Epithelium

The connective tissue on which epithelia rest, lines the cavity of internal organs (digestive, respiratory, and urinary systems)

- Type IV collagen
- Glycoproteins (laminin and antactin)
- Proteoglycans

- Little extracellular material
- Avascular
- Have both free surface and basal surface
- Nerve supply
- High capacity for renewal

Synthesized by the connective tissue of the lamina propria

- Formed by invaginations in the connective tissue
- Allows for blood vessels to supply nutrients to the epithelia

- Type of cell adhesion molecule
- Interacts with the extracellular matrix
- Affects cell movement and shape

- An avascular type of skin that lines the world around you and lines the tubes in your body
- One of the four main tissues in the body.

Type 3 collagen and connective collagen

- Type of intercellular junction
- Wrap entire cells and connect cytoskeleton (actin filaments) of one cell to another

- Type of intercellular adhesion
- Very strong spot links between cells
- Reinforce the adhesion of the zonula adherens

- Mechanical protection
- Absorption
- Secretion of materials
- Lubrication of surfaces
- Formation of a surface for diffusion

- The attachement side of epithelial cells
- Binds epithelial cells to the underlying connective tissue
- Only seen with an electron microscope

- Binds type IV collagen and integrins (hemidesmosomes)
- Allows for attachment

- Formed by 2 laminae: basal and reticular
- Two laminae together make it visible under a light microscope

- Type of intercellular seal
- Tight junctions that close off intercellular space (fusion sites)
- Prevents diffusion between cells

- Adhesions
- Cell adhesion molecules (CAM)
- Seals
- Communication

- Covering epithelia
- Glandular epithelia

- Types of intercellular junctions
- Joins epithelial cells to the underlying basal lamina using integrins

- Type of cell adhesion molecule
- Glycoproteins that anchor cells together in zonula adherens
- Role in suppressing epithelial tumor cells

Where actin fiber bind at the base of the microvilli to remain upright

- Special stratified epithelium that lines pelvis of kidney, uterus, urinary bladder, and part of urethra
- Cells change according to the degree of distension of the organ

- Tubular
- Acinar/alveolar

- Scattered within an epithelium
- Secrete mucins that form mucus (goblet cells)

- Can absorb much more readily
- Have a non-cornified, wet outer layer

Multiple cell layers

- Cells disintegrate when secreting
- Secrete secretion and dead cell parts found in sebaceous glands near hair follicles

Flat shaped cell

- Has endocrine and exocrine glands
- Most of the glands are exocrine

- Superficial layers are flatter
- Deeper layers are more cuboidal
- Deepest have continuous cell division
- Function in protection

- Relaxed looks cuboidal
- Stretched looks squamous

- Single layer
- Cube or hexagonal shape
- Important in secretion (ex tears) or absoprtion (ex water)
- Seen in sweat glands (secretions) and kidneys (absorption)

- Forms gap junctions
- Consists of 6 integral proteins calls connexins
- Aligned like docking station

- Functions to increase surface area
- Seen in brush border of kidney tubule cell
- Also seen in striated borner of intestinal absorptive cell

- Structure
- Type of secretion
- Mode of secretion

Space in the gland that allows for secretion

- Simple
- Compound (branching)

Internal lining of ventral body cavities

1. Epithelium invaginates, cells grow down to the connective tissues beneath it
2. The connection with the surface epithelium disappears
3. Balls of epithelial cells that are not attached to the epithelium differentiate into endocrine cells (hormonal cells) that secrete into the bloodstream

- Endocrine glands
- Secrete hormones
- Many blood vessel in the area

- Thin and watery secretion
- Found in glands that are far away from the location they need to secret to
- Long ducts

- Tough and water resistant
- Cornified and dry outer layer

- Single layer
- Tall and cylindrical shape
- Important in protection, secretion, and absorption

- Attachment side of epithelial cells
- Binds epithelial cells to the underlying connective tissue
- Can only be seen with an electron microscope

- Formed by two laminae: basal and reticular
- The two laminae together make it visible under a microscope

- Process by which a cell takes in liquid from the surrounding environment
- How epithelial cells "drink"

- Mix between eccrine and holocrine glands
- Release secretions and sometimes dead cells
- Found in sweat glands in armpit or groind (body odor in puberty)

- Single layer
- Flat shape
- Allows for passive and active movement of substances (gas, fluid, etc) through the tissue

- Appears to be multiple layers but is not
- All cells are attached to the basal laminae
- Secrete or may be ciliated
- Seen mostly in respiratory system

- Columnar cells that have cilia
- Moves mucous and other substances

Single-cell layer

- Simple columnar non-ciliated epithelium
- Secrete mucous

- Simple columnar non-ciliated epithelium
- Have microvilli used for absorption

- Columnar cells that do not have cilia
- Secrete mucus or function in absorption

- Have thick and viscous secretion
- Found in glands that are right next to the locations they need to secrete to
- Short ducts

- Produce secretions that enter the lumen of the exocrine gland and leave through the duct to the outside world
- Release contents via exocytosis
- Sweat glands all over the body

Glands shaped like a sac or sphere

- Secrete through ducts to internal or external world
- Usually are divided into lobes and lobules

1. Epithelium invaginates, cells grow down to the connective tissue below the epithelia
2. The center core of the invagination hollows out
3. End of the invagination becomes the secretory portions of the gland (sweat, tears, saliva, digestive enzymes, etc.)

Internal lining of heart and blood vessels

- Secretory sheet
- Tubular invagination
- Ex. Lining of stomach

- Ductless
- Primarily associated with the endocrine system
- Secrete into extracellular fluids
- Diffuse into bloodstream

Cube or hexagonal-shaped cell

- Most apical junction separating lumen for intercellular spaces
- Involves transmembrane proteins occluden and claudin
- No crossing can occur between cells

- Move mucus and other substances
- Primarily found in trachea, bronchi, oviduct

- Long microvilli
- Only seen in epididumis and sensory (hair) cells of inner ear

- Commonly squamous
- Rarely cuboidal or columnar

Secrete a mix between watery and viscous secretion