TBL 20 Flashcards
What else are retroperitoneal organs, like the kidneys?
the adrenal (suprarenal) glands and ureters
What is each kidney surrounded by?
Perinephric fat that extends into its hollow center called the renal sinus
What encloses the perinephric fat and the kidney, adrenal glands and ureters?
Kidney and perinephric fat are enclosed by the fibrous renal fascia that is prolonged along the ureter as the periureteric fascia
What is the renal fascia continuous with?
It is continuous superiorly with the diaphragmatic fascia.
What separates the adrenal gland and kidneys?
fascial septum
What is the primary fascial attachment of the adrenal glands?
It is to the diaphragmatic fascia and NOT the renal fascia.
Where do the kidneys lie in the body?
Due to the liver:
Right kidney: deep to 12th rib
Left kidney: deep to the 11 rib
When can vertical movement of the kidneys occur?
during respiration
changing from supine to erect positions
Why is only the right kidney palpable in lean adults and when can the left kidney be palpated?
Palpation of the right kidney is possible because it is 1-2cm inferior to the left one. The left kidney is usually not palpable unless it is enlarged or a retroperitoneal mass has displaced it inferiorly.
Why can kidneys descend when the body is erect? Do the adrenal glands descend with the kidneys?
Because the layers of the renal fascia do not fuse firmly inferiorly to offer resistance, abnormally mobile kidneys may descend more than the normal 3cm when the body is erect.
When the kidneys descend, the adrenal glands remain in place because they lie in a separate fascial compartment and are firmly attached to the diaphragm.
What is the renal pelvis?
It is the funnel shaped superior end of the ureter that lies posterior to the renal vessels at the hilium of the kidney.
What do long ureters (25-30 cm) pass over to enter the pelvis?
bifurcation of the common iliac arteries
What are three potential sites where kidney stones (aka calculli) can obstruct the ureters?
1) uteropelvic junction
2) crossing the external iliac artery and/or pelvic brim
3) ureter traverses the bladder wall
Where do renal arteries arise from? What supplies the adrenal glands?
Renal arteries arise from teh abdominal aorta is close proximity to the SMA.
Adrenal glands are supplied by small branches arising from the renal arteries and the aorta.
Where do lymph from the kidneys, ureters and adrenal glands drain into?
lumbar lymph nodes positioned bilaterally along the abdominal aorta
Where do fibers of the lesser and least splanchnic nerves synapse?
aorticorenal ganglion
What forms plexuses that surround the renal arteries?
postsynaptic sympathetic fibers
branches of the vagus nerves
What does sympathetic mediated vasoconstriction contribute to in the kidneys/ adrenal gland?
regulation of blood flow to the kidneys
fibers of the least splanchnic nerve directly enter the medulla of the adrenal glands to synapse with modified sympathetic neurons
Why are varicoceles (varicosities of the pampniform venous plexus) more common on the left side?
Venous blood from the left testicular vein must drain upward to the left renal vein before emptying into the IVC. There is a chance of backflow due to gravity, resulting in left-sided testicular varicoceles.
How is intermittent pain from nephroptosis relieved?
Symptoms of intermittent pain in the renal region , relieved by lying down, appear to result from traction on the renal vessels.
Why is the donor kidney positioned in the iliac fossa?
The site supports the transplanted kidney, so that traction is not placed on the surgically anastomosed vessels. The renal artery and vein are joined to the external iliac artery and vein, respectively, and the ureter is sutured into the urinary bladder.
Why in males, can hematuria and/or proteinuria, left flank pain, vomiting, and left testicular pain result from renal vein entrapment syndrome?
Downward traction on the SMA may compress the left renal vein resulting in renal vein entrapment syndrome. The symptoms appear in men because it is related to the left testicular vein draining into the left renal vein proximal to the compression.
What happens to the mesoderm during gastrulation?
It forms three bilateral columns– including the intermediate mesoderm.
What does the intermediate mesoderm form in the cervical region? thoracic and lumbar regions?
cervical region: rudimentary pronephros (nonfunctional excretory system that disappears)
thoracic and lumbar region: during regression of the pronephros, mesonephros and mesonephric (aka wolffian duct)
What does segmentation of the mesonephros create?
epithelium-lined excretory tubules that open into the eptihelium-lined mesonephric duct, which terminates in the cloaca.
Lengthening of the excretory tubules forms S-shaped loops that acquire a glomerulus (loop of capillaries) at their medial ends.
