Epithelial Cells

Question: To find which organs contain the different epithelial tissues.

1. What are Epithelial Tissues?

• Epithelial tissue is a sheet of cells that covers a body surface or lines a body cavity. Two forms occur in the human body:

a. Covering and lining epithelium- forms the outer layer of the skin; lines open cavities of the digestive and respiratory systems; covers the walls of organs of the closed ventral body cavity.

b. Glandular epithelium- surrounds glands within the body.

2. How are Epithelial classified?

• Epithelium has two names. The first name indicates the number of cell layers; the second describes the shape of its cell. Based on the number of cell layers, epithelia can either be simple or stratified.

• Simple epithelia- consist of a single cell layer (found where absorption, secretion, and filtration occur).

• Stratified epithelia- are composed of two or more cell layers stacked on top of each other.

All epithelial cells have six sides but they vary in height.

3. What are the three ways to describe the shape and height of epithelial cells?

1. Squamous cells- are flat and scale-like.

2. Cuboidal cells- are box-like (same height and width).

3. Columnar cells- are tall (column shaped).

Simple squamous epithelium:

Simple squamous epithelium- is close fitting and flattened laterally. They’re found where filtration occurs (kidneys, lungs). Two simple squamous epithelia in the body have special names reflecting their location.

1. Endothelium- provides a friction-reducing ling in lymphatic vessels and all hollow organs of the cardiovascular system (heart, blood vessels, and capillaries).

2. Mesothelium- is the epithelium found in serous membranes (membranes lining the ventral body cavity and covering the organs within it).

Simple cuboidal epithelium- consists of a single layer of cells with the same height and width. Functions include secretion and absorption (located in small ducts of glands and kidney tubules).

Simple columnar...