Renal Flashcards
How do ACE inhibitors and NSAIDS impact glomerulus function?
ACE inhibitors stops the function of ANG2 which itself causes constriction of the efferent arteriole (-tensin the second one). Due to this, the efferent is dilated - allows blood to flow out quickly.
NSAIDS stop the dilation of the afferent arteriole by blocking prostaglandin action. They cause afferent vasoconstriction, limiting the flow of blood into the glomerulus.
Why might Hb be raised during hypovolemia?
Haemoconcentration
What does high sodium in the urine indicate?
Can be CKD, diuretics, crappy aldosterone activity
Which drug can reduce thirst response even in dehydration?
ACEi
Which 4 body mechanisms regulate GFR?
- Autoregulation - macula densa and myogenic both act on afferent arteriole
- RAAS - starts with renin release from granular cells
- SNS
-ANP/BNP
How does ADH work?
Increases number of aquaporins to resorb more water
How does aldosterone work?
Causes the body to resorb more sodium and subsequently secrete potassium - ENaCs in collecting duct
Name 3 causes of a pre-renal kidney issue?
All due to volume.
- hypovolemia - sepsis
- dehydration
- occlusion of arteries
- triple whammy drugs
What are the major cation and anion exchangers involved in acid/base homeostasis?
H+/K+
and
HCO3-/Cl-
What does percussive tenderness over the kidneys indicate?
Pyelonephritis
How does nephrotic syndrome cause edema?
Nephrotic syndrome is associated with mass proteinuria, peeing out albumin will lower oncotic pressure, allowing fluids to stay in the interstitium.
Compare potassium levels in an AKI vs CKD.
AKI will have whack potassium levels, too high in blood due to trying to counter acidosis.
CKD tends to have pretty normal potassium as the nephrons have adapted.
Why does CKD cause low bicarb?
Due to shitty nephrons unable to secrete H+, the blood is acidic and the bicarb is used to mop that up.
Bicarb is also made in the nephrons so if the nephrons are dying they cant make it.
How can you workout where urinary blood came from?
If from the kidneys - they will be deformed cos they’ve been through the wringer. Red cell casts.
If it’s from the bladder, they’ll be normal RBC.
Should ACEi be used in AKI and CKD?
AKI - NO - we need more filtration.
CKD - Yes, we want the nephrons to take it easy, take the pressure off them.
Should NSAIDS be used for AKI or CKD?
Neither, ever.
Describe the anatomy of the glomerulus?
Capillaries enter and the first layer is endothelial cells. Then the basement membrane, then the podocytes, then bowmans space.
Which structure of the glomerulus is usually damaged in nephrotic syndrome?
Podocytes
Brown casts in the urine usually indicate which condition?
Acute tubular necrosis
How does acute interstitial nephritis impact urine?
Without the functioning of the tubules, urine cannot be properly formed so it will be very dilute.
The glomerulus is spared.
What are the main causes of CKD?
HTN, T2D, Glomerulonephritis
Which structures are in front of the right kidney, which structures are below it?
In front - liver and duodenum.
Beneath - right colic flexure, small int.
Which structures are in front of the left kidney, which structures are below it?
In front - pancreas and left colic flexure
Beneath - descending colon and jujunum.
Describe the internal anatomy of the kidney?
Cortex on the outside, medulla on the inside forming pyramids, minor then major calyx.
Describe the origin and path of the arteries that supply the kidneys.
The renal arteries arise from the abdo aorta, the left one must go higher, the right must go longer and passes posterior to the IVC.
What are the 3 ureter stricture points?
- Uretopelvic junction
- Pelvic inlet at iliac bifurcation
- Entrance to bladder
Which 3 molecules should ideally never be in the urine?
BiCarbonate, glucose and albumin
Which cell type supports the glomerular capillary?
Mesangial cells
Frothy urine is typically due to what molecule?
Albumin
Which molecule is used to test glomerular function?
Creatinine
What is the oncotic pressure in the Bowman’s space?
Typically 0! There should not be any albumin in this space.
How does afferent arteriole dilation impact GFR and how?
Dilate = more blood coming in = more hydrostatic pressure = more filtration = higher GFR
Autoregulation can control GFR between which MAPs?
80 and 180
Describe the mechanisms of autoregulation in the kidneys.
Myogenic - local contraction of the afferent arteriole in response to stretch. Will constrict afferent arteriole.
Tubuloglomerular feedback - Macula Densa cells sitting at the distal tubule (next to afferent arteriole) - detect increase GFR/pressure and cause vasoconstriction of afferent arteriole.
What is the major buffer in the ECF and intracellularly?
ECF - bicarb
Intracellular - phosphate
Define volatile acids and fixed acids.
Volatile acids - can be turned into gas and breathed out - eg. bicarb binding to H+ allows for carbon dioxide to be made and breathed out
Fixed acids - cannot be turned into a gas and must be excreted