Epithelial tissue Flashcards
There are 2 MAIN TYPES of epithelial tissue classified by ________
…function
The two types of epithelial tissue
Membranous & Glandular
Function of MEMBRANOUS epithelial tissue
(usually laid out in thin sheet)
-Protection/barrier
-Sensory = get outside info
Function of GLANDULAR epithelial tissue
-Secretion (of useful substances
-Absorption (intestines –> nutrients)
-Filtration (kidneys –> waste)
-Excretion
Another way glandular epithelium is classified
How the product is delivered
Definition of gland
One or more cells that makes/secretes aqueous fluid
The two types of Glandular Epithelium
Endocrine & Exocrine
Glandular Epithelium [Endocrine]
No contact w/ exterior of body (ductless/pipeless); produce hormones
(ex: pituitary, thyroid, adrenals, pancreas)
Glandular Epithelium [Exocrine]
Open to exterior of body via ducts (sweat/oil)
Structural classifications of Epithelial Tissue:
Unicellular & multicellular
Unicellular exocrine gland
Single cells scattered in an epithelial sheet amid cells with other functions
Multicellular exocrine gland
-Most of supportive connective tissue, secretory unit, blood supply, nerves
-3 main types
How are the types of multicellular exocrine glands classified
Based on changes in the gland as they release product
3 main types of multicellular exocrine gland
-Merocrine gland
-Apocrine gland
-Holocrine gland
Merocrine gland
-Sweat glands/cool off
-Vesicles use exocytosis to release into duct, which goes to the skin
Definition of exocytosis
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
Aprocrine gland
Shares product inside cell & piece of cell comes off so it can be released
Holocrine gland
Part of gland dies to release product
Generalizations regarding epithelial tissue
-Limited space btwn cells
-Basement membrane attached to membranous epithelium
-Apical surface is “free”
-Avascular (few blood vessels)
-Cells connected via desmosomes & tight junctions
Features of APICAL surfaces of epithelium
Microvilli & Cilia
Features of APICAL surfaces of epithelium [Microvilli]
-Finger-like extensions of cell membrane
-Increases surface area for absorption
(Ex: in small intestine)
Features of APICAL surfaces of epithelium [Cilia]
-Whip-like motile tensions
-Moves mucus, etc. over surface one way
(Ex: respiratory tubes)
Features of BASAL surface of epithelium
Basal lamina & Basement membrane
Features of BASAL surface of epithelium [Basal lamina]
Supportive sheet btwn epithelium & underlying connective tissue
-Selective filter
Features of BASAL surface of epithelium [Basement membrane]
Basal lamina + underlying reticular fiber layer
-Attaches epithelium to connective tissue below