What forms the glomeruli that are associated with Bowman’s capsules?
Angiogenic outgrowths from the dorsal aorta form the glomeruli that become associated with Bowman’s capsules, which differentiate at the medial ends of the excretory tubules.
What constitutes the renal corpuscles?
glomeruli and Bowman’s capsules
What happens to the mesonephric excretory tubules in females? in males?
females: the mesonephric excretory tubules and all but the distal end of the mesonephric duct degenerate and disappear
males: caudal excretory tubules and the mesonephric duct persist to participate in formation of the genital system
What forms the ureteric bud?
epithelial outgrowth from the distal mesonephric duct near its entrance into the cloaca.
It grows into the metanephros which is derived from the intermediate mesoderm in the sacral region
What forms the renal pelvis? collecting tubules?
Within the metanephros, dilation of the ureteric bud forms the renal pelvis that splits into multiple calyces
epithelial outgrowths from the calyces create collecting tubules and branches of the tubules penetrate deeper into the metanephros
What makes up a nephron?
At the terminal end of each collecting tubule, the surrounding metanephros forms a nephron
Each nephron consists of an excretory tubule and its associated renal corpuscle.
What happens as the excretory tubule lengthens?
It differentiates into a distal convoluted tubule, which unites with the collecting tubule (U-shaped loop of Henle) and a proximal convoluted tubule that unites with Bowman’s capsule.
How many nephrons reside in each kidney at birth?
Nephron formation continues until birth when approximately 1 MILLION nephrons reside in each kidney.
What causes the kidneys to ascend to the lumbar region?
Remember the ureteric bud and metanephros originate in the sacral region and diminution of body curvature and lengthening of the lumbar and sacral regions cause the kidneys to ascend into the lumbar region
Why do anuria, oligohydramnios and hypoplastic lungs characterize relatively uncommon bilateral renal agenesis? Why is unilateral agenesis compatible with life?
Bilateral renal agenesis results in renal failure. The baby presents with Potter sequence.
When does a horseshoe kidney occur and is it fatal?
The kidneys are pushed so close together during their passage through the arterial fork, that the lower poles fuse, forming a horseshoe kidney. It is usually at the lower lumbar vertebrae, since its ascent is prevented by the root of IMA.
NOT FATAL?
What does the renal cortex cover?
It covers the cone-shaped pyramids (which constitute the renal medulla).
What does the coalescence of collecting tubules in the medulla form?
Large collecting ducts
In the apices of the medullary pyramids, where do the collecting ducts empty into?
funnel-shaped calyces
What happens to the renal artery after entering the hilium?
It splits into multiple parenchymal branches.
The parenchymal branches course along the corticomedillary junction.
It generates terminal branches at right-angles that penetrate into the cortex.
Cortical branches generate afferent arterioles that end in the glomeruli of the renal corpuscles.
What happens to blood in glomerular capillaries?
They drain into efferent arterioles.
Remember: if the efferent arterioles that drain glomeruli adjacent to the corticomedullary junction (aka juxtamedullary glomeruli) empty into vasa recta (recurrent capillary loops that run parallel into medullary pyramids)
That drains into peritubular capillaries. (clusters of RBCs surrounding the proximal and distal convoluted tubules).
What runs parallel to one another?
vasa recta, collecting ducts and loops of Henle.
What two things drain into tributaries of the renal vein that course adjacent to the parenchymal arteries back to the hilium?
medullary vasa recta and cortical peritubular capillaries
What are some things that are a part of renal corpuscles?
- afferent arterioles
- glomerular capillaries
- efferent arteriole
- parietal and visceral layers of Bowman’s capsule
What is the importance of looping the capillaries into glomeruli?
extensive endothelial surface area for blood filtration.
What are podocytes?
They form the visceral layer of the Bowman’s capsule and have multiple processes that terminate as pedicels to embrace the basement membrane associated with the glomerular capillary endothelium.
Why do pedicels interdigitate?
To envelope the basement membrane and filtration slits between the pedicles are bridged by slit membranes
What constitutes glomerular filtration barrier?
filtration slits
slit membranes
basement membrane
What perforates the capillary endothelium?
fenestrae (or transcellular openings).
it permits unrestricted passage of plasma proteins and fluid across the endothelium into the basement membrane.
What repels plasma proteins in the basement membrane?
anionic sites in the basement membrane.
