non-glandular epithelial tissue

cellularity

closely packed cells with limited extracellular material

cellular connections

tight junctions and desmosomes

tight junctions

neighboring cell membranes are extremely close; prevents substances from moving between cells; important barrier

desmosomes

mechanically attach neighboring cells; fibers tether cells together; gap is large enough to allow material to move between cells

tight junction example

brain tissue

desmosome example

epidermis

cellular organization

apical surface in contact with fluid or air; basal cell layer in contact with basement membrane (lamina)

epithelial tissue is supported by…

connective tissue

what is DEEP to the basement lamina

reticular lamina (layer of connective tissue)

basement membrane organization

basement lamina + reticular lamina

epithelial tissue qualities

innervated (supplied with nerves); avascular (no blood vessels)

cell division

highly regenerative

why does epithelial tissue experience cell loss

friction and contact with hostile environments

simple squamous

1 layer; flat shape and thin; nucleus is flat, thin, and oval; allows substances to move across easily (diffusion and filtration); alveoli, heart, aorta, vena cava, capillaries

simple cuboidal

1 layer; cube shaped; nucleus is large, round, and centrally located; secretion and absorption; nephron in kidney; microvilli on apical surfaces

simple columnar

1 layer; tall cells; nucleus is tall and oval and near basal lamina; absorption and secretion of mucus; stomach and intestines; villi and microvilli, goblet cells, cilia

pseudostratified columnar

1 layer (looks like many since the cells have different heights); irregularly shaped but all touching basement membrane, not all reach apical surface; at varying heights; mechanical movement of material, secretion and propulsion of mucus; in nose, fallopian tubes, epididymis; cilia and goblet cells

stratified squamous

multiple layers; surface cells are squamous (flat) and cuboidal or columnar in basal layers; nucleus is round at the base and flattened or absent in the dead surface cells; protection; epidermis, surface of tongue, end of digestive tract, opening of female reproductive tract; keratin in surface cells to make them tough and waterproof

stratified cuboidal

multiple layers; cube shaped cell; nucleus is round and centrally located; protection and durability; in ureter

stratified columnar

rare; multiple layers; apical cells are tall and rectangular; nucleus is elongated; protection and secretion; urethra, ducts of exocrine glands

transitional epithelia

multiple layers; basal cells are cuboidal, apical cells are dome shaped; cells change shape and appearance changes as the tissue stretches without tearing; urinary bladder, ureter, urethra; umbrella shaped cells change shape to allow stretching