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296 Cards in this Set

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What is the functional unit of the kidney?
The nephron
What occurs in the Bowman's capsule/glomerulus?
Filtration
Where does reabsorption and secretion occur?
In the tubules
What is the primary energy source for reabsorption?
The Na+/K+ ATPase pump
Where does water get resabsorbed in the kidney?
The proximal convoluted tubule
Where does ADH primarily work in the kidney?
In the distal convoluted tubule
When does urine become concentrated?
As it moves through the collecting tubule
What is the normal rate of GFR?
125 ml/min or 180 L/day
How much gets reabsorbed?
99%
How much sugar is filtered per day?
180 grams
How much of the sugar filtered gets reabsorbed?
100%
What does the kidney do?
Makes urine continuously by filtration at the glomerulus and by reasorption and secretion by the tubules
Where is urine stored?
In the bladder
What can cause frequent urination?
Large volumes of urine
Irritation of the bladder by infection
Obstruction (BPH)
Pregnancy
Besides filtration, what else does the kidney do?
Excretory organ
Regulatory organ
Endocrine organ
How does the kidney work as an excretory organ?
Secretes metabolic products (urea, uric acid, creatinine, hemoglobin metabolism products) and foreign substances (drugs, pesticides)
How does the kidney work as a regulatory organ?
Maintains body fluid volume and osmolality
Electrolyte balance
Acid-base balance
How does the kidney work as an endocrine organ?
Adds the final OH- to make active Vitamin D3
Secretes renin in response to low volume
Secretes erythropoietin
What must be maintained by the kidney within a very narrow range for normal body functions?
pH (6.8-7.8 are the extreme compatibles with life)
How much H+ must the average person excrete per day?
70 million nEq
How is the H+ and pH kept in balance throughout the day?
Buffers and coordinated action of the lungs and kidneys
How much of the cardiac output does the kidney get? Why?
25%---Consuming a lot of energy by reabsorption so it needs a lot of O2
What are the pyramids composed of?
The collecting duct and loop of henle
What is different about the juxtamedullary nephron?
It has a vasa recta that dips down into the medulla
What is the vasa recta important in?
Concentrating the urine
How do sickle cell and vasa recta relate?
Vasa recta have a low O2 tension causing the RBC's to sickle in sickle cell disease--causes sickle pts to have dilute urine and frequency
How is osmolarity calculated?
mmol/L x # of particles in solution
What is osmolarity?
# of solute particles per 1L of solution--mOsm/L
What is osmolality?
The number of solute particles per 1 kg of solvent
Is osmolality or osmolarity temperature dependent?
Osmolarity
What is the tonicity of a solution?
Related to its effect on the volume of a cell
What is a solution that causes no change in cell volume?
Isotonic
What is a solution that causes a cell to swell?
Hypotonic
What is a solution that causes a cell to shrink?
Hypertonic
What is required to be an effective osmole?
The solute must not permeate the membrane--if a solute freely crosses the membrane then it is ineffective
What is urine specific gravity?
Measures the amount of particles in a solution
What osmolality is a specific gravity of 1.010 equal too?
300-350 mosmol/kg
What value of specific gravity is considered to be isothouric?
1.010
What value of specific gravity is considered to be concentrated?
1.040
What is total body water?
42L
What compartments is the total body water divided into?
ECF and ICF
What compartments is the ECF divided into?
The interstitial fluid and the plasma
How much of the total body water does the ECF make up?
14L
How much of the total body water does the ICF make up?
28L
How much of the ECF does the interstitial fluid make up?
10.5L
How much of the ECF does the plasma make up?
3.5L
If you expand the ECF by 1L with an isotonic solution, how much does the vascular volume expand?
250cc
What percentage of body weight is total body water?
60%
What is an example of an isotonic solution?
Normal Saline---0.9%
How many osmoles is normal saline (NaCl)?
308 osmoles
What is the first thing to do when a patient has low BP?
Replace the volume with an isotonic solution
Besides NS, what is another example of an isotonic solution?
Lactated Ringer's
After one liter of NS, where is the fluid shift?
The fluid goes into the ECF, but there is no fluid shift because it is an isotonic fluid
What is a hypotonic solution?
Half normal saline--0.45%
What is a hypertonic solution?
Hypertonic saline--3%
Is D5W considered a isotonic, hypotonic, or hypertonic solution?
Isotonic solution--glucose gets metabolized
Where does D5W distribute?
In the total body water--cell volume does not change
What solution should be used if a patient is hypovolemic?
Normal saline
How much does D5W increase the plamsa volume?
0.33L or 82.5 mL
What does D5W get metabolized to?
Sterile water
What fluid choice would you give a person that is having a GI bleed?
Normal saline--eventually packed red cells
What is renal clearance?
The amount of substance you remove from plasma that gets excreted in the urine
What is renal clearance an estimate of?
How the kidneys handle certain substances
How do we figure the removal rate from plasma?
Px * Cx mg/min

