module 7: epithelial tissue

what are the characteristics of epithelial tissue?

• lots of cells

• little extracellular matrix

what are the characteristics of connective tissues?

• few cells

• lots of extracellular matrix

what is the purpose of epithelium?

protects the outside and inside of of the body

what does the free (apical) do?

lines the lumen of ducts or inside of vessels

what does the basal surface do?

its attached to the basement membrane - and holds the cells together

what is the purpose of the basement memebrane?

its like an acellular glue holding all the cells together

does epithelium have a direct blood supply?

No its avascular

what is the purpose of microvilli?

• they are stationary

• they increase area for absorption or secretion

what is the purpose of cillia?

they help move materials across the cell surface

what are the 3 numbers of layers of epithelium called?

1. simple

2. stratified

3. pseudostratified

what does simple epithelium mean?

its one layer of cells - the all conec t to the basement membrane

what does stratified epithelium mean?

more than one layer - only the bottom layer attaches to the basement membrane

what does pseudostratified epithelium mean?

the tissues appears to be stratified however all cells contact the basement memebrane

what are the 3 shapes epithelium cells can be?

1. squamous

2. cuboidal

3. columnar

what does squamous epithelial cells look like?

they are flat scale like

what do cuboidal epithelial cell look like?

they look like little cubes

what do columnar epithelial cell look like?

they are taller than wide - look like columns

what is the function of simple epithelium?

allows for diffusion, filtration, secretion and absorption - this is because its a single layer so its easy to be passed through

what is the function of stratified epithelium?

since its multiple layers it provides protection against abrasion

what is the function of pseudostratified epithelium?

to secrete and move mucus

what is the function of squamous epithelium?

allows for diffusion or acts as a filter

what is the function of cuboidal or columnar epithelium?

secretion or absorption many include goblet cells

what do goblet cells do?

they produce and secrete mucus

what is the structure if simple squamous epithelium?

single layer of flat cell

what is the structure if simple squamous epithelium?

where is simple squamous epithelium located?

• lining of blood vessels

• bowman’s capsule of kidney

• alveoli of the lungs

whats the function of simple squamous epithelium?

diffusion, secretion and filtration

what is the structure of simple cuboidal epithelium?

single layer of cube - shaped cells

where is simple cuboidal epithelium located?

kidney tubules, glands and surface of ovaries

whats the function of simple cuboidal epithelium?

secretion and absorption

what is the structure of simple columnar epithelium?

its a single layer of tall narrow cells - some have cilia or microvilli

where is simple columnar epithelium located?

• glands

• bronchioles

• uterine tubes

• stomach

• intestines

• gallbladder

• ventricles of the brain

what is the structure of transitional epithelium?

they are stratified cells that are able to change shape

where is transitonal epithelium located?

lining of the urinary system

whats the function of transitional epithelium?

to accommodate for fluctuations of volume in organs

what are endocrine glands? and what do they do?

they are glands with no open contact to exterior of body - they produce hormones

what do exocrine glands do? and where are they located?

they have open contact with the exterior of the body (lumen of ducts) - they also have ducts

eg. sweat glands and mammary glands