Renal Anatomy and Histology Flashcards
Where do the kidneys lie?
retroperitoneal lying about T12-L3
lower on right
What is the transpyloric plane?
horizontal plane
left hilum there, top of right kidney is near this line
Where is the inferior pole of the right kidney?
approx index finger superior to iliac crest
What are the structures surrounding the kidney from closest to the kidney capsule to farthest away?
perinephric fat –> renal fascia –> paranephric fat
What type of tissue makes up the renal capsule?
dense irregular CT on surface w/ inner layer of myofibroblasts (contractile capabilities)
What is the renal cortex?
outer portion of the kidney containing renal corpuscles (lighter colored)
What are renal pyramids?
cone-shaped masses in medulla projecting into calyx
What are renal columns?
tissue lying btw pyramids running from cortex to the calyx
What is contained in a renal lobe?
single pyramid plus surrounding adjacent cortex
What is the renal pelvis?
collecting funnel for urine in the center of the kidney
out-pocketings of pelvis = cayxes
What do the renal arteries arise from?
abdominal aorta
What 6 arterial branches supply the ureters?
GRAIPS gonadal renal abdominal aorta iliac pelvic superior vesicular
What is the path of blood from the aorta to a glomerulus?
aorta –> renal artery –> segmental artery –> interlobar A –> arcuate A –> cortical radiate A –> glomerulus
What is the sympathetic innervation of the kidneys?
Lesser splanchnic (T10-11) and least splanchnic (T12) synapse in aorticorenal ganglia lumbar splanchnic nerves (L1-L2)
What is the parasympathetic innervation of the kidneys
vagus n –> presynaptic to plexus –> kidney
What makes up a nephron?
(urine forming unit) renal corpuscle and renal tubules
What is the path from an afferent arteriole to collecting duct?
afferent arteriole –> glomerulus –> bowman’s capsule –> proximal convoluted tubule –> proximal straight tubule –> thin lop of henle –> thick ascending loop of henle –> distal convoluted tubule –> collecting duct
Where are renal corpuscles
only in cortex of kindeys
What are cortical/medullary rays?
aggregations of collecting ducts and straight tubules running btw the renal corpuscles and convoluted tubules w/in cortex
What important function occurs in the renal interstitium?
fibroblasts produce EPO
What is a glomerulus?
tuft of fenestrated capillaries
afferent arterioles go in
efferent arterioles go out
contained in the cortex
What is the glomerular/bowman’s capsule?
covers the glomerulus; 2 layers:
parietal and visceral
What is the parietal layer of the glomerular capsule made of?
The visceral layer?
parietal = simple squamous epithelium
visceral layer = podocytes w/ foot processes and cytoplasmic extensions of podocytes
What characterizes the glomerular endothelium?
truly open fenestrations, but complete basement membrane
thick luminal glycocalyx (negatively charged proteolgycans)
large numbers of aquaporin channels
can generate NO and PGE2
What stimulates glomerular endothelium to release nitric oxide and PGE2?
angiotensin II
What is the function of podocytes on the visceral layer of the glomerular capsule?
part of filtration barrier
critical in regulating size, patency, and selectivity
What is special about the basement membrane of of the glomerulus/capsule?
it is formed by both the capillary endothelium and podocytes
What are filtration slits?
spaces btw foot processes of podocytes in the glomerular capsule
What can pass through the glomerulus/capsule filtration membrane?
water ions glucose amino acids urea
What types of collagen are in the glomerular basement membrane?
type 4 and 18
18 is negatively charged - repels other negatively charged things
What is albuminia?
albumin in urine
indicative of damage to glomerular basement membrane
What are mesangial cells?
support glomerular loops and extracellular matrix of podocytes
phagocytic and can control glomerular filtration rate
can contract if high glomerular BP
secrete growth factors and cytokines in response to injury
What is the most active tubule in resorption and secretion?
proximal convoluted tubules
What characterizes the proximal convoluted tubule in general (not histology)?
found only in the renal cortex
most abundant tubule and most active in resorption and secretion
one cell layer
What characterizes the PCT histologically?
simple cuboidal to columnar epithelium w/ abundant microvilli
abundant mitochondria
basal and lateral cell membranes highly folded to increase surface area
Na, K ATPase pumps and aquaporins
glucose and AA transporters
How does the proximal straight tubule compare to the PCT histologically?
not as tall as PCT w/ smaller brush border
high affinity sodium-glucose cotransporters (sGLT1)
What type of glucose transporter is in the PCT?
SGLT2
Where is the loop of henle located in the kidney?
What is its main function
loops down into medulla and then back up into the cortex; terminates near vascular pole
sets up hyperosmotic gradient
What are the main parts of the loop of henle?
thin limb = thin simple squamous w/out brush border
thick ascending segment = simple cuboidal w/ numerous microvilli but no brush border
Where is the distal convoluted tubule?
confined to cortex
What characterizes the distal convoluted tubule?
simple cuboidal epithelium w/ sparse microvilli
luminal surface smoother than PCT
cells taller than thick ascending LoH
What hormone acts on DCT and what is its effect?
angiotensin II –> DCT –> Na+ resorption
Where are the collecting ducts and what is their function?
extends from cortex to medulla
each receives primitive urine from several nephrons
water reabsorption
several join together to form larger papillary ducts –> renal minor calyx
What type of cells makes up the collecting ducts?
lined w/ simple cuboidal at beginning and are simple columnar at the ends
light cells/principal = target of aldosterone
dark cells/intercalated = involved in H+ and bicarbonate transport
What kidney structure determines final urine osmolality?
collecting ducts
What hormones target the collecting ducts?
ADH and aldosterone –> increase Na reabsorption and water retention
What vessels arise from the efferent arterioles?
peritubular capillaries
vasa recta
What are peritubular capillaries?
arise from efferent arterioles
surrond convoluted tubules
lined w/ fenestrated endothelium –> re-uptake of H2O and salts
What are vasa recta and what do they do?
thin walled vessels that arise from efferent arterioles of juxtamedulary glomeruli
descending lined w/ continuous endo
fenestrated when ascending
run along loop of henle
What makes up the juxtaglomerular apparatus?
macula densa = distal end of thick ascending LoH - acts as a chemoreceptor by monitoring salt levels –> signals release of renin from juxtaglomerular cells if sodium is low
What layers make up transitional epithelium?
supericial layer - closest to urine/lumin; stretched and relaxed
intermediate = sliding layer
basal = stem cells
What are fusiform vesicles?
found in urothelium/transitional epithelium - continuously fuse and are endocytosed to allow stretching of membrane
What are urothelial plaques?
found in urothelium/transitional epithelium to form impermeable barrier
uroplakin proteins are in btw lipid bilayer
What is the histology of the ureter?
transitional epithelium
muscularis - 3 indistinct layers (inner longitudinal, outer circular, outer longitudinal)
adventitia = typical connective tissue
What is the trigone?
inferior/posterior wall where ureters and urethra open
What makes up the bladder wall
lined w/ transitional epithelium
3 layers thick smooth muscle = detrusor muscle
fibrous adventitia
What type of epithelium lines the urethra?
transitional - found at origin near the bladder
pseudostratified columnar - majority of urethra
stratified squamous - at very distal end
Which urethral sphincter is voluntary?
external
internal is involuntary that is really part of bladder wall
What are the 3 regions of the male urethra?
prostatic
membranous - through urogenital diaphragm; homologous to that found in female
spongy/penile - passes through length of penis
What is polycystic Kidney disease?
autosomal dominant
cysts form that crush tissue and impede drainage –> kidney failure and BP mis-regulaton
