Final Exam Review Flashcards
What are the functions of epithelia?
Protection (mechanical, chemical, infectious) (skin), absorptions (GI tract), filtration (kidneys), excretion (kidney), secretion (glands) and sensory reception (taste buds)
What are the 5 characteristics of epithelial tissue?
- Polarity
- Specialized contacts
- Supported by connective tissue
- Innervated but avascular
- Regeneration
How are epithelial cells classified?
By shape (squamous, cuboidal, columnar)
By number of layers (simple, stratified)
Describe simple squamous epithelium
Single layer of flattened cells; diffusion, filtration and secretion; found in kidneys, lungs, heart, blood vessels, lymphatic vessels and serosae
Describe simple cuboidal epithelium
Single layer of cuboidal cells; secretion and absorption; found in kidney tubules, ducts and secretory portions of small glands and ovary surface
Describe simple columnar epithelium
Single layer of tall cells; many have microvilli or cilia; may contain mucus-secreting unicellular glands; absorption and secretion; found in digestive tract, gallbladder, excretory ducts, small bronchi, uterine tubes and regions of the uterus
Describe pseudostratified columnar epithelium
Single layer of cells of differing heights (all touch basement mem., not all reach surface); may contain mucus-secreting cells and bear cilia; secrete substances (particularly mucus); non-ciliated in sperm-carrying ducts and ducts of large glands; ciliated line trachea
Describe stratified squamous epithelium
Basal cells are cuboidal or columnar and metabolically active, surface cells are squamous; protects underlying tissues in areas subjected to abrasion; linings of esophagus, mouth and vagina, skin
Describe stratified cuboidal epithelium
Rare in the body; found in sweat and mammary glands; has 2 layers of cuboidal cells
Describe stratified columnar epithelium
Rare; small amounts found in pharynx, male urethra and glandular ducts; occurs in transition areas; only apical layer is columnar
Describe transitional epithelium
Basal cells are cuboidal or columnar; surface cells dome shaped (squamous-like); stretches readily; lines ureters, bladder and part of urethra
Describe endocrine glands
Internally secreting; ductless (empty hormonal products into blood); mostly compact multicellular organs, some unicellular
Describe exocrine glands
Externally secreting; secrete products onto body surfaces or into cavities (i.e. mucous, sweat, oil, saliva)
Describe unicellular exocrine glands
No ducts; found in epithelial linings of intestinal and respiratory tracts; mucous and goblet cells; exocytosis
Describe multicellular exocrine glands
Consist of an epithelium-derived duct and secretory unit; supportive CT surrounds secretory unit, supplies it with blood vessels and nerve fibers
Describe merocrine glands
Secrete products by exocytosis; pancreas, salivary glands and most sweat glands
Describe holocrine glands
Accumulate products until they rupture; replaced with underlying cells; sebaceous (oil) glands
Describe apocrine glands
Accumulate products just beneath the free surface; apex of cell pinches off, releasing secretory granules; controversial; mammary glands are both holocrine and apocrine
What are the functions of connective tissue?
Binding and supporting (ligaments, bones); protecting (bone, adipose); insulating (fat tissue); storing reserve fuel; transporting (blood)
What are the 3 characteristics of connective tissue?
Common Origin - arise from mesenchyme (embryonic tissue); Degrees of Vascularity; Extracellular Matrix - largely composed of nonliving extracellular matrix which separates living cells; allows tissue to bear weight
What is connective tissue ground substance?
Unstructured material that fills the space between the cells and contains fibers; composed of interstitial fluid, cell adhesion proteins (CT glue) and proteoglycans (trap water, GAGs); molecular sieve for nutrients and other substances to diffuse through to capillaries/cells
Describe collagen CT fibers
Cross-linked; extremely tough
Describe elastic CT fibers
Branching network; snap CT back into place after being stretched
Describe reticular CT fibers
Collagenous fibers; delicate network; surround blood vessels and support soft tissue of organs