bio animal tissues 1 (epi) Flashcards
subtopic: epithelial tissues
tissue
group of cells with similar structure, function and origin
how are tissues organised to form an organ
in specific proportion and pattern
why do the structure of cells vary?
to adapt to their specific function
name four types of tissues
epithelial
connective
muscular
neural
epithelial tissue
consists of cells arranged in continuous sheets either in single or multiple layers
where does it grow
on other tissues
this tissue has ____ which faces either _____ or ______
free surface, a body fluid, outside environment
why do they always have a free surface
because no other tissue grows over them
vascular vs avascular?
avascular
what does it mean to say that epithelial cells are avascular
epithelial cells have their own blood supply but lack their own blood supply. blood vessels that help in diffusion are located in the adjacent connective tissues. exchange occurs through diffusion between epi and conn. tissue cells
in general, epi cells facing outwards of the body are ____ and those that do inwards are _____
keratinous, non-keratinous
types of epithelial tissue
simple(1 layer)
compound(many layers)
where can we find simple epithelium?
as a lining for body cavities ducts and tubes
where can we find compound epithelium
skin
on which basis can we divide epithelial tissue in 3 categories?
on the basis of structural modification in the cells
what are the three types of epithelium
squamous
cuboidal
columnar
squamous epithelium
a single layer of flattened cells with irregular boundaries
where is squamous epithelium found
walls of blood vessels, alveoli, etc
functions of squamous epithelium
diffusion
filtration
cuboidal epithelium
a single layer of cube-like cells
where is cuboidal epithelium found
ducts of glands
tubular parts of nephrons in kidneys
functions of cuboidal epithelium
secretion
absorption
which epithelium has microvilli
pct in nephrons
columnar epithelium
a single layer of tall and slender cells
two structural features of columnar epithelium
nuclei are located at the base
the free surface may have microvilli
where is columnar epithelium found
lining of stomach and intestine
functions of columnar epithelium
secretion and absorption
ciliated epithelium
if the columnar or cuboidal epi cells have cilia on their free surface they are called ciliated epithelium
function of ciliated epithelium
move particles or mucus in a specific direction over the epithelium
where are ciliated epi cells present
inner surface of hollow organs like bronchioles,fallopian tubes etc
study of tissues
histology
father of histology
bichat
founder of histology
marcello malpighi
origin of tissues
from the germ layers in the embryo which differentiate into diff cell types and tissues
microvilli
minute finger-like projections that increase the absorption surface area of cells
stereocilia
long non-motile processes found in epididymis,vas deferens, hair cells of internal ear etc
apical surface of epithelium
1)faces body surface/cavity
/lumen of internal organ
/tubular duct that receives cell secretions
2)may contain cilia or microvilli
any tissue with cilia/villi is called
brush bordered tissue
lateral surfaces of epithelium
may contain: tight junctions adhesive junctions gap junctions desmosomes
basal surface of epithelium
opposite to apical surface
deepest layer of cells that adhere to extracellular materials
basement membrane
thin extracellular layer that consists of
basal lamina
reticular lamina
basal lamina
closer to and secreted by epi cells
functions as point of attachment
contains two proteins:collagen,laminin
reticular lamina
closer to underlying connective tissue and contains proteins like collagen produced by conn tissue cells called fibroblasts
basic difference between cuboidal and columnar cells
THE MAIN DIFFERENCE LIES IN THE FUNCTION WITH RESPECT TO LOCATION.
origin of epi tissue
ecto, endo and mesoderms
muscular tissue origin
mesoderm
origin of conn tissue
mesoderm
origin of neural tissue
ectoderm
