Epithelial Tissue (pg 2)

Tissue = collection of cells that have similar structure and function together as a unit

Tissue = collection of cells that have similar structure and function together as a unit

Histology = Study of tissues

Epithelial Tissues

• Form the covering of all body surfaces, line body cavities and organs, and form glands

Epithelial Tissues

• Form the covering of all body surfaces, line body cavities and organs, and form glands

• Cells are tightly packed

Epithelial Tissues

• Form the covering of all body surfaces, line body cavities and organs, and form glands

• Cells are tightly packed

• One free surface

Epithelial Tissues

• Form the covering of all body surfaces, line body cavities and organs, and form glands

• Tightly packed

• One free surface

• Avascular (no blood vessels)

Epithelial Tissues

• Form the covering of all body surfaces, line body cavities and organs, and form glands

• Tightly packed

• One free surface

• Avascular (no blood vessels)

• Regenerate quickly

Shapes1. Squamous = flat cells, thin nuclei

Shapes1. Squamous = flat cells, thin nuclei

2. Cuboidal = cubelike cells, spherical central nuclei

Shapes1. Squamous = flat cells, thin nuclei

2. Cuboidal = cubelike cells, spherical central nuclei

3. Columnar = Tall narrow

cells, nuclei near bottom

Number of Layers

1. Simple = 1 layer

Number of Layers

1. Simple = 1 layer

2. Stratified = Multiple layers of cells. Named according to the type of cells at the free surface of the tissue

Number of Layers

1. Simple = 1 layer

2. Stratified = Multiple layers of cells. Named according to the type of cells at the free surface of the tissue

3. Pseudostratified = appears to be multiple layers, but is really only 1 layer

Glandular Epithelium

• Exocrine glands = secrete products onto a surface via a duct

Glandular Epithelium

• Exocrine glands = secrete products onto a surface via a duct

• Can be unicellular (goblet cells) or multicellular

Exocrine Glands

Classified according to STRUCTURE1. Simple: duct has no branches

2. Compound: duct has branches

Exocrine Glands

Classified according to STRUCTURE1. Simple: duct has no branches

2. Compound: duct has branches

3. Tubular: gland has the same diameter as the duct

4. Acinar (Alveolar): gland is saclike

Exocrine GlandsClassified according to SECRETIONS

1. Merocrine: fluid released by exocytosis

Example: salivary and pancreatic glands

Exocrine Glands• Classified according to SECRETIONS

1. Merocrine: fluid released by exocytosis

Example: salivary and pancreatic glands

2. Apocrine: small portion of cell is pinched off

Example: Mammary glands

Exocrine Glands• Classified according to SECRETIONS

1. Merocrine: fluid released by exocytosis

Example: salivary and pancreatic glands

2. Apocrine: small portion of cell is pinched off

Example: Mammary glands

3. Holocrine: Cells fill with product and rupture

Example: Sebaceous (oil) glands