NCC content

Question 1

non-excretory functions of renal system

Answer 1

• produces renin (regulates blood pressure)
• produces erythropoietin (initiated by hypoxia, hypovolemia, hypotension)
• metabolizes vitamin D
• degrades insulin
• produces prostaglandins (renal medulla does this)

Question 2

define nephron

Answer 2

functional unit of the kidney

Question 3

define GFR

Answer 3

the rate at which blood flows through capillaries in the nephron
-afferent and efferent arterioles dilate and constrict to control GFR (& BP)

Question 4

when does nephrogenesis start and finish?

Answer 4

• starts at 7-8 weeks

- completed by 34 weeks

Question 5

what are the three main functions of the nephron

Answer 5

• filtration
• reabsorption (occurs through remainder of tubules)
• secretion (active transport of substances back into the tubules)

Question 6

what happens in the proximal tubule?

Answer 6

major site of reabsorption (Na, H20)

Question 7

what happens in the descending loop of Henle?

Answer 7

reabsorption of H20

Question 8

what happens in the ascending loop of Henle?

Answer 8

reabsorption of Cl, K, Na, Bicarb, Ca

Question 9

what’s an important characteristic of the ascending loop of Henle?

Answer 9

IMPERMEABLE TO H2O

Question 10

what happens in the distal tubule?

Answer 10

reabsorption of H20 & Na

-aldosterone acts on distal tubule to cause it to reabsorb more Na and H20 and to secrete K

Question 11

what happens in the collecting ducts?

Answer 11

• presence of ADH allows for filtrate within ducts to become more concentrated by making ducts more permeable to H20
• H20 reabsorbed

Question 12

How much Na do preterm babies have the ability reabsorb?

Answer 12

85-90% vs 95% in term infants

-can’t get rid of excess Na due to decreased GFR

Question 13

How much of what is filtered by the kidneys (Bowman’s capsule) is reabsorbed by the body?

Answer 13

99%

Question 14

what are the 2 clinical correlates associated with ADH?

Answer 14

• DI

- SIADH

Question 15

when does GFR reach adult levels (120 ml/min)?

Answer 15

around 2 years of age

Question 16

where is ADH made and stored?

Answer 16

• made in the hypothalamus

- stored in the posterior pituitary

Question 17

what happens in DI?

Answer 17

• insufficient ADH

- collecting tubules become impermeable to H20 and body can’t reabsorb it

Question 18

what happens in SIADH?

Answer 18

• too much ADH

- collecting tubules are very permeable to H20 so lots of it reabsorbed

Question 19

which babies are prone to SIADH?

Answer 19

-CNS abnormality, midline defect, asphyxia, pneumothorax, post-operative babies

Question 20

what does the RAAS system do?

Answer 20

regulates the extracellular fluid compartment

• helps body maintain fluid balance and blood pressure
• causes systemic vasoconstriction, body hangs on to more Na and H20, increase in intravascular volume

Question 21

how is the RAAS system initiated?

Answer 21

release of renin

-produced by the juxtamedullary cells by afferent arterioles

Question 22

How does renin function?

Answer 22

after release, it goes systemically to act on angiotensinogen, which is produced by the liver

Question 23

how does angiotensinogen function?

Answer 23

it produces angiotensin I

Question 24

how does angiotensin I function?

Answer 24

it goes through the pulmonary circulation where angiotensin-converting enzyme (ACE) changes it to angiotensin II

Question 25

how does angiotensin II function?

Answer 25

causes vasoconstriction to increase blood pressure and acts on adrenal medulla to release aldosterone

Question 26

how does aldosterone function?

Answer 26

causes distal tubule to reabsorb Na and H20

Question 27

normal GFR in a term infant that can maintain homeostasis who isn’t stressed

Answer 27

30 ml/min

Question 28

define anuria

Question 29

define oliguria

Question 30

normal urine output

Answer 30

3-5 ml/kg/h

Question 31

define polyuria

Answer 31

> 5 ml/kg/h

Question 32

what is acute renal injury/failure?

Answer 32

• loss of water and electrolyte homeostasis

- secondary to abrupt decrease in GFR

Question 33

what causes acute renal injury?

Answer 33

• sepsis
• perinatal asphyxia
• hypotension not associated with sepsis
• just being premature

Question 34

what is most common type of acute renal failure?

Answer 34

prerenal (80%)

Question 35

what can happen if prerenal problems aren’t treated appropriately?

Answer 35

it can progress to intrinsic ARF

Question 36

in postrenal ARF, where do the obstructions typically take place?

Answer 36

• ureter
• bladder
• urethra

Question 37

what is the most common type of intrinsic ARF?

Answer 37

acute tubular necrosis

Question 38

what is the most common cause of acute tubular necrosis?

Answer 38

untreated prerenal ARF

Question 39

other causes of intrinsic ARF

Answer 39

• infection (fungal balls)
• aortic/renal artery thrombosis (UAC)
• renal vein thrombosis (dehydrated babies, babies with perinatal asphyxia, IDM)
• DIC
• congenital renal abnormalities

Question 40

what rate of rise is abnormal for creatinine?

Answer 40

0.3-0.5 mg/d

Question 41

what does a urinalysis tell you about the tubules?

Answer 41

reflects the structure of the tubules/glomerulus

Question 42

what does FeNa tell us?

Answer 42

how well the tubules are functioning

• normally we should have low Na urine levels, so low FeNa levels
• can be used to differentiate prerenal from intrinsic failure
• elevated FeNa may indicate intrinsic failure (>2.5%)
• FeNa