Renal

Question 1

4 major processes in the nephron

Answer 1

1. Glomerular filtration
2. Tubular resorption
3. Tubular secretion
4. Water regulation

Question 2

What does GFR depend on?

Answer 2

1. renal blood flow
2. Number of functional nephrons
3. Hydrostatic pressure
   Rate substances are cleared from plasma via glomerular

Question 3

Osmolality

Answer 3

Concentration of solutes per kg of water

Question 4

Osmometer

Answer 4

Measures number of particles in a volume of water
Not convenient but more accurate

Question 5

Urine specific gravity

Answer 5

Refractometer is convenient but less accurate, Depends on particle weight and how each particle bends light
Prone to interference

Question 6

Getting osmolality from USG

Answer 6

Multiply the last two digits by 30
Rough estimate

Question 7

ADH

Answer 7

Made in hypothalamus and secreted by posterior pituitary. Opens water channels via aquaporin proteins

Question 8

Stimulation of ADH secretion

Answer 8

-Plasma hyperosmolality
-Decreased cardiovascular pressure

Question 9

Result of ADH

Answer 9

Conserve body water to decrease plasma osmolality and increase blood volume

Question 10

Major events in the proximal CT

Answer 10

Removes volume but no change in concentration

Question 11

Major events in the Descending LOH

Answer 11

Removes H2O and increase concentration

Question 12

Major of events of the ascending LOH

Answer 12

Removes solute
Dilution due to decreased concentration

Question 13

Major events of the distal nephron

Answer 13

Removes H2O and increases concentration

Question 14

What is needed to produce concentrated urine

Answer 14

1. Adequate # of nephrons
2. Adequate ADH
3. Distal nephron is responsive to ADH
4. Hypertonic interstitium in the renal medulla (Urea, Na, Cl)

Question 15

What happens to the expected values of USG in dehydrated animals

Answer 15

Dog> 1.030
Cat> 1.35
Horses and cattle> 1.025

Question 16

Isosthenuria

Answer 16

Urine osmolality and plasma osmolality are equal. In dehydrated pt means kidneys have not concentrated nor diluted the tubular fluid (1.007-1.013)

Question 17

Hyposthenuria

Answer 17

Urine osmolality < plasma osmolality.
in dehydrated pt, Kidneys have not actively diluted the tubular fluid. Not renal failure (1.006)

Question 18

Pollakiuria

Answer 18

Increased frequency of urine but doesn’t indicate urine volume

Question 19

Ways to assess GFR

Answer 19

-Urea nitrogen
-Serum creatinine
-SDMA ( not as common)

Question 20

Ways to asses integrity of glomerular structure

Answer 20

-Urine protein
-Urine protein: urine creatinine ration

Question 21

Ability of renal concentration and dilute urine

Answer 21

-USG (compare urine and plasma osmolality)
-Water deprivation test

Question 22

Urinalysis assessment

Answer 22

-USG
-Chemistry
-Sediment examination
Assesses more than urinary tract

Question 23

Azotemia

Answer 23

Increased concentration of Urea unitrogen (BUN or UN) and or creatinine

Question 24

Increased urea formation

Answer 24

-High protein diet
-GI hemorrhage
-Disorders that increase endogenous protein catabolism

Question 25

Decreased urea formation

Answer 25

-Hepatic failure/shunt -Malnutrition -Diuresis

Question 26

Alternate routes of UN for rumenants and horses

Answer 26

Saliva, sweat, GI tract UN is not a sensitive indicator of GFR in those species

Question 27

Important contribution by urea

Answer 27

Easily diffuses across most cell membranes and contributes the renal medullary concentration gradient and drives recovery of water/ concentration of urine in the collecting ducts

Question 28

Measuring urea nitrogen

Answer 28

Serum (red top) or plasma (green top)

Question 29

What is creatinine

Answer 29

Waste product from normal breakdown. Excreted in urine and not resorbed by tubules. The amount formed daily is constant for a given animal. May be proportional to muscle mass

Question 30

Increased Creatinine

Answer 30

Does not mean increased muscle catabolism -Decreased GFR

Question 31

Decreased creatinine

Answer 31

May not be clinically significant(needs to be really really low) -Decreased muscle mass -Hypoproteinemia

Question 32

UN and creatinine in dogs and cats

Answer 32

UN and creatinine increase in parallel when GFR is decreased from renal failure

Question 33

UN and creatinine mismatch in dogs and cats

Answer 33

-Prerenal azotemia-> greater increase in UN -GI hemorrhage-> increased UN -Anorectic or low protein diet-> decreased UN -Extremely cachectic-> decreased creatinine

Question 34

Horses and ruminants UN and creatinine

Answer 34

Creatinine more specific for renal compromise due to alternate urea metabolism by bacteria