AGN help

the nephron is the filtering unit of the kidney where urine is made. each nephron consists of

• the glomerulus - a clump of capillaries surrounded by a membrane called bowman's capsule
  
• a long coiled collecting renal tubule - formed from the bowman's membrane, it catches the filtrate siphoned from the glomerular capillaries and is where reabsorption of the fluid and electrolytes that the body needs takes place and turns the remainder of the filtrate into urine. notable landmarks along the tubule are the proximal tubule, loop of henle and distal tubule.
  
• peritubular capillaries - the capillaries that swirl and surround the entire length of the coiled collecting tubule where the chemical reabsorption of fluid and electrolytes is taking place.
  
• the collecting duct - this is where the end product, urine, emerges and moves on to the pyramids of the kidney
  
  • http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/image_preview.html?image=//media.tiscali.co.uk/images/feeds/hutchinson/ency/c01860.jpg&caption=the
    
  • http://www.3dscience.com/3d_images/human_anatomy/urinary/nephron_glomerulus.php
    
  • http://www.siumed.edu/~dking2/crr/rnguide.htm - here's everything you want to know physiologically about nephrons
    

think of the nephron as a big factory with an assembly line coming into it (the renal artery). what the factory workers (nephrons) at the separating room (glomerulus) do is separate the blood cells from the serum of the blood and send the serum (filtrate) on for processing (renal tubule) where it is acted upon by eager cells looking to retrieve back some of what they lost (fluids and electrolytes) at the separating room (peritubular capillaries) so they can continue on their way out the back door of the factory and get the heck out of dodge (the renal vein)!

as gfr decreases, plasma creatinine levels increase proportionately without regulatory adjustment. as sodium delivery to the nephron increases, less is reabsorbed, and sodium deficits and volume depletion follow. the kidney becomes incapable of concentrating and diluting urine. when gfr decreases by 30% to 40% (meaning 30-40% of the blood serum is no longer being separated out and sent onward for processing in the renal tubules), progressive metabolic acidosis ensues and tubular secretion of potassium increases. total-body potassium levels may increase to life-threatening levels requiring dialysis.

i've answered several previous questions about renal pathophysiology. i've listed the threads. this stuff is not initially easy to understand with one reading. even i have to sit down and cogitate on it for a while and i worked on a renal unit!

• https://allnurses.com/nursing-student-assistance/esrd-pathophysiology-278036.html
  
  
• https://allnurses.com/nursing-student-assistance/renal-system-360367.html
  
• https://allnurses.com/nursing-student-assistance/chronic-renal-failure-409384.html