epithelial tissue Flashcards
define tissues
Groups of cells (can be different) with a common role
whats the 4 basic types of tissue
Epithelial
– covers and lines body surface and cavities, they serve to protect organs
Connective
– protects & supports
Muscular (very specific type of tissue)
– generates physical force for movement
Nervous (is found in nervous system)
– coordinates body activities – by generating and transferring info through nerve impulses. They also respond to chemical stimuli
what are the common features of epithelial tissue
Cells close together – continuous sheets, so provides protection and separation of organs and body cavities
Cover surfaces & line cavities - always a free surface associated with epithelial tissue = Apical surface = uppermost surface, eg may be the covering of the outermost layer of the skin
Have a Basement membrane of connective tissue
No blood vessels – so referred to as avascular
Have a nerve supply – so highly innervation
High capacity for cell division. Due to where are in body and their lining nature
what are the 2 epithelial cell categories
simple and stratified
whats Simple Epithelium
1 layer of cells
whats stratified epithelium
more than 1 layer of cells
what are the cell shapes of simple and stratified epithelium
squamous – flat cell type
cuboidal – shape that name suggests
columnar – shape that name suggests
transitional (able to change shape)
explain squamous simple epithelium
Squamous= single layer of flat cells. – polygonal appearance (many sides) when viewed from above
Important role for filtration (kidneys) or diffusion (lungs & capillaries)
They turn over and replace themselves every few weeks
squamous simple epithelium are called endothelium when….
Called endothelium (type of simple epithelium that lines the interior surface of blood vessels and lymphatics) when lining heart, blood and lymphatic vessels, forming an interface between circulating blood or lymph in the lumen and rest of vessel wall
squamous simple epithelium are called mesothelium when …
Called mesothelium ( membrane composed of simple squamous epithelial cells) when in serous (watery) membranes – line a body cavity that does not open to the exterior e.g. pleura, pericardium and peritoneum (sac that surrounds the heart).
They produce a lubrication fluid that’s released between layers providing slippery non adhesive and protective surface facilitating movement and reduce friction
what does the connective tissue form
forms the basement membrane and helps to anchor
the many sides to a simple squamous epithelial cell is referred to what
polygon
give ex of where find simple squamous epithelial
peritoneum
small intestine
describe simple cuboidal epithelium
cube shaped cells, rounded nuclei
single layer
Found on surface of many diff organs
In pancreases and overies
Provide protection
And pump material in and out of lumen
describe simple columnar epithelium
May be ciliated or non-ciliated
Elongated shape
found in Stomach, small intestine and large intestine will be lined with this including uterus as well
where is non ciliated simple columnar epithelial cells found
found in GI tract, and may be brush bordered as opposed to ciliated
where is ciliated simple columnar epithelial cells found
Ciliated are involved with movement of mucus and other substances via cilia found there, particularly in the upper respiratory tract , fallopian tubes and uterus and centeral part of spinal cord
Transports egg from follicle its moved towards uterus by cilia
describe pseudostratified columnar
appears stratified: nuclei at various levels
Although only a single layer of cells it suggests there is a stratified structure due to cell nuclei position.
It rarely occurs a squamous or cuboidal, its usually considered synonymous with term pseudo stratified columnar
explain stratified squamous epithelial
Stratified = multiple layers
Apical (top) layer of cells are flat
Deep layers vary from cuboidal to columnar
Cells in the basal layer divide and move upward toward apical surface –to help repair surface wear & tear
Found mostly in organs and areas of body where lots of physical wear and tear, removing the top layers of the cell
Found in skin, mouth, vagina, and oesophagus
describe Stratified Cuboidal Epithelium
Rare but Found in gland like sweat gland, salivary glands
Lumen of the duct as associated with glands
describe Stratified Columnar Epithelium
rare
also associated with ducts – like esophagus, parts of the eye, and male urethra, salivary glands
Function is secretion and protection
Cell shape change in the layers
describe Transitional Epithelium
variable in appearance — cells can stretch
Gets its name from fact that its variable in appearance as stretches and expands
Its found in organs or vessels that expand and contract like urinary bladder the ureters, and gland ducts of the prostate
Appearance of cells change in appearance as( bladder) expands and stretches
describe glandular epithelium (endocrine)
Endocrine glands = collection of glands that secrete hormones directly into the circulatory system, so these will be deposited into the blood so help blood vessels very close to them
Ex, thyroid gland
describe glandular epithelium (exocrine)
Ex, of exocrine - sweat gland in skin produce sweat that’s deposited onto surface of the skin
