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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.

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



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


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.


Reticular CT

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.


Dense Elastic

ligaments and large arteries, allows tissue to recoil after stretching,


Hyaline Cartilege

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.


Elastic cartilege

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)


Skeletal muscle

Desc: long, cylindrical, multinucleate, obvious striations

Func: voluntary, locomotion, manipulation

Location: attached to bones or skin


Cardiac Muscle

Desc: branching, striations, generally uninucleate, joined at intercalated discs

Func: as it contracts, it propels blood into the circulation, involuntary

Location: heart walls


Smooth Muscle

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


Nervous tissue

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.


Cutaneous membrane

SKIN! (stratified squamous epidermis + connective tissue dermis). exposed to the air and is a dry membrane.


Mucous 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.


Serous membrane

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.


Tissue repair

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)


Developmental aspects of tissues

primary germ layers: ectoderm, mesoderm, endoderm
nerve = ectoderm, muscle + CT from mesoderm, epithelial from ALL.