L1: Intro to Renal Function Flashcards
How do you calculate balance?
Total input - total output
Input: food/beverage, oxidative water
Output: fecal, sweat, insensible
If urine flow is = 110 ml/day, then the subject is in
steady state
If urine flow is > 110 ml/day, then the subject is in
negative water balance (losing more than 1100 ml/day)
If urine flow is < 110 ml/day, then the subject is in
positive water balance (losing less than 1100 ml/day)
List 3 conditions that cause negative water balance
Diarrhea
Diuretic medications
Insufficient aldosterone (regulates Na to maintain BV)
List 3 conditions that cause positive water balance
Excess steroids
CHF
Salt-retaining disease
What is the osmolarity of the proximal tubule
Isosmotic
Where are osmotic gradients generated in the nephron
Loop of henle (urine becomes concentrated)
Where is the final concentration of urine adjusted in the nephron? How is water permeability controlled here?
Collecting duct
H20 perm. controlled by vasopressin (ADH)
The ability to produce concentrated urine is proportional to _____
the number of juxtamedullary nephrons (deep medulla)
Are nephrons in series or parallel
Parallel (collecting ducts shared by many nephrons)
What are granular cells?
Surround afferent and efferent arterioles
What are the 2 functions of the JGA?
- Helps control GFR
2. Controls renin secretion (BP and volume)
What cells contract in response to AGII?
Mesangial cells (between capillary loops) AGII helps increase blood pressure (vasoconstrict)
Are the two arteries and two capillary beds (glomerular and peritubular) in parallel or series?
Series
Which nephrons have a vasa recta?
Juxtamedullary (think medulla)
Vasa recta is important for the:
recovery of water
What type of stimulation do the renal nerves receive (PNS or SNS)? What neurotransmitters are released and to what receptors
Sympathetic (NO parasympathetic innervation!)
Norepi and dopamine
Alpha 1 receptors
What is the SNS effect on renal nerves? How is this opposed?
SNS: reduces RBF and GFR
Opposed by: Prostaglandins, PGE2 and PGI2, so reductions are minimized
Granular cells are innervated by the SNS. What do they release upon stimulation of what kind of receptors?
B1 receptors stimulated —> Renin released
