Phys of Renal Disease 2 Flashcards
What is the osmolality of Water re-absorption along the nephron?
300mOsm/L in glom 300 in PCT 600 DEC Tub 1200 in Loop 100 in ascending tube 300 in DCT 600 in CD
What are the basic requirements for forming concentrated urine?
- High osmolality of renal medullary interstitial fluid
2. High ADH (vasopressin)
What is the ascending loop of henle permiable to?
Na but not water
What is the role of the counter multiplier system in the loop of Henle?
Produces Hypertonic Urine in the Renal Medulla
What is the Purpose of the vasa recta?
Serve as counter current exchangers minimizing washout of solutes from interstitium
Minimizes loss of solute from interstitium
How is ADH release initiated?
Inc in fluid osmolality, plasma Na Conc => Osmoreceptor cells shrink => supraoptic nuclei release ADH
What is charicteristic of the Autoregulatory range?
There is less rise in Renal BF and GFR in response to rise in Renal perfusion pressure. (Plateau)
How is Tubuloglomerular feedback mediated?
Changes in GFR by Afferent arteriolar and Efferent Arteriolar constriction
What is the role of Angiotensin II?
Powerful Na retaining Hormone
Increases Na and H2O re-absorption
What is the effectof of Aldosterone on the cells of the cortical collecting tubule?
Increase Na re-absorption and K+ secretion
How does our diet effect the serum levels of Aldosterone?
High Na decreases Aldosterone
High K increases Aldosterone
When does the Renal Sympathetic nerve activity effect GFR?
During Severe, Acute Disturbances
What is renal Clearance?
Volume of plasma that is completely cleared of the substance by the kidney per unit time
What is the Renal Clearance Equation?
Cx * Px = Vx * Ux
Cx = (V * Ux)/Px
What is represented by the variable V in renal Clearance? Ux? Px? Cx?
V= Urine flow rate Ux = Urine Conc of X Px = Plasma conc of X Cx = Clearance of Substance x
How are GFR and plasma Creatinine Related?
They are inverely proportional
Dec GFR by 50% will mean a doubling of Creatinine
What is the Cockroft & Gault Equation for Males? Females?
Ccr= ((140-Age) x (BW, kg))/72xPcr mg/dl For Females (mult by 0.85)
What is the role of the Cockroft & Gault Equation?
Estimates GFR from Serum Creatinine
What is the Effect of HTN on the kidney?
Exacerbate injury to the kidney by altering renal hemodynamic and tubular re-absorption
What is the Effect of Kidney function on BP?
Renal lesions reduce the ability of the Kidney to excrete Na and H2O
How can the kindey CAUSE HTN?
1) Inc renal vasular resistance
2) Dec Glomerular Cap filtration fraction coeff
3) Excessive tubular Na re-abs
What are Pre- Renal causes of Acute Kidney injury?
Kidney Hypoperfusion
- Vol depletion
- MI
- Anaph Shock, sepsis
- Thromb of renal Art
What are Renal causes of Acute Kidney injury?
Vascular- Vasculitis
Glomerular
Tubular- Ischemia, Toxins
Interstitial- Pyelonephritis
What are Post- Renal causes of Acute Kidney injury?
Urinary Tract Obstruction
-Stones
What are the effects of Acute Kidney injury?
Water and Na overload
Inc in K concen
Metabolic Acidosis
Anuria
