tissue histology the four primary tissue types epithelial connective muscular nervous
TRANSCRIPT
Epithelial Tissue
Epithelium / -a = cell layer (barrier)– Covering or lining—inside and out– Permeability control– Sensation– Glands = secretory structure
BM
apical
basal
Structural Characteristics of Epithelia
Cellularity
Polarity
Avascular
Innervated
Regenerative ability
Classification of EpitheliaThe function of the epithelium determines
which type.
Typically classified according to
1. Number of cell layersSimple vs. Stratified
2. Shape of cellSquamous, cuboidal, columnar
Special features Cilia, villi, goblet cells
End with epithelium to complete the naming
Simple Squamous Epithelium
1 cell thick
Friction reduction
Diffusion/filtration
Locations:
•Lining of ventral body cavities, e.g. peritoneum•Lining of blood vessels (endothelium)
•Alveoli
Simple Cuboidal Epithelium
• Function:
Secretion
Absorption• Location:
Lining of ducts
Glands (salivary, pancreas, thyroid)
Kidney tubules
Simple Columnar Epithelium
• FunctionsSecretionAbsorption
• LocationsGI tractExcretory ductsReproductive tract
• Special Features
Pseudostratified Ciliated Columnar Epithelium
Function:Mucociliary Blanket
Mixture of cell heights nuclei located at various distances from surface.
LocationsRespiratory tract except for lungs Male reproductive ducts
Stratified Squamous Epithelium
• Multiple layers = better protection
• Keratinized vs. non-keratinized
• Location? Where we need protection!Skin surfaceEntrances/exits of body
Transitional Epithelium
• Function
Extreme expansion & recoil
• Layered appearance due to overcrowding.
• Location
Bladder, ureters
Connective Tissue: Supports, protects, binds tissues
Structural characteristics:
• Specialized cells
• Extracellular matrix– Protein fibers – Ground substance
• Mostly highly vascular
Connective Tissue ProperTypes:
Areolar Dense regular ReticularAdipose Dense irregular
Types of Fibers:
CollagenElasticReticular
Defense:
MacrophagesPlasma CellsMast CellsOther WBC