Tubular structure and function Flashcards
2 routes of movement from lumber of tubule to interstitial space:
- Paracellular
- Transcellular
Basolateral membrane:
Towards cell/blood
Apical membrane
Towards lumen of tubule
Primary active transport system on basolateral membrane:
Na+-K+-ATPase
Secondary active transport systems on apical membrane:
- glucose-Na+ and amino acid-Na+ cotransorters
Cells lining the PCT have:
Microvilli
Type of cells in thick ascending limb:
Cuboidal
Hormones chemically similar to aldosterone:
Oestrogen
Oestrogen’s influence on tubule:
Enhance NaCl reabsorbtion. Retain fluid during menstrual cycle.
Progesterones influence on tubule:
Block effect of aldosterone. Decrease Na+ reabsroption, diuretic-like effect
Glucocorticoid influence on tubule:
Enhance tubular reabsorption of Na+. BUT promote increase GFR which may mask this effect.
As fluid passes down collecting duct, pass through tissue with ever decreasing water potential. This is an ex of
Hairpin countercurrent multiplication
Reabsorbed in PCT:
HCO3- Na+ Glucose Amino acids Lactate Urea
Secreted into PCT:
NH4+
Medications
Organic acids
Name some transporters on the PCT:
- Na+-glucose/amino acid cotransporter
- GLUT1, GLUT2
- Na+-K+ ATPase
- Na+-H+ exchanger
- Na+-HCO3- co transporter
In the PCT in Na+-K+ATPase acts to:
Keep intracellular [Na+] low so it can move down conc. gradient (secondary active transport w/glucose)
Thin descending limb is impermeable to…
Ions
Reabsorbed in thin descending limb:
Diffusion of Na+ and Cl-
Reabsorbed in thick descending limb:
Na+, Cl-, K+ active transport
Pump on apical surface on thick descending limb:
Na+-K+-2Cl- cotransporter
Transporters on basolateral surface of Thick DL:
Na+-K+ ATPase
K+ and Cl- channels
Reabsorbed in DCT:
Na+, Cl-, Ca2+
Secreted in DCT:
K+
Aldosterone acts on the:
DCT and collecting duct
