Epithelial cells Flashcards
Apical-basal polarity
polarity = positioning of the cell, the cell has an apical and basal surface and will always face accordingly (basal towards basement membrane)
blood vessels in epithelial tissue
avascular - uses diffusion through basement membrane to obtain nutrients from connective tissue
endothelium vs mesothelium
endo = epithelium which lines the inner surface of BVs, lymph vessels, heart -> from endoderm
meso = epithelium which lines peritoneum, pleura, percardium -> from mesoderm
How to define stratified tissue by cell type
Define by the shape of the cells at the surface
Mucosa vs serosa
epithelium and connective tissue relationship which lines organs
mucosa - lines the inner surface/lumen
serosa - lines the outer free surface of organ
‘anexome’
the arrangement of microtubules in cilia
9+2 arrangement
Desmosome
strong attachment site between cells
attaches to intermediate filaments in cells
involves the interactions/interdigitations of ‘cadherins’
Hemidesmosome
structural attachment of epithelial basal layer to the basement membrane
Simple squamous epithelium
Location: lines areas where passive diffusion of gases occur (e.g. alveoli)
Function: diffusion, absorption
simple cuboidal epithelium
Location: glands, ducts, kidney tubules
Function: secretion, absorption
Simple columnar epithelium
Location: respiratory tracy, uterus, stomach, small intestine
Function: have extensions
- cilia: movement of oocyte in ovary, particles in lungs
- microvilli: absorption in stomach, small intestine
Stratified squamous epithelium
Location: mouth, anus, vagina, palms, sole of feet
Function: protection against abrasion, infection
Stratified cuboidal epithelium
Location: Salivary glands, sweat glands
Function: absorption, secretion, protect against infection
Pseudostratified columnar epithelium
Location: trachea, bronchi, fallopian tubes
Function: have extensions such as cilia which move particles and ovum. also synthesises and secretes mucous
Transitional epithelium
Location: urinary tract
Function: accommodates the fluctuations of the vessel size. Dome shaped cells which line lumen contain extra reservoir membrane to allow for stretching
Cilia
Function for movement - move secretions, particles
Supported by microtubules which are arranged in an anexome = 9 pairs around the outside + 2 centrally
found on pseudostratified columnar
2-10um
micro-villi
non motile, function to increase SA and help with absorption of nutrients in digestive system
supported by actin filaments in cytoplasm
1-3um
sterocilia
long extensions, non motile, increase SA
found in epididymis to help with absorption of fluids, and are sensory cells of ear
25-120um
pseudostratified columnar
Types of glands
exocrine = have ducts which are used to secret mucous or serous
endocrine = no ducts, just secrete directly into bloodstream (glands in close contact with BVs)
Exocrine gland arrangements
alveolar (tear dropped) vs tubular
can be branched (becomes like a 4 leaf clover)
can be simple (single) or compound (a number of glands together)
stratified epithelium will never have….
cilia
