Gut book 6: Kidneys, ureters, & Suprarenal Gland Flashcards
Kidney- general description
Paired retroperitoneal abdominal organs which lie on either side of the vertebral column within the paravertebral gutters
Paravertebral gutters
formed by the intersection of three muscles: the psoas major overlaying the vertebral column, the quadratus lumborum, and the transversus abdominis muscle passing forward along the course of the ribs.
Kidneys: function
by filtering the blood, function to remvoe/ conserve H2O, remvoe metabolic waste, balance Na+ and K+ through selective secretion/ reabsorption, reabosorb glucose and amino acids, and participate in the renin-angiotensin system.
Comparison of kidneys
left kidney is somewhat longer than right
right kidney is slightly lower than left due to presence of liver
Kidneys: physical position
inferior poles lie more laterally than do superior poles
hilar area faces anteromedially due to the slope of the paravertebral gutter
vertebral projection: T12-L3 (LEFT: T12-L2; RIGHT: L1-L3)
retroperitoneal; embedded in layers of fascia and fat
Renal fascia and fat- derivation and function
derived from extraperitoneal connective tissue; support and protect the kidneys
Renal fascia
anterior and posterior lamina surround both kidneys, their associated suprarenal glands and invest the intervening renal vessels, aorta and IVC
The laminae overlap in the midline, fuse and adhere to the intervening vascular structures across the spine such that each kidney is isolated in its own compartment
Prolonged along the ureter as PERIURETERIC fascia
open inferiorly
periureteric fascia
prolongation of the renal fascia along the ureter
Types of renal fat
perinephric and paranephric
Perinephric- located internal to the renal fascia in direct contact with the kidney; surrounds the kidney and helps to locate it on the posterior abdominal wall
paranephric- retroperitoneal fat external to the renal fascia located posteriorly between the kidney and the quadratus lumborum/ diaphragm
perinephric abscess
due to the position of the renal fascia, perinephric abscess can lead to inflammation of the psoas major fascia (psoas abscess), which can descend from the abdomen to the pelvis or femoral triangle. Note that due to the fusion of the renal fascia in the midline surrounding the aorta and IVC, perinephric abscess cannot cross the midline to the opposite kidney.
nephroptosis
Due to the inferior opening of the renal fascia, kidneys can “drop” resulting in pain due to the kinking of the ureters.
Renal ectopia
kidney not located in its normal anatomic position
can be distinguished from nephroptosis in that in the former, the ureters are not kinked.
discuss placement of transplanted kidneys
Transplanted kidneys are placed in the iliac fossa so that the re-anastomosed vessels and ureter are not under any traction and remain patent
Right kidney- anterior relations
posterior abdominal wall peritoneum right suprarenal gland right lobe of the liver 2nd part of hte duodenum right colic flexure small intestine
left kidney- anterior relations
posterior abdominal wall peritoneym left suprarenal gland stomach spleen pancreas left colic flexure small intestine (jejunum)
posterior relations- right and left kidney
diaphragm psoas mm quadratus lumborum transversus abdominis lumbocostal arches (lateral and medial arcuate ligaments) subcostal n. iliohypogastric and ilioinguinal nerves
rib protection for kidneys
Within the musculofascial composition of the posterior abdominal wall ribs 11 and 12 provide protection for the posterior surface of the left kidney, while only the 12th rib affords protection for the right kidney
Kidneys: external structure
ovoid in shape in both the superior-inferior and anterior-posterior dimension
approx size: 10x5x2.5 cm
reddish brown in color in the fresh state
Surfaces: anterior and posterior
poles: superior and inferior
borders or margins: lateral- convex, medial- somewhat concave due to the presence of a central indented hilum
Renal capsule
fibrous connective tissue layer on the external surface of kidney
hilum
area through which renal vessels (aa., vv., & lymphatics), renal pelvis, and renal plexus enter and exit the kidney
renal sinus
area inside hilum, internal to the kidney containing vessels (aa., vv., & lymphatics), nerves, renal pelvis, calyceal system and perinephric fat
Kidneys: internal structure
divisible into five vascularly defined lobes or segments
cortex
medulla
cortex of the kidney
outer more granular appearing layer (due to the presence of glomeruli)
Medulla of the kidney
inner more striated zone due to the presence of straight tubules and collecting ducts; organized into pyramids (8-18) the bases of which face the cortex
medullary rays
portions of the medulla that extend into the cortex
renal or cortical columns
portions of the cortex that extend toward the pelvis between medullary pyramids
Intrarenal duct system
each pyramid has its apex (renal papilla) oriented twoard the renal sinus.