What prevents the passage of smaller molecules?
slit membranes
What does glomerular filtrate normally include?
water, glucose and amino acids
Why are hematuria and proteinuria symptomatic of Alport syndrome?
It is an inherited progressive nephropathy. A genetic mutaiton results in abnormal type IV collagen in the glomerular basement membrane and leads to renal failure.
Patients have blood and protein in urine, because of leakage of erthrocytes and plasma proteins across the defective membrane.
What cells contribute to the filtration barrier?
Phagocytic activity of MESANGIAL CELLS interspersed between the glomerular capillary loops
What happens to glomerular filtrate?
About 180 L of glomerular filtrate cross the filtration barrier daily.
It enters the Bowman’s space, which is enclosed by the simple squamous epithelium that forms the parietal layer of Bowman’s capsule.
Bowman’s space is continuous with the lumen of the proximal convoluted tubule and 99% of filtrate is reabsorbed into peritubular capillaries and vasa recta as the filtrate moves along the nephrons, collecting tubules and collecting ducts.
Which tubule is longer? Proximal convoluted tubule or distal convoluted tubule?
Proximal convoluted tubule
What is special about proximal convoluted tubular epithelium?
greater numbers of mitochondria and surface microvilli enable tubules to actively resorb 70% of the glomerular filtrate
(filtrate then enters the bloodstream via peritubular capillaries)
Why do darker stained proximal convoluted tubules constitute more of the cortical parenchyma than the lighter stained distal convoluted tubules?
They are longer and contain more mitochondria
Why is acute necrosis of the tubular epithelium the most common cause of acute renal failure?
Acute tubular necrosis is a seirous disorder with the histologic feature of destruction of epithelial cells of proximal and distal tubules, which leads to impaired renal function.
Necrosis of epithelial cells, plus a denuded brush border, lead to tubular obstruction and increased intraluminal pressure which leads to acute renal failure.
Where do 90% of malignant kidney tumors originate and why is renal cell carcinoma fatal?
usually from proximal tubule epithelium
it has a lack of early warning signs, diverse clinical signs and resistance to treatment by radiation or chemo once metastasis has occurred.
What is each distal convoluted tubule connected to?
It contacts the afferent arteriole of its parent renal corpuscle.
The epithelial cells contacting the arteriole contain closely packed nuclei; those cells are called the MACULA DENSA.
What forms juxtaglomerular (JG) cells?
modified smooth muscle cells of the afferent arteriole
What does the macula densa do?
it moniters Na+ concentrations of the glomerular filtrate
when Na+ concentration decrease, JG cells release renin into the afferent arteriole and the circulating hormone acts by stimulating the adrenal glands
What are loops of Henle?
Loops of Henle of the juxtamedullary nephrons course deeply into medullary pyramids. The simple squamous epithelium that lines the loops of Henle is highly permeable to water and contributes to the regulation of urine toxicity.
What line the collecting ducts?
simple cuboidal epthelium
What does ADH do?
Antidiuretic hormone (ADH) is a product of the pituitary gland that increases water resorption across the epithelium for uptake by vasa recta, and thereby decreases urine volume.
Why do inhibitors of ADH produce polyuria?
ADH normally constricts blood vessels and causes the body to retain water by increasing resorption of water in the collecting ducts of the kidney nephrons. Without ADH, water is not reabsorbed.
How is the ureteric muscularis externa organized?
longitudinal and circular bundles of smooth muscle
during peristaltic contraction in response to distention, urine is delivered to the bladder
What is urothelium?
stratified epithelium restricted to the lower parts of the urinary tract (renal pelvis, ureters, urinary bladder, and urethra)
the epithelial cells near the surface of the urothelium adapt to repetitive distention and contraction of the lower parts of the urinary tract by flattening and thickening respectively.
How is back flow into the ureters prevented when the bladder is filled?
The ureters pierce the bladder wall obliquely as they enter it so their walls will be pressed together when the bladder fills with urine, which helps prevent back flow.
What forms the primitive adrenal cortex?
Adjacent to the mesonephros, proliferation of mesenchymal cells in the intermediate mesoderm forms the primitive adrenal cortex
What forms chromaffin cells? What do chromaffin cells transform into?
Ectoderm-derived neural crest cells form chromaffin cells that infiltrate the paravertebral and prevertebral sympathetic ganglia.
They migrate into the primitive cortex of the suprarenal gland and transform its central portion into the adrenal medulla.