Px=concentration of x in plasma (mg/mL)

Cx=clearance of x from plasma
(mL/min)
How do we figure the excretion rate?
Ux * V (flow rate) mg/min

Ux=concentration of x in urine (mg/min)

V=urine flow rate (mL/min)
In clearance what does the removal rate from plasma and the excretion rate have to be in relation to each other?
Equal
What is clearance equal to?
Cx ml/min=Ux * V/Px
When is a substance freely filtered?
If the filtered plasma has the same concentration of a substance as the unfiltered plasma
What is the ultrafiltrate?
Contains no cellular elements and is protein free
What are examples of substances that are freely filtered?
Na, K, Cl, HCO3, glucose, urea, creatinine,Inulin and I-131
Does albumin get filtered?
No
Where will albumin be in higher concentration, the afferent or efferent arteriole?
The efferent arteriole because the glomerulus has filtered out the water
What are the units of renal clearance?
mL/min
If the substance is freely filtered, not reabsorbed, nor secreted, nor metabolized by the urine, what can its clearance be referred to as?
The GFR
What is the filtration fraction (FF)?
Relationship between renal plasma flow and GFR--the portion of plasma that is filtered from the glomerulus
What is the equation for filtered fraction?
FF = GFR/RPF
What is the FF usually?
0.2
What is the filtered load?
What gets presented to the tubules--used when dealing with GFR
What is the equation for Filtered Load?
Filtered load = Px * GFR
What are the units for filtered load?
mg/min
What does filtered load tell us?
Gives us the amount removed from plasma by filtration, and it ingnores any secretion or reabsorption
What is the clearance of glucose?
Zero--all of it gets reabsorbed
What is the fractional excretion?
The fraction of the filtered load that is excreted in the urine
What is the equation for fractional excretion?
FE = Excretion rate/Filtered load
What is the equation for excretion rate?
Ux * V (flow rate)
What does the fractional excretion of Na+ tell us?
If we have low vascular volume or if we have acute tubular necrosis
What is the FeNa+ when the vascular volume is low?
<1%
What is the FeNa+ when acute tubular necrosis is present?
>2%
How do we calculate FeNa+?
Sodium clearance/Creatinine clearance

Una+ * Pcr/Pna+ * Ucr
What is the filtration fraction (FF)?
Relationship between renal plasma flow and GFR--the portion of plasma that is filtered from the glomerulus
What is the equation for filtered fraction?
FF = GFR/RPF
What is the FF usually?
0.2
What is the filtered load?
What gets presented to the tubules--used when dealing with GFR
What is the equation for Filtered Load?
Filtered load = Px * GFR
What are the units for filtered load?
mg/min
What does filtered load tell us?
Gives us the amount removed from plasma by filtration, and it ingnores any secretion or reabsorption
What is the clearance of glucose?
Zero--all of it gets reabsorbed
What is the fractional excretion?
The fraction of the filtered load that is excreted in the urine
What is the equation for fractional excretion?
FE = Excretion rate/Filtered load
What is the equation for excretion rate?
Ux * V (flow rate)
What does the fractional excretion of Na+ tell us?
If we have low vascular volume or if we have acute tubular necrosis
What is the FeNa+ when the vascular volume is low?
<1%
What is the FeNa+ when acute tubular necrosis is present?
>2%
How do we calculate FeNa+?
Sodium clearance/Creatinine clearance

