Kidney Flashcards by Joanna Brown

There are three pathways that promote renal vasodilation:

Prostaglandins
Natriuretic Peptide
Dopamine Receptors

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How do prostaglandins influence renal artery dilation?

The IEDs won’t kill your kidneys

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What do natriuretic peptides do?

Released from the atria with distention

Inhibit renin release and promote sodium and water excretion

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What dopamine receptors are present in the kidney?

Increase cAMP, leading to vasodilation

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What is fenoldopam?

It’s a D1 agonist that increases renal artery dilation without causing systemic dilation. Very useful in cardiac patients during aortic surgery

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Trace the nephron from beginning to end

Afferent arteriole
Glomerulus
Proximal Tubule
Loop of Henle
Distal Tubule
Collecting Duct

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Which nephron components are located in the cortex?

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Which nephron features are contained in the medulla?

Everything that involves concentrating is in the medulla:
loop of henle
Collecting duct

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What triggers erythropoietin release from the kidneys?

Hypoxia, from high altitude, heart failure, anemia etc)

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Which prostaglandins vasoDILATE the renal artery?

PGI2 and PGE2

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Which prostaglandins vasoCONSTRICT the renal artery?

Thromboxane A2

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How does the kidney impact calcium levels?

In response to PTH stimulation, it produces calcitriol, which stimulates bone breakdown, decreases Ca renal excretion, and increases Ca reabsorption from GI tract

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Which two organs can perform gluconeogenesis?

The kidneys can too! they rival the liver in producing glucose in fasting states!

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The kidneys receive _____% of the cardiac output

20-25

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What percentage of RBF is filtered in the glomerulus?

20%

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What percent of filtrate is excreted as urine?

Only 1%!!

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Renal blood flow decreases ____% each decade after ______

10% each decade after 50

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Which region of the kidney is most sensitive to ischemia?

The medulla. It has a much lower PaO2 at baseline and much less blood flow

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When do infants achieve normal RBF levels?

about 2 years

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How quickly does RBF change in the newborn?

Doubles in the first two weeks!

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What are the two most important methods of autoregulation in the kidney?

Myogenic
Tubuloglomerular Feedback

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Describe the myogenic mechanism

When blood pressure in the afferent arteriole increases, it constricts to prevent the glomerulus from being overloaded

When pressure is low, it dilates

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The juxtaglomerular apparatus is located in the:

distal tubule

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Innervation of the kidneys occurs at what spinal level?

T8-L1

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What is the generalized effect of SNS stimulation on the kidneys?

Decreased GFR Increased Na/H2O retention Decreased UO

What renal structures are innervated by the SNS?

Afferent and Efferent arterioles

What does the Juxtaglomerular device measure?

Na and Cl concentration

Angiotensin causes constriction of the _______

EFFERENT arteriole

How is urine output autoregulated?

IT ISN'T! It has a linear relationship with MAP above 50mmHG

Where is aldosterone released from?

zona glomerulosa of The adrenal gland

There are three things that trigger renin release:

Afferent Autoregulation: Decreased renal perfusion pressure Sympathetic Stimulation: Beta 1 Tubuloglomerular Feedback

What is the MOA of aldosterone?

Stimulates the Na/K ATPase pump in the distal tubule AND collecting duct

What effect does aldosterone have on serum osmolarity?

NONE! it effects sodium and water reabsorption equally

In addition to RAAS activation, Aldosterone is stimulated by:

Hyponatremia Hyperkalemia

Conn's disease is:

excess aldosterone Exhibits all the "cons" of aldosterone

Addison's disease is:

Inadequate cortisol and aldosterone Need to "add" aldosterone

What is osmolality?

Osmoles per Kg

What is osmolarity?

Osmoles per Liter L is NOT FOR LITER

Where is ADH produced?

Nuclei of the HYPOTHALAMUS

What is the calculation for Serum Os?

You can't get a sugar daddy until you're 18

Where is ADH stored and released?

The posterior pituitary

There are two things that control ADH release:

1. Increased osmolarity 2. Decreased blood volume

ADH stimulates _______ receptors

V1 and V2

What does V1 stimulation cause?

Vasoconstriction in the PERIPHERY

What does V2 stimulation cause?

Activates aquaporin channels in the collecting ducts, leading to water reabsorption

What is a normal serum os?

280-290

What is a normal GFR?

