regional transport Flashcards
proximal tubule
- isotonic fluid
- Na
- K
- Cl
- H2O
- glucose
- lactate
- amino acid
- inorganic PO4
- 2/3 of HCO3 is reabsorbed
- no net gain and net lost of HCO3 in the PT
- is to recover 90% of the filtered HCO3
TM system is
- secondary active transport at the luminal membrane
a defect in recovering 90% of filtered HCO3 in the PT
- causing HCO3 in the urine
- type II renal tubular acidosis
- causing metabolic acidosis
type II renal tubular acidosis
- a defect in recovering 90% of filtered HCO3 in the PT
- causing metabolic acidosis
- HCO3 in the urine
maximum effect of ADH on the KIDNEY
- most of the WATER IS REABSORBED IN THE PROXIMAL TUBULE 2/3
ACTION OF ADH
- COLLECTING DUCT
MOST OF ANYTHING IS ABSORBED
- magnesium
- PROXIMAL TUBULE
a DEcrease in CONCENTRATION MEANS
- substance is completely reabsorbed and secreted
- glucose is absorbed in early proximal tubule
INULIN
- freely filtered
- INcreases in CONCENTRATION as it reabsorbs water
- substance is NOT reabsorbed
- 3.0
- PCT
NORMAL RATIO
- 1.O
lowest concentration of INULIN
- BOWMAN’S SPACE
- at the beginning of the system
highest concentration of INULIN
- COLLECTING DUCT
- end of the system
Thin descending limb of loop of Henle
- The thin descending limb has low permeability to ions and urea, while being highly permeable to water.
- The loop has a sharp bend in the renal medulla going from descending to ascending thin limb.
Thin ascending limb of loop of Henle
The thin ascending limb is impermeable to water, but it is permeable to ions.
Thick ascending limb of loop of Henle
- Sodium (Na+), potassium (K+) and chloride (Cl−) ions are reabsorbed from the urine by secondary active transport by a Na-K-Cl cotransporter (NKCC2).
- The electrical and concentration gradient drives more reabsorption of Na+, as well as other cations such as magnesium (Mg2+) and calcium (Ca2+).
Cortical thick ascending limb
The cortical thick ascending limb drains urine into the distal convoluted tubule.
if no water is reabsorbed in the proximal tubule
DUE TO COMPLETE INHIBITION OF THE SODUIM POTASSIUM PUMP
- no substance is reabsorbed either
- meaning reabsorption in the proximal tubule is dependent on the amount of water reabsorbed
PROXIMAL TUBULE IS POWERED BY
- NaKATPase pump
urea
- counter current multiplier
inner medulla
- maximum amount 1200
greatest osmolarity
- at the TIP OF THE LOOP OF HENLE and end of collecting duct w/ the maximum effect of ADH
thick ascending limb of the loop of henle
- have a big decrease of osmolarity passing thru
- DILUTING SEGMENT OF THE NEPHRON
- ## HYPOTONIC
lowest osmolarity
- early part of the distal tubule MAIN ANSWER
- SECOND CHOICE or the fluid leaving the loop of henle
uncontrolled diabetes
- not absorbing glucose in the proximal tubule
- large volume of dilute urine is formed even if high ADH
- unable to form concentrated urine
distal tubule
- NaCl reabsorption
- PTH acts at the basal membrane
primary active transport
- ATPase breaking down ATP
that directly supplies the energy at the distal tubule
secondary active transport at the early distal tubule
- 3 sodium entering the cell them pump out 1 calcium out of the cell
- powered NaKATPase pump
last part of the distal tubule is
- distal nephron
- has principal cells
- intercalated cells
collecting duct
- has principal cells
- intercalated cells
aldosterone mainly act on the
- PRINCIPAL CELL
most filtered PO4 is reabsorbed in the
- proximal tubule
H+ ion are secreted as
- dihydrogen PO4 (H2PO4) aka as TITRATABLE ACID
- 1/3 of the normal hydrogen secreted is buffered by PO4
AMMONIA IS PRODUCED BY
- KIDNEY
acidosis
- increase NH4
alkalosis
- decrease NH4 2/3 loss in the urine
total acid loss in the urine
- titratable acid (H2PO4) plus NH4
- equals the HCO3 formed in the intercalated cells
type I renal tubular acidosis
- fails to secrete titratable acid (H2PO4) plus NH4
- unable to pump H+
- urine pH is not affected
NH4 is the major component of losing
- H+ ions in the urine
- urine anion gap to estimate the amount of NH4 lost in the urine
urine anion gap
Na+ plus K+ plus NH4+ equals
= Cl` concentration
urine anion gap
Na+ plus K+ minus Cl`
= -NH4 meaning a lot of NH4 in the urine
- losing a lot of fixed acid in the urine
urine anion gap
Na+ plus K+ minus Cl`
= zero or positive there is NO NH4 in the urine
