Week 1 Review Session Flashcards
I did a kidney biopsy last week. The needle inadvertently went through the cortex and into the medulla. Which artery was most likely to have been punctured in the process?
Arcuate artery
Arcuate artery is between the cortex and medulla
An increase in flow/NaCl delivery at the macula densa leads to which one of the following?
Afferent arteriolar vasoconstriction
Because more NaCl delivery = more kidney wants to retain shit = decrease GFR
Upregulates renin and modulates afferent arteriole
Does not say shit about efferent arteriole
Why doesn’t capillary hydrostatic pressure not vary by much?
Because of modulation by afferent and efferent arteriole
Which one of the following is most likely to increase GFR?
Afferent arteriolar dilatation
Which one of the following is an important features that makes a substance a good marker of GFR?
Neither secreted nor reabsorbed
Example: Inulin
What is clearance?
The volume per unit time of plasma from which the solute was completely removed
No single ml is actually cleared of all that substance, but rather some smaller quantity is removed from each of the many ml that pass through the kidneys
Question 5: What is serum creatinine determined by?
Muscle mass
GFR
Higher muscle mass = greater GFR
Under steady state conditions, which one of the following is correct?
ICF osmolarity = ECF osmolarity
ECF volume is a function of ECF effective solute content
ICF volume is a function of ICF effective solute content
How do you quickly estimate plasma osmolality?
2*Na + 10
How do you quickly estimate plasma tonicity?
2*Na + 5
On the first day of your surgery clerkship, the Attending tells you to make sure her patient gets some extra IV saline overnight since her serum Na is low and therefore she is volume contracted. You tell her which one of the following?
Answer: But, Dr. I seem to recall learning that the serum Na does NOT tell us about the intravascular volume. I better go examine the patient
Volume depletion must be found through physical exam
What is a more effective volume expander?
Saline > water
That’s because water will distribute to ALL compartments (ICF and ECF)
Salt will only distribute to ECF
What are the most significant features of proximal tubule?
Highest water permeability
But urine remains nearly isotonic to plasma along PT length
Which one of the following increases PT Na reabsorption?
An increase in filtration fraction
-because you are delivering more fluid into the lumen
-also because you have higher oncotic pressure in blood, further reabsorbing shit in the PT
Angiotensin 2 = increases sodium reabsorption at proximal tubule, so ARB would decrease PT Na reabsorption
The permeability to water increases most in response to AVP in which nephron segment?
Collecting duct
You develop a technique to stick a long but very skinny pipette into a single nephron of a human. In one of your classmates, you find that whether water-deprived or water-loaded, the tubule fluid osmolarity is
The late distal convoluted tubule
Only place where it is hypotonic
Berns’ favorite question!
What is the specific gravity?
1.010 = normal plasma specific gravity
-represents urine osmolality of 300 mosm/kg
1.020 = abnormal = too much
Means osmolality is now 600 mosm/kg in plasma
Which one of these diuretics would be most useful in treating someone with hyponatremia?
Furosemide (loop diuretic)
Reduce ability to concentrate urine in order to help with hyponatremia
Other diuretics do NOT reduce ability to concentrate urine
You calculate an electrolyte free water clearance in a patient with hyponatremia to be 100 ml/day. Which one of the following statements is correct?
Hyponatremia will worsen if he drinks more than 500 ml/day
Remember tonicity is different from volume and last two answer choices point to ways to correct volume
