Kidney APEX Flashcards
Body fluid compartments
ECF-14L (vascular 3L, interstitial 11L)
ICF- 24L
What compartments are in the cortex of the kidney?
Glomerulus/ bowmans capsule
PCT
DCT
What compartments are in the medulla
Loop of Henle (ascending and descending)
Collecting duct
The kidney produces ___
Renin (JG cells)
Calcitrol (active vitamin D3)
EPO stimulates stem cells in the bone marrow
Prostaglandins control blood flow
Glucose from amino acids (gluconeogensis)
The kidneys receive _____% of cardiac output, ____ L/min
25
1
Renal blood flow formula
RBF = (MAP-Renal venous pressure)/ Renal vascular resistance
Blood flow thru the kidney
Renal artery
Afferent arterioles
Glomerular capillary bed
Efferent arterioles
Peritubular capillary bed
Renal segmental vein
At what map mmHg can RBF autoregulate?
50-180
Renal autoregulation is carried out by what processes?
Myogenic mechanism- constricts or dilates afferent arterioles
Tubuloglomerular feedback/ JG apparatus-
PGs, ANP, SNS, RAAS
What states can decrease RBF?
Sepsis
Surgical stress
Ischemia
After 50 years old, RBF decreases by _____
1% per year
What increases renin release?
PEEP reduces renal blood flow
Beta 1 stimulation from circulating or exogenous catecholamines
Hemorrhage
CGF
Liver failure w ascites
Sepsis
Diuresis
Decreased sodium and chloride delivery to the DCT (Tubuloglomerular feedback
Hypovolemia
Hyponatremia
BP is regulated by what 3 systems?
SNS
RAAS
Vasopressin
Beta 1 ____ renin
STIMULATES
Plasma osmolarity formula
(2Na) + (glu/18) + (BUN/2.8)
What is the normal plasma osmolarity?
280-290
What pathways promote renal vasodilation?
PGs
Natriuretic peptide
Dopamine receptors
D1 vs D2
D1- vasodilation, increased RBF
D2- decreases norepi release
How can NSAIDs affect RBF?
Inhibit PGs- prevent vasodilation- decrease RBF
The plasma is slightly ____ charged
positively because it has more cations such as sodium and potassium
What term refers to the pressure that prevents osmosis?
Osmotic
If an isotonic solution is added to ECF, the effect will be ____
An increase in ECF only
A rapid correction in ______ can cause permanent brain damage
Hyponatremia from 3% hypertonic saline
Intracellular edema can lead to ____
Lack of nutrients to the cells
Depression of metabolic function
Reduced blood flow, oxygen, and nutrients
Inflammation increases cell permeability
What can cause increased capillary pressure?
1- increased capillary pressure (Kidney retention of salt and water, high venous pressure, low arteriolar pressure)
2- Decreased plasma proteins (nephrotic syndrome, wounds, liver disease)
3- Increased cap permeability (toxins, immune reactions, infections, burns)
4- Lymph blockage (cancer, surgery)
In heart failure, blood flow to the kidneys is _____, which stimulates _____, causing _______
Decreased
Renin
AT2 & aldosterone which will cause additional salt and water retention by the kidneys
What 3 factors prevent edema?
Low interstitial compliance (-3mmHg)
Drainage (lymphatic) (7mmHg)
Wash down of IF proteins as lymph is washed away (7mHg)
Thus, capillary pressure could rise to 17 (double the normal value) before edema would occur
Plasma filtration occurs in the ____
glomerulus
The kidneys receive ____ % of CO
20
What are the two types of nephrons?
Cortical- short loops of henle
Juxtamedullary- Long loops of henle, concentrate urine, higher GFR, larger glomeruli
How fast do we lose nephrons?
10% every 10 years after 40 (apex says 50)
Each nephron contains what?
A glomerulus
A renal tubule- where filtered fluid become urine
The bowmans capsule and glomerulus form the ___
Renal corpuscle- where GFR begins
____ % of RBF is filtered by the glomerulus, the remaining ___% is delivered to the _____
20%
80% goes to the peritubular capillaries
The normal GFR is ____
125ml/min
Where does most sodium get reabsorbed?
