Urinary System Flashcards
kidney functions
produce urine
eliminate nitrogenous waste
maintains electrolytes and water balance
release renin and erythropoietin
location of the kidneys
posterior abdominal wall
behind peritoneum
each side of vertebral column at T12 - L3
epigastric, hypochondriac, lumbar, umbilical regions
why is the right kidney slightly lower than the left
the liver is above the right kidney
external features of kidneys
two poles, surfaces and borders
hilum - renal vein, artery, pelvis
coverings of kidneys
from within outwards
fibrous capsule (true capsule)
perirenal (perinephric) fat
renal fascia (false capsule)
pararenal (paranephric) fat
role of perirenal and pararenal fat
perirenal fat supports the kidney positionally
pararenal fat cushions and prevents the kidney hitting T11-12
relations of the right kidney
liver, duodenum, colon, jejunum
only T12
relations of left of kidney
stomach, pancreas, jejunum, colon, spleen
T11 and T12
macroscopic structure of outer cortex
located below renal capsule and extends between the renal pyramids as renal columns which divide lobes
macroscopic structure of inner medulla
5 - 11 dark renal pyramids with inner apex and outer base
form projections which invaginate the minor calyces
renal sinus
cavity of considerable size within the kidney
opens at the medial border of the kidney as hilus
contains renal pelvis, calyces, vessels, nerves and fat
microscopic structure
nephron is functional unit: glomerulus and tubule system
functions of nephrons
filtration, selective reabsorption, secretion
cortical vs juxta-medullary nephrons
cortical nephron: sodium resorption
more superficial with loops of Henle confined to cortex
juxta-medullary nephrons: water resorption
nephrons start more near the cortex-medulla junction with longer loops that extend into medulla
renal corpuscle
mainly located in cortical arches
consists of capillaries and Bowman’s capsule
vascular pole
proximal convoluted tubule
low columnar to cuboidal epithelium
luminal surface has microvilli brush border
main function: active reabsorption
glucose, amino acids, Na, Cl, HCO3, water
loop of Henle
thin descending limb and thick ascending limb
function: reabsorbs water, Na, Cl
distal convoluted tubule
begins from the vascular pole of the nephron
lined by cuboidal epithelium but no brush border
function: reabsorbs Na, Cl, water
major blood supply of kidneys
arterial supply: renal artery branching from abdominal aorta
venous drainage: renal vein into IVC
renal circulation
renal arteries divides into anterior and posterior on either side of renal pelvis
branches into segmental then lobar arteries
become interlobar arteries between medullary pyramids then arcuate arteries
then interlobular arteries which form glomeruli
drain via same but opposite
juxtaglomerular apparatus
what is it made of
involved in regulation of blood pressure
made up of:
JG cells
macula densa
Lacis / Polkissen cells
JG cells
modified smooth muscle cells
in tunica media of afferent arteriole at DCT
sensitive to blood pressure
responsible for RAAS
macula densa
specialised regions in the wall of the DCT that contacts JG cells
columnar cells instead of cuboidal cells in the DCT
sensitive to conc of Na in DCT fluid
Lacis / Polkissen cells
extraglomerular mesangial cells
at the vascular pole in close relationship with macula densa
what causes activation of RAAS
RAAS pathway
decreased BP or Na
Renin converts angiotensinogen to angiotensin I
ACE converts Ag I to Ag II
Ag II causes vasoconstriction and release of aldosterone which increase NaCl absorption
why is 8 mL of dye is inserted for urography
any more would distort the anatomy and less would be inaccurate
congenital polycystic kidney disease
occurs because the DCT and CD have different embryonic origins
if they do not fuse correctly, urine does not drain properly and cysts form
horseshoe kidney
fusion of the inferior poles of the kidneys
causes increased risk of stones and UTIs and impaired functions
renal transplants
needed when there is chronic failure
surgery via the right iliac fossa for ease due to vessels
ureter
narrow, thick walled, expansile, muscular tube
25 cm
3.5 mm
abdominal and pelvic are above and below the pelvic bone
site of anatomical constrictions of the ureter
Pelviureteric junction
pelvic brim where it crosses the common iliac artery
utero-vesical junction (entry to bladder)
blood supply of the ureter
arterial supply form the arteries related to it
divide superiorly and inferiorly
abdominal ureter supplied by arteries medial to it
pelvic ureter supplied from arteries lateral to it
where is the urinary bladder
situated in the anterior of the lesser pelvis immediately behind pubic symphysis
external features of urinary bladder
apex at anterior and base at posterior
two ureters enter at either side of the base
superior surface and inferior neck
in males prostate sits at the neck
relations of the urinary bladder
anterior is pubic bone (symphysis)
posterior in males is rectum, vas deferens and seminal vesicle
posterior in females is vagina and uterus
interior of the urinary bladder
rugae when empty but disappear as it stretches
trigone of the bladder on the interior posterior surface which has no rugae because submucosa and muscular layer are fused
two inputs from ureters
one output to urethra
urethra
longer in males than females
females get UTIs more often but harder to treat in males
membranous part is more internal and spongy part is in the penis
sphincters of the urethra
internal sphincter is at the base of the bladder and involuntary
external sphincter is at the base of the penis or before orifice and voluntary
internal relaxes during urination but closes during ejaculation
histology of the kidney
outer renal capsule
round structures: Bowman’s capsule
fuzzy lumen: PCT
clear lumen: DCT
long structures: CDs and some LoH
inner medulla is more condensed
histology of ureter
upper ureter has two layers of muscle: outer circular and inner longitudinal
lower has three: outer longitudinal, middle circular, inner longitudinal
histology of the bladder
dome shaped cells
below is muscle which is not distinctly arranged
