Chapter 27: Urine Formation By The Kidneys II Flashcards
Transport of water and solutes through the cell membranes themselves
Transcellular route
Both Glomerular Filtration and Tubular Reabsorption are non-selective. True or False
False. GF is mon-selective. TR is highly selective
Transport of water and solutes through the spaces between the cell junctions
Paracellular route
Mechanism by which water and solutes are transported through the peritubular capillary walls into the blood mediated by hydrostatic snd colloid osmotic forces
Ultrafiltration (bulk flow)
Transport coupled directly to an energy source such as hydrolysis of ATP
Primary active transport
Transport coupled indirectly to an energy source, such as due to an ion gradient
Secondary active transport
4 Primary active transporters of the kidneys
Na-K ATPase
H ATPase
H-K ATPase
Ca ATPase
Secondary active transporters in the kidneys
Na-Glucose co-transporters (SGLT1 & SGLT2)
Na-amino acid co-transporters
Na-H exchanger
1-Na, 2-Cl, 1-K co-transporter
Reabsorption of large molecules such as proteins occurs through which mechanism?
Pinocytosis
Refers to the limit to the rate at which the solute can be transported. This is due to the saturation oft he specific transport systems involved when the tubular load exceeds the capacity of the carrier proteins and specific enzymes involved in the transport process.
Transport maximum
Refers to the amount of solute delivered to the tubule
Tubular load
Process by which water carries some of the solutes as it moves across the tight junctions by osmosis
Solvent drag
Hormone that greatly increases the water permeability in the distal and collecting tubules
ADH
2 Methods by which Cl is reabsorbed
Passive diffusion (paracellular pathway) Co-transport with sodium
Percentage of the filtered load of sodium and water reabsorbed by the proximal tubule
65%
2 cellular characteristics giving proximal tubules high capacity for reabsorption
Highly metabolic and have Large numbers of mitochondria
Extensive brush border loaded with protein carrier molecules
Sodium reabsorption in the first half of the proximal tubule occurs through which mechanism?
Co-transport of Na with glucose, aa, bicarbonate, organic ions
Sodium reabsorption in the second half of the proximal tubule occurs through which mechanism?
Co-transport with Cl ions
Portion of the loop of Henle which is permeable to water.
Thin descending limb
Transporters in the thick ascending limb of the loop of Henle
Na-K ATPase in the basolateral membrane
1-Na, 2-Cl, 1-K co-transporter in the luminal membrane
Na-H counter-transport
Site of action of loop diuretics
Thick ascending limb of the loop of Henle
Otherwise known as the diluting segment as it avidly reabsorbs most of the ions but is virtually impermeable to water and urea
Second part of the early distal tubule
Site of action of thiazide diuretics
Na-Cl co-transporter in the early distal tubule
Action of principal cells
Na reabsorption and K secretion by Na-K ATPase in the basolateral membrane
2 distinct cells in the late distal tubule and cortical collecting tubule
Principal cells
Intercalated cells
Site of action of potassium-sparing diuretics
Principals cells
Aldosterone antagonists on Na-K ATPase
Sodium channel blockers on Na channel
Action of Intercalated cells
Hydrogen secretion H-ATPase and H-K ATPase
Bicarbonate and Potassium reabsorption
Vasopressin controls the permeability of which tubular segments
Late distal tubule and collecting ducts
Final site for processing urine and plays a role in determining final urine output of water and solutes
Medullary collecting duct
Used to estimate renal plasma flow
Para-aminohippuric acid clearance
Polysaccharide used to measure GFR
Inulin
Intrinsic ability of tubules to increase their reabsorption rate in response to increased tubular load. It also acts as second line of defense to buffer the effects of spontaneous changes in GFR and urine output.
Glomerulotubular balance
Determinants of reabsorptive force
Peritubular hydrostatic pressure
Peritubular capillary colloid osmotic pressure
Renal interstitial hydrostatic pressure
Renal interstitial colloid osmotic pressure
Effect of afferent and efferent arteriolar constriction on peritubular capillary reabsorption
Increased reabsorption due to decreased peritubular capillary hydrostatic pressure
Effect of decreased renal plasma flow on reabsorption
Increased reabsorption. Dec renal plasma flow –> inc filtration fraction –> inc colloid osmotic pressure
Small increases in arterial pressure causes pressure natriuresis and pressure diuresis. Give 3 events that lead to this.
- increased GFR
- increased peritubular capillary hydrostatic pressure
- reduced angiotensin II formation
Cells that secrete Aldosterone
Zona glomerulosa cells oft he adrenal cortex
Body’s most powerful sodium-retaining hormone
Angiotensin II
3 main effects of angiotensin II
- aldosterone secretion
- efferent arteriolar constriction
- directly stimulates Na reabsorption on Na-K ATPase pump on the basolateral membrane, Na-H exchanger in the luminal membrane and Na-HCO3 co-transporter in the basolateral membrane
Effect of parathyroid hormone on tubular reabsorption
Inc calcium reabsorption in the distal tubules and loops of Henle
Dec phosphate reabsorption in the proximal tubule
Magnesium reabsorption in the loop of Henle
Effect of SNS activation on sodium and water
Increased reabsorption through:
- decreased excretion d/t renal arteriolar constriction
- increased renin release and agiotensin II formation
