chapter three: tissues

what is a tissue?

collection of specialized cells and cell products that work together in functionally related communities

t/f: tissues only have living components

false: they also have non-living extracellular components

what are the four types of tissues and what is their basic function?

connective: support, epithelial: covering, muscle: movement, nervous: control

what tissue type forms most of the body’s glands?

epithelial

epithelial tissue function

protection, secretion, absorption, ion transport and diffusion, filtration, and sensory reception

epithelial tissue cellularity

composed mostly of cells with limited extracellular matrix

epithelial tissue specialized contacts

cells joined by special junctions

epithelial tissue polarity

cell regions of the upper surface differs from the basal lower surface

what is the basement membrane?

underlying connective tissue layer that provides support

epithelial is avascular but innervated. what does this mean?

epithelium lacks blood vessels but has nerves

epithelial cells are highly regenerative. what does that mean?

lost cells are quickly replaced by cell division

what are microvilli?

finger-like extension of the plasma membrane of apical epithelial cells that increase surface area for absorption

what is cilia?

whip-like, motile extension of plasma membrane that moves stuff over epithelial surfaces

example of where microvilli is found?

small intestines

example of where cilia is found?

respiratory tubes

what is flagella?

extra long cilia that helps move cell

what is an example of where flagella is found?

spermatozoa

epithelial lateral surface features

connections to neighboring cells by linking proteins or cell junctions

interdigitate vs following contour of cells

cells need to mingle; cells are wavy

what are the types of cell junctions?

desmosomes, tight junctions, gap junctions

what do desmosomes do?

adhesive spots on lateral sides linked by filaments that holds tissues together

what do tight junctions do?

fuse plasma membrane of adjacent cells at apical area so nothing passes

what do gap junctions do?

spot-like junction occurring anywhere made of hollow cylinders of protein

what is the basal surface?

sheet between the epithelial and connective tissue layer that attaches epithelium to connective tissue below

what is the basal surface made of?

basal lamina and reticular fiber layer

what is the purpose of the basal lamina?

thin, noncellular supportive sheet of proteins found in the superficial layer that acts as a selective filter and assists in epithelial cell regeneration by moving new cells

basal lamina is made of what two layers?

lamina lucida (clear layer) and lamina densa (dense layer)

what is the reticular fiber layer?

the deeper layer that provides support

what does simple epithelium mean?

one layer

what does stratified epithelium mean?

it has multiple layers

what are the shapes of epithelium cells and what do they look like?

squamous (disk shaped), cuboidal (cube shaped), and columnar (column shaped)

what is pseudostratified columnar epithelium?

columnar epithelium that looks like multiple layers of columns but is actually only one layer

simple squamous epithelium description

single layer of flat cells with disc-shaped nuclei; thin and permeable

simple squamous epithelium function

allows for passage of small ions vis passive diffusion and filtration

simple squamous epithelium locations

renal corpuscles, alveoli of lungs, lining of heart, blood, and lymphatic vessels, lining of ventral body cavity

simple cuboidal epithelium description

single layer of cube like cells with large, spherical central nuclei

simple cuboidal epithelium function

secretion and absorption

simple cuboidal epithelium location

kidney tubules, secretory proteins of small glands, ovary surface

simple columnar epithelium description

single layer of column shaped cells with oval nuclei, some have cilia at apical surface, may contain goblet cell

simple columnar epithelium function

absorption; secretion of mucus, enzymes, and other substances

simple columnar epithelium location

nonciliated: lines digestive tract, gallbladder, ducts of some glands

ciliated: lines small bronchi, uterine tubes, and uterus

pseudostratified columnar epithelium description

all cells originate at basement membrane, only talls cells reach the apical surface, may contain goblet cells and bear cilia, nuclei lie at varying heights within cells

pseudostratified columnar epithelium function

secretion of mucus, propulsion of mucus by cilia

pseudostratified columnar epithelium location

nonciliated: ducts of male reproductive tubes; ducts of large glands

ciliated: lines trachea and most of upper respiratory tract

what is the major function of stratified epithelium?

protection

stratified squamous epithelium description

many layers of squamous cells where deeper layers may appear cuboidal or columnar; thickets epithelial tissue

what are the two types of stratified squamous epithelium?

