Epithelial Tissues Bio 223

Epithelial Tissues

Found on every internal and external body surface, primarily acts like barriers between the body and the external environment and between our organs and fluid filled cavities.

Functions of epithelial tissues are

proection, immune defense, secretion, transport into other tissues, and sensation.

Simple epithelial tissues

single layer -

squamous, columnar, and cuboidal

Location of squamous, columnar, and cuboidal?

squamous - alveoli

columnar - lining of the stomach

cuboidal - thyroid glands or kidneys

Straifited epithelial tissues

Mulitple layers of cells-

squamous, pseudostratified, transitional

location of stratified squamous, columnar, and cuboidal

squamous - lining of the esophagus

pseudostratified - lining of the trachea

transitional - lining the bladder

function of simple squamous epithelium

This tissue allows for large amounts of transport including diffusion, osmosis, filtration, and secretion

Function of simple cuboidal epithelium

This tissue is located in areas where secretion and absorption occur, and it provides limited protection

Function of simple columnar epithelium

Absorption and secretion, often with cilia or microvilli to aid in these processes

Function of pseudostratified columnar epithelium

Secretion and movement of mucus, often with cilia.

function of stratified squamous epithelium

protection from mechanical stresses and microorganisms, and prevents most water loss through skin

function of transitional epithelium

protection, gives tissues added distensibility

exocrine glands

release their secretions to the apical surface of the epithelium, generally to the exterior of the body or into a hollow organ that opens to the outside of the body. An exocrine gland secretes its product through a duct lined with epithelial cells. These secretions have local actions only—they can affect only the cells in their general vicinity. think about goblet cells

endocrine glands

lack ducts and secrete their products, which are usually hormones, directly into the blood; multicellular glands

What are the three types of exocrine secretion?

merocrine, holocrine, apocrine