Integumentary System + Tissues || Ch 4+5

amount of cells in the body

about 200 different types

epithelial tissue

includes epithelia & glands; avascular layers of cells that cover internal or external surfaces

glands

composed of secreting cells derived from epithelia

characteristics of epithelia

cells bound closely together

free (apical) surface exposed to environment or to some internal chamber/passageway,

attachment to underlying connective tissue by basement membrane,

avascular

continual regeneration

functions of epithelia

* provide physical protection: protect from abrasion, dehydration, and destruction by chemical or biological agents
* control permeability: any substance that enters of leaves the body must cross an epithelium
* provide sensation: detect changes in the environment and relay information about such changes to the nervous system
* produce specialized secretions: gland cells/glandular epithelium producing secretions

gland cells

epithelial cells that produce secretions

glandular epithelium

most or all cells produce secretions:

exocrine

secretions discharged onto the surface of the epithelium

discharge through duct or tube onto surface

* enzymes entering digestive tract
* perspiration on skin
* milk produced by mammary glands

endocrine

secreting internally to surrounding tissue fluid & blood; hormones

secreted by ductless gland

* chemical messengers that regulate/coordinate the activates or other tissues, organs, and organ systems
* produced by pancreas, thyroid and pituitary gland

cell adhesion molecules (CAMs)

proteins found on surface of most cells; aids in binding the cell to the extracellular matrix or to other cells

(cell glue!)

tight junction

firm seal between two adjacent animal cells created by protein adherence; a type of inter-cellular junction that prevents the leakage of material (water, solutes) between cells; common in tissue exposed to power enzymes/chemicals (i.e. stomach)

gap junction

two cells held together by embedded membrane proteins; allows small molecules & ions to pass from cell to cell; most abundant in cardiac & smooth muscle tissue to allow contraction

desmosome

cell membranes of two cells locked together by inter-cellular cement & membrane proteins connected to intermediate filaments that that fasten & support cells together; abundant in between cells in superficial layers of skin, with damaged cells coming off in sheets rather than individual cells

inter-cellular cement

substance that binds, adds structural strength, & mediates biochemical interactions between cells

apical surface

the upper free surface of epithelial cells that are exposed to the body exterior or the cavity of an internal organ

microvilli

finger-like extensions of plasma membrane of apical epithelial cells, increase surface area, aid in absorption, exist on every moist epithelia, but most dense in small intestine & kidney; on columnar epithelia

basement membrane

layer between epithelium & underlying connective tissue; provides strength, resistance to distortion, & underlying molecules from connective tissue into epithelium

stem cells

unspecialized cells that continually divide to regenerate the epithelium; found in the deepest layers of the epithelium, near the basement membrane

simple epithelium

* single layer of cells covering the basement membrane
* thin and fragile layer that cannot provide much mechanical protection --→ found in protected areas inside the body
* line internal compartments and passageways; ventral body cavities, heart chambers, and blood vessels
* areas in where secretion and absorption occur
* thinness advantage to reduce time for materials to diffuse across epithelial barrier

stratified epithelium

* provides greater degree of protection because of the several layers of cells above the basement membrane
* found in areas subject to mechanical or chemical stresses; surfaces of skin, linings of mouth, anus

squamous epithelium

* thin and flat
* nucleus occupies thickest portion of the cell
* looks like friend eggs laid side by side!

cuboidal epithelium

* resembles squares
* nuclei lie near the center of each cell
* form a neat row

columnar epithelium

* hexagonal but taller and more slender
* similar to rectangles
* nuclei crowded into narrow band close to the basement membrane and height of the epithelium is several times the distance between two nuclei

simple squamous epithelium

* single layer of flattened cells
* found where absorption & secretion takes place
* (controls permeability) & reduces friction
* kidney tubules, exchange surfaces of lungs, ventral body cavity, blood vessels, inner surface of the heart

simple cuboidal epithelium

* single layer of cube shaped cells
* provides limited protection
* occurs where secretion and absorption takes place
* secrete enzymes and buffers in the pancreas and salivary glands
* line the ducts that discharge secretions
* kidney tubules

simple columnar epithelium

* a single layer of tall cells that fit closely together
* lines the GI tract & many excretory ducts
* protection, secretion, absorption

