cells in the body

what is a tissue?

group of cells with similar structure and function plus extracellular substances

What are the 4 types of tissues?

epithelial, connective, muscle, nervous

epithelial tissue-location

conver body(internal and external) ex. skin,kidney,trachea,glands,etc.

epithelial tissue- characteristics

-cells close together

-form most glands

-have free surface

-basal surface

basal surface

attaches epithelial cells to underlying tissues

epithelial tissue-functions

1.protect

-ex.skin

2.act as a barrier

-ex. skin keeps bateria out

3.diffusion and filtration

-ex. lungs and kidneys

4. secretion

-sweat glands

5. absorption

ex.small intesine

epithelial tissue-classification

classified according to number of cell layers and cell shape

simple and stratified-

number of cell layers

squamous,cuboidal,columar,transitional

cell shape

simple epithelium-structure

1 layer of cells

stratified epithelium-structure

many layers of a cells

simple squamous-structure,function,and location

structure: 1 layer of flat,tile-like cells

function: diffusion and filteration

location: blood vessels,lungs,heart,kidney

simple cuboidal-structure,function,and location

structure: 1 layer of square-shaped cells

function: secretion

location: gland, ovaries, kidneys

simple columnar

structure: 1 layer of tall narrow celss

function: sercrete mucus and absorbtion

location: stomach,intestine, resp. tract

psuedostratified columnar

structure: 1 layer of tall narroe cells, appers stratified but isnt

function: secrete mucus and propel debris out of resp. tract (cila)

location: nasal cavity and trachea

stratified squamos

structure: many layer of flat, tile like cells

function: protect and acts as a barrier

location: skin,mouth,throat,esophagus

transitional epithelium

structure: special type of stratified epi. changes shape (streched squamous, not streched cubodial)

function: hold fluid

location: urinary bladder

Free Cell Surfaces

-surface not in contact with other cells

-smooth to reduce friction=damage

mircovilli

increase cells surface area

ex. small intestine

Cilia

move materials across cells surface

ex.trachea

goblet cells

produce mucus

ex. stomach

tight junctions

bind adjacent cells together ex.intestines

Desmosomes

mechanical links that bind cells together

Hemidesmosomes

bind cells to basement membrane

gap junctions

-small channels that allow molecules to pass between cells

-allows cells to communicate

-most common

What are glands?

structures that secrete substances onto a surface, into a cavity, or into blood

exocrine glands

exo-exit

• glands with ducts

ex sweat or oil glands

types of exocrine glands

-Simple: no branches

-Compound: many branches

-Tubular: end of duct

-Alveolus: sac-like structure

endocrine glands

endo: enter

no ducts(directly to bloodstream)

ex. thyroid,thumus,pituitary glands,etc

connective tissue characteristics

• cells are far apart

-contains large amounts of extracellular matrix(more fluid)

-classified based on type of extracellular matrix and function

what do blast cells do

build

what do clast cells do

crave/distroy

what the extracellular matrix contain

-3 componets

-protein fibers,ground substances, fluid

ground substances

proteins and fibers

collagen fibers

look like ropes and are flexible but resist stretching

reticular fibers

supporting network that fills spaces between organs and tissues (grid like)

elastic fibers

recoil after being stretched

functions of connective tissues

enclose and separate, connect tissues, support movement, storage, cushion and insulate,transport, protect

enclose and separate

around organs and muscles

connect tissues

tendons: connect bone to muscle

liagments: connect bone to bone

support and movement

bones

storage

bone store calcium and adipose tissues stroes fat

cushion and insulate

adipose tissue protects organs and helps conserve heat

transport

blood

protect

immune cells

loose tissue

location: between oegans,muscles,glands,skin

structure: collagen fibers far apart

function: support and protect

dense tissue

location:tendons,ligaments, skin

structure: collagen fibers packed close together

function: connect and can withstand pulling forces

adipose tissue

location: under skin and around organs

structure: collagen and elastic fibers, cells filled with lipids

function: storage insulate, cushion

cartilage

-type of connective tissue

-composed of chondrocytes

-contains collagens

-withstands compressions

-provides support, flexibility, strength