A&P Chapter 4 Flashcards
What is epithelial tissue?
A sheet of cells that covers body surfaces or cavities
What are the two main forms of epithelial tissue and where are they located?
- Covering and lining epithelia, located on external and internal surfaces (like skin)
- Glandular epithelia, located in secretory tissues in glands (like salivary glands)
What are the main functions of epithelial tissue?
Protection, absorption, filtration, excretion, and sensory reception
What are the special characteristics of epithelial tissues?
Polarity, apical surface, basal surface, specialized contacts, avascularity, innervated, regeneration, and specialized contacts
What is the polarity (top and bottom) of epithelial tissues?
- The apical surface, upper free side, is exposed to the surface or cavity
- The basal surface, lower attached side, faces inward towards the body
What is the apical surface’s texture?
Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli
What does the basal surface attach to?
The basal lamina, an adhesive sheet that holds the basal surface of epithelial cells to underlying cells
The apical and basal surfaces differ in ______?
Structure and function
What are the specialized contacts of epithelial tissues?
Epithelial tissues have tightly packed cells, and had desmosomes and tight junctions
Epithelial tissue is _____ by underlying tissue
Nourished
What is regeneration?
Abundant cell division
What are the two names of all epithelial tissues?
First name indicated the number of cell layers, and the second name indicated the shape of the cells
What is the tip to identifying the shape of the cells?
Look at the apical (top) surface to determine cell shape
What are the names for the cell layers?
Simple = one layer and stratified = more than one layer
What are the names for the cell shapes?
Squamous = flat, cuboidal = cube-like, and columnar = taller than it is wide
What is simple squamous epithelium?
A single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm. It is the simplest of epithelia
What is the function of simple squamous epithelium?
Allows materials to pass by diffusion and filtration in sites where protection is not important. It also secretes lubricating substances in serosae
What is serosae?
Linings of the ventral body cavity
What is the location of simple squamous epithelium?
Kidney glomeruli, air sacs of lungs, the lining of the heart, blood vessels and lymphatic vessels, and serosae
What is simple cuboidal epithelium?
Single layer of cube-like cells with large, spherical central nuclei
What is the function of simple cuboidal epithelium?
Secretion and absorption
Where is the location of simple cuboidal epithelium?
Kidney tubules, ducts and secretory portions of small glands, and the ovary surface
What is simple columnar epithelium?
Single layer of tall cells with round to oval nuclei, many cells have microvilli, some have cilia, this tissue may contain goblet cells
What are goblet cells?
Mucus-secreting unicellular glands
What is the function of simple columnar epithelium?
Absorption, secretion of mucus, enzymes, and other substances. The ciliated type propels mucus or reproductive cells by ciliary action
What is the location of simple columnar epithelium?
Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands. The ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus
What are pseudostratified columnar epithelium?
Single layer of cells of differing heights, some not reaching the free surface, nuclei seen at different levels, may contain goblet cells and cilia
What is the function of pseudostratified columnar epithelium?
Secretes substances, particularly mucus, propulsion of mucus by ciliary action
What is the location of pseudostratified columnar epithelium?
Ciliated variety lines the trachea and most of the upper respiratory tract. Nonciliated variety is in males’ sperm-carrying ducts and ducts of large glands
What are stratified squamous epithelium?
Thick epithelium composed of several cell layers, basal cells are cuboidal or columnar and metabolically active, surface cells are flattened (squamous). In the keratinized type, the surface cells are full of keratin and are dead. Basal cells are active in mitosis and produce the cells of the more superficial layers
What is the function of stratified squamous epithelium?
Protects underlying tissues in areas subjected to abrasion
What is the location of stratified squamous epithelium?
Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina. Keratinized type forms the epidermis of the skin, a dry epithelium
What are stratified cuboidal epithelium?
Two or more layers of cells, cells at the apical surface are about as tall as they are wide
What is the function of stratified cuboidal epithelium?
pROTE
What is the function of stratified cuboidal epithelium?
Protection and secretion
What are stratified columnar epithelium?
Two or more layers of cells, cells at the apical surface are taller than they are wide
What is the function of stratified columnar epithelium?
Protection and secretion
What is the location of stratified columnar epithelium?
Large ducts of salivary glands, male urethra, and pharynx
What is transitional epithelium?
Resembles both stratified squamous and stratified cuboidal, basal cells are cuboidal or columnar, surface cells are dome shaped or squamous-like, depending on the degree of organ stretch
What is the function of transitional epithelium?
Stretches readily, permits stored urine to distend urinary organ
What is the location of transitional epithelium?
Lines the urethra, bladder, and part of the urethra
What is a gland?
One or more cells that makes and secretes an aqueous fluid called a secretion
What are glands classified by?
The site of product release and the relative number of cells forming the gland
What are the sites of product releases in glands?
Endocrine = Ductless and internally secreting (hormones), and Exocrine = have ducts and externally secreting (sweat)
What is the relative numbers of cells forming the gland?
Unicellular (goblet cells) or multicellular (salivary)
Multicellular epithelial glands form by ________?
Invagination (inward growth) of an epithelial sheet
What do exocrine glands retain?
Connecting cells, which forms a duct that transports secretions to the epithelial surface
What do endocrine glands lose?
Their ducts during development
Where do endocrine glands secrete hormones?
Into the interstitial fluid, which then enters the blood
What do mucous and goblet cells produce?
Mucin
What is mucin?
A sugar-protein that can dissolve in water to form mucus, a slimy, protective, lubricating coating