Flashcards in Renal Deck (197)
When does nephrogenesis begin?
early in the 4th week as 3 sets of kidneys
When does the final set of kidneys develop and become functional?
develop in 5th week and functional around 9th week
What is the major component of amniotic fluid after 18-20 weeks?
urine; this is when AFI becomes crucial
When is nephrogenesis complete?
at 34-36 weeks
What is the effect of prematurity on post-natal nephrogensesis?
not accelerated and may be blunted; may be all the nephrons you get (at birth)
What are the primary functions of the renal system?
1) maintenance of body homeostasis
2) endocrine regulation
What hormones does the renal system control?
What is erythropoietin?
hypoxia-sensing cells that stimulate bone marrow to make more RBCs
What is calcitriol?
active form of vitamin D that works together with parathyroid hormone to maintain Ca++ balance
What is renin?
controls the volume of blood and therefore BP
How does the renal system maintain systemic homeostasis?
- disposes of nitrogenous wastes
- controls composition of blood
In what way do the kidneys control the composition of blood?
- regulates electrolyte homeostasis
- regulates acid-base balance
What is pyelectasis (or pelviectasis)?
mild dilation of the renal pelvis; measures 4-10mm in 2nd trimester; 97% will spontaneously resolve
What is hydronephrosis?
an exaggeration of pelviectasis; dilation >10mm; seen in 1-4% of all pregnancies; M>F
Why is it important to f/u a suspected hydronephrosis?
etiology is typically an obstruction
The term kidney typically has how many nephrons?
~ 1 million (300k- 2million)
A nephron consists of what two portions?
glomerulus & renal tubule
What are the two different types of nephrons?
cortical nephron & juxtaglomerular nephron
What is a cortical nephron?
the glomerulus and tubular system in the outer cortex
What is a juxtaglomerular nephron?
the tubular system that penetrates into the medulla
How does blood ENTER the glomerular tuft?
How does blood EXIT the glomerular tuft?
How many capillaries does the glomerular tuft have?
~ 50 tiny capillaries
What do the slit-like pores in the arterioles of the glomerulus permit?
allow passage of H20 and small solutes and restrict larger molecules, like proteins and red blood cells, from transferring into the bowman's capsule
Which arteriole is more dilated in the glomerulus?
the A-fferent; this allows more blood to enter the capsule than is leaving generating a higher hydrostatic pressure facilitating diffusion
What is GFR?
the amount of filtrate that flows out of all renal nephrons of both kidneys in 1 minute
How does the GFR of a FT infant at birth compare to an adult?
term GFR 30-50% of adult; nephrogenesis is complete by 32 weeks, but maturity takes awhile
How does the GFR of a PT infant (28 wks) at birth compare to a FT infant?
1/2 of term functioning
Describe the progression of GFR maturation in the FT infant postnatally.
- determined by renal vascular resistance (very high in the fetus and falls after birth)
- doubles in 1st 2 weeks
- reaches adult value by 2 years of age