple columnar epithelium
• pseudostratified columnar epithelium

a flat layer of cells that makes exchange of materials quick & easy.

Endothelium & Mesothelium

produces a slick slippery surface

serves as a middle covering as part of serosa found in body cavities

a layer of cube like cells, their height and width are just about equal. it forms gland ducts & tubules

a layer of tall cells that line the digestive tract & functions in absorption, secretion, & ion movement.

a single layer with cells of different heights appearing as if there are different layers.

• short cells - undifferentiated & give rise to tall cells
• tall cells - function of scretion & absorption

two or more layers of cells, cells rise from basal side. main function is protection

• stratified squamous epithelium,
• stratified cuboidal & columnar epithelium
• transitional 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

rare tissue that forms only large ducts of glands

lines hollow urinary organs & has the ability to stretch from six to three cells thick

• 1. apical surface features: microvilli & cilia
• 2. lateral surface features: cell junctions
• 3. basal surface features: the basal lamina

• 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.

cell junctions - cells are held together by proteins that attach the different cell surfaces

the basal lamina: thin non-cellular support sheet made up of proteins, controls what enters epithelium, assist in regeneration

groups of epithelial cells that make & secrete a substance

unicellular or multicellular

Exocrine Glands & Endocrine Glands

substances like mucus, sweat, & saliva are secreted onto body surfaces or cavities. Has ducts

have no ducts, secrete hormones into blood stream

exocrine glands