Why are cells that synthesize and store the catecholamines designated chromaffin cells?
oxidation of epinephrine and norepinephrine by potassium chromate is called the chromaffin reaction.
it results in the chatecholamines staining a reddish brown color
What synapses with chromaffin cells of the adrenal medulla?
presynaptic fibers of the least splanchnic nerve
the synaptic activation results in secretion of norepinephrine and epinephrine into the medullary capillaries
What is the clinical consequence of a pheochromocytoma?
Pheochromocytoma is a tumor of the adrenal medulla. It is a neoplasm that arises from catecholamine-producing cells that cause elevated levels of epinephrine or norepinephrine in the blood resulting in sustained or intermittent HYPERTENSION.
What is the adrenal gland segmented into?
outer cortex
central medulla
What happens to arteries that enter the adrenal gland?
1) directly supply the cortical capillaries
2) traverse the cortex to directly supply the medullary capillaries
Where does the venous system of the adrenal gland lie?
medulla; the medulla has a dual arterial supply
How does the dual arterial supply of the adrenal medulla contribute to the fight or flight response?
HELP
What does the essential adrenal cortex consist of?
thin zona glomerulosa beneath the capsule
thick zona fasciculata
thin zona reticularis adjacent to the medulla
What does renin stimulate the cells of the zona glomerulosa to do?
Stimulates it to release aldosterone into the cortical capillaries and after ciruclating the kidneys, aldosterone elevates Na+ resorption across epithelia of the distal convoluted tubules and collecting ducts.
Resorbed ions subsequently elevate Na+ concentration in the blood (renin is secreted in response to decreased Na+ concentration in the glomerular filtrate)
What does the zona fasciculata release?
cortisol into the blood stream and after circulating to the liver, cortisol stimulates the hepatocytes to synthesize glucose that is both stored as glycogen and released into circulation
What does the zona reticularis do?
It synthesizes weak androgens that can be converted to testosterone and estrogen in peripheral tissues
What occupies the central part of the posterior abdominal wall?
five lumbar vertebrae which provide proximal attachments for the psoas major muscle
associated IV discs
What forms the iliopsoas muscle?
the ilacus and the psoas major muscle
it is the chief flexor of the thigh
What forms the muscular posterior abdominal wall?
superior: diaphragm
central: transverse abdominis
inferior: quadratus
What lines the posterior abdominal wall?
endoabdominal fascia named by the muscles it covers : transversilis, psoas, diaphragmatic fasciae
Which abdominal organs when inflamed would elicit a postive psoas test and how is the test administered?
abdominal test: kidneys, ureters, cecum, appendix, sigmoid colon, pancreas, lumbar lymph nodes, nerves of the posterior abdominal wall
iliopsoas test: person is asked to lie on the unaffected side and extend the thigh on the affected side against resistance of the examiners hand. Positive = elicitation of pain
What are hiccups and how is their characteristic sound produced?
They are involuntary, spasmodic contractions of the diaphragm causing sudden inhalations that are rapidly interrupted by spasmodic closure of the glottis that checks the inflow of air and produces the characteristic sounds.
What nerves course inferolaterally on the anterior surface of the muscular portion of the posterior abdominal wall?
subcostal (t12)
iliohypogastric and ilioinguinal (L1)
these nerves supply skeletal muscles and skin of the inguinal and hypogastric regions
What does the genitofemoral nerve do?
it pierces the psoas muscle and supplies the cremaster muscle. it is sensory to the proximal thigh
What do the ilioinguinal nerve do? femoral nerve? obturator?
ilioinguinal: somatic sensory fibers to superomedial thigh
femoral: somatic innervation to the anterior thigh
obturator: somatic innervation to the medial thigh
Why can pain from ureteric calculi extend from the hypogastric region into the proximal anterior thigh?
Calculi are composed of salts of inorganic/organic acids that can form in the calices of the kidneys, ureters or urinary bladder.
The pain is referred to the cutaneous areas innervated by spinal cord segments and sensory ganglia, which also receive visceral afferents from the ureter.
GENITOFEMORAL NERVE (L1,L2)
Why does rupture of an aortic anuerysm cause severe abdominal or back pain?
It irritates the parietal peritoneum which is innervated by somatic sensory nerves from the back.
Compare the drainage fields of the left and right renal veins.
Left renal vein: receives from the left suprarenal, left gonadal and communicated with the ascending lumbar vein
Right renal vein: none of the above
