what are some "things" typically seen on the apical domain of epithelial cells? 5
enzymes, receptors, ion channels, carrier proteins, special structures (microvilli, cilia)
Microvilli: what are they? role? found? compoisition?
finger like extensions of the plasma membrane and cytoplasm. increase absorptive surface area of epithelial cells. brush border of renal tubules and striated border on surface of intestinal epithelial cells. Actin filament core w/ web of myosin and tropomyosin that enables the microvillie to contract
stereocilia: what? location? role?
long immotile microvilli. found in hair cells of innner ear, vas deferens, and epididymis. Sense movement (mechanoreceptors)
Cilia: types, composition
motile cilia and non-motile cilia. Composed of microtubules
microtubule arrangement of motile cilia
9+2 arrangement. 9 doublets (A+B microtubules) surrounding a central doublet
how is the "beating" of cilia accomplished?
dynein and the 9+2 arrangement enables for beating
what type of epithelium can be ciliated? where do we see this?
pseudostratified columnar epithelium. seen in respiratory tract
what is the mucociliary escalator?
the upward movement of mucus (from the lungs to the mouth) produced by the cilia
what is the role of nodal cilia?
fount only in the embryo. play a large role in determining L+R asymmetry of internal organs
What is Primary Ciliary Dyskinesia? (Karagener syndrome). Cause? symptoms?
Auto rec. of motile cilia caused by loss of dynein. Cillia beat in an uncoordinated way. Results in poor mucus clearance, immotile sperm (flagella are modified cilia), and situs inversus
what is situs inversus? why does it make sense that cilia dysfunction is involved?
condition in which internal organs are mirror images of what they should be. Nodal cilia play a role in determining asymmetry of our bodies
what are primary cilia?
note: these do not cause primary ciliary dyskinesia!! non-motile cilia that lack dynein and have MT arrangements of 9-0 (no central doublet)
what is the function of primary cilia? location?
bend passively with fluid flow and trigger calcium influx. serve as mechanoreceptors found all over the body
what proteins make up primary cilia?
polycystin-1 and polycystin-2
Autosomal Dominant Polycystic Kidney Disease (ADPKD): cause? results in?
loss of ADPKD 1 and 2 genes that encode of polycystin proteins. Patients develop enlarged, cystic kidneys
what two broad locations are golblet cells found?
digestive and respiratory tract
1. basal body: what cilia are attached to
3. Goblet cells