Epithelium

Front 1

Where is Stratified Cuboidal Epithelium found?

Back 1

Lines the duct of sweat glands but is otherwise uncommon

Front 2

Where is Stratified Columnar Epithelium found?

Back 2

Relatively uncommon, but is occasionally found in the large excretory ducts of some glands and in the cavernous urethra

Front 3

Where is Pseudostratified Epithelium found?

Back 3

Lines the trachea, primary bronchi, excretory ducts in the parotid gland, etc.

Front 4

Where is Transitional Epithelium found?

Back 4

Lines excretory passages in the urinary system (from the renal calcyes to the urethra)

Front 5

What is the function of the zonula occludens and where is it found?

Back 5

Zonula Occludens (tight junction) Most apical Region where outer leaflets of adjacent plasma membranes fuse to form a zone around the entire apical perimeter of the cells In freeze-fracture preparations, the end face view of this zone of fusion reveals a branching anastomosing network of intramembranous strands on the P face and grooves on the corresponding E face Complexity and number of strands (in apical to basal direction) determine the

Back 6

What is the function of the zonula adherens and where is it found?

Front 7

What is the function of the macula adherens and where is it found?

Back 7

Macula Adherens (desmosome) Third component of the junctional complex but also commonly found elsewhere attaching epithelial cells together A focal, diskshaped adhesive junction between adjacent epithelial cells The adjacent cells are separated by a 15 to 30nm space, and a dense plaque is present on the cytoplasmic surface of each of the opposing plasma membranes Intermediate (10nm) keratin filaments (tonofilaments) from the cytoplasm loop into and out of the dense plaques. Intercellular space between the two halves of the desmosomes has dense material and delicate striations representing transmembrane linkers that are believed to assist in stabilizing this junction

Front 8

What is the function of the gap junction and where is it found?

Back 8

Gap Junction (nexus, communicating junction) Plaque-like specialization composed of an ordered arrary of subunits Not limited to epithelium but common cells in the central nervous system, as well as between cardiac muscle and smooth muscle cells (where it was discovered and given the name

Front 9

Describe the structure and function of Basal Surfaces.

Back 9

Acellular (20-100nm) Produced by the cells resting on it Two zones lamina rare (lamina lucida) Low density, next to the plasma membrane Lamina densa a more dense meshwork of filaments Reticular lamina comprises the

Front 10

What is the function of a Hemidesmosome and where is it found?

Back 10

Hemidesmosome (incomplete desmosome) Attaches cells to the underlying basal lamina An attachment specialization that has the appearance of one half of a desmosome Present along the basal surface of cells in certain epithelium, such as the basal cells in stratified squamous epithelia, myoepithelial cells in the mammary gland and salivary glands, and basal cells in the tracheal epithelium

Front 11

Describe the features and function of Microvilli.

Back 11

General Structure Average 1-3 um in length Bundle of actin fillament anchored in the terminal web Cross-Section Core of actin filaments cross-lined by actin-bundling proteins; diameter 50-100 nm Motion Trajector Passive movement due to contraction of terminal web Localization and Function Increases absorptive surface of cell Located in the brush border and kidney tubule cells

Front 12

Describe the features and function of Sterocilia.

Back 12

General Structure Very long 120um Actin filament bundle anchored in the terminal web capable of regeneration (inner ear) Cross-Section Core of actin filaments cross-lined by actin-bundling proteins; diameter 100-150 nm Motion Trajector Passive movement due to fluid flow (genital system) or vibration of endolymph (inner ear) Localization and Function Male reproductive system, epididymis Proximal part of ductuc deferens Have absorptive function In sensory hair cells as mechanoreceptors

Front 13

Describe the features and function of motile cilia

Back 13

General Structure 5-10um in length Cross-Section 9+2 microtubules arragemtn 250nm in diameter Motion Trajector Active movement; rapid forward movement with slow recover stoke (half cone trajectory) Localization and Function Found on epithelia that transport secretions, proteins, foreign bodies Are the flagella in sperm

Front 14

Describe the features and function of primary cilia.

Back 14

General Structure Average 2-3 um in length Have axoneme and basal bodies Specialized plasma membrane with Ca2+ entry channels and intraflagellar transport system Cross-Section 9+0 pattern 250nm in diameter Motion Trajector No active movement passively bend due to fluid flow Localization and Function Found on almost all cells in the body Sensory antennae Generate and trasmit signals from extracellular space into cell

Front 15

Describe the features and function of nodal cilia

Back 15

General Structure 5-6 um in length Have structure similar to primary cilia except they have an ability for active movement Cross-Section 9+0 pattern 250nm in diameter Motion Trajector Acgive rotational movement (full cone) Localization and Function Embryo during gastrulation on the bilaminar disc near the area of primitive node Essential in developing left right asymmetry of internal organs