Una+ * Pcr/Pna+ * Ucr
What tests need to be ordered to figure out the FeNa+?
A spot utine for sodium and creatinine and a plasma sodium and creatinine
What does the renal blood flow have to take into account?
The hematocrit
What are broad casts or muddy brown casts a good indicator of?
Usually acute tubular necrosis
What is speical about inulin?
It's neither secreted or reabsorbed--it all gets excreted in the urine
What is special about PAH?
Whatever PAH does not get filtered gets secreted to then be excreted--none goes to the renal vein
What is Tm?
The largest filtered load that the tubule can handle w/o spilling substance--maximum tubular reabsorptive capacity
When does glucose typically appear in the urine?
When the plasma glucose exceeds 180-200 mg/dl
What is included in a Chem 6?
Na, K, Cl, Glucose, BUN, Creatinine
Is Blood Urea Nitorgen a good measure of GFR?
No
When does urea production increase?
High protein diet
Enhanced tissue breakdown
Decreased tissue anabolism
What decreases urea production?
Severe liver disease
Low protein intake
How much of filtered urea gets reabsorbed?
40-50%
Is urea reabsorption passive or active?
Passive--it is driven by the concentration of the urea in the tubules--which in turn is driven by the resporption of sodium and water
In hypovolemic states, what is the BUN?
The BUN is high because more sodium and water are getting resabsorbed
What is the BUN to plamsa creatinine ratio?
Normal is 10-15:1

If >20:1 then suspect urea production due to volume depletion
Where does creatinine come from?
The breakdown of creatine in skeletal muscle
What is the normal range of creatinine in men?
0.8 - 1.3 mg/dL
What is the normal range of creatinine in women?
0.6 - 1.0 mg/dL
When does plasma creatinine reflect GFR?
Only in a steady state
What is the rate of production of creatinine proportional to?
The muscle mass and production is constant
If your patient's creatinine level is increasing slowly during their hospital stay, what does this mean?
They are in kidney failure because muscle is not broken down that fast
What do small changes in creatinine mean for GFR?
Big changes in GFR therefore big changes in kidney function
What do big changes in GFR mean for creatinine?
Big changes in creatinine
When will the creatinine curve shift to the left?
When there is decreased muscle mass--usually in the elderly
Is creatinine a good measure of GFR?
It's an imprecise measure of GFR
What is the Cockcroft-Gault formula?
Ccr = 140-age/Pcr * lean body wt/72

