water and na+ undergo – but no —
- reabsortion
- no secretion
the Na+ reapsortion is an — requires all – except —-
- active process
- tubules
- descending limb of loop of henle
water reabsorption is by — and is dependent on —-
- osmosis , passive process
- na+ reabsorption
in primary active sodium reabsorption, the primary active transport of Na — and — the interstitial fluids
- out
- into
in primary active sodium reabsoription the transport is achieved by:
Na+ /K+ - ATPase pumps.
The active transport of Na+ out of the cell keeps the intracellular concentration of Na+ — compared to the tubular lumen so Na moves downhill from —- into —–
- low
- tubular lumen
- tubular epithelial cells
-The movement of Na+ across the apical membrane varies from segment to segment of the tubule.
MECHANISM OF ππ! REABSORPTION IN THE PROXIMAL TUBULE
- cotransport w/organic material as: glucose
- counter transport w/ h+
the main function of the reabsorption in the ascending limb of loops of henle is — and is done by —–
-reabsorption NaCl not water
- Na-K-2Cl cotransporter ( NKCC)
the NKCC is a — in — transport of —- and it depends on —-
- protein
- active
- na, k , chloride into the cell
na+ concentration created by Na/k-atpase pump
The K+ absorbed through the the NKCC from the tubular lumen and is recycled back
potassium channels
where does the event of diffuse through the sodium channels occur
cortical collecting duct
Na!, water, and other molecules absorbed into the interstitial space are now reabsorbed by
bulk flow into the blood
most secretion occurs in – and lesser in —
- distal convoluted tubule
- collecting duct though all parts of the nephrons may secrete small amount
active secretion is the reverse of — and is usually in —
- absorption
- basal channels
Active secretion requires active transport and is usually coupled to the
reabsorption of Na+
the principle secretion are
- k , potassium
- hydrogen
- urate ions
- drugs as penicillin
the level of – is important as the excess in the blood leads to — and eventually —
- potassium
- cardiac arrthmia
- cardiac arrest
Reabsorption and secretion is mainly controlled by these three hormones:
- ADH , anti-dirutic hormones
- Aldosterone
-ANP , artial natriuretic peptide
ADH is secreted in the —- under the control of the —- where the — are sensitive to the na+ levels in the blood
- pituitary glands
- hypothalamus
- osmoreceptor cells
the release of adh leads to
-increases the permeability of the collecting duct and
perhaps the distal tubule to water, so water is removed from the urine
- more water is reabsorbed , more hypertonic urine produced ,
-low urine volume
- High plasma volume
low levels of ADH leads to
- more diluted hypo-osmotic extracellular fluid
- less water absorbed
- more urine produced
- low na levels
— is a steroid hormone which stimulated the na reasobrotion in the —- and the —-
- aldeterson
- distal convoluted tubule
- cortical collecting duct
aldosterone is secreted by
adrenal cortex
low secretion of aldeteron leads to –
high secretion of aldosterone leads to –
- na is nor reabsorbed but is excreted
- na is reabsorbed
