The kidney and urinary tract Flashcards
What does the urinary tract consist of
Kidneys
Ureters
Urinary bladder
Urethra
Where does the kidney lie
Retroperitoneal in upper abdomen
They lie on the posterior abdominal wall
What surrounds the kidney
Surrounded by dense fibrous capsule
Outside the capsule is a fascial pouch (renal fascia) containing the peri-renal adipose tissue
Paranephric fat may be found outside the renal fascia
the fat allows the kidneys to move
Describe the differences between the right and left kidney
Right kidney is usually slightly lower than the left
Superior pole of the R kidney lies at the level of the 11th intercostal space and that of the L at the 11th rib
Hilum lies at about the level of L1 (R & L)
L1 is a large vertebrae- this is why they have their hilum at the same vertebral level
What are the kidneys overlapped by postero-superiorly
Overlapped postero-superiorly by the diaphragm and pleural cavity
The diaphragm intervenes between the kidneys and ribs
Describe the renal fascia
At the lateral margins of each kidney, the anterior and posterior layers of the renal fascia may fuse and connect with the transversalis fascia
Medially, and anteriorly, the fascia continues over the vessels in the hilum and fuses with the connective tissue associated with the abdominal aorta and IVC, in some cases it may continue to the other side and fuse with its companion layer
Posteriorly and medially, passes through the fascia surrounding the quadratus lumborum, and fuses with the fascia containing the psoas major
Inferiorly, both the anterior and posterior fascia fuse to enclose the ureters.
Where does the paranephric fat accumulate
Posteriorly and postero-laterally
Describe the posterior relations of the kidneys
The superior part of each kidney is related to the diaphragm which intervenes between ribs 11 and 12.
Laterally, the kidney is related to the transversus abdominis muscle
more medially, the quadratus lumborum muscle
more medially, the psoas major muscle
Also posteriorly related to the subcostal nerves (and some intercostals), iliohypogastric and ilio-inguinal nerves
Which nerves supply the kidney
The nerves (posterior) that supply the kidneys include: Relate to below.
o 11th intercostal and sub-costal nerves.
o Iliohypogastric nerve.
o Ilioinguinal nerve.
From renal, aortic, superior hypogastric, and inferior hypogastric plexuses
Describe the anterior relations of the right kidney
Liver (huge part of upper surface of kidney- separated from liver by a layer of peritoneum)
Medially- the desencing part of the duodenum ( region 2) is retro-peritoneal and contacts the kidney (hilus behind the duodenum)
Hepatic flexure
Describe the anterior relations of the left kidney
Superior pole- covered by intraperitoneal stomach and spleen
Moving inferiorly, the retroperitoneal part of the pancreas covers the middle part of the kidney
Also related to splenic flexure
What is meant by the flexures
Hepatic- ascending becomes transverse
Splenic- transverse to descending
Why do the flexures exist
Corners of colon attached to the posterior abdominal wall- giving an M- SHAPE of large intestine
Summarise the blood supply to the kidney
Abundant blood supply via renal arteries - short direct branches from abdominal aorta
Blood pressure drives ultrafiltration by glomerular capillaries
Renal veins drain into the IVC
renal arteries need to be short to keep the blood at high pressure for ultrafiltration
Describe the difference between the right and left renal arteries
The left renal artery usually arises from the abdominal aorta a little higher than the right
Right renal artery is longer ( aorta is to the left of the midline) and passes posteriorly to the IVC
Describe the difference between the right and left renal veins
The IVC usually lies to the right of the midline
Left renal vein is longer and passes in front of aorta underneath the superior mesenteric artery
Where do the renal arteries arise from
Just inferior to the origin of the superior mesenteric artery
What is a consequence of the passage of the left renal vein
Aneurysms ( in SMA or aorta) can occlude flow from the left kidney into the IVC
What happens to the renal arteries at the hilum
the renal arteries divide to anterior and posterior branches to supply the parenchyma
Describe the gonadal arteries
Arise at the same place in both sexes
Arise below the renal arteries
As gonads develop in the abdominal cavity- they descend (further in males)- dragging their blood supply with them
