Junctions, Glads and Membranes Flashcards
(23 cards)
Define cell juntions.
contact points between the plasma membranes of tissue cells.
define tight junctions.
work like “zippers” to connect cells in epithelium that lines the body cavities.
what is the purpose of tight junctions.
prevent digestive juices from seeping between the epithelial cells that line the stomach and intestines.
What are desmosomes.
work-like “snaps” to attach adjacent cells to one another in tissues that need to resist mechanical stresses.
where are desmosomes common.
among cells in the superficial layer of the skin and between myocytes. heart mucles.
Define gap junctions.
use protein channels called connections to form tiny, fluid-filled channels between adjacent cells.
location of gap junctions.
in intercalated dics where the nerve signals travel very quickly through the heart. and are allowed electrical signals to pass from one myocyte to another.
Composition of glands.
epithelial cells that produce and release aqueous secretions.
define exorine glands.
secrete their products into ducts to be released at the surface of the body or into the lumen of another organ.
define endocrine glands.
have no ducts and secretes hormones into the extracellular fluid.
what can exorine glands be calssified as?
unicellular which can be mucous cells or goblet cells.
multicellular glands which are usually enclosed within a capsule that divided into lobes, which are subdivided into lobules. example are salivary glands, pancreas, mammary glands.
serous glands.
produce thin wateray fluids, such as perspiration or tears.
mucous glands.
produce the glycoprotein mucin that absorbs water to become sticky mucus.
merocrine (eccrine) glands.
release their secretions by exocytosis. examples salivary, sweat, pancreatic glands.
apocrine glands.
similary to merocrine but are sweat glands in the armpit or mammary gland.
holocrine glands.
produce secretion that consists of dead cell fragments and chemicals. oil glands in skin.
Cutaneous membrane.
it is also known as the skin and is the largest membrane, consists of a layer of stratified squamous epithelium that rests on top of a layer of underlying connective tissue. Dry membrane
Mucous Membrane
also known as mucosa. layer of epithelium, layer of areolar connective tissue called lamina propria and a layer of smooth muscle called muscularis.
location and function of mucous membrane
lines the body cavities and/or tracts that open to the exterior. mucus moistens and lubricates the tissues and traps bacteria and foreign particles.
Serous membrane
known as serosa. thin layer of areolar connective tissue that is covered with simple squamous epithelium.
location and function of serous membrane.
lines internal body cavities; forms pleurae that covers lungs, forms pericardium that covers heart. forms peritoneum cover abdominal organs. lubricates these membranes to reduce friction.
Synovial membrane.
only connective tissue without any epithelium.
locations and functions of synovial
lines joint cavities. secretes a slippery synovial fluid that lubricates and nourishes the cartilage that covers the ends of the bones.
