Basic Kidney Function Flashcards
What is osmolarity?
The sum of the moles of each component of a solution: 2mM solution of MgCl2=6mM per liter (2x3(Cl) + 2x 1(Mg))
Major difference in osmolality and osmolarity?
Osmolality: the moles of solute per kilogram of solvent
Osmolarity: number of moles per liter in solution
What is osmolality?
Moles of a solute per kilogram of solvent
What concentration of NaCl is isosmotic to cells?
150mM
How many liters of water is filtered by kidneys each day?
180L
What is the process of producing hypo-osmotic urine?
Thick ascending limb of Henle’s loop reabsorbs more solute than water
What is the process of producing hyper-osmotic urine?
Water reabsorbed from lumen into a hyper-osmotic medullary interstitium
How are medullary interstitial cells made hyper-osmotic?
- ) Addition of Na+ to interstitium
- ) Vasculature that minimizes removal of Na+
- ) Recycling urea between medullary collecting ducts and deep portions of loops of Henle
What are the seven major renal functions?
- ) Water of and electrolyte balance
- ) Acid base balance
- ) Excretion of waste
- ) Arterial blood pressure
- ) Red blood cell
- ) Vitamin D production
- ) Gluconeogenesis
What are the three fundamental elements of renal function?
- ) Glomerular filtration
- ) Tubular secretion
- ) Tubular reabsorption
What are podocytes?
Cells that wrap around the capillaries of the Bowman’s capsule
What are the macula densa?
A sensor of tubular Na+ content that exerts renal control of granular cells
Where are the macula densa (juxtaglomerular apparatus) located?
Between the afferent arteriole and the distal convoluted tubule
What innervates the macula densa and what does it release?
Sympathetic innervation for release of renin
What is the macula densa response to blood sodium levels being too high?
Contraction of the afferent arteriole
What is the Bowman’s filtrate most similar to?
Blood plasma minus large proteins
What does the descending limb do?
Reabsorbs water out of the tubule (impermeable to ions)
What does the ascending limb do?
Reabsorbs ions out of the tubule (impermeable to water)
What is meant by counter current?
As ions are absorbed out into the tubule from the ascending limb the ions pull water out from the descending limb
What is the distal convoluted tubules function?
To reabsorb more ions (Na, Cl, etc.)
Function of the proximal convoluted tubule?
Reabsorb water, Na+, glucose, AA
What does the collecting duct reabsorb?
Water, Urea
What is the function of the juxtaglomerular apparatus?
Control blood pressure
How do the kidneys regulate Ca++ and phosphate?
Excrete Ca++ in urine
Activates vitamin D
How do kidneys regulate acid-base balance?
By excreting or producing H+
What is renal excretion rate dependent on?
Rate of filtration
Rate of reabsorption
Rate of secretion
Formula for excretion rate:
Ux x V
Ux= [x]
V= urine flow per unit time
What is renal clearance?
The virtual amount of plasma that would be completely cleared of a solute in a given amount of time (mL/min)
Example: what does it mean if the renal clearance of urea is 65mL/min?
That the kidneys remove all of the urea present in 65mL of plasma each minute
Renal clearance formula:
Cx= (Ux x V)/Px
Px= [x] in systemic blood plasma
Function of PTH?
Ca++ reabsorption
Phosphate (i) excretion
Hydroxylation of Vitamin D precursor into active Vitamin D