What does the celiac trunk supply
the foregut
Describe the differences in the drainages of the gonadal veins
right- drains into IVC
left- drains into renal vein which then drains into IVC
Where does blood from the gut drain into
The portal vein- goes to liver first
Describe the hilus
Anteriorly veins
Arteries
ureter
Describe the development of the kidneys
Develop as functionally distinct lobes- which coalesce into one structure
each pyramid is therefore a developmental lobule of the kidney
Sometimes- the pyramids fail to coalesce- and so it is quite common to see distinct arteries and veins
Summarise the structure of the kidney
Cortex granular-looking because of random organisation (glomerulus)
Medulla striated because of radial arrangement of tubules (loop of Henlé) and micro-vessels
Human kidney is multilobar – like a lot of simple kidneys stuck together
Each lobe drains through its own papilla and calyx
Describe the renal columns
Each kidney consist of an outer renal cortex and an inner renal medulla
Extensions of the renal cortex (renal columns) project into the inner aspect of the kidney, dividing the renal medulla into the renal pyramids.
Describe the renal pyramids
The bases of the renal pyramids are directed outwards towards the renal cortex, while the apex projects inwards towards the renal sinus
the apical projection is surrounded by a minor calyx
Describe the minor calyx
The minor calices receive urine and represent the proximal parts of the tube that will eventually form the ureter.
In the renal sinus, several minor calices join to form the major calyx- and 2 or 3 of these unite to form the funnel shaped end of the renal pelvis- which is the funnel-shaped superior end of the ureters.
What forms the glomerulus
renal arteries supplying each pyramid curve around the base and become arcuate arteries, where they anastomose with the branch curving around the same pyramid- glomerulus found here.
Summarise the ureters
Run vertically down posterior abdominal wall in the vertical plane of the tips of the transverse processes of the lumbar vertebrae
Cross the pelvic brim anterior to the sacro-iliac joint & bifurcation of the common iliac arteries
Descend anteromedially to enter bladder at the level of the ischial spine
Describe the passage of the ureters
Renal pelvis forms ureters at uretero-pelvic junction
Ureters descend retroperitoneally on the medial aspect of the psoas major muscle
At the pelvic brim the ureters cross either cross the end of the common iliac artery of the beginning of the external iliac artery, enter the pelvic cavity and continue their journey into the bladder (move anteriorly and medially in bladder)
Describe the blood supply of the ureters
Takes blood supply from every major blood vessel that it passes
o A renal arterial branch.
o A testicular or ovarian arterial branch.
o Small direct braches of the aorta itself.
o External and internal iliac arterial branches
Where are the sits of constrictions of the ureters
3 sites of ureteric constriction:
1. pelviureteric junction
2. where ureter crosses pelvic brim
3. where ureter traverses bladder wall
Constrictions are sites of renal colic caused by kidney stones attempting to pass
Kidney stones lodge in these constrictions- as the upper muscle contracts- makes the pain worse
How is urine transported by the ureter and how does the ureter enter the bladder
Urine transported by peristalsis of their smooth muscle walls
Open obliquely through bladder wall
Describe the epithelium of the ureter
Transitional epithelium Individual cells slide over each other- looks stratified squamous- but when stretch they separate out and become simple squamous Tight junctions- impermeable to urine circular muscle- peristalsis more sparse striated muscle
Summarise the bladder
Pelvic organ
Triangular pyramid with apex pointing anteriorly and base posteriorly
Lined by urothelium (transitional epithelium)
3-layered epithelium with very slow cell turnover
Large luminal cells have highly specialised low-permeability luminal membrane
Prevents dissipation of urine-plasma gradients
if you pass a stone without help, where will you experience pain
All 3 sites of constrictions
What happens when the bladder is full
Rises into the abdomen
As ureter runs obliquely in, as the bladder swells (due to corrugated internal membrane), the ureters are pushed back and function as a self-shutting valve.