pseudostratified columnar epithelium

* distances between the cell nuclei and exposed surface vary
* epithelium appears layered, or stratified; not truly stratified because all the cells contact the basement membrane
* typically possess cilia

transitional epithelium

* tolerates repeated cycles of stretching and recoiling
* changes to unstretched to stretched state
* urinary bladder
* unstretched - appears cuboidal
* stretched - appears squamous

statified squamous epithelium

* found where mechanical stresses are severe
* surface of the skin, lining of the mouth, tongue, esophagus, anus

exocrine glands

glands that secrete substances outward through a duct

endocrine glands

glands that secrete chemicals called hormones directly into the bloodstream

unicellular glands

exocrine; single celled glands (goblet cells)

secretory sheet

simplest multicellular exocrine gland

merocrine secretion

secretions released by exocytosis; i.e. sweat

apocrine secretion

involves the loss of cytoplasm as well as the secretory product; i.e. milk, sweat from underarms

holocrine secretion

secretions released by cell bursting; i.e. sebum

serous glands

produce thin, watery secretions containing enzymes

mucous glands

supply a lubricant that keeps the skin moist in the air; allows for respiration

mixed glands

contains both serous & mucous cell types & produces a mixture of the two types of secretions

connective tissues

bind tissues, provide structure & protection, serve as framework; formed from (1) specialized cells, (2) protein fibers), & (3) ground substance; many are highly vascular

extracellular matrix

provides support for surrounding cells; accounts for most of connective tissues' volume; protein fibers and fluid phase (ground substance)

ground substance

* fills up spaces between cells and surrounds connective tissue proper

mostly water along with adhesion proteins & polysaccharide molecules; consistency similar to syrup, slows movement of pathogens; fills space

functions of connective tissues

support & protection, transportation of materials (i.e. blood), storage of energy reserves (i.e. adipose tissue), defense of the body (i.e. lymph)

connective tissue proper

loose connective tissue & dense connective tissue

fluid connective tissue

blood & lymph

supporting connective tissues

cartilage & bones

fibroblasts

most abundant cells in loose connective tissue; permanent residents responsible for producing & maintaining the connective tissue fibers & ground substance

macrophages

scattered throughout matrix, consume (phagocytize) damaged cells, pathogens, & mobilizes immune system; called monocytes in blood; in LCT

fat cells

adipocytes; permanent residents; stores lipids; LCT

mast cells

found often near blood cells in connective tissue; responds to injury, infection, or allergy by producing and releasing substances, including histamine; LCT

antibodies

proteins that destroy invading microorganisms or foreign substances

connective tissue fibers

collagen, elastic, reticular

collagen fibers

long, straight, & unbranched; most common fibers in connective tissue proper; flexible & strong; tendons & ligaments; provides toughness

elastic fibers

contain protein elastin; branched & wavy & after stretching they will return to original length; produces resilience

reticular fibers

least common of the three, commonly form a branching, interwoven framework in various organs; supports cells

loose connective tissue

areolar; contains all cells & fibers found in any connective tissue proper, in addition to an extensive blood supply; separates skin from underlying muscles, providing padding & independent movement

adipose tissue

loose connective tissue dominated by adipocytes; provides padding, shock absorption, insultation, & energy storage

dense connective tissues

bone and cartilage, form the joints and framework of the body

tendons

cords of dense regular connective tissue that attach skeletal muscles to bones; collagen fiber goes in 1 direction

ligaments

dense regular connective tissue that anchors bone to bone

blood

fluid connective tissue; red & white blood cells (blue), platelets (small white dots), & plasma (matrix of blood)

lymph

fluid connective tissue; immunity

interstitial fluid

liquid found between the cells of the body that provides much of the liquid environment of the body

extracellular fluid

plasma, lymph, & interstitial fluid makes up most of this

cartilage

avascular; must get nutrients & eliminate wastes through diffusion through the matrix; lacunae - small pockets that contain the chondrocytes in the matrix; limited ability to repair itself; huge cells

perichondrium

covers cartilage; contains capillaries, the only blood supply for cartilage; sets apart surrounding tissues from the cartilage

hyaline cartilage

most abundant cartilage type; provides firm support with some pliability; connects ribs to sternum, supports passageways of respiratory tract, covers opposing bones surfaces within joints

