CH 4 - Tissues Pt 1

slides 1-41

cells live and work together in communities called

tissues

tissues -

groups of similar cells that perform a common function

extracellular matrix -

nonliving material between cells

four basic tissue types

epithelial, connective, muscle, nervous

epithelial basic function

covering and protection

connective tissue basic function

support

muscle tissue basic function

movement

nervous tissue basic function

control

epithelial tissue properties

• covers a body surface or lines a body cavity

• forms parts of most glands

functions of epithelia

protection, secretion, absorption, diffusion, filtration, sensory reception

special characteristics of epithelium - cellularity

tightly packed cells (separated by minimal extracellular material)

special characteristics of epithelium - specialized junctions

connect adjacent cells

special characteristics of epithelium - avascular

no blood vessels, but are innervated (epithelia receive nutrients from underlying connective tissue)

special characteristics of epithelium - regenerative abilities

lost cells are rapidly replaced by cell division

special characteristics of epithelium - supported by

an underlying layer of connective tissue

special characteristics of epithelium - polarity

apical and basal surfaces which differ in structure and function

epithelia - first name of tissue indicates

number of layers

simple epithelia

single layer of cells attached to basement membrane

stratified epithelia

multiple layers of cells

• basal layer of celled attached to basement membrane

epithelia - last name of tissue describes

shape of cells

squamous

cells are wider than tall (plate-like)

cuboidal -

cells are wide as tall, like cubes

columnar -

cells are taller than they are wide, like columns

epithelia - shapes of nuclei

conform to the shapes of the cell

simple squamous function

• passage of material by passive diffusion and filteration

• secretes lubricating substances in serosa

simple squamous location

• renal corpuscles

• alveoli of lungs

• lining of heart, blood, and lymphatic vessels

• singing of ventral body cavity (serosa)

  • tend to be located in places where protection is not important

simple squamous description

single layer; flat cells with disc-shaped nuclei

simple cuboidal location

kidney tubules; ducts and secretory portions of small glands; ovary surface

simple cuboidal description

single layer of tubelike cells with large, spherical central nuclei

simple cuboidal function

secretion and absorption

simple columnar two types

nonciliated and ciliated

simple columnar nonciliated location

lines most of the digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands

simple columnar ciliated location

lines small bronchi, uterine tubes, and some regions of the uterus

simple columnar description

single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells)

simple columnar function

absorption; secretion of mucus, enzymes, and other substances; ciliated types propels mucus (or reproductive cells) by ciliary action

psuedostratified columnar

• all cells originate at basement membrane

• only tall cells reach the apical surface

• may contain goblet cells and have cilia

• nuclei lie at varying heights within cells

psuedostratified columnar nonciliated type location

in male’s sperm-carrying ducts and ducts of large glands

psuedostratified columnar ciliated type location

lines the trachea, most of the upper respiratory tract

psuedostratified columnar description

single layer of cells of different heights, some not reaching the free surface; nuclei seen at different levels; may contain muscus-secreting goblet cells and bear cilia

psuedostratified columnar function

secretion, particularly of mucus; propulsion of mucus by ciliary action

stratified epithelia properties

• contain two or more layers of cells

• regenerate from below (basal layer)

• major role is protection

• named according to shape of cells at apical layer

stratified squamous description

• many layers cells are squamous in shape

• thickest epithelial tissue

• adapted for protection from abrasion

stratified squamous nonkeratinzied type location

forms the moist lining of the esophagus, mouth, and vagina

stratified squamous keratinized location

forms the epidermis of the skin, a dry membrane

stratified squamous function

protects underlying tissues in areas subject to abrasion

stratified cuboidal location

largest ducts of sweat glands, mammary glands, and salivary glands

stratified cuboidal description

generally two layers of tubelike cells

stratified cuboidal function

protection

stratified columnar description

several cell layers; basal cells usually cuboidal; superficial cells elongated and columnar

stratified columnar location

small amounts in male urethra and in large ducts of some glands

stratified columnar function

protection; secretion

transitional epithelium description

• has characteristics of stratified cuboidal and squamous

• superficial cells dome shaped when bladder is relaxed, squamous when full

transitional epithelium function

stretches readily and permits dissension of urinary organ by contained urine

transitional epithelium location

lines the ureters, bladder, and part of the urethra

two types of glands

endocrine anemia exocrine

endocrine glands -

ductless glands that secrete hormones directly into the bloodstream

exocrine glands -

secrete their substances into ducts that deliver secretions to the epithelial surface (sweat, saliva, milk)

