renal embryology

Question 1

kidney embroylogy timeline

Answer 1

Pronephros appears at wk 4, but then degenerates

mesonephros: functions as an interim kidney for the 1st trimester and later contributes to the male genital system
metanephros: permanent. first appears in 5th week of gestation. nephrogenesis continues through 32-36 wks gestation

Question 2

early kidney embryology

Answer 2

1. ureteric bud. derived from the caudal end of the mesonephric duct. gives rise to the ureter, pelvises, calyces, and collecting ducts. fully cannulizes at week 10
2. metanephric mesenchyme: ureteric bud interacts with the metanephric mesenchyme. interaction induces differentiation and formation of glomerulus through to distal convoluted tubule.
3. aberrant interaction btw these two tissues may result in congenital malformation of the kidney

Question 3

What is the most common site of kidney obstruction (hydronephrosis) in a fetus)

Answer 3

ureteropelvic junction. it is the last to cannulize.

Question 4

potter sequence: definition, causes, manifestations

Answer 4

oligohydramnios –> compression of developing fetus (the baby has no cushion) –> limb and facial deformities (like low set ears and retrognathia). also causes chest compression, which causes pulmonary hypoplasia. pulmonary hypoplasia is the cause of death.
causes: ARPKD, posterior urethral valves, bilateral renal agenesis.
POTTER: pulmonary hypoplasia, oligohydramnios (trigger), twisted face, twisted skin, extremity defects, renal failure (in utero).

Question 5

horseshoe kidney

Answer 5

inferior poles of both kidneys fuse. as the ascend from the pelvis during fetal development, horseshoe kidneys get trapped under the INFERIOR MESENTERIC ARTERY and remain low in the absomen. kidney functions normally, but there is an incr. risk of ureteropelvic junction obstruction, hydronephrosis, renal stones, and renal cancer (Wilms).
associated with Turner syndrome.

Question 6

multicystic dysplastic kidney

Answer 6

abnormal interaction beween the ureteric bud and the metanephric mesenchyme. causes a nonfunctional kidney consisting of cysts and CT. if unilateral (most common), generally asymptomatic with compensatory hypertrophy of contalateral kidney. often diagnosed prenatally with ultrasound

Question 7

tumor lysis syndrome

Answer 7

acute renal failure with hyperkalemia. also see hypocalcemia, hyperphosphatemia, and metabolic acidosis. results for dumpint of intracellular contents of tumor cells after beginng cytotoxic therapy. purine sare metabolized to uric acid, which may overwhelm the kidney. can be prevented with use of allopurinol (though not with azathioprine/6-mercaptopurine).

Question 8

which kidney is taken during living donor transplantation and why? Where are the kidneys located in the abdominal cavity?

Answer 8

left kidney is taken because it has the longer renal vein. in transplant, renal artery is connected to the external iliac artery.
kidneys are located at vertebral level T12-L3 and are covered by the 11th and 12 ribs. right kidney is slighly lower and more lateral than the left. it is also slightly smaller than the left. this is because of the liver.

Question 9

course of the ureters

Answer 9

ureters exit the kidney, pass over the external iliac vessels, under the gonadal vessels (in woman, these are found within the infundibulopelvic ligament), and then course retroperitoneally and lateral to the internal iliac. before entering the bladder, they course under the vas deferens (in men) or uterine vessels (found in the cardinal ligament that connects the cervix and the side wall of the pelvis).

Question 10

What are the retroperitoneal structures?

Answer 10

SAD PUCKER
suprarenal/adrenal glands, aorta and IVC, most of duodenum, pancreas (except tail), ureters, colon (descending and ascending), kidneys, lower 2/3 of esophagus, most of rectum

Question 11

fluid compartments. how do you measure each compartment?

Answer 11

60% of total body weight is fluid; 40% ICF, 20% ECF. of the ECF, 1/4 is plasma and 3/4 are interstitial fluid.
plasma vol measured by radiolabeled albumin. ECF measured by inulin.

Question 12

What makes up the glomerular filtration barrier?

Answer 12

filters plasma by size and net charge.

1. fenestrated capillary endothelium (size barrier)
2. fused basement membrane with heparan sulfate (negative charge barrier- heparin is negatively charged)
3. podocyte foot processes (epithelial layer)