Classification of Epithelial Tissues

Stratified Squamous

1. Many layers of flat cells. - Surface cells flat -Lower cells rounded and undergo mitosis continually to produce new cells to replace hose worn off surface. 2. Epidermis made up of stratified squamous cells. -Surface cells are dead -This epithelium is considered keratinizing because it produces the Keratin protein. 3. Stratified squamous lines the oral cavity, esophagus, & vagina. 4. In these locations, the surface cells are living and make up the mucous membranes of these organs. -This tissue is a barrier to microorganisms becuz the cells are very close together.

Simple Columnar Epithelium

1. One layer of column-shaped cells -Specialized for secretion and absorption 2. Stomach lining made up of columnar epithelium that secretes gastric juices for digestion 3. Lining of small intestine- secretes digestive enzymes but also absorb end products of digestion from the cavity of the intestine into the blood & lymph. * To absorb efficiently, columnar cells of the small intestine have microvilli, which increase surface area for absorption.

Ciliated Epithelium

1. One layer of column-shaped cells with cilia on their free surfaces 2. Ciliated epithelium lines the nasal cavities, larynx, trachea, and large bronchial tubes. - Cilia sweep mucus with trapped dust and bacteria from the inhaled air toward the pharynx to be swallowed. 3. Cilicated epithelium also the lines the walls of the fallopian tubes. -It sweeps the ovum towards the uterus.

Types of Epithelial Tissue

1. Simple Squamous 2. Stratified Squamous 3. Transitional 4. Cuboidal 5. Columnar 6. Ciliated

2 distinctive layers of Epithelial Cells

1. Simple- single layer of cells 2. Stratified- many layers of cells

Simple Cuboidal Epithelium

1. Single layer of cube shaped cells. 2. This type of tissue makes up functional units of the thyroid gland & salivary glands. 3. Thyroid & Salivary epithelial tissue are examples of glandular epithelium, whose function is secretion. -In these glands, cuboidal cells are arranged in small spheres and secrete into the cavity formed by the sphere. -In the thyroid gland, the cuboidal epithelium secretes the thyroid hormones -In the salivary glands, the cuboidal cells secrete saliva. 4. Cuboidal epithelium also makes up portions of the kidney tubules. They contain microvilli and their function is the reabsorption of useful materials back to the blood.

Simple Squamous

1. Single layer of flat cells -These cells are thin & very smooth -Alveoli & capillaries are composed of this tissue. -Alveoli- thinness of the cells permits diffusion of gases between the air & blood. -Capillaires- permits the exchange of gases, nutrients, and waste products between the blood & tissue fluid. -Interior surface of capillaries are very smooth and this is important because it prevents abnormal blood clotting within blood vessels.

3 Distinctive shapes of Epithelial Cells

1. Squamous- flat 2. Cuboidal- cube 3. Columnar- tall & narrow

Transitional Epithelium

1. Type of stratified epithelium in which the surface cells change shape from round to squamous. 2. The urinary bladder is lined with transitional epithelium -When bladder is empty, the surface cells are rounded. -As bladder fills, these cells become flattened. -Transitional epithelium enables the bladder to fill and stretch without tearing the lining

Classification of Epithelial Tissues

Based on: 1) type of cell in which the tissue is made of 2) shape 3) number of layers of cells