Do Now What is the definition of a tissue? Think about what makes up a tissue. Take a look at your brachial. What kind of tissues do you think make up your brachial?

Histology- Study of Tissues Chapter 5 Pages: 92-111

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Do Now Look back at the list you made of the types of tissues that make up the brachial. What do you think are the functions of those tissues?

Objectives Explain the difference between the different kinds of tissues To Identify the types of Epithelial Tissues To list the locations of each type of epithelial tissue

Have an issue? Need some tissues? Tissues: Groups of specialized cells which are similar in structure and perform common functions. 4 Types of Tissues Epithelial Form protective coverings Function in secretion and absorption Connective Provide support and protection Bind structures together Nervous Control and coordinate body activities Muscle Produce body movements * Most organs contain all 4 types

Epithelial Tissue: Where is it located? Forms covering of body surfaces Covers organs Forms inner lining of body cavities Lines hollow organs Major tissue in glands

Epithelial Tissue: Functions Protection from physical/chemical injury, infection, and dehydration Secretion, excretion, filtration and reabsorption of materials Ex: mucous glands and sweat glands Diffusion of certain gases, ions, and nutrients Sensory reception Has Sensory Neurons

Epithelial Tissue: Special Characteristics One free surface always exposed to the outside or open internal space: apical surface Attached to basement membrane on the other side Cells are tightly packed together Avascular: NO blood vessels!! Rely on diffusion from underlying connective tissue Divides rapidly by mitosis to replace damaged cells Classified according to top layer of cells

How to Classify Epithelial Tissue 1. Layers: Simple: just one layer Absorption Secretion Filtration Stratified: 2 or more layers Protection

How to Classify Epithelial Tissue Continued 2. Shape: Squamous: thin and flat Disc shaped nucleus (scale-like) Columnar: columns Oval nucleus Cuboidal: cubed (square shaped) Center round nucleus

Squamous Epithelium 1. Simple Squamous Single layer that is delicate (can be easily damaged) Functions: Diffusion Absorption Filtration Secretion Locations: Alveoli of the lungs Capillary walls Lines blood and lymph vessels

Squamous Epithelium 2. Stratified Squamous Multiple layers of cells (helps make tissue thicker) Functions: Protection against abrasion Protection against Pathogens Protection against chemicals Two Types: A. Keratinized: Layers of dry, dead squamous cells Cells produce a protein called keratin through a process called keratinization to harden and then die. Prevents water/substance loss Helps block chemicals and other organisms from entering Location: Epidermis B. Non-Keratinized: Cells kept moisten Locations: Oral Cavity Esophagus Vagina Anal Canal

Cuboidal Epithelium 2. Stratified Cuboidal Simple Cuboidal About 2-3 layers of cube-shaped cells Rare Function: Secretion Absorption Larger ducts of glands Location: Mammary glands Sweat glands Salivary Glands Pancreas Simple Cuboidal Single layer of cube-shaped cells Functions: Secretion Absorption Locattion: Ovaries Kidney tubules Ducts of glands (salivary, thyroid, pancreas and liver)

Columnar Epithelium 2. Stratified Columnar 1. Simple Columnar Multiple layers of tall, thin cells resting on layers of cuboidal cells Rare Functions: Secretion Absorption Locations: Small portion of male urethra Parts of the pharynx 1. Simple Columnar Single layer of tall, narrow cells Nuclei are near the basement membrane Can contain Cilia Goblet cells are often present These secrete mucus to protect tissues Functions: Absorption Secretion Locations: Uterus Stomach Intestines Most organs of digestive tract

Columnar Epithelium 3. Pseudostratified Ciliated Columnar Appeared stratified but are only a single Layer of cells Nuclei appear scattered to give this effect All cells touch basement membrane and have cilia on apical surface Goblet cells are also present Functions: Move material across the surface Locations: Nasal cavity Passageway of respiratory system

Transitional Epithelium Changes in response to tension Relaxed: Looks like stratified cuboidal Stretched: Looks like squamous Function: Tolerates excessive stretching Location: Bladder Ureters Urethra