Epithelial Tissue

epithelial, connective, muscular, and nervous

four basic tissue types

ECM

If it's outside the cells, helps hold the tissue together, and is made by the cells

connective tissue

tissue producing very abundant ECM

muscle tissue

made up of elongated cells specialized for contraction and movement

nervous tissue

cells with long, fine processes specialized to receive, generate, and transmit nerve impulses

parenchyma and stroma

most organs can be divided into __

parenchyma

composed of the cells resposible for the organ’s specialized function
e.g. alveoli in the lungs

stroma

cells that play a supporting in the organ

brain and spinal cord; stroma

in the__, the __ is always connective tissue.

epithelial tissues

closely aggregated POLYHEDRAL cells adhering strongly to one another and to a thin layer of ECM

epithelia

line all external and internal surfaces of the body and all substances MUST cross this type of tissue to enter or leave the organ

cover, lining, and protecting surfaces

absorption

secretion

main functions of epithelial tissues

elongated

shape of nuclei in columnar cells

flattened

shape of nuclei in squamous cells

spherical

shape of nuclei in cuboidal/pyramidal cells

stained nuclei

Because the lipid-rich membranes of epithelial cells are frequently indistinguishable by light microscopy, the number and shape of their ___ are important indicators of cell shape and density.

connective tissue

where does epithelia get its nutrients and O2 from since it does not have blood vessels

lamina propia

the connective tissues that feeds epithelia lining in digestive, respiratory, and urinary systems

papillae / L. papula; skin or tongue

The area of contact between the two tissues may be increased by small evaginations called —- projecting from the connective tissue into the epithelium. Papillae occur most frequently in epithelial tissues subject to friction, such as the covering of the —-

basal pole

The region of the cell contacting the ECM and connective tissue is called the —-

apical pole

This part faces the outside world like a balcony or window facing a hallway or the outside. It’s where things come in or go out (like nutrients, mucus, or waste).

lateral surfaces

Regions of cuboidal or columnar cells that adjoin neighboring cells comprise the cells’ ——; cell membranes here often have numerous folds that increase the area and functional capacity of that surface.

basement membrane

The basal surface of all epithelia rests on a thin extracellular, felt-like sheet of macromolecules referred to as the ——

basal lamina and reticular lamin

basement membrane has 2 layers, these are:

basal lamina

• Right under the epithelial cells

• Looks like a thin, dense layer of fine threads

• Made mostly by the epithelial cells themselves

  • Think: the top part of the welcome mat

reticular lamina

• Just below the basal lamina, closer to connective tissue

• More fibrous and loose-looking

• Made by the connective tissue cells

  • Think: the bottom part of the welcome mat that’s fuzzier

tight or occluding

—- junctions form a seal between adjacent cells

adherent or anchoring

—- sites of strong cell adhesion

gap

—- junctions are channels for communication between adjacent cells

desmosomes

type of anchoring junction; attaches cell to another cell

hemidesmisomes

type of anchoring junction; attaches cell to the basal membrane

tight junction

Defects in —- may compromise the fetal blood–brain barrier, leading to severe neurologic disorders

e-cadherin

Loss of —- in epithelial cell tumors (carcinomas) promotes tumor invasion and the shift to malignancy

desmogleins and desmocollin

UNDER DESMOSOMES; under cadherin family proteins

desmoglein I

Autoimmunity against —— leads to dyshesive skin disorders characterized by reduced cohesion of epidermal cells

integrin

Mutations in the —- gene are linked to some types of epidermolysis bullosa, a skin blistering disorder

connexin

Mutations in various —- genes have been linked to certain types of deafness and peripheral neuropathy

adherens junction

like a rubber band that wraps around at the apical part of the cell and glues it with other cells

desmosome

like a rivet and provides a strong point of contact in between 2 cells

occludins, claudins, zo proteins

major transmembrane proteins in tight junction - zonula occludens

e cadherin, catenin

major transmembrane proteins in adherens junction - zonula adherens

cadherin family proteins - desmogleins and desmocollin

major transmembrane proteins in desmosomes - macula adherens

integrins

major transmembrane proteins in hemidesmosome

connexin

major transmembrane proteins in gap junctions

microvilli, stereocilia, cilia

whats special about apical ends of many columnar and cuboidal epithelial cells

celiac disease

autoimmune disorder where the autoimmune system attacks the microvilli when u eat gluten; creates malabsorption, stomach problems, and gut damage - microvilli heals when u stop eating it

microvilli

eli5: for absorbing nutrients from your food. More —- = more surface area = faster and better absorption. Like turning one sponge into 30 sponges!