Renal papilli drain via papillary ducts to a minor calyx
Two or more minor calyces, of which there are eight, drain to a major calyx
Two or three major calyces drain to the renal pelvis which in turn is drained by the ureter
Renal arteries
left and right renal arteries branch from the aorta at approximately LV2 just below the superior mesenteric artery
course transversely to reach the kidney, passing anterior to the crura of the diaphragm and psoas muscles
the right renal artery courses posterior to the IVC, head of the pancreas, 2nd portion of the duodenum and right renal vein before entering the hilum.
what else the renal arteries supply
each renal artery provides its corresponding suprarenal gland with an inferior suprarenal artery, and its corresponding ureter with ureteric branches.
lobar or segmental arteries
Before entering the renal sinus, the renal arteries branch into segmental or lobar arteries
Each of the five arterial lobar branches of the renal artery are “end arteries” which supply the five “segments” of the kidney.
Interlobar arteries
branch from lobar arteries and course within renal cortical columns
Arcuate arteries
reaching the junction of the cortex and medulla, the interlobar arteries provide arcuate arteries which course BETWEEN the cortex and medulla.
Interlobular arteries
branch from the arcuate arteries to course peripherally within the cortex (perpendicular to the renal capsule). They will provide the afferent arterioles of the glomerulus.
efferent arterioles
the direct continuation of the afferent arterioles form a plexus around the tubules of the kidney (peritubular capillary plexus)
Veins of the kidney
drain in a pattern similar to the arteries, except that there are NO efferent or afferent venules.
Renal veins exit the renal sinus, pass anterior to the renal arteries to join the IVC.
What else does the left renal vein receive?
the left gonadal vein as well as the left inferior phrenic vein before passing ANTERIOR to the aorta to join the IVC
vessels formed during renal development are sometimes…
retained as the kidney “ascends” from the pelvis leading to the existence of ectopic vessels which should have been resorbed as newer vessels formed.
Renal Vein Entrapent Syndrome,
= nutcracker syndrome
results from entrapment of the left renal vein between the superior mesenteric artery and aorta. Downward traction on the SMA by an engorged small bowel can also compress part three of the duodenum. Symptoms include hematuria, left flank pain, nausea, vomiting, and left testicular pain in males (left pelvic pain in females).
Ureter- function
conveys urine from kidney to bladder
Ureter- structure
thick walled muscular tube with a narrow lumen (approx 25-30 cm)
Ureter- course
entire course is retroperitoneal
Descends on the surface of the psoas muscle parallel to the tips of the lumbar transverse process, crosses the pelvic brim at the bifurcation of the common iliac a., course inferomedially on the lateral pelvic wall to gain the inferior surface of the urinary bladder. In the male, the ureter passes inferior to the ductus deferens; in the female, it passes inferior to the ovarian artery.
What structures cross the ureters, respectively?
the right ureter originates behind the 2nd part of the duodenum and is crossed by the right colic and iliocolic and gonadal vessels as it descends.
The left ureter is crossed by the gonadal, left colic and sigmoid vessels and the sigmoid colon.
Ureter- arteries
upper 1/3- branches from the renal a.
middle 1/3- branches from the gonadal a.
lower 1/3- branches from the internal iliac a.
