Epithelial Transport

Question 1

• Generic NaCl and water in epi transport to blood? (4 steps) ATP used?
• Basic Transport for glucose and AA’s? (4 steps)
• Tight Junction?
• Loose junction?
• Trans epithelial potential?

Answer 1

1. ) Na+ picked up on apical side (high perm) 2.) Na pumped out via Na+/K+ pump to basolateral side 3.) Cl- passively follows Na 4.) Water follows NaCl; no all passive
2. ) Glucose/Sugar/AA enter apical side via 2ndary active transport (Na+) 2.) Diffuse out BL side 3.) Picked up at target cells by secondary active transports 4.) glucose diffuses in but is phosph.
   - Increased seal to decrease back flux
   - Less seal with lots coming in and many pumps
   - TPD = Vm (BL) - Vm(apical)

Question 2

• Secretion by epithelial? (4 steps)
• Disease example of this? (2)
• Important substances that are never pumped?
• Metabolic waste removal: GI? kidney? Lung?
• How does kidney function?

Answer 2

1. ) Ach causes Na+ to leak in BL side, Cl follows 2.) cAMP gated chloride channels open and move Cl out apical side; Na and water follow 3.) serous substance is being excreted
2. ) CF: Chloride channel not properly implanted
3. ) Cholera: Toxin opens Cl channel
   - CO2, H2O, O2, Urea
   - Small but vital role; gets rid of volatile stuff; gets rid of non-volatile waste
   - I know what I like: Form ultrafiltrate in glomerulus and reabsorbs everything it wants back…very energetically costly