Renal Flashcards
what is the nephron
the basic unit of the kidney, the cells of the kidney
what is the glomerular filtration rate (GFR)
the amount of renal blood flow filtered per unit of time (ml/min)
- directly related to renal perfusion
what do the GFR values indicate
N = 90ml/min or higher is normal N = 60-89ml/min might be normal to some people, especially those above 60 year olds N = below 60ml/min is abnormal and GFR should be repeated and would have CKD N = 15ml/min is kidney failure
what are the functions of the kidney (2)
- excretory: nephrons filter the blood of waste, and conserve fluids and electrolytes that the body needs = create/excrete pee
- secretory:
- Trigger: hypoxia; and low blood volume = release of renin and erythropoietin
- Control of blood pressure = RAAS b/c of low sodium and decreased renal perfusion
- Red blood cell production
- Vitamin D synthesis and calcium balance = w/o the kidney, vitamin D remains inactive
- Glucose homeostasis, if BG reaches threshold, the kidney starts to spill out glucose into pee
= has to secrete important substances
within the nephron, what does the glomerulus do?
tuft of capillaries from which blood is filtered at the Bowman’s capsule, allows substances like water, Na, Bicarb, and urea out of the blood BUT NOT albumin
describe the pathway of creating urine from the nephrons
- blood is filtered at the Bowman’s capsule, allows substances like water, Na, Bicarb, and urea out of the blood
- then to the proximal tubule where large amounts of water, Na, and potassium are reabsorbed into the bloodstream
- The remaining substances reach the Loop of Henle = large amount of Na is again reabsorbed.
- Aldosterone increases water and Na reabsorption too - then the remaining substances/fluids reach the distal tubule, where water and Na are further reabsorbed into the bloodstream
= urine is formed - whatever remains reaches the collecting duct, where ADH increases reabsorption of water in the collecting duct if the body needs more water
= URINE.
renal function tests (6)
- BUN (Blood urea Nitrogen)
- Creatinine
- 24-hour urine collection for creatinine clearance
- urinalysis
- intravenous pyelogram
- PSA (prostatic-specific antigen)
what is BUN
normal: 7-18 mg/dl
- end/waste product of protein metabolism = urea and excreted by the kidney
- the second best indicator of kidney functions b/c it also picks up liver failure so can be confused
what is creatinine (test)
normal: 0.6-1.2 mg/dl
- formed when creatinine phosphate is used in skeletal muscle contractions = excreted entirely by the kidney
- the best indicator of kidney functions, only picks up kidney
what is the 24-hour urine collection for creatinine clearance (test)
Measures the GRF and is dependent upon renal artery perfusion and glomerular filtration
what is urinalysis
- Cloudy, foul-smelling, + WBC= UTI
- Dark yellow = dehydration or B complex + vitamin C causes dark yellow pee
- urine smells like acetone or glucose = DM
- positive for protein = injured glomerular membrane, but if its minimal it could be related to exercise but should return to normal in 24-48 hours
- ketones = fatty acid metabolism
- crystals = kidney stones
what is intravenous pyelogram (test)
IV- administered radiopaque dye that allows visualization of kidneys, renal pelvis, ureters, bladder
what is PSA (test)
Used to screen prostatic cancer
what is acute renal failure or AKI and the 3 causes
This is the sudden loss of renal function; this is reversible and common among critically ill patients, can be abrupt and can be reversed within 24 hours
causes:
- prerenal
- intrarenal
- postrenal
what are prerenal conditions of AKI
- These are conditions that disrupt blood flow to the kidney.
These include:
- Extremely low blood pressure or blood volume
- Heart dysfunction