Anatomy and Histology of the Kidney Flashcards
organization of the kidney
surrounded by a dense, fibrous CT capsule
distinct cortex and medulla
blood vessels, nerves, and lymphatics enter and leave at the hilus
blood vessels, nerves, and lymphatics enter and leave at the hilus
urine leaves via the ureter
capsule
connective tissue covering kidney surface
hilus
entry point for renal blood vessels, nerves, lymphatics, and ureter
pelvis, major and minor calyces
collection area for urine
components of the cortex
outer region containing:
cortical labrynth including glomeruli and convoluted tubules
straight tubules called medullary rays (not part of medula)
the renal columns are cortical regions that extend between the pyramides of the medulla
medulla
inner region organized into pyramids containing straight tubules, collecting ducts, and capillaries
lobe
medullary pyramid + asspcoated cprtex
Describe the system of arteries supplying the kidneys.
renal artery
interlobar artery
arcuate artery
afferent arteriole
glomerular capillaries
efferent arteriole
peritubular capillaries or vasa recta
What does the renal artery divide into?
interlobar arteries - separates the kidney into lobes
arcuate artery
enters a lobe at the cortico-medullary border
interlobular arteries
arteries that ascend within the centers of the cortical labyrinths
afferent arterioles
branch off from the interlobular arteries, giving rise to glomerular capillaries
efferent arterioles
vessels that exit the glomeruli becoming either peritubular capillaries or descending vasa recta
What is the difference between peritubular capillariies and the descending vasa recta?
the peritubular capillaries supply the superficial glomeruli, whereas the descending vasa recta feeds into the juxtamedullary glomeruli
Describe the benous return for the kidney
beings with the interlobular vein and ascending vasa recta
starting at the arcuate vein, outflow parallels inflow
What is the ratio of cortical to medullary blood supply
7:1 - most of this to glomeruli
two types of regions in the renal cortex
maze-like regions consisting of tubules (cortical labyrinth)
regions with straight tubules that can be though of as extensions of the medulla (medullary rays)
components of a nephrone
renal corpuscle and renal tubule
renal corpuscle
beginning of the nephrone that consists of:
Bowman’s capsule
endothelial cells of glomerular capillaries
glomerular basement membrane (GBM)
specialized phagocytic cells
Bowman’s Capsule
consists of an encircling layer of parietal epithelium (squamous), an open space (Bowman’s space, and a layer of visceral epithelium, the podocytes, which envelop the glomerular capillaries
visceral epithelium (podocytes)
highly arborized cell that envelops the glomerular capillaries with many first, ssecond, and third degree pedicels (food processes)
endothelial cells of glomerular capillaries
cells with open fenestrations, each about 70-90 nm in diameter
glomerular basement membrane (GBM)
the fused basal laminae of the glomerular endothelium and podocytes
specialized phagocytic cells of the renal corpuscle
intraglomerular mesangial cells
extragomerular mesangial cells (Lacis cells)
glomerular filter
composed of:
the glomerular capillary endothelium (70-90 nm fenestrations)
GBM (main barrier)
complex interdigitated pedicels and slit diaphragms (~25 nm) of the podocytes
intraglomerular cells keep the filter clean
J-G apparatus (JGA)
place where the renal tubule of the nephrone returns to contact the renal corpuscle at the vascular pole
comprised of the macula densa and the juxtaaglomerular cells
macula densa
specialized cuboidal epithelia
in the region closest to the vascular pole, the cuboidal cells of hte Thick Ascending Limb have a very different morphology than the rest of the TAL cells
they are taller, thinner, and have a darker staining cytoplasm
juxtaglomerular cells
modified smooth muscle cells of afferent and efferent arterioles (more on afferent side)
these cells synthesize and secrete renin
divisions of the renal tubule
proximal tubule (PT)
loop of Henle
distal tubule (DCT)
collecting system
components of the proximal tubule
convoluted segment (PCT)
straight segment (PST)
divisions of the loop of Henle
a very thin walled segment in the shape of a hairpin
a straight thick ascending limb (TAL)
collecting system
connecting the collecting tubules of the cortex
inner and outer medullary collecting ducts
collecting duct
receive input from many individual tubules
in the medulla, many medullary collecting tubules merge into larger caliber ducts (ducts of Bellini) which empty into a minor calyx
What distinguishes PCT from DCT?
stellate lumen
lumen wiht “fuzz”
larger diameter
more numerous
