Theme C lecture 4 Flashcards
What is the function of the kidneys?
Adult kidneys filter 25% of CO (1.1L/min)
Regulate pH, H2O, salt homeostasis, BP, renal hormones, and waste removal.
What does fetal programming in the kidneys cause?
Number of nephrons you are born with are the most you will have throughout your lifespan.
Defects in renal formation can lead to long term health deficits in adult life.
What are the 3 types of kidney like organs found during development?
pronephros -> mesonephros -> metanephros
Which germ layer do the developmental intermediaries of the kidneys arise from?
from intermediate mesoderm
What is the pronephros and when does it form?
it is a transient organ that forms at 21 - 22 days in the human.
It is only important in amphibians and fish but not in humans.
What is the glomus?
The primitive glomerulus which is used by the pronephros to filter blood
What is the mesonephros? When does it form?
Another intermediary which develops on the 25th day of development.
What is the function of the mesonephros?
induces mesonephric mesenchyme to undergo mesochyme epithelial transformation to form the renal vesicle
Where does the mesonephros form?
mesonephros forms underneat the pronephros’s degeneration point on the wolfian duct
What does the mesonephros look like?
several glomeruli connected to wolfian ducts via mesonephric tubules.
Does the mesonephros contain a loop of henle?
No
Does the mesonephros contain glomeruli?
Yes
Does the mesonephros contain a juxtaglomerular apparatus?
No
What other structure does the mesonephros contain?
Mesonephric tubules
What does the mesonephros ultimately become?
mesonephros forms an S shaped tubule which ends up becoming the proximal tubule.
Mesonephros forms about 40 nephrons.
Mesonephros also forms the efferent tubules of the testis
When is the mesonephros at its largest size? How big is it relative to other organs?
On day 33 it is at its largest size and is the most prominant organ in the region.
Which is bigger the mesonephros or metanephros?
Mesonephros
When does the metanephros develop?
day 30 but finishes just before birth and coexists with the mesonephros for a while.
When does the kidney finish development?
kidney finishes development just before birth with approximately 1 million nephrons.
*lots of variation in numbers 1 million is only an average.
How important is the metanephros before and after birth?
Metanephros is not essential for fetal survival but is essential after birth.
What processes regulate final nephron number?
Ureteric bud branching
Mesenchymal epithelial transformation (for mesenchyme to become nephrons).
Apoptosis
What happens during ureteric branching?
Ureteric Branching causes outgrowth at caudal end of wolffian duct, the UB invades the metanephric mesenchyme and induces Ureteric Bud to grow and branch.
What structures does the ureteric bud form post natally?
Tree forms the collecting ducts, calyces, and renal pelvis.
Part that does not enter the metanephric mesenchyme forms the ureter.
How does nephrogenesis take place?
UB induces MM to condense causes cap formation and formation of pretubular aggregate which undergoes Mesenchymal epithelial transformation to form a renal vesicle.
Renal vesicle becomes comma shaped then S shaped. This S shape forms the nephron.
What does the upper portion of the S shape of the renal vesicle form?
Distal convoluted tubule
What does the central portion of the S shape of the renal vesicle form?
Proximal tubule, loop of henle, and the distal straight tubule.
What does the lower portion of the S shape of the renal vesicle form?
Renal corpuscle and glomerulus
How long does branching occur for? What happens after this?
Tip branching occurs up to week 15 after this week arcades are formed and each arcade forms 7 - 10 nephrons
What happens to nephrons after week 20?
Nephrons form along the length of a collecting duct and form arcades which allow a greater number of nephrons to form.
When do adrenergic nerves innervate fetal kidneys?
Adrenergic nerves innervate fetal kidneys from 20 weeks in humans.
What is the function of adrenergic nerves during fetal life?
Adrenergic nerves regulate renal vasodilation and are important for growth and development of fetal kidney.
They also regulate renin release in fetus.
Where do adrenergic nerves act in fetuses?
Adrenergic nerves form in both cortex and medulla.
In cortex they reach adult levels by week 28
in medulla innervation decreases in later gestation
What can be said about the renal blood supply of the fetus?
Kidney is highly vascularised.
What happens to the kidneys during the 8th to 10th week?
During the 8th to 10th week the S shaped bodies have blood vessels around them.
*Capillaries appear around UB the day after it has entered the MM.
What happens to nephron formation during birth?
Birth interferes with nephron formation.
What do kidneys do in utero?
Kidney functions in utero. it filters blood and produces urine in the amniotic fluid.
Produce formones such as renin and erythropoietin.
How is urine removed from the amniotic fluid?
fetal swallowing or via membranes
What can’t the fetal kidneys do?
they can’t concentrate urine like in adults.
What is the result of impaired renal development in fetuses?
impaired renal development could cause downstream problems with other organs such as the lungs.
What is different about fetal kidneys compared to adult kidneys?
fetus excretes more sodium and water and doesn’t function in a way to maintain homeostasis.
What is Potter’s syndrome?
Baby survives in utero without kidneys but dies afterwards.
No urine produced in utero
lack of amniotic fluid produces causes gross abnormalities.and death soon after birth causing lung insufficiency.
This problem could cause only one kidney to go allowing normal life. However, nephron number is halved.
What causes hydronephrosis?
constriction in the ureter causes a buildup of urine in the kidneys which causes damade to the kidneys.
What are some examples of congenital abnormalities of the kidneys and urinary tract?
Bilateral renal agenesis
Hydronephrosis
Polycystic kidney disease
What can maternal drug use cause?
It can cause congenital kidney problems
What is the incidence of CAKUT?
CAKUT maks up approximately 1/3rd of abnormalities detected by a routine ultrasound.
What is CAKUT?
comprised of several congenital conditions related to the kidneys. It includes renal hypoplasia, dyplasia, hydroureter, vesicouteric reflux.
What is the effect of maternal use of ACE inhibitors on the fetus?
They cross the placenta and inhibit urine production and this affects renal development in the fetus
What is the effect of COX-1 inhibitors on the fetus?
inhibits fetal renal function and development.
What is COX-1 typically used for?
Treatment of polyhydramnios.
What is the variation in nephron number accross the human population?
nephron number varies 10 fold.
Some populations have lower nephron number
many pregnancy insults can reduce nephron number
Why is nephron number important?
It is associated with adult disease and is the result of fetal programming.’
Reduced nephron endowment results in impaired renal function and dysregulation of BP.