exocrine glands are characterized by

structure

• can be unicellular or multicellular

goblet cell

unicellular exocrine gland that generates “mucin”

mucin + water =

mucus

goblet cells function

protects and lubricates many internal body surfaces

• within epithelial lining of intestines and respiratory tubes

multicellular exocrine glands have two basic parts

epithelium-walled duct and secretory unit

multicellular exocrine glands classed by structure of duct

simple (unbranched duct) and compound (branched duct)

multicellular exocrine glands categorized by form of secretory unit (cells)

tubular, alveolar, and tubuolalveolar

form of secretly cell - tubular

gland whose secretory cell form a tube

form of secretly cell - alveolar (acinar)

describes secretory cells that form a bulblike sac

form of secretly cell - tubuloalveolar

contain both tubular and alveolar secretory units

cell junctions

tight junctions, desmosomes, gap junctions

tight junctions -

close off intercellular space

• impermeable junctions prevent molecules from passing through the intercellular space

desmosomes -

main auctions for binding cells together (anchors)

• anchoring junctions bind adjacent cells together and help form an internal tension-reducing network of fibers

gap junctions -

passageway between two adjacent cells (communication)

• communicating junctions allow ions and small molecules to pass form one cell to the next for intercellular communication

the basal lamina located at the

boundary between the epithelium and connective tissue

the basal lamina is a

noncellular supporting sheet between the epithelial tissue and the connective tissue due to it

the basal lamina consists of

proteins secreted by epithelial cells

the basal lamina acts as a

selective filter, determining which molecules from capillaries enter the epithelium

• and as scaffolding along which regenerating epithelial tissue cells can migrate

the basal lamina and reticular layers of the underlying connective tissue deep to it form

the basement membrane

apical surface features - microvilli

fingerlike extensions of plasma membrane

microvilli

• have a core of actin filaments that stiffen the microvillus

• abundant in kidney tubules and small intestine

• maximize surface across which small molecules enter or leave cells

apical surface features - cilia

whiplike, highly motile extensions

cilia

contain a core of microtubules held together by cross-linking and radical proteins

cilia movement is generated when

adjacent doublets grip each other with the motor protein dynein

microtubules arranged in pairs called

doublets

cilia originate as

microtubules assembled around centrioles

connective tissue

• form basis of skeleton (bone and cartilage)

• store and carry nutrients (fat tissue and blood)

• surround blood vessels and nerves (CT proper)

• lead fight against infection

• all CT’s share the same simple structural plan pes

special characteristics of CT

• few cells, abundant extracellular matrix

• matrix is produced by cells of the CT

• common embryonic origin is mesenchyme

• degrees of vascularity

extracellular matrix is composed of

ground stances embedded with fibers (ground substance varies with each type of tissue)

degrees of vascularity

many types of CT have a rich blood supply (exceptions are cartilage (avascular), and dense CT (poorly vascularized))

ground substance -

composed chiefly of interstitial fluid, cell adhesion proteins, and proteoglycans

• composition of ground substance alters properties extracellular matrix (liquid, semisolid, gel-like, hard)

ECM - fibers

provide support, include collagen, elastic, and reticular fibers

four main classes of CT

CT proper (fat tissue, fibrous tissue of ligaments), cartilage, bone tissue, blood

differences in cells and composition of the ECM account for

the different physical properties of CT’s

CT proper subclasses

loose and dense CT

loose CT includes

areolar, adipose, and reticular

dense CT incluses

dense irregular, dense regular, and elastic

areolar tissue has many

structural components common to the other types of tissues

• serves as a model to understand CT properties

caroler CT

• underlies epithelial tissue, widely distributed

• surrounds small nerves and blood vessels, packages organs

• has structures and functions shared by other CT’s

• borders all other tissues in the body

areolar CT functions

support, defense, cushioning, nutrient storage

areolar CT contains three types of fibers

collagen, elastic, reticular

collagen fibers -

strongest, most abundant type of fiber, resists tension

elastic fibers -

made of elastin protein, stretches and recoils