What is contained within the Urinary system?
Kidneys, ureters, urinary bladder, urethra
What are the Ureters?
Muscular tubes transporting urine from kidneys to the bladder; continuous with the renal pelvis - formed by the condensation of 2/3 major calices
What is the Uteropelvic Junction?
Narrowing of the renal pelvis where it becomes continuous with the ureter
What is the course of the Ureters?
Descend retroperitoneally on the medial aspect of Psoas major to the pelvic brim, where they cross the common iliac/proximal end of the external iliac artery to enter the pelvic cavity and enter the bladder (at the level of the ischial spine)
What are the 3 constrictions for the Urinary system?
Ureteropelvic junction Point of crossing the common iliac vessels at the pelvic brim Entrance to the bladder
How is the Renal system innovated?
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)
Where is the bladder?
Most anterior element of the pelvic viscera; triangular pyramid with the apex pointing anteriorly
Describe the lining of the bladder:
Lined by the urothelium (3-layered membrane with slow cell turnover and large, impermeable luminal cells)
What is the Apex of the bladder?
Directed towards the top of the pubic symphysis and attached to the umbilicus via the medial umbilical ligament
Describe the base of the bladder:
Inverted triangle and points posteriorly; ureters enter at upper corners, with the urethra draining inferiorly from the lower corner of the base
What does the bladder look like?
What is the Trigone?
Smooth area between openings of ureters and urethra
Describe the neck of the bladder:
Anchored in position by tough fibromuscular bands, connecting neck/pelvic part of the urethra to the posteroinferior aspect of each pubic bone
What is the difference in the necks of the bladder in men and women?
- Women: pubovesical ligaments - supported by peritoneum and associated muscles
- Men: puboprostatic ligaments - blend with fibrous capsule of the prostate which surrounds the neck of the bladder
What is the bladder reflex?
(Including motor innovation)
Bladder filling activates sensory PSNS stretch fibres, leading to S2-4 motor neurones to signal detrusor muscle to cause contraction and open internal sphincter
Describe the lymphatics of the bladder:
Iliac nodes; with ureter drain to para-aortic nodes
What are the two Urinary Sphincters?
Two are present - s. urethrae and s. Vesicae - needed to maintain urinary continence
What is the Sphincter vesicae?
Internal smooth muscle sphincter at the neck of the bladder that opens reflexively in response to bladder wall tension - relaxed by PSNS and contracts due to SNS
What is the sphincter urethrae?
External striated muscle sphincter in the perineum, whose tone is maintained by somatic nerves in the pudendal nerve (S2-4), opened by voluntary nervous inhibition
Describe the Urethra of a female:
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 of a male:
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)
Describe a diagram of the bladder and vagina:
Describe a diagram of the bladder and penis:
What is above each kidney?
Diaphragm for Right
Spleen for left
Which kidney is higher, and what are the surface landmarks of each kidney and the hilum?
Left is higher
Apex of left is 11th rib, apex of right is 11th ICS
Hilum = L1
What are the anterior relations of each kidney?
Right: liver, hepatic flexure
Left:stomach, pancreas, spleen and splenic flexure
What is the hilum of the kidney?
Deep vertical slit through which the renal vessels, lymphatics and nerves enter/leave (continuous internally with the renal sinus)
What is the renal cortex?
Outer layer of the kidney - continuous band of place tissue, with projections called renal columns into the inner aspect to divide the medulla to discontinuous aggregations[Granular]
What is the Renal medulla?
Pyramid shaped regions of the kidneys where nephrons are present[Striated]
What are the minor calicies?
Apical projections of the renal pyramids
What is the major Calyx?
Unity of several minor calices - multiple major calices unite to form the renal pelvis
Describe the renal arteries:
Lateral branches of the abdominal aorta that supply each kidney; arise inferior of the SMA origin at L2/3, with the left renal artery shorter and higher
Branches on entering the kidney to form interlobar arteries within the columns, which then form acruate arteries that anastomose with their neighbours to supply the nephrons
Describe the vasculature at the hilum:
The renal arteries divide to anterior and posterior branches to supply the parenchyma
Describe the renal veins:
Are formed by multiple smaller veins, and run anterior to the arteries; left renal vein crosses anterior to aorta but posterior to the SMA, and can be compressed by aneurysms in either vessel
Describe the afferent arterioles:
Have a high pressure due to proximity to aorta, and are larger than efferents to generate a pressure gradient
Describe the renal corpuscle:
Glomerulus of capillaries forms, surrounded by the Bowman's capsule; filtration is provided by:
Fenestrations in the capillary endothelium
Specialised basal lamina
Filtration slits of the podocytes that restrict passage of ions/molecules <50k mw
Describe the PCT:
Reabsorbs ions, glucose, amino acids, proteins and water; has a cuboidal epithelium sealed with tight junctions and a brush border to maximise the surface area
Describe the Loop of Henle:
Descending limb has a simple squamous epithelium to allow for passive osmotic equilibration, while ascending limb has a thicker lining to actively pump out sodium ions whilst being impermeable to water, hence creating a concentrated tubular solution; supplied by the vasa recta
Describe the DCT:
Have no brush border but adjusts sodium, potassium, hydrogen and ammonium ion concentration in urine using a cuboidal epithelium with few microvilli (ions controlled by aldosterone and osmosis by vasopressin)
Describe the Collect ducts:
Passes through medulla, excreting to renal pelvis; reabsorbs water in response to ADH, which controls [AQP2] on the apical surface
Describe the efferent arterioles:
Smaller diameter than the afferents to increase the pressure in the glomerulus and generate a pressure gradient