Page 371 - Critical Care Nursing Demystified

356 CRITICAL CARE NURSING DeMYSTIFIED

KEY WORDS

ADH – antidiuretic hormone Hemodialysis
ARF – acute renal failure High-ceiling diuretics
Arteriovenous (AV) fistula KUB – kidney ureter bladder x-ray
Arteriovenous (AV) graft Kussmaul’s respirations
ATN – acute tubular necrosis PD – peritoneal dialysis
Bruit Peritonitis
CRRT – continuous renal replacement RAAS – renin-angiotension-aldosterone
therapy system
Disequilibrium syndrome Renal osteodystrophy
ESRD – end-stage renal disease Steal syndrome
FENa – fractional excretion of sodium Thrill
Fluid rebound Vascular access sites
GFR – glomerular filtration rate

Anatomy and Physiology of the Renal System Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.

The kidneys are two pear-shaped organs that lie in the superior, posterior abdo-
men or retroperitoneal space. They are coated with a protective layer of fat,
which also covers the adrenal glands sitting on top of the kidneys. The kidneys
contain 2 to 3 million functional units called the nephrons (see Figure 8–1).
The microscopic nephron contains an afferent arteriole that brings arterial
blood to the glomerulus. The glomerulus is a tough working network that is
encapsulated by Bowman’s capsule. The job of the glomerulus is to filter out
waste products that are molecularly small. It is the glomerular filtration rate
(GFR) that determines the quality of kidney functioning.
GFR is dependent on the glomerular filtration, the pressure in Bowman’s
capsule, and the plasma oncotic pressure (pressure of the plasma proteins).
A mean arterial BP must be maintained between 80 and 100 mm Hg to sustain
blood flow to the kidneys. Because they are large particles, blood and protein
cells are too large to filter out; therefore, they stay in the intravascular space,
not the filtrate. The filtrate in the glomerulus starts the production of urine.
Once the filtrate proceeds to the proximal convoluted tube, it collects more
sodium and water. The next stop for the filtrate is the loop of Henle, which is
thinner and reabsorbs additional water. The loop of Henle is where loop diuret-
ics work enhancing excretion of water.