PCT- 65%
Reabsorption of what requires ATP?
Electrolytes
NOT water- water occurs via osmosis
What is the primary function of the Loop of Henle?
Forming dilute or concentrated urine- separating the handling of sodium and water
What are the vasa recta?
Peritubular capillaries that run parallel to the Loop of Henle
Which part of the Loop of Henle is permeabile to water?
Descending IS permeable
Ascending is NOT permeable
Target location of Loops, osmotics, CA inhibitors, and Thiazides, K sparing
Loop diuretics- loop of henle
CA Inhibitors- PCT
Osmotics- PCT
Thiazides- DCT
K sparing- Collecting ducts
Spironalactone MOA
Aldosterone antagonist
Blocks K secretion and Na reabsorption
Side effects of K sparing diuretics
Hyperkalemia (especially if taking with nsaids, BBs, ACEis)
Gyno
Side effects of loop diuretics
Hypokalemic hypochloremic met alkalosis
Hypokalemia can increase risk of digoxin, and potentiate NMBs
Ototoxicity
Side effects of Osmotics
If BBB is disrupted, mannitol will enter brain and cause edema
Side effects of CA inhibitors
Met acidosis (reabsoprtion of H ions while excretion of CA and HCO3)
May exacerbate COPD depression from hypercarbia because of the loss of bicarb buffer
What is the best test of tubular function?
Urine osmolality
Fractional excretion of sodium
What are to best tests of GFR?
BUN (although this is a better indicator of uremic symptoms from the metabolism of protein)
Creatinine clearance
Normal urine sodium
130-260mEq/day
Urine specific gravity
1.003-1.030
What could be some causes of low BUN (<8)
Overhydration
Decrease urea production (malnutrition, liver disease)
What could cause high BUN (>20)
Dehydration
Increased protein input (high protein diet, GI bleed, hematoma breakdown)
Catabolism (trauma, sepsis)
Decreased GFR
Creatinine is produced by ___, and is directly proportional to ___
skeletal muscle, it is a breakdown of creatine
muscle mass (lower in women and elderly)
A 100% increase in creatinine indicates a ___ reduction in GFR, why so?
50% reduction
Creatinine only undergoes renal filtration, no reabsorption (half the process)
BUN undergoes ____, Creatinine undergoes ___
filtration and reabsoprtion
filtration only
The normal BUN: Cr ratio is ___, and is useful for evaluating ___
10:1
Hydration status
____ is the4 most useful tool for GFR
creatinine clearance
GFR formula
[(140-age) x BW] / (72 x serum Cr)
x .85 for women to account for smaller muscle mass
Failing kidney __ sodium
waste
Pre renal vs ATN urinary sodium
Pre renal- urinary sodium <20,
ATN- urinary sodium >20,
What are intrinsic causes of ATN?
Ischemia
Nephrotoxic drugs- nsaids, abx, contrast dye
____ maintain GFR and UOP better than levo or phenyl
Vaso!
d/t constriction of the EFFERENT arterole
What is the most important pump of the ascending LOH?
Na K 2 Cl
Site of acrtion for Loop Diuretics
ADH and aldosterone are counteracted by ____
ANP in the collecting ducts
What are the stages of CKD
Measured by GFR
1- normal >90ml/min
2- 60-89
3- 30-59
4- 15-29
5- Kidney failure, requires dialysis <15
Most common cause CKD is ___, and the second most common cause is ___
Diabetes mellitus
Hypertension
What are the symptoms of uremic syndrome?
Anemia
Fatigue
N/V
Anorexia
Coagulopathy
Decreased EPO leads to ____ ____ anemia
Normochromic normocytic
Acidosis shifts the oxyhemoglobin dissociation curve to the ___
right
Dialysis is indicated when K exceeds ___
6 mEq/L
Treatments to reduce serum K are ____
Glucose 50g + insulin 10 units
Hyperventilation- for every 10mmHg decrease in paco2, K will decrese by 0.5
HCO3 100mEq
Calcium chloride 1g
Most common cause of death in dialysis/ chronic renal failure patients
CAD
Then Infection d/t impaired WBC, low protein diet
What is the most accurate predictor of bleeding risk in kidney patients?
Bleeding time