stereocilia

are long, immotile projections found on certain epithelial cells, such as those in the male reproductive tract and inner ear, where they function in absorption and sensation of soundrespectively

kartagener syndrome

mutations in described proteins of cilia and flagella; immotile cilia = chronic respiratory infection and male infertilize casued by immotile spermatozoa

lining of vessels

serous lining of cavities - pericardiun, pleura, and peritoneum

alveoli lining

loop of henle

parietal layer of bowmans capsule

inner and middle ear

blood vessels

lymphatic vessels

;

factilitating the movement of the viscera, active transport by pinocytosis, secretion

distribution of SIMPLE SQUAMOUS EPITHELIUM; for __

Covering the ovary

Lining of distal and proximal convoluted tubules(kidney)

Ovary

Thyroid gland

;

covering and secretion

distribution of SIMPLE CUBOIDAL EPITHELIUM; for __

lining of GI and stomach

;

protection, lubrication, absorption, and secretion

distribution of SIMPLE COLUMNAR EPITHELIUM; for __

stratified squamous keratinized

has a tough, dry, waterproof outer layer made of keratin (a protective protein).

stratified squamous non keratinized

Thinner multilayered squamous cells without keratinized layer. “Wet epithelium”

keratinized

found in epidermis and skin - for protection, prevents water loss

non keratinized

found in mouth, esophagus, larynx, vagina, anal canal, and tongue - for protection, secretion, and prevents water loss

stratified cuboidal

found in sweat glands, developing ovarian follicles - for protection and secretion

stratified transitional

found in urinary passages - for protection and distensibility; dome shaped when relaxed and flat when stretched

stratified columnar

found in CONJUNCTIVA, pharynx, ANUS, uterus, MALE URETHRA, vas deferens, duct of salivary and sweat glands, respiratory surface of epiglottis - for protection

psueostratified

single layer of cells with variable shape and height with 2 or more distinct levels of nucleil; USUALLY CILIATED and found in the respiratory tract

exocrine glands

— remain connected with the surface epi thelium, the connection forming the tubular ducts lined with epithelium that deliver the secreted material where it is used.

endocrine glands

— lose the connection to their origi nal epithelium and therefore lack ducts. Thin-walled blood vessels (capillaries) absorb their secreted hormone products for transport in blood to target cells throughout the body.

simple gland; compound gland

Imagine a tree with a trunk (the duct) and branches (the secretory parts). Exocrine glands are classified by how simple or branched they are—and what the shape of the secretory parts look like.

If the trunk doesn’t split, it’s a — (just one duct).

If the trunk splits into multiple branches, it’s a —.

tubular, acinar, tubuloacinar

Now for the gland endings—those are the parts that actually make the stuff (like sweat, saliva, etc.):

If they’re —, they look like tiny tubes.

If they’re —, they’re round like little grapes.

If they have both, they’re called —

merocrine

cell makes a product and puts it in a tiny vesicle, and sends it out by exocytosis; cell stays intact

sweat and salivary glands

example of merocrine

holocrine

cell keeps building up product inside until its full then it bursts releasing contents and the cell dies

sebacious glands

example of holocrine

apocrine

product gathers at the top part of the cell, top part pinches off, releasing the product with a bit of cell membrane and cytoplasm ; cell is not destroyed but loses a chunk

carcinomas

malignant tumors of epithelial origin are called —-

adenocarcinomas

malignant tumors derived from glandular epithelial tissues are called —