For women, multiply by 0.85
When can the Cockcroft-Gault formula be used?
Only in a steady state
What is the best approximation of creatinine clearance?
24 urine collection
What is the problem with using the MDRD equation?
If the patient is not in a steady state, then the estimation of the GFR is erroneous
What is the normal value of creatinine excretion is men and women?
20-25 mg/kg for men
15-20 mg/kg for women
If measuring creatinine excretion using a 24 urine, if the measurements are way off from the normal values, what does this suggest?
That the patient did not do the collection correctly
If GFR is falling, what happens to the creatinine excreted?
It increases--can increase by as much as 50%
What are the two things required for filtering?
Charge and ion size
What charge does the basement membrane have?
Negative
What is Alport's syndrome?
X-linked recessive defect in Type IV collagen--often associated with hearing loss and ocular abnormalities
What is the main determinant of GFR?
Glomerular capillary hydrostatic pressure
Is there protein in the Bowman's capsule?
No
What is responsible for ultrafiltration?
The Starling forces
As you make an ultrafiltrate, what is left behind?
Protein
What drug causes efferent arteriole constriction?
Angiotensin II
What happens if the efferent arteriole is constricted?
Increase in GFR
Decrease in PTC
Decrease in RPF
What happens if the efferent arteriole is dilated?
Decrease in GFR
Increase in PTC
Increase in RPF
What happens if the afferent arteriole is constricted?
Decrease in GFR
Decrease in PTC
Decrease in RPF
What happens if the afferent arteriole is dilated?
Increase in GFR
Increase in PTC
Increase in RPF
How do renal plasma flow and resistance relate?
They are inversely related to each other
If you have an increase in arterial pressure, what will happen?
The afferent arteriole will constrict to decrease the RPF
If you have a decrease in arterial pressure, what will happen?
The afferent arteriole will dilate to increase the RPF
If you have an increase in NaCl, what will happen?
The afferent arteriole will constrict to decrease RPF
If you have a decrease in NaCl, what will happen?
The afferent arteriole will dilate to increase the RPF
What are the two mechanisms of autoregulation?
Myogenic and Tubuloglomerular feedback
What does the myogenic mechanism respond to?
Increase or decrease in stretch
What does the tubuloglomerular mechanism respond to?
An increase or decrease in the concentration of NaCl
Where is the juxtaglomerular apparatus located?
At the distal end of the ascending loop of henle
What does the juxtaglomerular complex consist of?
Macula Densa
JG cells
Extraglomerular mesangium
What does the macula densa do?
Cells in the thick ascending limb of the loop of Henle--monitor changes in NaCl delivery and stimulate the release of renin for the JG cells
What do the JG cells do?
Modified smooth muscle cells located in the afferent arteriole--monitor changes in blood pressure and respond to sympathetic nerves and secrete renin
What does the extraglomerular mesangium do?
Mediates signals from the macula densa cells for transmission to JG cells
What does Angiotensin II do?
Constricts the efferent arteriole in response to a decrease in blood pressure--maintains the GFR
Where does protein resabsorption occur?
In the proximal tubule
Are proteins filtered by the glomerulus?
Yes--peptide hormones, small protiens, and small amounts of albumin
What is the protein concentration of the ultrafiltrate?
40 mg/L or 7.2 g/day
What is the normal daily protein excretion?
150 mg
How much of the daily protein excretion is albumin?
Less than 20 mg/day
What is persistent albumin excretion between 30 and 300 mg/day called?
Microalbuminuria
What do values above 300 mg/day say about the albumin?
Macroalbuminuria--the level at which the standard dipstick becomes positive
What is a good estimate of the potential for a diabetic's kidney function?
Microalbuminuria
What drugs are good at slowing the progression of microalbuminuria?
ACE inhibitors
What does the dipstick react with in the urine?
Mainly reacts primarily with albumin--does not detect immunoglobulin light chains
What is a better screening test for protein in the urine than the dipstick?
Sulfosalicyclic acid--will precipitate with any protein
Does the dipstick pick up microalbuminuria?
No
What exactly does the dipstick measure?
Protein concentration--not amount
What amount is trace protein picked up on dipstick?
Between 15 and 30 mg/dl
What is 1+ protein on dipstick?
Between 30 amd 100 mg/dl
What is 2+ protein picked up in the urine?
Between 100 and 300 mg/dl
What is 3+ protein picked up in the urine?
Between 300 and 1000 mg/dl
What is 4+ protein picked up in the urine?
>1000 mg/dl
What is the "gold standard" for measuring protein in the urine?
24 hour urine collection
What is a more convenient way to measure protein in the urine than the 24 collection?
The protein/creatinine ratio obtained from a random urine collection
What is the average creatinine excretion per day?
1g/day/1.73m2
What is focal nephritic disease?
Associated with inflammatory lesions in less than one-half of the glomeruli--UA has red cells, occasional red cell cast and mild proteinuria
What is diffuse nephritic disease?
Heavy proteinuria, edema, hypertension, and/or renal insufficiency--affects almost all of the glomeruli
What is nephritic disease?
An active urine sediment, a lot of protein, and inflammation
What is pathognomonic for glomerulonephritis?
Red cell casts
What is the difference between nephrotic and nephritic disease?
