I. Tissue Groups

Galena Park High SchoolA&

P

Instructor: Terry E. Jones

A. Definition

1. A group of closely associated cells that perform related functions and are similar

in structure.

B. Major Groups

• 1. Epithelia – surfaces• 2. Connective – support• 3. Muscular – movement• 4. Nervous - control

II. Epithelia Tissue

• A. Epithelium: sheet of cells that covers a body surface or lines a body cavity; also form most of the body’s glands

• B. Roles: as interfaces and as boundaries

• C. Functions:Protection AbsorptionSensory reception Ion transportSecretion Filtration Formation of slippery surfaces for

movement

D. Classification of Epithelia 1. According to thickness

a. “simple” - one cell layerb. “stratified” – more than one layer of cells (which are named according to the

shape of the cells in the apical layer)

• 2. According to shape a. “squamous” – wider than tall b. Used for protection c. Found in areas where diffusion is important

Simple Squamous

3. “cuboidal” – as tall as wide a. Found where there is exretion and absorption going on b. Large because of production of materials

Cuboidal

• 3. “columnar” - taller than wide a. Secretion of mucous b. Found commonly lining the digestive system c. Some with cilia line the bronchiole tubes of the lungs

• 4. “pseudostratified” – false layers a. appear to be in layers, but they are not b. All are in contact with the basal layer of cells c. They line the trachea

Pseudostratified

• E. Formation of Glands 1. Epithelial cells form them 2. Production & secretion of needed substances

3. Are aqueous (water-based) products

4. The protein product is made in rough ER, , packed into secretory granules by Golgi apparatus, released from the cell by exocytosis

• F. Classification of Glands 1. Exocrine: external secretion onto

body surfaces (skin) or into body cavities

2. Endocrine: secrete messenger molecules (hormones) which are carried by blood to target organs; “ductless” glands

Goblet Cell

Makes Mucus

G. Examples of exocrine gland products 1. Sweat glands of skin 2. Oil glands of skin 3. Salivary glands of mouth 4. Liver (bile) 5. Pancreas (digestive enzymes) 6. Mammary glands (milk