Nephrology/urology

Question 1

what are the 3 layers of the glomerulus

Answer 1

1. Epithelium: podocytes with slit pores, make up the filtration barrier
2. Endothelium: fenestrated with lots of fixed negative charges.
3. Basement membrane

Small positively charged will pass through the barrier.

Question 2

What is primarily absorbed in the proximal convoluted tubule

Answer 2

Na, Cl, water - 75%
Calcium - 80%
Bicarb - 80-90%
Glucose and amino acids- 100%
Urea 40-50% (primary transporter is UT-1)
Only 1/4 of Mg is reabsorbed

Question 3

Where is the majority of magnesium reabsorbed

Answer 3

the thick ascending loop of hence

Question 4

what receptors are responsible for glucose reabsorption in the proximal convoluted tubule

Answer 4

-SGLT2 is more proximal and is responsible for 90%
-SGLT1 is more distal and responsible for 10%

Question 5

What is primarily reabsorbed in the descending loop of henle

Answer 5

water is leaving the nephron, the concentration becomes more osmotic

Question 6

what is primarily reabsorbed in the thin ascending blood of henle

Answer 6

Sodium and chloride
Passive reabsorption is occurring

Question 7

What is primarily reabsorbed in the thick ascending loop of henle

Answer 7

where the majority of magnesium is reabsorbed
loop diuretics work here (work on sodium and potassium channels) –> continued Na and Cl reabsorption, but active

Question 8

What is primarily reabsorbed in the distal tubule

Answer 8

location of the macula densa
NaCl is detected –> if solutes are too hyponatremic –> RAAS is stimulated to increase GFR and increase Na reabsorption
-thiazide diuretics work on this segment of the nephron

Question 9

Collecting ducts

Answer 9

Composed of principal cells and intercalated cells (A- and B- type)

• intercalated cell type A: secretes acid (hydrogen) and reabsorbs bicarb
• intercalated cell type B: secrete bicarb and reabsorb hydrogen

Question 10

What are the features of the vasa recta helps preserve high solute concentrations

Answer 10

1. sluggish blood flow is sufficient to meet metabolic needs and minimize solute loss from medullary interstitium
2. serves as countercurrent exchangers –> minimizes washout of solutes from the medullary interstitial (feature due to the U shape of the vasa recta capillaries)

Question 11

What does USG indicate

Answer 11

Assesses the ability for the loop of henle to dilute urine and distal tubules to concentrate urine

Question 12

How does proteinuria reflect proximal tubular disease

Answer 12

glomerular barrier alterations (altered permeability): considered a functional proteinuria, and can be transient
can become severe as injury progresses

indicates proximal tubular dysfunction

Question 13

What can create false positives and false negatives when assessing proteinuria

Answer 13

False positives:
-alkaline urine, very concentrated urine, pigmenturia

False negatives:
-dilute urine, Bence-Jones proteinuria, microalbuminuria

Question 14

What can glucosuria indicate

Answer 14

Overload hyperglycemia: can indicate tubular dysfunction
- persistent: diabetes mellitus, hyperadrenocortcism, acromegaly, pheochromocytoma

abnormal proximal tubular function
-physiologic in young puppies
-renal tubule damage: drugs (amino glycosides), hypoxia, infections, secondary to copper toxicity, idiopathic fanconi syndrome