Epithelial Tissue Banner

[Home] [Free Gift] [Study Tips] [Class Notes] [About Me]

[Awards] [Links & Rings] [Site Map] [Graphics] [Online Tests]

*Epithelial tissue always has a free surface.  Cells are close together and attached to basement membrane.

*Epithelial tissue types are named by their shape and number of layers.  

Layer Designations

Simple

One layer of cells

Stratified

More than one layer of cells

Pseudostratified

One layer of cells that appears to be many layers.

Cell Shapes

Squamous

Flat cells

Cuboidal

Cube shaped cells

Columnar

Column shaped cells, tall and skinny

 

Types of Epithelial Tissue

Simple Squamous

Found in the alveoli of the lungs, lines blood vessels.  One layer of flat cells permits filtration and diffusion.

Stratified Squamous

Two types: keratinized and non-keratinized.  Keratinized found in dry areas like the skin and non-keratinized stratified squamous is found in wet areas like the esophagus and vagina.  The many layers of cells offer protection of these areas.

Simple Cuboidal

One layer of cube shaped cells.  Simple cuboidal lines the kidney tubules.  It's function is secretion and absorption.

Stratified Cuboidal

Many layers of cube shaped cells.  Stratified cuboidal lines the mammary glands and salivary glands.  Like stratified squamous, it's function is to offer protection of the areas it lines.

Simple Columnar

2 types: ciliated and non-ciliated.  Non-ciliated can be found in the GIT.  You will also find goblet cells here (which secrete mucus).  Ciliated simple columnar lines the fallopian tubes, and the cilia beat to move the oocyte through the tube.

Stratified Columnar

Like other stratified epithelial types, it's function is to protect.  Also secretion.  Rarest epithelial type.

Pseudostratified Columnar

Lines the Upper Respiratory Tract where it functions to produce and move mucus.  (Has cilia and goblet cells).

Transitional

Found in the lining of the urinary bladder.  The cells change shape from a rounder appearance to a flatter one as the bladder fills, so their function is to permit distention of the bladder.

Glandular Epithelium

Endocrine glands: Release their products (hormones) directly into the blood.  Examples of endocrine glands are the thyroid, pituitary, and ovary.

Exocrine glands: release product (sweat, oil, ear wax, milk, etc) into a duct.

Three Types of Multicellular Exocrine Glands

Holocrine

Apocrine

Merocrine

The whole cell and contents are secreted into duct.  Example: Sebacceous glands

Part of the cell pinches off and is secreted into the duct.  Example: mammary glands.

Only the products are secreted into the duct.  Most exocrine glands are this type.

 Image Back to Anatomy Index

 

[Home] [Free Gift] [Study Tips] [Class Notes] [About Me]

[Awards] [Links & Rings] [Site Map] [Graphics] [Online Tests]