What in the Cell Are You Talking About? An Introduction to the Fundamental Epithelial Cells of the Human Body

Opening Questions: 1.List the three (3) primary shapes of human epithelial cells. 2.Where in the human body would one find transitional epithelium? 3.What type of epithelial cell is our skin?

Objectives of Lesson Recognize the various types of epithelial cells found in the human body Identify various shapes of epithelial cells Identify characteristics of epithelial cells Identify significant parts of each cell Determine tissues associated with cells based on specific morphology

The Human Body Tissue - Group of similar cells and their intercellular substance that performs a specialized function. Histology - The study of tissues

Overview of 4 Basic Tissue Types: –Epithelial: tissues that cover the body’s surfaces, lines the body cavities, hollow organs, ducts and houses glandular cells –Connective: protects, supports the body and organs, binds organs together, stores energy reserves as fat and produces immunity –Muscle: movement of tissue -Nervous: initiates and transmits nerve impulses that coordinate body activity

Epithelium Background: –The term "epithelium" comes from the Greek roots "epi-" which means "upon" and "thele" = "breast," and originally meant only the skin on the breast, particularly around the nipple.

Epithelial Tissue Characteristics: –Epithelial tissue covers surfaces with an uninterrupted layer of cells. -Epithelial cells are attached to one another. –Intercellular spaces in epithelium are small. –Epithelial cells are polarized. -Epithelial cells are separated from the underlying tissue by a basement membrane.

Cellular Shapes Squamous: flat and attached together similar to tiles Cuboidal: cube or hexagonal shaped Produce secretions (sweat, enzymes, etc.) Able to absorb (intestinal tract) Columnar: tall, narrow, cylindrical protection of underlying tissue- specialized for secretion and absorption Can be ciliated Transitional: vary in shape Flat to columnar due to stretching of the associated tissue

Arrangement of Layers: Cellular examples: a. squamous b. cuboidal c. columnar -Simple: single layer of cells found in areas where passive and active transport are needed

Arrangement of Layers: Cellular examples: a. squamous b. cuboidal c. columnar d. transitional -Stratified: two or more layers used for protection of underlying tissue in areas of “wear and tear”

Arrangement of Layers: Cellular examples: a. columnar -Pseudostratified: single layer of a mixture of cell shapes; appears to be multi-layered

Glandular Epithelium Primary Function: - Secretory purposes -Cells found below the outer epithelium a.Endocrine: ductless glands; hormones b.Exocrine: secreted into ducts; mucus, sweat, oil and digestive enzymes

Now, let’s take a look…

Simple Squamous Epithelium Characteristics: –Single Layered –Oblong, polyhedral- shaped with a prominent nucleus Examples: –Bowman’s capsule in kidney –Alveoli of the lung

Simple Cuboidal Epithelium Characteristics: –Shaped like a cube –Single layer Examples: –Collecting tubules of kidney –Ducts of many glands –Ciliary body of eye

Simple Columnar Epithelium Characteristics: –Long and thin (columns) –Single layer Examples: –Mucous membrane of stomach –Large and small bowels –Small bronchi of respiratory system

Stratified Squamous Epithelium Characteristics: –Oblong, polyhedral- shaped with a prominent nucleus –stacked in symmetrical layers –Keratinized and non- keratinized Examples: –Epidermis of skin –Mucous membranes (esophogus)

Stratified Cuboidal Epithelium Characteristics: –Cube-shaped –Found in layers Examples: –Ducts of sweat glands found throughout the body –Sebaceous glands of skin

Stratified Columnar Epithelium Characteristics: –Rare –Shaped liked columns –Stacked on each other in symmetrical layers Examples: –Pharynx –Larynx –Urethra

Pseudostratified Columnar Epithelium Characteristics: –Ciliated –Stacked hap-hazardly in layers of columns Examples: –Tracheal mucosa of airways

Transitional Epithelium Characteristics: –Vary in shape: cuboidal and squamous –have the capacity to stretch and flatten Examples: –Renal calyces and pelvis –Ureter –Urinary Bladder

Test Time!!!

SIMPLE COLUMNAR EPITHELIUM

PSEUDOSTRATIFED CILIATED COLUMNAR EPITHELIUM

SIMPLE SQUAMOUS EPITHELIUM

STRATIFIED SQUAMOUS EPITHELIUM

TRANSITIONAL EPITHELIUM

SIMPLE CUBOIDAL EPITHELIUM

Citations Illustrations: