Flashcards in Tissue Deck (43)
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.
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.
Desc: resembles both stratified squamous and stratified cuboidal.
Func: stretch when needed
Loc: ureters, bladder, urethra
One or more cells that makes and secrets an aqueous fluid called a secretion
ductless glands (secretions not released into a duct), secret hormones that travel through lymph or blood to their target organs.
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
Function of ct
bind + support, protect, insulate, store fuel, transport substances within body
Structure of CT
ground substance + fibers = extracellular matrix. + cells
Ground Substance in CT
ground substance = unstructured material that fills the space between the cells and contains the fibers. made up of interstitial fluid, cell adhesion proteins (glue), and proteoglycans (proteins + polysaccharides)
Fibers in CT
3 types: collagen, elastic, reticular
collagen: strongest, most abundant, tough
elastic: long thin elastin fibers that allow stretch + recoil
reticular: short, fine, highly branched collagenous fibers, branch and offer more give.
Cells in CT
BLAST cells - forming cells. secrete ground substance and fibers.
fibroblasts - in CTP, chondroblasts - in cartilege, osteoblasts - in bone, hematopoietic stem cells - in bone marrow
CYTE - mature form, maintain matrix
chondrocytes in cartilege, osteocytes in bone.
Cells in CTP
macrophage (phagocytize foreign materials like bacteria and dust, dispose of dead tissue cells),
mast cell (detect microorganisms and initiate local inflammatory responses against them),
plasma cell (produce antibodies),
fat cell (stores nutrients)
CTP Loose Areolar
most widely distributed. gel-like matrix with all 3 fiber types; cells: fibroblasts, macrophages, mast cells, and some WBCs. defends against infection.
CTP Loose Adipose
Matrix is like areolar but sparse, closely packed with adipocytes (fat cells), nucleus pushed to side by large fat droplet. richly vascularized.
resembles areolar but fibers are reticular fibers. fibroblasts are called reticular cells. supports free blood cells in lymph nodes, spleen and bone marrow.
Dense Regular CT
closely packed bundles of collagen fibers running parallel to direction of pull. fibroblasts make fibers and ground substance. few cells. poorly vascularized.
Dense irregular CT
same elements as dense regular but bundles of collagen are thicker and irregularly arranged. resists tension from many directions.
ligaments and large arteries, allows tissue to recoil after stretching,
most abundant. matrix appears has no structure but is firm, and collagen fibers form an undetectable network, chondroblasts produce the matrix when mature chondrocytes lie in lacuna.
similar to hyaline cartilage but with more elastic fibers in matrix.
intermediate btw hyaline and dense regular connective tissue. thick collagen fibers predominate.
hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. very well vascularized. compact: very few gaps and spaces, very little porosity. spongy bone found on inside of bone - porous + have a sponge like appearance.
RBC ("erythrocyte") + WBC ("leucocyte") in fluid matrix (plasma), & platelet (for clotting)
Desc: long, cylindrical, multinucleate, obvious striations
Func: voluntary, locomotion, manipulation
Location: attached to bones or skin
Desc: branching, striations, generally uninucleate, joined at intercalated discs
Func: as it contracts, it propels blood into the circulation, involuntary
Location: heart walls
Desc: Spindle shaped cells with central nuclei, no striations, cells arranged closely to form sheets
Func: propels substances/objects along passageways, involuntary
Location: hollow organs
Neurons are branching cells, cell processes (axon/dendrites) are long and extend from nucleus-containing cell body. also contain supporting cells which protect and support neurons. Neurons transmit signals from sensory receptors to effectors.
SKIN! (stratified squamous epidermis + connective tissue dermis). exposed to the air and is a dry membrane.
line all body cavities that open to the body (digestive, respiratory, urogenital tracts) - wet or moist membranes, bathed by secretions (mucous or urine). for absorption or secretion. lamina propria.
moist membranes found in closed ventral body cavities. simple squamous + thin areolar connective tissue. parietal line cavity walls, visceral cover internal organs. serous fluid in between layers. pleurae, pericardium, peritoneum.
regeneration - same kind of tissue replaces destroyed tissue. original function is restored.
fibrosis - connective tissue replaces destroyed tissue. original function lost.
1. inflammation (release of inflammatory chemicals, dilation of blood vessels, increase in vessel permeability, clotting occurs)
2. organization restores blood supply (blood clot is replaces with granulation tissue, epithelium regenerates, fibroplasts produce collagen fibers to bridge gap, debris is phagotized)
3. Regeneration & fibrosis (scab detaches, fibrous tissue matures, epithelium thickens & resembles adjacent tissue, underlying scar tissue)