Ureters enter at supero-posterior angles
Describe the structure of the bladder
Apex: directed towards the top of the pubic symphysis and attached to the umbilicus via the medial umbilical ligament
Base: inverted triangle and points posteriorly; ureters enter at upper corners, with the urethra draining inferiorly from the lower corner of the base
Interior: mucosal lining is smooth and firmly attached to underlying tissue
Trigone: smooth area between openings of ureters and urethra
Inferolateral surfaces: cradled by pelvic muscles
What is special about the trigone
smooth- tightly adherent to the layers below- where bladder cancers are most likely to arise
What happens to the superior surface of the bladder when it is full
slightly domed when empty
balloons upwards as the bladder fills and pushes visceral peritoneum backwards- allowing us to insert a catheter
What is the role of the pubovesical ligament
Hold the urethra in place in females
What is the role of the puboprosatic ligament
Holds the prostate in place (urethra passes through prostate)
urethra has to pass through perineal membrane- fixed structure
Describe the difference between males and females
Women have 2 holes in the inferior peritoneum (vagina and ureter) while men have 1 (and a prostate).
Describe the Sphincter vesicae (internal sphincter – smooth muscle)
At neck of bladder Reflex opening In response to bladder wall tension Relaxed by parasympathetic NS Contracts by sympathetic NS
Describe the Sphincter urethrae (external sphincter – striated muscle)
In perineum
Tone maintained by somatic nerves in pudendal nerve (S2, 3, 4)
Opened by voluntary inhibition of nerves
in terms of the sphincters, what is different between males and females
§ In women, these sphincters are VERY close.
§ In men, these sphincters are further apart.
Describe voluntary control of the external sphincter
Stretch receptors in bladder wall relay information to the spinal cord- which inhibits the motor neurone to the external sphincter- causing it to relax- babies and people with incontinence
However, cerebral cortex can learn to override this inhibition and keep the motor neurone stimulated to keep external sphincter closed
Describe reflex control of the internal sphincter
Bladder fills stretch receptor activated PSN stimulated Bladder contracts internal sphincter opens
Describe the urethra
different in each sex, beginning at the base of the bladder and ending with an external opening in the perineum
Describe the urethra in women
short urethra, travelling inferiorly through the pelvic floor and deep perineal pouch/membrane to open into the vestibule between the labia minora; small Skene’s (mucous) glands associated with lower end
Describe the urethra in men
longer urethra, passes inferiorly through the prostate, through the deep perineal pouch and perineal membrane and enter the root of the penis (divided to preprostatic, prostatic, membranous and spongy parts)
Why are women more at risk of STIs and bladder infections (cystitis)
urethra is shorter in women
warm, moist environment of vestibule
Describe the lymphatics of the urethra
Follows the arterial supply Common iliac nodes roots of gonadal artery nodes inferior/superior mesenteric nodes these are called paraaortic nodes
List the parts of the male urethra
Internal urethral orifice Bladder neck, Bladder outlet Prostatic urethra Membranous urethra Bulbar urethra Penile urethra Navicular Fossa External urethral meatus
Hard to pass catheter through as two bends
1st bend once it leaves the deep perineal pouch to course anteriorly in the root of the penis
when flaccid- the penis makes another bend, this time passing inferiorly when passing from the root to the body of the penis
Describe the innervation of the kidney
renal, aortic and sup/inferior hypogastric plexuses all innervate (visceral efferents from both SNS and PSNS sources - visceral afferents return to T11-L2 leading to referred pain at their dermatomes - e.g. Posterolateral abdominal wall pain)
Describe the lymphatics of the kidney
lateral aortic (lumbar) nodes at the origins of the renal arteries
