Tissue Flashcards
Characteristics of Epithelial tissue PCARS
Polarity - apical (upper free) - smooth, slick, have microvilli, sometimes cilia & basal surface (lower, attached)
Connective Tissue Support - rests on and are supposed by connective tissue. deep to basal lamina is reticular lamina - network of collagen fibers. basal lamina and reticular lamina form basement membrane, which reinforces the epithelial sheet and resists stretching and tearing.
Avascular but innervated - no blood, but supplied by nerve fibers. nourished by underlying connective tissue.
Regeneration - highly regenerative as long as they receive adequate nutrition.
Specialized contacts - covering and lining fit closely together and form continuous sheets, also bound laterally w/ tight junctions and desmosomes.
Functions of ET PSAFES
Protection, secretion, absorption, filtration, excretion, sensory reception
Simple Squamous ET
Desc: single layer of flattened cells with flat nucleus, sparse cytoplasm. simplest.
Function: where rapid diffusion is necessary, filtration, secretion
Location: kidney, air sacs of lungs, lining of heart, blood and lymphatic vessels, ventral body cavity lining.
Simple cuboidal ET
Desc: Single layer of cube cells with large, spherical nuclei
Function: Secretion, absorption
Location: Kidney tubules, ducts / secretory portions of small glands, ovary surfaces
Simple Columnar ET
Desc: single layer of tall, closely packed cells w/ oval nuclei, may contain mucus secreting gob cells
Func: Absorption, secretion, ciliated types propel
Location: digestive tract, gall bladder, bronchi, uterus
Pseudostratified Columnar ET
Desc: Cells vary in height, nuclei at different levels. Appear stratified, but aren’t.
Func: Secretion, absorption, propulsion
Location: nonciliated: vas deferens, ciliated: trachea
Stratified Squamous ET
Desc: most widespread, thick membrane composed of several cell layers. basal cells are cuboidal/columnar & active in mitosis, surface cells are squamous and dead.
Func: protection
Location: nonkeratinized: mouth, esophagus, vag. keratinized: epidermis of skin!
Stratified Cuboidal ET
Desc: Rare. Typically 2 layers thick.
Loc: some sweat, mammary glands
Stratified Columnar ET
Desc: rare, only the apical layer is columnar.
Location: pharynx, male urethra, some glandular ducts, transition areas between two other types of epithelia.
Transitional ET
Desc: resembles both stratified squamous and stratified cuboidal.
Func: stretch when needed
Loc: ureters, bladder, urethra
Gland
One or more cells that makes and secrets an aqueous fluid called a secretion
Endocrine gland
ductless glands (secretions not released into a duct), secret hormones that travel through lymph or blood to their target organs.
Exocrine gland
Secretions released onto body surfaces (skin) or into body cavities, more numerous than endocrine glands. secrete products into ducts, ex: mucous, sweat, oil, saliva.
Unicellular Exocrine gland
mucous cells + goblet cells, found in epithelial linings of intestinal and respiratory tracts, produce mucin, which dissolves in water to form mucous.
Multicellular exocrine gland
composed of a duct and a secretory unit, usually surrounded by supportive connective tissue, which supplies blood and nerve fibers, extends into and divides gland into lobes. classified by structure and type of secretion.
Multicellular gland types
Structure: Simple - unbranched duct VS Compound: branched duct
Secretory units: Tubular: has tubes, VS Alveolar/acinar: small, flask-like sacs, VS tubuloalveolar: both types of secretory units.
Secretion: Merocrine (secrete products by exocytosis as produced), holocrine (accumulate within, then rupture), apocrine (accumulates within, but apex of cell pinches off, releasing the granule) - may not exist in humans
Characteristics of connective tissue
Common origin - arise from mesenchyme
Degrees of vascularity - cartilage = avascular, dense CT = poorly vascularized. other types = richly vascularized.
Extracellular matrix - nonliving cells