Kidney - External Macro Anatomy
Jan 17, 2016
Kidney - External Macro Anatomy
Kidney Anatomy
Corte
x
Kidney - Internal Macro Anatomy
Base
Medulla
Papillae
Colu
mn
Nephron
Renal Corpuscle
Renal Tubule
Renal Corpuscle
Renal corpuscle – Site of fluid filtration– 2 components
glomerulus – group of capillary loops– fed by afferent
arteriole– removed by efferent
arteriole
glomerular (Bowman's) capsule – double walled epithelial cup– outer wall (parietal layer) separated from inner wall (visceral layer) by
capsular (Bowman's) space
Nephron Renal tubule - where
filtered fluid passes from capsule– proximal convoluted
tubule (PCT)
– distal convoluted tubule (DCT)
– loop of Henle (nephron loop)
– short connecting tubules – collecting ducts – merge to papillary duct
then to minor calyx 30 pap ducts/papillae
Nephron Cortical vs.
juxtamedullary nephrons – Name depends on
length of LofH– 15-20% have long
loops and reabsorptive capabilities
Renal Corpuscle Histology Each nephron
portion has distinctive features
Histology of Glomerular filter– Three layers of tissue– From inside to out
prevents movement of progressively smaller particles
Renal Corpuscle Histology1) Endothelium of glomerulus
– Single layer of endothelium w/ fenestrations– Restricts RBC movement
Renal Corpuscle Histology2) Basement membrane of glomerulus
– Between endothelium and visceral layer of glom capsule– Prevents large protein movement
Renal Corpuscle Histology3) Filtration slits in podocytes
– Podocytes specialized epithelium of visceral layer footlike extensions w/ slits between extensions
– Restrict medium-sized proteins
Renal Corpuscle Histology
Tubule Histology In general, tubule is a single layer of epithelial cells
on basement membrane PCT
– cuboidal w/ brush border of microvilli on apical border surface area for reabsorption
Tubule Histology Descending loop of
Henle, beginning of ascending loop– simple squamous
epithelium– only permeable to
water
Remainder of ascending loop– cuboidal to low
columnar epithelium– only permeable to
ions
Tubule Histology DCT, collecting ducts -
cuboidal w/ some modifications in late DCT collecting ducts– principal cells– intercalated cells
Tubule Histology
– Macula Densa special cells in this area monitor Na+Cl- content in blood able to work w/ JG cells
– Both work together to regulate BP
– Juxtaglomerular (JG) cells modified smooth muscle secrete vasoconstrictors
Juxtaglomerular apparatus (JGA)– Ascending LofH contacts
afferent arteriole
Renal Blood Supply Important in
italics– Renal artery
20-25% of resting CO
1200 ml/min– Segmental
arteries– Interlobar arteries
- through columns – Arcuate arteries– Interlobular
arteries
Renal Blood Supply Important in Italics
– Afferent arterioles - each renal corpuscle receives 1
– Glomerular caps– Efferent arterioles -
drain blood from glomerulus
– Peritubular caps - around PCT and DCT
– Vasa recta - long loop from efferent arteriole around LofH
Renal Blood Supply Important in
italics– Interlobular
veins– Arcuate veins– Interlobar veins– Segmental veins– Renal veins -
exits hilus
Renal Nerve Supply Nerves from renal plexus of SNS Vasomotor nerves that accompany renal
arteries and branches– What is the role of SNS stimulation on renal blood
flow?– Fight or flight– Decrease flow
The Final Common Pathway Ureter
– extension of kidney pelvis
– enter bladder medially from posterior
Histology - 3 layers– mucosa
mucous membrane w/ transitional epithelium
secrete mucous– muscularis - smooth
inner longitudinal outer circular
– serosa
The Final Common Pathway Urinary bladder
– hollow muscular organ– generally smaller in females due to uterus– retroperitoneally in pelvic cavity posteriorly to pelvic
symphysis– freely movable
Structure - trigone
The Final Common Pathway Histology
– mucosa - mucous membrane of transitional epithelium and underlying lamina propria
– muscularis detrusor muscle 3 layers
of inner longitudinal, mid circular, outer longitudinal
around opening to urethra
– circular fibers form internal urethral sphincter
– lower is external urethral sphincter - skeletal muscle for control
– serosa - peritoneum
The Final Common Pathway
The Final Common Pathway Urethra
– small tube from floor of bladder to exterior of body females fairly straight path out through vagina males passes through the prostate gland
– histology female three coats
– inner mucous, intermediate thin layer of spongy tissue w/ plexus of veins
– outer muscular coat continuous w/ bladder male two layers
– inner mucous membrane – outer submucous tissue connects w/ structures that it passes