Human anatomy Tissue

next step after cells

a collection of cells

have a collective function or job

may be hard (bone), semi-solid (fat) or liquid (blood)

tissue

physician that examines tissue to help other physicians

pathologist

covers body tissues

lines hollow organs, body cities, and ducts

forms glands

the body interacts with internal and external environment through tissue

epithelial tissue

protects and supports body and organs

connective tissue

for contraction and generation of force

muscular tissue

detects changes in conditions inside and outside body

generates action potentials

activate muscular contraction and gland

nervous tissue

has cells tightly packed together

has little to no extracellular matrix

epithelial tissue compared to connective

has a few scattered cells

cells are surrounded by large amount of extracellular matrix 

connective tissue compared to epithelial

form surface layers and therefore is not covered by any other tissues

avascular: does not have its own blood supply

provides covering of skin and some internal organs

forms linings or vessels, ducts, and body cavities 

surface epithelial tissue

uni-laminar = one layer

very thin

allows diffusing, osmosis and filtration and absorption to pass through them

oxygen and carbon dioxide diffuse through them in the lungs

can function with absorption: absorption of fluids and other substances

simple epithelial tissue

looks like more than one layer, but it’s not

pseudo stratified

two or more layers

more layer = more protection

appears where there is considerable wear and tear

stratified

fat cells

store triglycerides

adipocytes

tendons and ligaments

flexible / ground substance has abundant fiber

proper connective tissue

cartilage and bone

dense network of collagen and elastic fibers

high tensile strength

supporting connective tissue

blood plasma

liquid connective tissue

flat sheets of pliable tissue

cover/line body parts

membranes

majority of membranes

consists of epithelial layer attached to underlying connective tissue

epithelial membranes

mucous, serous, cutaneous

types of epithelial membranes

line body cavities that open to exterior/secrete mucus

mucous membrane

line cavities that don’t open to exterior

lines inner walls of body cavities and secretes lubricating fluid to reduce friction between oppsosing surface

serous membrane

covers surface of body (skin)

cutenous membrane

used when two bones articulate

do not open to exterior

lack epithelium thus are not epithelial membranes

composed of synoviocytes cells which secrete some component of synovial flud

synovial fluid lubricates and nourishes cartilage coving bones and joints

synovial fluid contains macrophages

synovial membranes (syn = together)

skeletal, cardiac, smooth

types of muscular tissue

consists of long, cylindrical, striated fibers

multicellular with nuclei located at cells periphery

controlled voluntarily

usually attached to bones by tendons

skeletal muscle

have branched striated fibers and only a single centrally located nucleus

attached end to end by intercalated discs

have gap junctions = proves a route for action potential to spread quickly throughout whole section of heart muscle

involuntary control

cardiac muscle

lack striations 

spindle shaped cells

cells have single centrally located nucleus

gap junctions

involuntary control

smooth muscle

consists of neurons and neurogila

dendrites and axons project from main neuron body

98% of this tissue is located in central nervous sytem

highly excitable : generates action potentials

nervous tissue

columnar cells

taller than wide (like columns)

function: protect underlying tissues (shock absorbers / absorption)

have microvilli to increase surface area for absorption

transitional (urothelium) cells

change shape: relaxed = cuboidal / stretched = Squamish

e.g. urinary bladder: cells can stretch to large size and collapse to smaller size

glandular epithelial tissue primary function

secretion

glands

either endocrine or exocrine

are epithelium tissue that secrete substance (via ducts) onto either

• a surface (exocrine)

• into blood (endocrine)

endocrine glands

secretions enter interstitial fluid then diffuse into bloodstream (secretions called hormones

exocrine glands

secrete into duct that empty onto a surface

many secretions would be harmful if they entered blood

example: pancreas secreting digestive juices onto surface of small intestine

connective tissue location

everywhere in body

connective tissue commonality

develop from same cell

they have different degrees of vascularity

connective tissues are mostly composed of non living material (extracellular matrix)

connective tissue composition

extracullular matrix, cells

marshmallows inside jello

cells of connective tissue

jell-o reperesents

extraceulluar matrix

extracellular matrix is made up of components

ground substance

fibers

connective tissue phases

immature , mature

immature phase of connective tissue

cells called “blasts” (means forming)

function: secrete ground substance and fibers

creates unique extracellular matrix

mature phase of connective tissue

blasts mature into “cites”

function of sites: maintain matrix health

connective tissue function

binds things together

supports and strengthens

protects

comparmentalizeds structure

adipose tissue (a connective tissue type = primary location of stored energy reserves

blood ( a connective tissue type = transport system to service cellsco

connective tissue is highly vascularized because

it provides blood supply to epithelial tissue 

exceptions include cartilage and tendons ( not highly vascularized nor associated with epithelial tissue

ECM location

between widely placed cells

ecm structure determines…

tissue function and qualities

ecm structure of bones

hard and inflexible

ecm structure of cartilage

firm but pliable

connective tissue properties based on

composition of extracellular matrix

ground substance

component between cells and fibers

supports cells, binds them together

provides medium for exchange between blood and cells

active role in tissue development and function

contains water and large organic molecules (polysaccharides and proteins) collectively know as GAG’s (glycosaminoglycans)

GAG’s (glycosaminoglycans)

trap water and make ground substance more jelly like

types of ecm fibers

collagen, elastic, reticular

collagen fibers

protein fiber: strongest and most abundant fibers (stronger than steel of same size)

resist pulling or stretching

elastic fibers

contain protein elastin

strong but can be stretched up to 150% then return to normal length

plentiful in skin

reticular fibers

made of collagen arranged in bundles with a coating of glycoprotein 

provide support for walls of blood vessels and form a supporting framework around many “soft” organs (spleen, lymph nodes)

connective tissue cells

fibroblasts, macrophages, plasma cells, mast cells, white blood cells, adipocytes

fibroblasts

large flat cells with branching processes

secretes fibers and ground substances

most common cell in connective tissue

marcophages

develop from monocytes and destroy bacteria by phagocytosis

plasma cells

part of adaptive immune system

mast cell

involved in triggering innate immunity inflammatory reponse

white blood cells

not found in significant numbers in normal connective tissue

respond to infection/pathogens

e.g

• neutrophils

• eosinophilis

neutrophils

destory pathogens with phagocytosis

eosinophils

migrate to sites of parasitic invasions

tight junctions

seal

ensures most materials to move through rather than between epithelial cells, as a form of selective permeability

adhering junctions

hold cells together and also support formationa dn maintenance of tight junctions

desmosomes

act like a structural spot weld between adjacent cells to lock them together and resist intense mechanical stress

gap junction

allow ions and small molecules to passs directly between cells for communcaiton

hyaline cartilage

smooth support
usually has perichondrium

fibrocartilage

absorbs shock

no perichondrium

elastic cartilage

flexible support

perichondirum present