Epithelium Flashcards
What is the function of the epithelium?
- forms secretory tissue of glands and ducts
- specialized receptors for senses
What is the structure of the epithelium from inner to outer?
apical layer< cellular layer< basal layer
What are the interior layers of the epithelium?
- mesothelium: inside body cavities, covering internal organs
- endothelium: vascular and lymphatic system
- endocardium: inside heart
What are the characteristics of the endothelium?
- cell junctions: connect cells to basal membrane and other cells
- polarity
- basement membrane: layer under epithelium
Where is epithelioid tissue located?
endocrine glands, epithelioreticular cells, epithelium-derived tumors
What is the difference between epithelial and epithelioid tissue?
epithelial: apical free surface
epithelioid: absence of apical free surface
What defines stratified and simple cells?
apical layer of cells and number of cellular layers
What is the mucosa?
surface epithelium + basement membrane + lamina propria (loose connective tissue)
Does the mucosa have muscle?
yes
What does the mucosa line?
digestive, respiratory, and genitourinary tracts
What is the serosa?
mesothelium + basement membrane + connective tissue
Does the serosa have muscle?
NO
What does the serosa line?
body cavities (peritoneal, pericardial, pleural)
What are pseudostratified columnar cells?
not all epithelial cells reach the surface; uneven rows
What is a transitional cuboidal cell?
plenty of cells; no uniformed row
Where is a simple cuboidal cell located?
surface of ovary -> barrier (germinal epithelium)
What is the function of simple cuboidal cells?
- kidney tubules -> absorption
- thyroid tubules -> absorption
- pancreas -> absorption
What are simple cuboidal cells?
small ducts of exocrine glands
What are stratified cuboidal cells?
large ducts of exocrine glands
Where are simple columnar cells located?
in small intestine (secretory function) + reproductive system
What type of cell serves as a sensory function in the eyes?
simple columnar cell
What are the roles of simple columnar cells?
- impermeable barrier against ingested bacteria
- permeable to necessary ions
- absorbs and transports nutrients
What are stratified columnar cells classified as?
ciliated or non-ciliated
What is the secretory function of stratified columnar cells?
large ducts of exocrine glands
What can pseudostratified columnar cells be classified as?
ciliated or non-ciliated
What is the secretory function of pseudostratified columnar cells?
respiratory system
Pseudostratified columnar cells can specialize to secrete what?
mucus (goblet cells)
What are simple squamous cells composed of?
endothelium and mesothelium