Week 4 Apical Domain Module

Question 1

what are some “things” typically seen on the apical domain of epithelial cells? 5

Answer 1

enzymes, receptors, ion channels, carrier proteins, special structures (microvilli, cilia)

Question 2

Microvilli: what are they? role? found? compoisition?

Answer 2

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

Question 3

stereocilia: what? location? role?

Answer 3

long immotile microvilli. found in hair cells of innner ear, vas deferens, and epididymis. Sense movement (mechanoreceptors)

Question 4

Cilia: types, composition

Answer 4

motile cilia and non-motile cilia. Composed of microtubules

Question 5

microtubule arrangement of motile cilia

Answer 5

9+2 arrangement. 9 doublets (A+B microtubules) surrounding a central doublet

Question 6

how is the “beating” of cilia accomplished?

Answer 6

dynein and the 9+2 arrangement enables for beating

Question 7

what type of epithelium can be ciliated? where do we see this?

Answer 7

pseudostratified columnar epithelium. seen in respiratory tract

Question 8

what is the mucociliary escalator?

Answer 8

the upward movement of mucus (from the lungs to the mouth) produced by the cilia

Question 9

what is the role of nodal cilia?

Answer 9

fount only in the embryo. play a large role in determining L+R asymmetry of internal organs

Question 10

What is Primary Ciliary Dyskinesia? (Karagener syndrome). Cause? symptoms?

Answer 10

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

Question 11

what is situs inversus? why does it make sense that cilia dysfunction is involved?

Answer 11

condition in which internal organs are mirror images of what they should be. Nodal cilia play a role in determining asymmetry of our bodies

Question 12

what are primary cilia?

Answer 12

note: these do not cause primary ciliary dyskinesia!! non-motile cilia that lack dynein and have MT arrangements of 9-0 (no central doublet)

Question 13

what is the function of primary cilia? location?

Answer 13

bend passively with fluid flow and trigger calcium influx. serve as mechanoreceptors found all over the body

Question 14

what proteins make up primary cilia?

Answer 14

polycystin-1 and polycystin-2

Question 15

Autosomal Dominant Polycystic Kidney Disease (ADPKD): cause? results in?

Answer 15

loss of ADPKD 1 and 2 genes that encode of polycystin proteins. Patients develop enlarged, cystic kidneys

Question 16

what two broad locations are golblet cells found?

Answer 16

digestive and respiratory tract

Question 17

Answer 17

1. basal body: what cilia are attached to
2. Cilia
3. Goblet cells