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metabolic end products are excreted in the kidney by ______
they are filtered into and then trapped within the renal tubule
list the endocrine fuctions of the kidney
  • Erythropoietin
  • renin-angiotensin system
  • Vitamin D: converts Vit D ot its active form Vit D3
what is the chemical name for Vitamin D3?
1, 25 Dihydroxycholecalcified
why does the patient with chronic renal disease become hypocalcemic?
b/c Vit D is required for calcium absorption in the intestine and in renal disease there is a Vit D deficiency b/c the kidneys activate Vit D
The kidney regulate Osmolality. How?
by regulating Sodium concnetration
Na salts contribute 90% to the extracellular fluid osmolality
Normal osmolality:
300 mOsm/kg (range 270-310
what % of CO goes to the kidneys?
1.25 Liters/min
Blood is delivered to the glomerulus via the ______ and exits via the _____
Afferent arteriole

Efferent arteriole (Exits the glomerulus)
Glucose is reabsorped in the ______
Proximal tubule
There are 2 types of nephrons:
what is the difference?
Cortical: short loops of Henle andlocated near the surface fo the kidney

Juxtamedullary: long loops of Henle and located deep in the cortex near the cortical medullary junction
what part of the kidney is most vulnerable to Ishemia?
the inner stripe of the outer medulla (juxtamedullary nephrons are located here)
the vasa recta constitute a ________
countercurrent exchange system
The parts of the nephron found in the cortex are:
proximal tubules
distal tubules
loops of Henle and collecting ducts are foudn in the cortex or medulla?
Glomerular Filtration:
movement, under pressure, of plasma water and most of its dissolved  constituents from the glomerulr capillary into Bowman's capsule.  the Beat of the heart creates the high glomerular hydrostatic pressure that is rewured for the filtration process
What does the loop of Henle do with NaCl?
the loop of henle establishes and maintians an  osmotic gradient in the medulla by depostiting NaCl in the medulla interstitium.  the osmolality in th emedulla increases from 300 (at the corticomedullary junction) to 1200-1500 deep in the medulla.  this gradient is required for making the urine concentrated or dilute
What is the main function of the proximal tubule?
reabsorbs the bulk (67%) of the glomerular filtrate
where does the fine tuning urine composition take place? what things can influence this?
distal tubules and collecting ducts
hormones can alter the fucntion of the distal tubules and collecting ducts: ADH controls Water excretion and Aldosterone controls Na and K excretion
where is glucose reabsorbed in the kidney?
all of the glucose filtered in the glomerulus is reabsorbed by the proximal tubule by active transport
When glucose is filtered in the glomerulus, does any of it not get reabsorbed by the proxomal tubule?
No, normally the amount of glucose filtered should not exceed the amount reabosrbed by the proximal tubule.  the proximal tubule has a "transport maxumum", so the glomerulus filtrate should not have more glucose in it than the amount allowed by the "transport maximum"
In DM, what happens in the glomerulus and proximal tubule?
since the pt with DM has high plasma glucose concentration,  the amount of glucose filtered in the glomerulus can exceed the "transport maximum" fo the proximal tubule.  If this happens, some of the filtered glusose will remain in the neprhon and end up in the urine (b.c the rest of the nephron is impermeable to glucose)
what happens to the urine output in the untreated pt with DM? why?
Urine output increases b/c the unreabsorbed glucoes cause an osmotic diuresis
where is ADH synthesized
in the paraventricular and supraoptic nuclei of the Hypothalamus
where is ADH stored?
in th eposterior portion of the pituitary gland (neurohypophysis)
what cranial nerve is the optic nerve
What causes the release of ADH?
An increase in extracellular fluid osmolality
-this causes the paraventricular and supraoptic nuclei to shrink and fire nerve potentials that cause the release of ADh from the post. pituitary
_________ is the most powerful stimulus triggering the release of ADH
In increase in estracellular fluid osmolality
what types of things can trigger the relaeas of ADH (besides an increase in osmolality)
Stresses: hypotension, pain, hypovolemia, trauma
the site of aciton of within the kidney of ADH is:
distal tubule and collecting ducts
-promotes the reabsorption of water (so a small volume of concentrated urine is formed)
what happens to the urine when there is no ADH cating on th edital tubules and collecitn ducts?
they become impermeable to water (so it cannot be reabsorbed)
there is a large volume of dilute urine is formed
what is the osmalality of urine when ADH level are high?
when they are low?
High ADH: small amt of concnetrated urine (1200-1500 mOsm)

Low ADH: large volume of dilute urine (50-100 mOsm)
list some things that can cause SIADH
  • surgery
  • intracranial tumors
  • hypthyroidism
  • porphyria
  • small (Oat's)cell carcinoma of the lung
list the 2 causes of Diabetes Insipidus
  • failure of ADH synthesis or release (most common)
  • Insensitivity of the distal tubule and collecting ducts to ADH (nephrogenic)
what is the major determinant of extracellular fluid volume?
sodium content (water follows sodium)
when there is an increase in osmolality, what is triggered?
thirst mechanism
what is the most important hormone for regulating extracellular fluid volume?
List the 3 things that control sodium excretion
  • GFR
  • Aldosterone
  • Atrial Natriuretic factor
aldosterone is produced in the _____
Zona glomerulosa of the adrenal cortex
aldosterone _____ Na reabsorption in the distal tubule and collecting ducts and _______ Na excretion
Increases Na reabsorption and
Decreases Na excrection
Aldosterone ______ K secretion into  the collecting ducts and ______ K excretion
Increases K secretion into the collecting ducts
Increases K excretion
Without Aldosterone the distal tubule and collecting duct are ______ to Na
Impermeable (so more Na get excreted)
where is the majority of the filtered K reabsorbed?
proximal tubules - 67%
ascending loop of Henle - 25%
-this happens regardless of conditions, the amount of K excreted is alterd in the distal tubule and collecting ducts
There are 3 factors that alter the K excretion.  they are:
  • Aldosterone
  • Distal tubular Flow rate
  • Bicarb concentration in the tubular fluid
the most important physiological regulator of K is
how does bicarb alter K excretion?
when the bicarb concentration in the distal tubule is increased (alkaline urine) the K secretion rate is increased
what part of the nephron do the loop diuretics work on?
ascending loop of Henle
they bind to the Na-K-Cl symporter and inhibit reabsorption of thses ions 9this inhibits the formation of an osmotic gradient, so the water reabsorption is reduced and water excetion is increased
what type of diuretic is spironalactone (aldactone)? how does it work?
potassium sparing
competitively inhibits aldosterone (inhibits Na reabsorption in the late distal tubule and collecint duct and inhibits K secretion)
spironolactone ______ Na excretion and _____K retention
Increases Na excretion and Increased K retention
Two types of diuretics that act on the distal tubules and collecting duct to inhibit Na reabsorption are:
Thiazide diuretics (diuril, Hydrochlorothiazide)
Potassium sparing diurectic (spironolactone, triamterene, amiloride)
What kind of diuretic is Diamox?
carbonic anhydrase inhibitor
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