Tissues

• Definition: Collections of cells and extracellular materials that perform specific functions

• Intercellular Connections

– Gap junctions

– Tight junctions

– Intermediate junctions and desmosomes

• Early Embryonic Tissue: the Primary Germ Layers

– Ectoderm

– Mesoderm

– Endoderm

• Primary Tissue Types (Derived from the Embryonic Tissue)

– Epithelial Tissue

– Connective Tissue

– Muscle Tissue

– Neural Tissue

Epithelial Tissue

• Specialization of Epithelial Cells

– Polarity

– Cilia *

– Stereocilia *

– Microvilli

• Characteristics of Epithelial Tissue

– Layers of cells that form a barrier

– Free surface

– Basement membrane

– Closely packed cells

– Avascular

– Regeneration abilities

• Functions of Epithelial Tissue

– Physical protection

– Permeability Control

– Sensations

– Secretions

Classification of Epithelial Tissue

• Functional Classification

– Glandular epithelium

– Lining and covering epithelium

• Anatomical Classification (based on shape of cells and number of cell layers)

– Simple Squamous

• Anatomical Classification (based on shape of cells and number of cell layers)

– Simple Squamous

– Simple Cuboidal

• Anatomical Classification (based on shape of cells and number of cell layers)

– Simple Squamous

– Simple Cuboidal

– Simple Columnar

• Anatomical Classification (based on shape of cells and number of cell layers)

– Simple Squamous

– Simple Cuboidal

– Simple Columnar

– Stratified Squamous

• Anatomical Classification (based on shape of cells and number of cell layers)

– Simple Squamous

– Simple Cuboidal

– Simple Columnar

– Stratified Squamous

– Transitional

– Pseudostratified Columnar

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• Maintenance of Epithelial Structural Integrity

– Intercellular connections

• Desmosomes and intermediate junctions

– Basement membrane

– Regeneration ability