Epithelium and Connective Tissue Flashcards
What are the four basic tissue types?
- epithelium
- connective tissue
- muscle
- nerve
What is epithelium tissue? Give examples.
It serves as a boundary, separates inside/outside world.
Ex: skin, lines the lumen of hollow organs, lines blood vessels
What is connective tissue? Give examples.
It has sparser cells within in extracellular matrix. characteristics depend on types of fibers present.
Ex: bone, blood, cartilage
What is muscle tissue? Give examples.
Striated or smooth; under voluntary or involuntary control; contracts to pump blood, move the skeleton, for perstalsis, etc.
Ex: found in the heart, skeleton muscle, and around arteries in the digestive track
What is nerve muscle? Give examples.
Nerve muscle has long axons to transmit information; involved in body control and reception. Controls movement, reception of different sensations, and controls the autonomic functions of the body.
Found in the central and peripheral nervous systems.
What are the different types of epithelia?
Epithelia are classified based on the shape of their cells and number of cell layers:
Either:
SIMPLE: single layer
STRATIFIED: multiple layers
Shape:
SQUAMOUS: flat
CUBOIDAL: cube-shaped
COLUMNAR: column-shaped
OTHER:
–> pseudostratified epithelium (type of simple); all cells (mostly columnar) touch the base, but do not reach the surface; respiratory epithelium, much of male reproductive tract
–> transitional epithelium: lining of much of urinary tract, including urinary bladder
Where do you find simple squamous epithelia?
lining of lung alveoli, some kidney tubules, endothelium (lining of blood vessels) and mesothelium (lining of body cavities)
Where do you find stratified squamous epithelia?
epidermis of skin (keratinized); lining of oral cavity, esophagus, anal canal, cervix, vagina, distal urethra (non-keratinized)
Where do you find cuboidal cells?
Kidney tubules, glands, ducts
Where do you find columnar epithelial cells?
simple: lining of GI tract, bronchioles in lung, oviduct, uterus in female reproductive tract
stratified: lining of some salivary gland ducts (rest are simple cuboidal)
What is the concept of epithelial cell polarity? How is it important in epithelial function?
The location of some cells makes them need to have organelles and surfaces in particular places/orientations. For example, in epithelium, gas transport happens at the basal surface (nearer to blood vessels and basal lamina). Cells at the apical surface may need to absorb nutrients, like in the digestive tract, so the apical side will have a brush border to increase surface area. The lateral surfaces will join together neighboring cells, and the different junction types (tight/occluding jxn, attachment/adherens jxns, communicating/gap jxns) will be found there depending on the location of the body.
the basal side will also contain junctions to bind the cell to the substrate.
Describe the structure and function of the apical surface membrane of a cell.
Faces the outside world. Often forms microvilli for absorption. May also have cilia.
Describe the structure and function of the basal surface membrane of a cell.
it is bound to the substrate or basement membrane. Hemidesmosomes and adherens junctions hold the cells to the basal lamina.
Describe the structure and function of the latera surface membrane of a cell.
They have desmosomes to anchor the cells to each other as well as tight junctions to prevent leakage of fluid between the cells. A zonula adherens is associated with the tight junction in order to stabilize the cells and anchor them to one another and to actin filaments in the cytoskeleton.
What is the structure and function of the basal lamina?
Basement membrane is secreted from epithelial cells, made of glycoproteins and other molecules. It serves as a foundation for the epithelium. It helps attach the epithelium to underlying CT.
What is Type I collagen?
It forms fibrils that combine to form fibers and then larger fibers. They are used for structural support in CT, especially blood vessels. Rebar of the body; mechanical support. Incorrect folding of Type I collagen can lead to hyperextendable skin joints.
