Epithelial Tissue Flashcards
what is an epithelium
one or more layers of cells that covers or lines the external and internal surfaces of various body parts
structure of epithelial tissue
variously shaped cells closely arranged in one or more layers
there is little intercellular material between the cells
what does the free surface of epithelial tissue face
body fluid or outside environment
two main groups of epithelial tissues
simple and compound
structure of simple epithelium
single layer of cells resting on a basement membrane
simple epithelium functions as
a lining for body cavities, ducts and tubes
types of simple epithelium
squamous
cuboidal/cubical
columnar
structure of squamous epithelium
single thin layer of flattened cells with irregular bodies
locations of squamous epithelium
innermost walls of blood vessels
air sacs of lungs
functions of squamous epithelium
forming a diffusion boundary
how are free surfaces of cuboidal epithelium
may be smooth or have microvilli
location of cuboidal epithelium
ducts of glands
proximal convulated tubule in nephrons of kidneys (microvilli)
functions of cuboidal epithelium
secretion and absorption
where do nuclei of columnar epithelium lie
near the bases of the cell
how is the free surface of columnar epithelium
smooth or bear microvilli
location of columnar epithelium
in the lining of stomach and intestine
functions of columnar epithelium
absorption
secretion
what is ciliated epithelium
if cuboidal or columnar cells bear cilia on their free surface
function of cilia
to move particles or mucus in a specific direction
where does ciliated epithelium occur
inner surface of hollow organs like fallopian tubes (oviducts) and bronchioles
what are glandular epithelium
some columnar or cuboidal cells get modified for secretion
glands are classified based on
cell number
mode of pouring of secretion
types of glands based on cell number
unicellular
multicellular
example of unicellular gland
goblet cells of alimentary canal
examples of multicellular glands
salivary gland
types of glands based on mode of puring of secretion
endocrine
exocrine
how is the secretion of exocrine glands
passed through ducts or tubes
examples of secretions by exocrine glands
mucus
saliva
earwax
oil
milk
digestive enzymes
how do endocrine glands secrete
directly into fluid bathing the gland which carry it to target organs
location of compound epithelium
dry surface of the skin
moist surface of buccal cavity
pharynx
inner lining of ducts of salivary glands
pancreatic ducts
types of junctions
tight junctions
gap junctions
adhering junctions
function of tight junctions
help to stop substances from leaking across the tissue
function of gap junctions
rapid transfer of ions, small molecules and sometimes big molecules
structure of gap junctions
connecting the cytoplasm of adjoining cells
adhering junctions perform ______ to keep the neighbouring cells together
cementing
