Epithelial Tissue Flashcards
What are the 5 characteristics of epithelium ?
- ) polarity
- ) specialized contacts
- ) supported by connective tissues
- ) avascular but innervated
- ) ability to regenerate
What are the two forms of epithelium that occur in the body?
Covering/lining
Glandular
What does ‘polarity’ mean in reference to epithelium?
All epithelial have an apical surface (upper free, exposed surface) and a basal surface (lower, attached surface).
What is the difference between microvilli and cilia?
Microvilli - finger like extensions on the plasma membrane which increase exposed surface area. Absorb and secrete substances
Cilia - motile, hairlike projections that propel substances along free surface.
What does ‘specialized contacts’ mean in reference to epithelium.
Epithelial cells fit closely together to form continuous sheets.
Name two types of specialized contacts
Tight junctions and demosomes
Where in the body can you find simple squamous epithelia?
Kidney glomeruli Air sacs of the lungs Lining of the heart Blood vessels Lymphatic vessels Lining of ventral body cavity (serosae)
Where in the body can you find simple cuboidal epithelia?
Kidney tubules
Ducts and secretory portions of small glands
Ovary surface
Where in the body can non-ciliated simple columnar epithelium be found?
Majority of digestive tract (stomach to rectum)
Gall bladder
Excretory ducts of some glands
Where in the body can you find ciliated simple columnar epithelium?
Line small bronchi
Uterine tubes
Some regions of uterus
Where in the body can you find non-ciliated pseudostratified columnar epithelium?
Male sperm-carrying ducts
Ducts of large glands
Where in the body can you find ciliated pseudostratified columnar epithelium?
Trachea
Most of upper respiratory tract
Where in the body can you find nonkeratinized stratified squamous epithelium?
Esophagus
Mouth
Vagina
Where on the body can you find keratinized stratified squamous epithelium?
Forms the epidermis of the skin (dry membrane)
Where in the body can you find transitional epithelium?
Lines uterus, bladder, and part of urethra
What is the function of endocrine glands?
Produces hormones through the process of exocytosis directly into the extracellular space
In what ways are glands classified?
- ) Where they secrete their products (endocrine or exocrine)
- ) unicellular vs. multicellular
What is the function of exocrine glands?
They secrete their products onto body surfaces or into body cavities.
Where can you find a simple alveolar gland?
There is no important example in humans
Where are simple tubular glands found in human body?
Intestinal glands
Where can simple branched tubular glands be found?
Stomach (gastric) glands
Where can the compound tubular glands?
Duodenal glands of small intestine
Where can simple branched alveolar glands?
Sebaceous (oil) glands
Where can compound alveolar glands?
Mammary glands
Where can compound tubuloalveolar glands be found?
Salivary glands
What are merocrine glands?
secrete their products by exocytosis as their being produced.
Examples of merocrine glands?
Pancreas
Most sweat glands
Salivary glands
What is the function of holocrine glands?
Accumulate their product within them, as they produce it, until they rupture.
What is the function of apocrine glands?
Accumulate their products beneath the free surface
Where can you find apocrine glands?
There is controversy whether apocrine glands exist in human body, but histologists suggest they exist in mammary glands.
What is an example of a holocrine gland?
Sebaceous glands of the skin
What are the general characteristics of epithelial tissue?
- ) cells have free or apical surface
- ) cells have inferior, attached basal surface
- ) cells are attached to underlying tissue by basement membrane
- ) avascular, but innervated
- ) cells are tightly packed together
- ) cells usually form sheets and/or layers
Classification of simple squamous epithelium:
Flattened, irregularly shaped cells that form a single layer
Allow for diffusion and other exchange processes
Classification of simple columnar:
Elongated cells that form a single layer
Goblet cells are present
Associated with absorption and secretion.
Classification of simple cuboidal:
Cubed cells
About as tall as they are wide
Associated with secretion and absorption
Classification of pseudostratified columnar:
Appears to be many layers
All cells touch the basement membrane, not all cells reach free (apical) apical surface
What is the difference between simple and stratified epithelium?
Simple epithelium has one layer
Stratified epithelium has two or more layers
What is the purpose of keratin?
It is a protein that waterproofs and protects the epidermis of the skin
What are goblet cells?
Unicellular glands that secrete mucus
Found within simple columnar epithelium
