What in the Cell Are What in the Cell Are You Talking About?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 ShapesSquamous: flat and attached together similar to tilesCuboidal: 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 absorptionCan be ciliated

Transitional: vary in shapeFlat to columnar due to stretching of the associated tissue

Arrangement of Layers:

Cellular examples:a. squamousb. cuboidalc. columnar

-Simple: single layer of cells found in areas where passive and active transport are needed

Arrangement of Layers:

Cellular examples:a. squamousb. cuboidalc. columnard. 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 EpitheliumPrimary Function:

- Secretory purposes-Cells found below the

outer epitheliuma. Endocrine: ductless glands; hormonesb. 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

CitationsIllustrations:

www.psbc.org/education/hematology/basics/cell.htm

www.users.tpg.au/users/amcgann/body/

www.echiropractic.net/what_is_a_subluxation.htm

www.webschoolsolutions.com/patts/systems/muscles.htm

www.bweems.com/sccafx.html

www.lima.ohio-state.edu/biology/epithelial_tissue.htm

www.unomaha.edu/~swick/2740epithelium.html#cub