Wall: Overview of renal structure and function Flashcards
what are the major cations of the ECFV and ICFV?
ECFV: sodium
ICFV: potassium
What determines the size of total body water (TBW)?
total body sodium (TBNa)
What is the major ECFV buffer?
bicarbonate
What is the major contributor to blood pressure?
Na+
total body sodium content determines ECFV which determines BP/blood volume
What are the major waste products eliminated by the kidney?
urea (from protein metabolism)
creatinine (from muscle metabolism)
uric acid (from nucleic acid breakdown)
What are the main endocrine functions of the kidney?
EPO production
1-alpha hydroxylase (produces calcitriol)
renin production
T or F: Bc the kidney regulates total body Na+ and therefore blood pressure, hypertensions is a kidney disease largely
T
Catabolism of what key peptide hormone occurs in the kidney?
insulin
What can happen with decreased nephron mass in terms of insulin catabolism?
slower degradation of insulin (increased half life)
How many liters/day are formed at the glomerulus?
180
what is an ultrafiltrate?
cell free, protein free filtrate of plasma that is iso-osmolar to plasma
the ultrafiltrate contains water and small solutes but not proteins or RBCs
each kidney gets what percentage of the cardiac output?
10%
How much filtrate is reabsorbed daily?
178 L/day (98-99% of the daily glomerular filtrate)
How much urine is made daily?
1-2 L (180 of daily filtrate- 178 of reabsorbed filtrate)
What is the best index of overall kidney function?
GFR
What drives the filtrate formation at the glomerular capillaries?
Starling forces
What are the 4 major processes involved in renal function?
filtration
reabsorption
secretion
excretion
Kidneys are situated in the retroperitoneum from spinal levels ___ to ____
T12 to L3
Renal cortex receives about ___% of total blood flow to the kidney
90%
Where do all glomeruli reside?
renal cortex
What is the vasa recta?
vessels from the juxtamedullary nephrons that follow the course of the loop of henle
What does the renal hilum consist of?
renal artery and vein renal pelvis ureter renal nerves lymphatics
What are the 3 sites of potential obstruction (via kidney stone) within the ureter?
- pelvic ureteral junction
- crossover of pelvic brim
- urinary trigone
Compare and contrast male and female urethra.
Male: longer, less UTI, goes through median lobe of prostate
Female: shorter, increase in UTI
Where is the most common spot for obstruction in male urethra?
prostatic urethra (obstructive uropathy)
What are the two types of nephrons?
cortical nephrons
juxtamedullary nephrons
compare and contrast cortical and juxtamedullary nephrons.
cortical: 85% of nephrons, smaller, further from aorta, lower pressure inside glomerular capillaries (decreased filtration rate), short loop of henle, never at 100% capacity (reserve capacity)
Juxtamedullary: 15% of nephrons, larger, closer to corticomedullary junction, higher glomerular pressure (higher filtration rate), longer loops of henle, always operate at full capacity
What provides the only arterial blood supply to the medulla?
the desceding vasa recta (coming from efferent arterioles) that surround the loops of henle in the juxtamedullary nephrons
the medulla is hypotonic/isotonic/hypertonic
hypertonic
90% of blood goes to the cortex and only 10% to the medulla. Why is this crucial?
Bc the medulla is hypertonic. If a large amount of blood were to flow through the medulla, it would wash out the medullary solute and we could not make concentrated urine.
How does the kidney maintain the medulla in a hypertonic fashion?
the vasa recta has countercurrent arrangement. Solute can be transferred between ascending and descending vasa recta
