• LINES the inside and outside of the body and CREATE GLANDS.
• Epithelial tissues have very little extracellular matrix and are mostly composed of cells.
• Composed of layers of closely packed cells that cover organ surfaces, line structures, and form glands.
• Named by shape of apical cells (cells at the very top)
• Has distinct tissue surfaces: Free, basal; lateral.
• Polar
• Nonvascular (no blood connections)
• High regeneration capacity.

Exposed to external environment or internal body space ( lumen).

Surface of an epithelial cell attached to underlying connective tissue.

• Protecting underlying structures
• Acting as barriers
• Secreting substances
• Absorbing Substances

• Allows diffusion (movement of objects from one side to another) of gases, filtration of blood, secretion, absorption.

• Simple - 1 layer, inside.
• Stratified - several layers on top of one another, outside.

• Location:
  • One layer of cells in which all cells rest directly on the basement membrane but appear to be arranged in layers.
  • All cells touch the basement membrane.
• Function:
  • Allows diffusion (movement of objects from one side to another) of gases, filtration of blood, secretion, absorption.

Named by shape of apical cells (cells at the very top)

• Location:
  • Some cells rest on top of others and do not touch basement membrane.
• Function:
  • Protection, particularly against abrasion.
  • Subjected to wear-and-tear.

• Squamous
• Cuboidal
• Columnar

Allows diffusion or acts as filter.

An epithelial cell who’s the height and width are about equal.

• Function:
  • Secretion or absorption.

Secretion or absorption.

• Exocrine
• Endocrine

Have contact with the body surface (exterior) by way of a duct.

i.e. sweat, tear, & mammary glands.

Have no open contact with the surface and have no ducts and secreted directly to blood.

• Produce hormones

• Holocrine
• Merocrine
• Apocrine

Shedding of entire cells. VERY RARE

• Cells accumulate a product and then the entire cell disintegrates.
• Secretion = mixture of cell fragments and synthesized substance
• Location:
  • Sebaceous (oil) glands of scalp, glands of eyelids.

Glands have vesicles that release their secretion by exocytosis.

• No cell destruction during secretion.

Location:

• Sweat, salivary and tear glands, pancreas, gastric glands, and others

Primarily merocrine mode of secretion but cells are pinched off. RARE

Location:

• Axillary sweat glands (armpits), mammary glands

Location:

• Blood and lymphatic capillaries
• Alveoli of lungs
• Membranes of body cavities: pleural, pericardial and peritoneal

• Diffusion
• Secretion/absorption of Serous fluid in cavities
• Protection against abrasion/friction (wear & tear)

• Cell Shape: Single layer of thin, disc-like flatten cells
• Nucleus = flattened and hence, CANNOT be seen.

• Kidney tubules
• Terminal bronchioles of lungs
• Glands and their ducts

• Secretion and absorption by kidney tubules
• Movement of particles in mucus by ciliated cells of terminal bronchioles
• Secretion of cells of glands

• Cell Shape: Single layer of square or rounded cube-like cells.
• Some have MICRIVOLI (i.e. kidney tubules) or CILIA (i.e. terminal bronchioles of the lungs).
• Nucleis: Circular, located in center of cell

• Glands
• Bronchioles of lungs
• Intestines

• Cell secretions of the glands
• Movement of particles out of the bronchioles of the lungs by ciliated cells
• Absorption by cells of the small and large intestines by microvilli

• Cell shape: single layer of tall, narrow cells (rectangles)
• May contain Goblet Cells that create mucus within non-secretory epithelia.
• May contain CILIA and may contain GOBLET CELLS.
• Oval-shaped nucleus in basal half of the cell (lines up nicely).
• Vertical oriented
• Usually in basal half of cell.

• Trachea
• Bronchi of lungs
• lining of nasal cavity and sinuses

• Not all cells reach the free surface (apical free surface), thus creating a false appearance of stratification (looks multilayered)
• Contains CILIA and may contain GOBLET CELLS.
• Cell shape: Single layer, tall and short columnar cells

• Synthesize and secret mucus.
• Move mucus that contains foreign particles out of passages.

• Keratinized: epidermis of skin
• Non-Keratinized: Mouth, esophagus, anus, vagina

• Protections against abrasion, barrier against infection and reduce water loss
• Protections against abrasion, barrier against infection

• Cell Shape: Stratified (multiple layers) that are cuboidal in the basal layer with cells becoming increasingly flat/scaly toward to surface.
• Basal area may be more cuboidal in shape.
• Can be keratinized (layer of compact dead cells without nuclei).

• Cell Shape: Stratified (multiple layers) of all shapes & sizes.
  • Surface cells change from round to flat when stretched.
• Surface layer of cells are bulging & irregular (like lumpy pillows).

• Sweat gland ducts,
• ovarian follicular cells

Cell Shape: Stratified (2+ layers of cells), surface cells that are square or rounded (cubed-like).

• Secretion
• Absorption
• protection from infection

• Mammary gland ducts
• Male urethra

• Secretion of milk components
• Protection against caustic urine

• Lining of Bladder
• Ureters

• Expansion and stretching
• Protection against caustic urine