4.03 Epithelium Flashcards
(29 cards)
Variation in morphology in epithelia depends on:
function and position in the body
Seven functions of epithelium
protection absorption secretion excretion sensory receptors filtration lubrication
T/F. The epithelium is derived solely from the ectoderm.
False. It is derived from all three germ layers.
T/F. The epidermis is derived solely from the ectoderm.
True.
T/F. Epithelia are vascular, because we bleed when we are cut.
False.
What is the purpose of microvilli?
To increase surface area for absorption
What is the difference between cilia and stereocilia?
The former is motile, while the latter is nonmotile
These operate as communication channels governing functions such as growth and cell division
cell junction
Three types of cell junctions
Tight junctions or zonula occludens
Adhering junctions or desmosomes, zonula adherens
Communication junctions or nexus junctions
What is the purpose of tight junctions?
block passage of molecules between adjacent cells
Purpose of adhering junctions
strong attachment in between cells, link the intermediate filaments to form robust structural framework for the entire epithelium
Purpose of communication junctions
provide a conduit for the passage of small molecules directly between adjacent cells; signaling; coordinate and synchronize functions of the epithelium
Kind of epithelium present in surfaces where the exchange of substances occurs
simple squamous
Kind of epithelium lining the intestines and the gall bladder
Simple columnar
Surface epithelium in tubules of kidneys, covering of the ovary, choroid plexus, capsule of lens.
Simple cuboidal
When the epithelium is keratinized, what happens to the cells?
The lose their nucleus and organelles
Kind of epithelium where all the cells are attached to the basal lamina, but not all of them reach the level of the lumen
pseudostratified columnar
Intermediate or transitional from between stratified squamous and columnar epithelia; this is characteristic of which organ system? hence what is it called?
transitional epithelium; urinary; uroepithelium
Epithelium composed of cells specialized in producing a secretion that differs in composition from blood or from intracellular fluid
Glandular epithelium
Glands that release their products into blood or lymph system for transport to target cells in another part of the body
Endocrine
Glands that take advantage of the principle of diffusion
Paracrine
Gland whose secretions is NOT discharged from the cell producing it
Accrine gland
- secretion released through the cell membrane with the cell remaining intact
- involves loss of a part of the apical cytoplasm
- release of the whole cell into the excretory ducts
- merocrine
- apocrine
- holocrine
- secretion is thin and watery
- secretion is thick and viscous
- mixture of 1 and 2
- secretion of cells
- serous
- mucous
- mixed
- cytogenic