Nephrotic disease is associated with heavy proteinuria and lipiduria, but few cells or casts
What defines nephrotic disease?
Heavy proteinuria, hypoalbuminemia, and peripheal edema--hyperlipidemia and thrombotic disease are frequently present--often associated with a bland vs. active sediment
What is pathognomonic for nephrotic disease?
"Maltese cross"--appearance of a fat droplet under microscope
What is the function of the tubulues?
Reabsorb what has been filtered and control the envirnoment
What does the proximal tubule reabsorb?
2/3 of H2O and Na+ and all of the bicarb--isotonic at proximal convuluted tubule
Where is water removed from the tubule but Na+ stays behind?
In the descending thin limb of the loop of henle
Where is the osmolality very high?
In the loop of henle
Where is Na+ removed from the tubule but water stays behind?
In the thin ascending limb of the loop of henle
Where is active transport of sodium done in the tubules?
In the ascending thick limb of the loop oh henle
Where does the urine become dilute?
In the distal convoluted tubule--150mOsm
Where does ADH work to concentrate the urine?
In the collecting duct
Where does the capillary network of the nephron come from?
It all comes out of the efferent arteriole
What is the transcellular pathway?
From the lumen through the apical membrane of the tubular cell and out the basolateral membrane into interstitial fluid
What is the paracellular pathway?
From the lumen through tight junctions into interstitial fluid
Where do molecules go from the interstitial fluid?
Through the basement membrane of the endothelial cell and into the peritubular capillary lumen
What substances can freely move across the lipid bilayer without using a transporter?
Lipids, blood gases, and steroids
What is an example of an antiporter system?
Na+ is reabsorbed and H+ is secreted
What does bicarb reapsorption mean about hydrogen ion secretion?
Bicarb reabsorption always means hydrogen secretion
What is an example of a symporter system?
Na+ and glucose moving into the cell together
What is the urine pH and why?
The urine pH is acidic--5 because all of the bicarb gets reabsorbed
What is the only site for water reabsorption to occur in the nephron?
The descending thin limb
In the thick ascending loop of henle, what is the lumen charge?
Positive--as the negatively charged chloride is reabsorbed, the lumen becomes positive
In the distal tubule, what is the lumen charge?
Negative--as the positively charged sodium is reabsorbed, a negative lumen charge is created
What is the primary pump used in the thick ascending limb?
A chloride pump
In the thick ascending limb, is the urine dilute or concentrated?
Dilute--the tubule is impermeable to water
What is the thick ascending limb responsible for?
Both diluting and concentrating the urine
What do loop diuretics inhibit?
The Na+/K+/Cl symporter in the thick ascending limb
What do loop diuretics do to urinary NaCl excretion?
Increases urinary NaCl excretion
What do loop diuretics do to the Ca++ and K+ reabsorption?
Inhibits K+ and Ca++ reabsorption
What do loop diuretics do to water excretion?
Increases water excretion by reducing the osmolality of the interstitial fluid
What do thiazide diuretics inhibit?
The NaCl symporter in the distal convoluted tubule
Do loop or thiazide diuretics dilute the urine?
Thiazide and loop diuretics both dilute the urine
Do loop or thiazide diuretics concentrate the urine?
Thiazide diuretics concentrate the urine
Which diuretics promote Ca++ reabsorption?
Thiazides-useful in treating renal stone disease
Which diuretics inhibit Ca++ reabsorption?
Loop--useful in treating hypercalcemia
Which diuretics are the first line of treatment for hypertension?
Thiazide diuretics
What do prinicpal cells do?
Reabsorb Na+ and H2O and secrete K+
What does aldosterone do to Na+ reabsorption?
Increases it
What is hyperaldosteronism and what are the signs and symptoms?
Increased BP
Hypokalemia
Metabolic Alkalosis
Decreased Renin
What is Liddle's syndrome?
An autosomal dominant disorder that has excessive Na+ reabsorption and K+ secretion
What is the difference between Liddle's Syndrome and Hyperaldosteronism?
Aldosterone is elevated in hyperaldosteronism and decreased in Liddle's syndrome
What do loop diuretics inhibit?
The Na+/K+/Cl symporter in the thick ascending limb
What do loop diuretics do to urinary NaCl excretion?
Increases urinary NaCl excretion
What do loop diuretics do to the Ca++ and K+ reabsorption?
Inhibits K+ and Ca++ reabsorption
What do loop diuretics do to water excretion?
Increases water excretion by reducing the osmolality of the interstitial fluid
What do thiazide diuretics inhibit?
The NaCl symporter in the distal convoluted tubule
Do loop or thiazide diuretics dilute the urine?
Thiazide and loop diuretics both dilute the urine
Do loop or thiazide diuretics concentrate the urine?
Thiazide diuretics concentrate the urine
Which diuretics promote Ca++ reabsorption?
Thiazides-useful in treating renal stone disease
Which diuretics inhibit Ca++ reabsorption?
Loop--useful in treating hypercalcemia
Which diuretics are the first line of treatment for hypertension?
Thiazide diuretics
What do prinicpal cells do?
Reabsorb Na+ and H2O and secrete K+
What does aldosterone do to Na+ reabsorption?
Increases it
What is hyperaldosteronism and what are the signs and symptoms?
Increased BP
Hypokalemia
Metabolic Alkalosis
Decreased Renin
What is Liddle's syndrome?
An autosomal dominant disorder that has excessive Na+ reabsorption and K+ secretion
What is the difference between Liddle's Syndrome and Hyperaldosteronism?