125 ml/min

Destruction of ______ leads to proteinuria

The basement membrane of the glomerulus

Where is MOST sodium reabsorbed?

65% of sodium and water is reabsorbed in the proximal tubule

Where are acids, bases, and hydrogen ions secreted?

The proximal tubule

What occurs in the descending loop of henle?

HIGHLY PERMEABLE TO WATER but not ions, and passes through counter-current, resulting in concentration of the filtrate 20% of water is reabsorbed here

What occurs in the ascending loop of henle?

IMPERMEABLE TO WATER 20% of sodium is reabsorbed here and pumped into the tubular interstitium, creating the countercurrent!

Is the distal tubule permeable to water?

It is impermeable EXCEPT in the presence of aldosterone or ADH

What three substances impact the collecting duct?

Aldosterone ADH Atrial Natriuretic peptides

What impact does aldosterone have on K and H secretion?

It INCREASES secretion of K and H

Where does calcium reabsorption occur?

Distal tubule

What is the MOA of carbonic anhydrase inhibitors?

Noncompetitively inhibit carbonic anhydrase in the PROXIMAL TUBULE This leads to excretion of bicarb and mild metabolic acidosis

What are the clinical uses for acetazolamide?

Open angle glaucoma (reduces aqueous humor production) Altitude sickness (acidosis increases RR) OSA (Increases RR)

What are the complications of acetazolamide?

HYPOkalemia Metabolic acidosis

which patients should not receive mannitol?

Patients who can't tolerate brief fluid overload Patients whose BBB is NOT intact (glucose can cross and cause seizures)

What is the MOA of loop diuretics?

Inhibits the Na-K-2CL pump transporter in the ASCENDING loop of henle

What is the MOA of thiazide diuretics?

Inhibit Na-Cl cotransporter in the DISTAL TUBULE

What is a unique feature of thiazide diuretics?

They cause hyperglycemia and increases calcium reabsorption

Name four thiazide diuretics

HCTZ Chlorthalidone Metolazone Indapamide

Name three potassium sparing diuretics

"SALT" Spironolactone Amiloride Triamterene

Where do potassium sparing diuretics exert their effects?

The COLLECTING DUCT

List five side effects of potassium sparing diuretics

Hyperkalemia Metabolic acidosis Gynecomastia Libido changes Nephrolithiasis

List three drug classes that increase the risk of hyperkalemia in a patient taking a potassium sparing diuretic

Beta blockers NSAIDS ACE-Is

Which blood tests assess GFR?

BUN and CR

Which blood tests assess tubular function?

Fractional excretion of sodium Urine Os

Creatinine undergoes renal _____ but not ______

filtration but not reabsorption

What is a normal BUN:Cr ratio?

10:1

A BUN:Cr ration greater than ________ indicates prerenal azotemia

> 20%

What is urea?

Primary metabolite of protein breakdown in the liver

Why is Cr a better indicator of GFR than BUN?

BUN undergoes filtration AND reabsorption

Who is at the highest risk for a perioperative AKI?

CHF Sepsis Renal Dx (duh) Advanced age

The risk of prerenal azotemia is reduced by:

Keeping the MAP > 65 providing adequate hydration

How does CKD impact coagulation?

Inhibits platelet function. This means bleeding time will be elevated, but PT/PTT/INR will be normal

What is a side effect of exogenous Epo administration?

HTN

You should assume that all patients with CKD also have _____

Coronary Artery Disease This is usually what kills them

What cardiac abnormality is associated with uremia?

Pericarditis

What pH abnormalities occur with CKD?

Anion gap acidosis from all the uremic acid built up

How does uremia impact the neurological system?

It impairs nerve conduction, leading to sensory AND motor neuropathy

Why are CKD patients at an increased risk for infection?

Impaired WBC function and the need for a low protein diet

What are the best NMBAs for patients with CKD?

Cis and Atracurium

Will patients with CKD need more or less propofol?

Maybe more, because they have hyperdynamic circulation and an impaired BBB

What can be done to avoid an AKI from contrast?

IV fluid bolus Bicarb Low-osmolar contrast

Which class of antibiotics is the worst for the kidneys?

Aminoglycosides (gentamycin etc)

What is the classic TURP syndrome triad?

HTN Bradycardia Decreased LOC

Correcting serum Na too quickly increases the risk of

central pontine demyelination

What are absolute contraindication to ESWL?

Pregnancy and anticoagulation