Ch. 4 Flashcards
What is the basic components of all tissues?
Cells and extracellular matrix
What are the four basic tissue types and their major general function?
covering, support, movement (blood, urine, etc.), control
What are general characteristics of epithelial tissue?
arranged in continuous sheets (single or multiple layers)
- cells are closely packed together and have very little extracellular matrix.
- found at interface environments (boundary between two different environments)
What are the general types of epithelium and their locations?
- Covering and lining epithelium
- –covers outer surfaces—> skin
- –lining inner surfaces —> stomach, mouth, nasal cavity, vagina, bladder, uterus (all hollow organs have epithethelium lining the inside)
- Glandular epithelium
- –forms most glands of the body
- –sweat glands, oil glands, milk glands, pituitary (releases hormones located in the brain
What are general functions of epithelium?
- Protection of underlying tissues
- secretion
- absorption
- diffusion
- filtration
- sensory reception
What are special characteristics of epithelia?
- High cellularity
- specialized contacts (specialized proteins that allow these cells to link up in special ways)
- Polarity (has two different sides; apical and basal surface)
- Support of connective tissue from the basement membrane
- avascular
- nervous innervation
- regeneration (set up to repair themselves very well because they are usually undergoing lots of damage)
What is the basement membrane?
Underlaying connective tissue
- basal lamina (secreted by the epithelial tissue; considered to be apart of the epithelial tissue)
- reticular lamina (secreted by underlaying connective tissue)
What is the function of simple squamous epithelium and where is it mainly located?
Function: allows the passage of stuff via diffusion or filatration in areas where protection is not really needed; also secrete serous fluid
Locations: kidney glomeruli, lung air sacs, lining of heart, blood vessels, lymphatic vessels, ventral cavity (lining)
What is endothelium and mesothelium?
Endothelium- simple squamous epithelial tissue lining the inside of blood vessels
Mesothelium- simple squamous epithelial tissue lining serous membranes.
What is the function of simple cuboidal epithelium and where is it mainly located?
Function: secretion and absorption
Locations: tubular like structures = kidney tubules, ducts and secretory portions of small glands.
What is the function of simple columnar epithelial tissue and where is it mainly located?
Contains goblet cells
Function: absorption; secretion of mucus, enzymes, and other substances. (some are ciliated but she will not show a photo of this).
Locations: forms most of the digestive tract.
What are goblet cells?
Single celled gland that secrete things on a free surface. there is no duct in this gland because it is single celled.
How do goblet cells work in the digestive tract?
They secrete mucin and when that mucin is combined with water is makes mucus and it serves as a lubricant for things passing through the digestive tract.
What is the function of pseudostratified columnar epithelial tissue and where is it mainly located?
-ONLY CILIATED EPITHELIUM SHE WILL ASK ABOUT
Function: secretion of mainly mucus (so lots of goblet cells) and propulsion of mucus via the ciliary action (mucus catches the stuff and the cilia move it up so we can swallow or spit it out)
Location: ciliated variety lines the trachea and most of the upper repiratory tract; nonciliated lines sperm carry ducts and ducts of large glands.
Everytime you have stratified epithelium, what is it’s main function?
Protection
What is the function of stratified squamous epithelium and where it is mainly located?
Function: protect underlying tissues in areas of abrasion
Locations: Nonkeratinized (nuclei in the apical surface) forms the lining of the esophagus, mouth, and vagina. Keratinized (no nuceli in the apical surface) forms the epidermis of the skin and a dry membrane.
What is the function of stratified cuboidal epithelium and the locations of it mainly?
-Rare; Generally found in two layers and either seen in tunnel like or ring like.
Functions: Protection
Locations: largest ducts of sweat glands, mammary glands, and salivary glands.
What is the function of stratified columnar epithelial cells and where are they mainly located?
Function: protection and secretion (has not cilia comparedto pseduostratified; good way to determine the difference on exam)
Location: rare in the body, small amounts in male urethra and in large ducts of some glands.
What is the function of tight junctions and where are they mostly located?
Function: to form a very tight seal between adjacent cells that form a fluid barrier so that none of the fluid can actually pass between cells —> prevent fluid from leaking between cells and making it to the basement membrane.
Locations: found in tissue types that are going up against fluid (urinary bladder, going up against urine).
How are these tight junctions formed?
In the plasma membranes of the cells there is an arrangement of transmembrane proteins (like a riveting pattern). in some locations these proteins come together and fuse and hold tightly
What is the function of desmosomes and where are they mostly located?
-Known as anchoring junctions
Function: bind adjacent cells together and help form an internal tension-reducing network of fibers.
Locations: found on areas where you have lots of distortion of tissues (skin).
How are these desmosomes (anchoring junctions) formed?
Transmembrane proteins called linker glycoproteins (cadherins) are embedded on a plaque that is located on the inside of the cell and from the plaque are intermediate filaments (keratin) extending.
The linker glycoproteins (cadherins) are joined together like the teeth of a zipper.
If they try to pull them apart, the linker proteins will catch on each other like the teeth of a zipper.
What is the function of gap junction and where are they mostly located?
Function: for cell coupling
Electrical coupling: passing of ions from one cell to the next
metabolic coupling: passing of glucose and other nutrients form cell to the next
Location: in electrical types of tissues =cardiac myocytes, epidermis (epithelium is avascular so they need to receive stuff from the underlaying connective tissue…this is how it’s done, allow for nutrients from the blood to go up into the epithelial tissue).
How do gap junctions work?
Two adjacent cells have transmembrane proteins in their plasma membranes, and these transmembrane proteins line up together and form a tunnel/channel called a CONNEXON so that ICF from each cell can travel through.
What are microvilli (microvillus single) and where are they mainly located?
- non motile finger like projections made up of actin mircofilaments that are running up the core of each microvillus.
- digestive tract
What is the function of microvilli?
To increase surface area to be able to absorb and secrete more.
-Actin filaments push the plasma membrane up increasing the surface area and therefore the amount that is absorbed or secreted.
What are cilia (cilium single)?
longer projections than microvilli made of microtubules and help move things along the surface of the cell by performing whip like actions.