Aldosterone is elevated in hyperaldosteronism and decreased in Liddle's syndrome
What do loop diuretics inhibit?
The Na+/K+/Cl symporter in the thick ascending limb
What do loop diuretics do to urinary NaCl excretion?
Increases urinary NaCl excretion
What do loop diuretics do to the Ca++ and K+ reabsorption?
Inhibits K+ and Ca++ reabsorption
What do loop diuretics do to water excretion?
Increases water excretion by reducing the osmolality of the interstitial fluid
What do thiazide diuretics inhibit?
The NaCl symporter in the distal convoluted tubule
Do loop or thiazide diuretics dilute the urine?
Thiazide and loop diuretics both dilute the urine
Do loop or thiazide diuretics concentrate the urine?
Thiazide diuretics concentrate the urine
Which diuretics promote Ca++ reabsorption?
Thiazides-useful in treating renal stone disease
Which diuretics inhibit Ca++ reabsorption?
Loop--useful in treating hypercalcemia
Which diuretics are the first line of treatment for hypertension?
Thiazide diuretics
What do prinicpal cells do?
Reabsorb Na+ and H2O and secrete K+
What does aldosterone do to Na+ reabsorption?
Increases it
What is hyperaldosteronism and what are the signs and symptoms?
Increased BP
Hypokalemia
Metabolic Alkalosis
Decreased Renin
What is Liddle's syndrome?
An autosomal dominant disorder that has excessive Na+ reabsorption and K+ secretion
What is the difference between Liddle's Syndrome and Hyperaldosteronism?
Aldosterone is elevated in hyperaldosteronism and decreased in Liddle's syndrome
What do the intercalated cells do?
Secrete H+, reabsorb K+--Secretion of H+ is stimulated by aldosterone
Where are the principal and intercalated cells located?
In the distal tubule and collecting date
What do Amilioride and Triamterene do?
K+ sparing diuretics--block the entry of Na+ into the cells and prevents K+ loss
Which diuretics competitively inhibit the effects of aldosterone?
Spirinolactone and eplerenone--effective in patients with cirrhosis and ascites, also heart failure
What is Pc inversely proportional to?
The resistance of the afferent and efferent arteriole
What is the oncotic capillary pressure proportional to?
The GFR at constant RBF
What does an increase in oncotic pressure do the reabsorption?
Increases reabsorption
When is ADH released?
Increased plama osmolarity
Decreased volume
Decreased BP
When is ADH not secreted?
Decrease plasma osmolarity
Increased volume
Increased BP
How much does the plasma osmolarity need to change before ADH is released?
1%
How much does fluid volume have to change for ADH to be released?
5-10% decrease in the effective circulating volume (ECV)
Besides volume and osmolarity, what other things stimulate the release of ADH?
Nausea
Stress
Pain
Hypoglycemia
Drugs
Besides volume and osmolarity, what other things inhibit the realease of ADH?
ANP
BNP
Ethanol
In a patient who is fresh post-op, what would you expect their ADH levels to be?
Increased ADH levels
What would happen to a patient with increased ADH levels after surgery that you gave 4L of fluid to?
They would become hyponatremic
What two things can decrease the set point of ADH release?
Decreased ECV and Pregnancy
What is central diabetes insipidus?
Inadequate release of ADH--results in large volumes of dilute urine
How do patient's with central diabetes insipidus compensate for their large loss of water?
Drink large volumes of water to maintain osmolality
What is the serum sodium in a patient with CDI?
Hypernatremia
What is the usual cause of CDI?
Head trauma
Brain tumors
CNS infections
How do we treat CDI?
Administer ADH
What is nephrogenic diabetes insipidus?
Principal cells of the collecting duct do not respond to ADH--do not respond to the administration of ADH
What is a usual cause of NDI?
Usually the result of decreased expression of aquaporin 2--Lithium toxicity, hypokalemia, low protein diet
How much must the plasma osmolarity increase in order to produce the thirst response?
2-3%
What stimulates the thirst center?
Angiotensin 2
What is the tubular fluid leaving the proximal tubule compared to the plasma?
Isotonic
What do we need to do to dilute the urine?
Must reabsorb solute in excess of water--Need Na+ not water
What do we need to do to concentrate the urine?
Must reabsorb water in excess of solute
What is the tubular fluid charge with respect to the blood in the thick ascending limb?
Positive
What does aldosterone do to sodium and potassium?
Increases sodium reabsorption and increased potassium and hydrogen ion excretion
What is hyponatremia almost always a problem of?
A water problem
What is SIADH?
Syndrome of inappropriate ADH
What accounts for all of the entire fall in the plasma sodium concentration in SIADH?
The combination of water retention and secondary solute loss
What is the sequence that the changes occur in SIDAH?
Hyponatremia is initially mediated by ADH-induced water retention

Then,

The volume expansion activates secondary natriretic peptides resulting in further loss of sodium and water
How is SIADH treated?
Treat only patients with symptoms rapidly--have to be very careful about speed of extraction of water because it can cause osmotic demylination

Water restriction

Salt administration and a loop diuretic

ADH receptor antagonist
What is central pontine myelinolysis?
When hyponatremia is corrected too quickly--patients are mentally retarded
What is the effective circulating volume?
The portion of the ECF volume that is contained in the arterial system and is EFFECTIVELY perfusing the tissues
Is a patient with heart failure and cirrhosis going to have decreased or increased ECV?
Decreased ECV