Abdomen 4 - Kidneys & Suprarenal glands Flashcards
what is the function of the kidneys?
regulates solute levels by filtering blood to remove waste products & concentrate them into urine with water
secretes hormones or blood pressure and solute regulation
what is the peritoneal classification of the kidneys?
retroperitoneal
at what vertebral level do the kidneys sit?
T12-L3 - in the posterior abdominal cavity
why is the right kidney lower & smaller than the left?
liver on the right side takes up lots of space
what structure is the medial border of the kidney close to?
close to the renal hilum - entry/exit point of renal neurovasculature, lymph vessels & ureter
what are the superior & inferior poles of the kidney?
upper and lower tips of the kidney
what is the order of protective coverings around the kidney, from innermost to outermost?
renal capsule
perinephric fat
renal fascia
paranephric fat
what is the renal capsule?
tough protective outer layer that directly covers the kidney’s surface
what fascia is the renal fascia continuous with?
transversalis fascia + fascia on diaphragm
(renal fascia forms collagen threads connecting it to transversalis fascia & peritoneum)
what is the clinical significance of the midline continuity of the renal fascia between kidneys?
potential spread of infection between kidneys via the renal fascia
what is the paranephric fat of the kidneys between?
between the renal fascia & peritoneum
what mainly protects the kidneys?
minimal bony protection from ribs 11-12
mainly protected by fat & fascia layers - renal capsule, perinephric fat, renal fascia & paranephric fat
what 3 muscles cover the posterior surface of the kidneys? (from medial to lateral)
psoas major
quadratus lumborum
transversus abdominis
what organ covers the anterior surface of the inferior pole of both kidneys?
small intestine (jejunum & ileum)
what covers the anterior surface of the superior pole of both kidneys?
suprarenal/adrenal glands (right and left)
from anterior to posterior/top-bottom, what is the order of appearance of the contents of the renal hilum?
renal vein
renal artery
renal ureter
(V-A-U)
what does the renal hilum give passage to?
lymphatic vessels
sympathetic fibres
renal vein
renal artery
ureter
what is the role of the sympathetic fibres entering via the renal hilum?
control blood flow by controlling vasoconstriction
more blood flow = more filtration = more urine production
how does the right renal artery pass relative to the IVC?
passes posterior to the IVC (right renal artery behind IVC)
how does the left renal vein pass relative to the SMA? what clinical condition is this linked to?
left renal vein passes under/inferior to the SMA
linked to nutcracker syndrome - compression of the renal vein by the SMA & aorta at the L1-2 boundary
what is nutcracker syndrome? what clinical consequences does this lead to?
compression of the left renal vein between the SMA & aorta at the L1-2 boundary
compression of left renal vein
- restricted left venous return
- increased blood pressure in left kidney
- leads to left kidney failure
what is the renal sinus? what does it contain?
a cavity continuous with the renal pelvis, filled with perinephric fat and containing blood vessels and nerves
what is the renal pelvis?
expanded upper part of the ureter for urine collection - all the major calyxes converge on the renal pelvis
what are the spaces in the renal pelvis filled by?
perinephric fat
what is the renal cortex? what does it contain?
pale outer band of tissue surrounding the inner renal medulla - contains glomeruli (filtration units)
what are the renal columns?
extensions of the renal cortex between the pyramids - contain glomeruli & blood vessels
what is the renal medulla composed of?
pyramids - with nephron loops (to concentrate urine) & collecting ducts (to transport urine)
renal papilla (apex of the pyramids) - collecting ducts empty urine into the minor calyxes at the renal papilla
what are renal pyramids and their role?
triangular structures in the renal medulla
they concentrate urine and transport it via collecting ducts
how does urine flow through the kidney?
collecting ducts in the medulla converge - minor calyxes - major calyxes - renal pelvis - ureter
empties into ureter via smooth muscle contractions of the calyxes
how is urine propelled through the kidney structures into the ureter?
smooth muscle contractions in the calyxes propel urine via peristalsis
what sort of innervation do the kidneys mainly have? why?
mainly sympathetic innervation - vasoconstriction controls blood flow, controlling filtration rate and thus urine production
describe the order of arterial supply of the kidneys from the renal artery
renal artery
(5) segmental arteries = one for each of the 5 segments
lobar arteries = a lobe consists of a renal pyramid & superior cortex surrounding it
interlobar arteries
arcuate arteries = arch over base of pyramid
interlobular arteries = ascend into cortex
afferent glomerular arterioles = into Bowman’s capsule
describe the order of venous drainage starting from the efferent glomerular veins of Bowman’s capsule
efferent glomerular veins from Bowman’s capsule
interlobular veins
arcuate veins
interlobar veins
multiple renal veins - converge
right/left renal vein
where are the suprarenal (adrenal) glands located?
on the superior pole of each kidney, enclosed in renal fascia
how do the shapes of the right and left adrenal glands differ?
right is pyramid-shaped
left is crescent-shaped
what are the two main parts of the suprarenal gland?
yellow cortex - derived from mesoderm
brown medulla - derived from neural crest
what does the suprarenal cortex secrete?
corticosteroids
androgens
what does the suprarenal medulla secrete?
catecholamines (adrenaline & noradrenaline)
how do the suprarenal cortex & medulla differ in what they secrete?
cortex secretes androgens & corticosteroids
medulla secretes catecholamines - e.g. adrenaline, noradrenaline
how does the adrenal medulla function similarly to the sympathetic nervous system?
acts like a sympathetic postganglionic neuron - releases adrenaline & noradrenaline into the bloodstream
why do the suprarenal glands have a highly vascularized blood supply?
to support rapid hormone production and release
what are the three arteries supplying the suprarenal glands? where do they each arise from?
superior suprarenal artery - from inferior phrenic artery
middle suprarenal artery - direct branch from aorta at T12
inferior suprarenal artery - branch of renal artery
what is the venous drainage pattern of the suprarenal glands?
right suprarenal vein drains directly into IVC
left suprarenal vein drains into left renal vein - then IVC
which suprarenal vein drains directly into the IVC?
right suprarenal vein
which suprarenal vein first drains into the left renal vein before reaching the IVC?
left suprarenal vein
which plexus innervates the suprarenal glands?
renal plexus (one of the pre-aortic plexi)
what makes the sympathetic innervation of the suprarenal glands unique?
there is no postganglionic neuron - preganglionic sympathetic fibres go directly to the adrenal medulla
what type of autonomic innervation do the adrenal gland have?
sympathetic
why is the adrenal medulla considered a neuroendocrine organ?
acts like a postganglionic sympathetic neuron - releases adrenaline & noradrenaline directly into the bloodstream
what type of neurotransmitters does the adrenal medulla secrete?
catecholamines - adrenaline & noradrenaline
what structure do the pyramids of the kidney contain?
collecting ducts
what is nephroptosis?
dropped kidneys - insufficient fusion of renal fascia layers lead to kidneys being abnormally mobile and descending
adrenal glands remain in place despite kidneys dropping due to their attachment to the diaphragm
how are the suprarenal glands attached to the diaphragm?
by diaphragmatic crura