Ureter- veins
follow arterial pattern to IVC
Potential constrictions for renal calculi traversing the ureter
junction of renal pelvis and ureter
crossing the pelvic brim
junction of the ureter with the urinary bladder
Components of the renal plexus on renal artery
Sympathetic- preganglionic fibers via lesser, least and lumbar splanchnic nn. (T10-L1)
Postganglionic fibers from the aorticorenal ganglion and scattered ganglial cells located in the renal plexus
Primary innervation is vasomotor to smooth muscle of the afferent and efferent arterioles
Afferents (acute pain due to distension) travel via thoracic spinal nerves T10-12, L1
Ureter- sympathetic innervation via
via:
a. aorticorenal plexus (T10-12) (Lesser & Least Splanchnics)
b. aortic plexus (L1-2) (Lumbar splanchnics)
c. pelvic plexus via sup. & inf. hypogastric plexuses (lumbar & sacral splanchnics)
Ureter- parasympathetic innervation
from the vagus via the celiac/ aorticorenal plexus
pacemaker tissue in the wall of the renal pelvis
The autonomic role of ureteral innervation is not yet clear. However, pacemaker tissue in the wall of the renal pelvis responds to filling reflexively causing ureteric peristalsis (protection of delicate renal tissue from hydrostatic pressure of overfilling of the renal pelvis). It is thought that autonomic innervation modulates the overall peristaltic activity of the ureter.
Visceral afferents for ureteric pain travel via
spinal nerves T11-12, L1,2
Renal calculi
As renal calculi (kidney stones) descend the ureter, they distend it causing reflex smooth muscle contraction resulting in renal colic (pain and cramping sensation) that is referred sequentially from above downward, from flank or loin (mid to lower lateral back) to the inguinal region, to the scrotum/ labia. Pain may also extend to the anteromedial thigh via the reference zone of the genitofemoral n. (L1,2)
Dermatomes of referred pain from kidney and ureter
Pain from the kidney refers to the T10-12 dermatomes, while pain from the ureter most often refers to the T11-L1 dermatomes.
Hydronephrosis & calculi
When kidney stones become wedged in the ureter, the flow of urine is blocked and the kidney retains urine in the renal pelvis causing distension and pain. (hydronephrosis). If this condition is not alleviated rather quickly, the calyceal system becomes dilated and the hydrostatic pressure caused by the accumulation of urine will blunt the renal papillae, compress the renal pyramids and cortex leading to renal necrosis.
inflammation/ abscess posterior to the kidney can result in..
irritation of the iliohypogastric and ilioinguinal nn. leading to reference pain at the anterior abdominal wall in the suprapubic and inguinal region dermatomes (T12-L1)
Suprarenal (adrenal) gland structure
Paired endocrine glands located at teh superior medial aspect of each kidney
encased in renal fascia
right gland is pyramidal in shape; the left is crescentic
approximately the size of a silver dollar; less than 1 cm thick
has hilum on anterior surface
Suprarenal gland- internal aspect
cortex- secretes steroid hormones necessary for life
Medulla- functions as a post ganglionic sympathetic neuron; secretes epinephrine and norepinephrine
Suprarenal gland- arterial supply
superior suprarenal arteries- branches of the inferior phrenic a.
Middle suprarneal artery- branches directly from the aorta just proximal to the origin of the renal artery
Inferior suprarenal artery- branch of the renal artery
Note: none of the suprarenal arteries enter the gland at the hilum
Venous drainage of the suprarenal gland
Solitary large CENTRAL VEIN exits the hilum
a. on the right side, the central vein drains to the IVC
b. on the left side it drains with the infrior phrenic vein to the left renal v.
Sympathetic innervation to the adrenal medulla
preganglionic sympathetic fibers originate from splanchnic nerves T6-8-T12, L1
Fibers travel to the gland via the celiac, aorticorenal, and renal plexuses
Fibers synapse directly on chromaffin cells of the adrenal medulla.
Chromaffin cells
secrete epinephrine and norepinephrine, therefore serving as postganglionic sympathetic nerve fibers.
Sympathetic innervation to the adrenal cortex
thought to be mainly vasomotor
Parasympathetic innervation to the adrenal cortex
Vagal parasympathetic preganglionic fibers from the celiac plexus are thought to innervate the suprarenal gland.
Postganglionic PS terminals have been identified in both the cortex and medulla
Postganglionic PS fibers are though tto play a role in vasomotor control in both the cortex and medulla
Visceral afferent fibers of adrenal gland
have been demonstrated in both dorsal root ganglia of spinal cord levels T6-8-L1 and vagal nuclei in the brain.
