The Tubule 2 Flashcards
PCT
Confined to renal cortex
Active reabsorption of amino acids, glucose, bicarbonate, phosphate, salt and water, potassium, chloride, urate
Metabolically active
What condition can you get if you don’t reabsorb phosphate properly?
Hypophosphataemic rickets
Bow-legged deformity, muscle weakness, slow growth
(most common form is X-linked)
Glucose transoportation
Glucose is co-transported with Na via sodium glucose transporter 2 (SGLT2)
Proximal Renal Tubule Acidosis (type 2)
Defect in Na/H antiporter so failure to reabsorb bicarbonate properly.
Treatment by alkali replacement.
Fanconi Syndrome
Generalised Proximal Tubular Disfunction, possibly due to failure to generate sodium gradient by Na/K ATPase
Thin part of Loop of Henle
water permeable
Thick ascending part of Loop of Henle
Water impermeable
Active sodium reabsorption
generates medullary concentration gradient via counter-current system
Countercurrent Multiplication
Generate a hypertonic medullary interstitium so that H2O can be sucked out of the tubule in impermeable distal segments, thus concentrating urine.
Distal Tube
Allows “fine tuning” of sodium reabsorption, potassium and acid-base balance.
Impermeable to passive movement of water and sodium
Distal RTA (Type 1)
Sodium channel or H-ATPase defect
Failure of acid secretion.
Collecting Duct
Mediates water reabsorption and maintains acid base homeostasis
Principle cells and intercalated cells
Principle cells
Sodium and water reabsorption and potassium excretion
ENaC - specific sodium transporter, main site of Na regulation
Aldosterone - increase the numner of open ENaC channels regulating Na absorption
Intercalated cells (alpha and beta)
Secrete H or HCO3
Essential for acid base homeostasis
Diuretics that effect the PCT
Carbonic anhydrase inhibitors
Diuretics that effect the loop of Henle
Loop diuretics
