Renal System Study Guide

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Renal System Study Guide
Med/Surg I
Major Functions of Kidney:
Regulation of Homeostasis
-Filters blood & regulates contents (water content & blood volume) -Maintain acid-base balance
-Control fluid & electrolytes
-Excrete metabolic waste products
-Control BP (renin-angiotensin-aldosterone)

Urinary System Structure:
Kidneys (produce urine), Ureters (transport urine to bladder), Bladder (stores urine), Urethra (conduct urine outside body)

*Nephron- working unit of kidney
*Kidneys receive 25% of cardiac output= approx. 1 Liter
*GRF= 125ml/min & increases at night

Renal Hormones:
ADH- works in DISTAL CONVOLUTED TUBULE
Aldosterone- made in ADRENAL CORTEX
ANP- inhibits secretion of renin-angiotensin-aldosterone & water absorption by kidney tubules Erythropoietin- stimulates marrow to make more RBC's
Renin- made & released in JUXTAGLOMERULAR APPARATUS
RENIN-ANGIOTENSIN-ALDOSTERONE
decreased renal perfusion= low BP
>JGA releases renin
>Liver releases angiotensin I
>Lungs convert angio I to angiotensin II
> Increase in BP due to VASOCONSTRICTION, myocardial contractility,
- VOLUME INCREASE becase ALDOSTERONE is released by ADRENAL CORTEX
>Aldosterone causes sodium & water to be REABSORPTION & potassium excretion **** This stops once BP is normal because it is a NEGATIVE feedback system
Lab Tests/Diagnostics:
Creatnine- 0.6-1.2 End product of muscle & protein metabolism
-reflects GFR, renal disease is the only condition to increase creatnine level (not effected by hydration status) BUN- 8-16 measures amount of urea (byproduct of protein metabolism in liver)
-factors affecting BUN: hydration/ urine flow, hypoperfusion, metabolic rate, drugs, diet
-Elevated BUN with normal creatnine= DEHYDRATION/Volume depletion/low perfusion
-Elevated BUN & Creatnine= RENAL FAILURE/Dysfunction
Specific Gravity- 1.003-1.030 measures ability of kidneys to concentrate urine
-increased spec. grav = (more concentrated urine) dehydration,...
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