keratinized and nonkeratinized

stratified squamous epithelium (keratinized) description and function

contains keratin, waterproof, surface cells are dead and full of keratin (prevents flaking), forms epidermis

stratified squamous epithelium (nonkeratinized) description and function)

forms moist lining of body openings and lining of mucous membranes, does not have keratin

stratified cuboidal epithelium description

two layers of cube shaped cells

stratified cuboidal epithelium function

protection and production of fluids

stratified cuboidal epithelium location

ductile glands (mammary glands, salivary glands, and larger sweat glands)

stratified columnar epithelium description

basal cells are usually cuboidal

stratified columnar epithelium function

protection and secretion

stratified columnar epithelium location

‘rare’; found in male urethra and large ducts of some glands

what are glands?

groups of specialized epithelial cells that make and secrete protein products

how are glands classified?

endo vs exo; unicellular vs multicellular

where do exocrine glands secrete products?

onto a body surface or into a body cavity

unicellular exocrine glands are/contain:

goblet cells that secrete mucin to lubricate internal body surface

what are the two basic parts of a multicelluar exocrine gland?

duct and secretory unit

how are multicellular exocrine glands classified?

by branching structures (one branch: simple, multiple: compound), and by secretory units (tubes: tubular, sacs: alveolar, hybrid: tubuloalverolar)

endocrine gland composition

no ducts; only secretory unit

how do endocrine glands function?

hormones travel to target organ to increase response

what are the four main classes of connective tissue?

connective tissue proper, cartilage, bone, and blood

what are the functions of connective tissue?

connect tissues and bind organs together, hold in body fluid, form basis of skeleton, store and carry nutrients, surround all blood vessels and nerves, and protect against infection

what are the connective tissue commonalities?

acellular, cells have embryonic origin, extracellular matrix is produced by cells of connective tissue class and is composed of ground substance and protein fibers, vascularized

blast vs cyte?

blast: actively secreting connective tissue matrix (having a blast making stuff)

cyte: maintenance (sit there in the *site* to maintain everything)

what is fibril made of?

collagen fibers, reticular fibers, and elastic fibers

collagen description

strong, resistant to tension, thick coils of cross-linked fibrils

what happens when collagen is destroyed?

organs move, structure changes, function changes, not good

reticular fibers?

type of collagen that form dense mesh network rather than coiling

elastic fiber?

contains elastin, pulls tissues back to original shape after being stretched out

what is elastin?

a rubber-like component that allows stretch

what are the structural features of connective tissue? what are the exception?

ground substance (extracellular) and interstitial fluid (between cells); blood: embedded in calcified mineral salts and blood: plasma that is not produced by blood cells

ground substance description and function?

generally gel-like with large sugar and sugar-protein molecules which hold and absorb interstitial fluid; cushions, protects, withstands compressive stresses

interstitial fluid description and function?

medium for nutrients; waste and oxygen travels to cells; found in ground matrix

connective tissue proper subcategories?

loose and dense

examples of loose connective?

areolar, adipose, reticular

what is loose connective tissue?

fibers are able to separate from each other

what is dense connective?

fibers are densely/tightly packed together

connective tissue proper basic functions

support and binding of other tissues together, holding body fluids, fighting infection, storing nutrients

loose connective tissue proper: areolar description and function?

most widespread, underlies almost all epithelium and surrounds almost all small nerves and blood vessels, borders all other tissues in the body

adipose description and function?

occurs beneath the skin, highly vascularized, high metabolic activity, insulates, produces energy, supports

white adipose tissue function

nutrient storing

brown adipose function

produces heat

reticular description and function?

only has reticular fibers, forms caverns to hold free cells, forms internal skeleton of some organs

dense connective tissue is resistant to:

extremely strong pulling forces

what types of dense connective tissue are there?

regular and irregular

dense regular connective tissue description and function?

regular fibers run same direction parallel to pull; wavy appearance; poorly vascularized with no fat or defense cells

dense regular connective tissue location?

fascia, tendons, ligaments

dense irregular connective tissue description and function?

thick irregular fibers, run in different planes and directions, resists strong tensions

dense irregular connective tissue location?

dermis, fibrous capsules at ends of bones

cartilage characteristics

firm, flexible, resists compression

cartilage location

nose, ear, trachea, meniscus

cartilage is composed of 80% -

water

cartilage is/is not innervated

is not

cartilage avascular or vascular?

avascular

when is cartilage more prominent?

in embryo

what are chondroblasts?

immature cartilage cells that actively secrete cartilage