Epithelium Classification Flashcards

Question

What is the function of stratified cuboidal epithelium?

Answer 1

Barrier Conduit

Answer 2

Large ducts of glands (ie. Parotid Salivary Glands)

Answer 3

Barrier Conduit

Answer 4

Multiple Layers Variable Cell Shape Surface Layer of dome cells that are often binucleated Ability to Stretch

Answer 5

Urinary System: Ureter, Bladder, Kidney

Answer 6

Protection Barrier

Answer 7

* Forms external/luminal surface of the cell * Exhibit various modifications * Microvilli (Can't see in lab) * Increase surface area (absorption) * Small Intestine, Kidney * Size - 1 x 0.01 micrometer * Core is formed by actin filaments bound together by fimbrin and fascin anchored into the membrane by lateral anchoring proteins such as myosin I * Amorphous apex formed by villin by which the actin filaments anchor into * Stereocilia * Uncommon modified microvilli * Long and sometimes branching * Core formed by actin filaments similar to microvilli * Found in the epididymis (absorption) and inner ear cochlea (sensory receptors) * Cilia * Move substances along the surface of the epithelium * Respiratory tract and oviduct * Formed by 10 pairs of microtubule (axoneme) * 9 doublets and 1 central pair * Thicker than microvilli 2-10 x 0.25 micrometers * Base is attached to centriole/basal body * 9 triplets * Primary ciliary dyskinesia * Dextrocardia * Impaired development of skull air sinuses * No mucus removal from lunds -\>infection * Infertility * Secretory Vesicles * Present in epithelium involved in production and secretion of macromolecules

Answer 8

* Cell junctions - allows functioning as a whole * Occluding Junctions (Tight) * Apically oriented * Zonula occludens * Virtually impermeable, functions to prevent diffusion by blocking paracellular pathways (4 nm) * Formed by sealing strands of transmembrane proteins * Found in cells with secretory or absoptive roles * Anchoring Junctions * Provide stability and mechanical strength by connecting adjacent cytoskeletons * Two major types * Zonula Adherins * Connect actin to actin and not as tight at occluding junctions (20 nm) * Composed of: * Actin binding proteins * Vinculin, alpha-actinin * Peripheral protein * Cadherin family (Ca2+ dependent) * Plays important role in control of cell behavior * Macula adherins (desmosome) * Connects intermediate filaments * Epidermis of skin and muscle * Composed of: * Intracellular plaque * Made of desmoplakin * Intermediate filaments go throught the plaque * Transmembrane Proteins * Cadherin family * Pemphigus disease * body produces abnormal antibodies to the proteins forming desmosomes * Presents as blistering of skin and mucous membranes * Communicating Junctions (Gap Junctions) * Allow diffusion of small molecules and ions b/t adjacent cells * Intercellular channels (2.8 nm in diameter) * Formed by a pair of connexons * Each consists of 6 connexins * Usually occur in patches * Most common in epithelia, cardiac, smooth musclem, and embryonic tissues * Communication and cell proliferation

Answer 9

* Basement membrane * Separates epithelium from underlying connective tissue * 2 Layers * Basal Lamina * Most external layer that belongs to the epithelium * Mostly composed of sheets of collagen type IV and laminin * Reticular lamina * Deeper layer that belongs to the connective tissue * Mostly composed of thin collagen fibers (Type III) * Epithelial cells attach via anchoring junctions * Focal Adhesions * Attach actin cytoskeleton of cell to extracellular matrix * Composed of * Actin-binding proteins * Vinculin, alpha-actinin attach to microfiliaments * Peripheral protein * Talin * Connects actin binding proteins to transmembrane proteins * Transmembrane proteins * Integrin (Ca2+ dependent) * Hemidesmosomes * Attach intermediate filaments from cell cytoskeleton to extracellular matrix * Composed of: * Intracellular plaque (made of desmoplakin) * Intermediate filaments end on plaque * Transmembrane proteins * Integrin family - attach to extracellular proteins

Answer 10

* Endocrine glands * Secrete their product into the intercellular space or underlying tissue which then diffuse into the blood * Cells usually arranged in cords along capillaries that supply the gland * Exocrine glands * Secrete their product into ducts or spaces lined with epithelium * Cells usually arranged in acini or tubules

Answer 11

1. Merocrine 2. Apocrine 3. Holocrine

Answer 12

* Secretory product is delivered in membrane bound vesicles to the apical surface * Fuse with membrane and release via exocytosis * Three subtypes * Serous glands * Secrete thin, watery, protein rich secretion * Vesicles small and densely stained * Better developed RER than mucous cells * Cell cytoplasm stains more basophilic * RER occupies basal part of cell forcing nuclei to middle of the cell * Cells are usually pyramidal in shape * Serous acini rounded in shape * Example: pancreas and parotid salivary gland * Mucous glands * Produce mucins that consist of long chains of negatively charged carbohydrates attached to a small protein core * Mucins are viscous and important to lubrication and protection * Secretory granules are large and stain very lightly w/ H&E * RER not well developed * Nuclei are heterochromatic and occupy the basal position * Cells columnar in shape * Mucous acini have a tubular shape * Example: Goblet cells, glands of soft palate, Brunner's glands * Mixed glands (Seromucous glands) * Have both serous and mucous glands * Mucous cells form tubules capped by serous cells that form serous demilunes * Example: Submandibular salivary gland

Answer 13

* Secretion of product involves pinching of the apical cytoplasm w/ the formation of secretory vesicles * Found in mammary gland where it is responsible for releasing large lipid droplets into milk

Answer 14

* Secretion involves whole cell rather than its parts * Cells accumulate secretory product and goes through apoptosis resulting in both the cellular content and cell debris to be released into the lumen of the gland * Typical of sebaceous glands of the skin

Answer 15

* Individual secretroy cells scattered within non-secretory epithelium * Goblet cells are the most common * Specialized for the secretion of mucus * Scattered within the columnar epithelia of the GI and respiratory tracts

Answer 16

* Composed of more than one cell * Most form tubular invaginations from the surface * Allows increase in surface area * Terminal part = secretory portion * Serves as a duct * Connects secretory cells to the surface * If shaped like a flask = alveolar or acinar * Most often serous * If shaped like a tube = tubular * Most often mucous * If secretory tube ends with a flask-shaped dilation = tubuloalveolar * Always mixed/seromuscous

Answer 17

* Are contractile cells present in some glands between the basal lamina and in the secretory portion of glands and ducts * Contain contractile proteins (myosin) * Contraction causes expulsion of secretory product * Present in sweat glands, salivary glands, and in the mammary gland

Answer 18

Adenocarcinoma