Epithelial Tissue Flashcards
4 types of tissue
Connective
Epithelial
Muscle
Nervous
Epithelial Tissue “covers”
Locations:
Body Surfaces
Linings of organs
Forms glands
Functions:
Protection: skin
Absorption: small intestine
Secretion: mucus glands
Diffusion: kidneys
Epithelial Distinct Tissue Surfaces
Apical Surface (free, upper):
-exposed to surface or cavity
-most smooth, some have microvilli
Basal Surface (lower, face inward toward body):
-attaches to basal membrane
-separates from underlying connective tissue
Cells connect…
…to surrounding cells and extra cellular matrix
-form continuous sheets
Lateral contacts
-tight junctions
-desmosomes
-gap junctions
Tight junctions
IMPERMEABLE JUNCTIONS
-block flow of fluids
-continuous seal around cell
-prevent molecules from passing between cells
Desmosomes
ANCHORING JUNCTIONS
-link with adjacent cells like molecular Velcro
-allow give between cells to reduce possibility of tearing under tension
Gap
COMMUNICATING JUNCTION
-form pores that allow small molecules to pass from cell to cell
-allow electrical signals to be passed
-allows tissues to coordinate responses to stimuli
-cardiac and smooth muscle cells
No vascular
-no blood vessels, on my nerve fibers
SO…epithelial cells get nutrients and oxygen through diffusion from capillaries
Regeneration
Die at rapid rate; requires adequate MITOSIS
Epithelial Tissues two names
1) Number of cell layers
2) Shape of cell
Epithelial Shape of cells
Squamous:
-flat, scale like
Cuboidal:
-cube shaped
Columnar:
-tall, column like
Number of Cell Layers Epithelial
Simple: one layer
Stratified: more than one layer
Pseudostradified: looks stratified but is one layer
Epithelial Glands
Endocrine glands:
-ductless since secretions diffuse into blood vessels (hormones)
Exocrine glands:
-secretions empty through ducts onto body surface or into cavities
-mucous, sweat, oil