elastic cartilage

extremely resilient & flexible; external ear, epiglottis, airway to middle ear

Fibrocartilage

extremely durable & tough; matrix dominated by collagen fibers, densely interwoven; resist compression, absorbs shock, prevents damaging bone-to-bone contact; between vertebrae, pubic bones of pelvis, around a few joints & tendons

bone

supporting connective tissue; matrix consists mainly of hard calcium compounds & flexible collagen fibers; lacunae within matrix contain bone cells; can repair itself considerably; small cells; covered by periosteum

canaliculi

little channels that connect lacunae to central canal

mucous membrane

mucosae; secretes mucus that lubricates the surface of organs & keeps them moist; found in the digestive, respiratory, reproductive, & urinary tracts

lamina propria

the connective tissue layer of a mucous membrane

serous membrane

membrane that lines a cavity without an opening to the outside of the body; secretes a fluid that keeps the membrane moist; also called serosa; parietal - covers outer surface, visceral - covers inner surface

cutaneous membrane

skin; covers surface of the body; consists of stratified squamous epithelium & underlying dense connective tissues; thick, relatively waterproof, & usually dry

synovial membrane

membrane lining the capsule of a joint; consists mostly of loose connective tissue & an incomplete layer of epithelial tissue; lubricates joints & permits smooth movement

Three types of muscle tissue

skeletal, cardiac, smooth

skeletal muscle

large, multinucleated (nuclei on outside of muscled fibers) cells that are long & slender; incapable of dividing, only partial repairs possible through division of stem cells (permanent tissue); striated voluntary muscle, on bones

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striations

actin & myosin filaments arranged in organized pattern (like bands)

cardiac muscle

weak striated, involuntary muscle tissue found; cells smaller than a skeletal muscle's; one nucleus off-center, branch to form a network that efficiently force & stimulus of contraction; very limited self-repair ability, permanent tissue

intercalated discs

attachment sites between cardiac muscle cells; electricity from heart passes through here

smooth muscle tissue

not striated & involuntary; cells can divide thus repairing any injuries; found in walls of blood vessels, around hollow organs such as the urinary bladder, in layers of respiratory, circulatory, digestive & reproductive tracts; one nucleus in center

neural tissue

contains neurons & neuroglia; neurons conducts electrical impulses; concentrated in brain & spinal cord; 90% is neuroglia

neuroglia

provides physical support for neural tissue, maintains chemical composition of the tissue fluids, provides nutrients to neutrons, & defends tissue from infections

neurons

longest cells of body; cannot divide under normal circumstances; (1) cell body - soma, (2) axon - sends info, (3) dendrites - receives info; synaptic terminal is full of neurotransmitters

tissue injury and repair

inflammation - area is isolated from neighboring healthy cells; blood vessels dilate & become more permeable;

regeneration - fibroblasts produces dense network of collagen fibers (scar/fibrous tissue) that is remodeled, gradually looking more normal

fibrosis

thickening & scarring of connective tissue, usually as a result of injury; replacement of damaged cells with scar tissue

tissues & aging

- Repair and maintenance become less efficient as one ages

how many Americans develop cancer in their lifetime

roughly 25%; 70-80% of cancer cases result from chemical exposure, environmental factors, or a combination of the two; 40% of these cancers are caused by cigarette smoke

cancer deaths each year in the U.S.

500,000 individuals, second to heart disease

dense regular connective tissue

collagen fibers parallel & packed tightly together aligned with force applied to it

dense irregular connective tissue

interwoven meshwork of collagen fibers, provides strength against force coming from many directions

compact bone

Hard, dense bone tissue that is beneath the outer membrane of a bone

spongey bone

layer of bone tissue having many small spaces found just inside the layer under the compact bone; has red & yellow bone marrow

central canal

contains blood vessels and nerves

ideal body fat

men: 12-20%

scar tissue

fibrous connective tissue that binds damaged tissue

Five signs of inflammation

warmth (fever), redness, swelling (edema), pain, loss of function

pulmonary fibrosis

formation of scar tissue in the connective tissue of the lungs

through the process of differentiation

each cell specializes to perform a relatively restricted range of functions