Epithelial Tissues- A&P 1

4 tissue types

epithelial, connective tissue, nervous tissue, and muscle tissue

simple

a simple layer

stratisfied

two or more layers

pseudostratisfied

appears to have many layers bc cells are different height and shape. Nuclei appear at different heights

squamous

flat or scalelike cells forming a mosaic pattern

cuboidal

cells appear to be cube-like in cross section

columnar

cells are long and cylindrical like a column

epithelial tissue

• covers the body

• lines the inside of large body cavities and blood vessls

• glandular tissue, made for absorption, excretion, and secretions. ex. sweat

• growing on vascular connective tissue

• attached to basement membrane

mesothelium

lining internal body cavity

endothelium

lining blood/lymph vessels

epidermis

keratinized, stratified squamous epithelial cells (usually 4-5 layers)

dermis

connective tissues, blood vessels, oil and sweat glands, nerves, hair follicles

characteristics of epithelial tissue

• cells are close together with no intercellular substances

• cells reproduce rapidly (rapid healing)

simple squamous function

diffusion and filtration

simple squamous location

lines lungs, kidneys and heart

simple squamous description

single layer of flattened cells, disc shaped nuclei, air sacs in lungs specifically

simple cuboidal function

secretion and absorption

simple cuboidal location

kidney tubules, ducts, ovaries

simple cuboidal description

single layer of cubelike cells with large central spherical nuclei. Lumen in the center of ring it forms in the kidney

simple columnar function

secretion, absorption, protection of underlying tissue

simple columnar location

digestive tract (intestines), uterus

simple columnar description

single layer of tall cells with round to oval nuclei.

• some have cilia

• may contain goblet cells

pseudostratified columnar function

secretion of mucus and moves it with cilia (mucus elevator)

pseudostratified columnar location

trachea

pseudostratified columnar description

single layer of cells at differing heights, nuclei at different levels, may have goblet cells and cilia

stratified squamous function

protection from abrasions

stratified squamous location

esophagus

stratified squamous description

multi layered, cells are the surface are worn and flat compared to the bottom

• keratin formed in older cells

stratified cuboidal function

protection

stratified cuboidal location

sweat, mammary and salivary glands

stratified cuboidal description

two layers of cube like cells, forms a lumen

stratified columnar function

protection, secretion

stratified columnar location

rare, male urethra and parts of the pharynx

stratified columnar description

basal cells cuboidal, surface cells elongated

transitional epithelium function

stretchable, blocks diffusion (no leakage)

transitional epithelium location

bladder

transitional epithelium description

resembles stratified squamous and cuboidal, surface cells dome shaped.

purpose of epithelial tissue

• tight fitting seal between cells

• sits on nonliving basement membrane with CT under it

• avascular, no blood suppy

• nutrients diffuse up via CT

• regenerates quickly

microvilli

small projections of cell membrane that increase surface area for maximal nutrient absorption.

mucus elevator

cilia moves mucus up and out of the trachea. (pseudostratified columnar)

basement membrane

noncellular, nonliving. attached epithelial cells to the dermis. in between epidermis and dermis. made of collagen. CT under it.