Anatomy: Urinary System Flashcards
Identify the main functions of the urinary system.
- Regulation of fluid balance
- Regulation of electrolyte concentration
- Production of renin
- Removal of end-products of protein metabolism and drug metabolism
- Re-absorption of glucose and amino acid
- Stabilization of blood pH
- Production of erythropoietin
- Vitamin D metabolism
Describe the anatomical location of the kidney.
- Retroperitoneal
- On the posterior abdominal wall, below the diaphragm
- Kept in place by the renal vessels and renal fascia
- Between upper borders of T12 and L3 vertebrae
- Deep to last 2 ribs
Describe the location of the R kidney relative to the L. Also describe the movement of both kidneys with deep inspiration.
Right kidney is 1 cm inferior due
to liver
May descend 1-2 cm with deep inspiration
Identify the layers which encapsulate the kidney.
From inside out:
- Fibrous capsule
- Perirenal (perinephric) fat
• Fills renal sinus as well - Renal fascia
• Covers suprarenal gland as well - Pararenal fat
Identify the main components of the kidney.
1) Renal cortex
2) Renal medulla
• Renal pyramids: x8-10
• Renal papilla: Project into minor calyx
• Renal columns of Bertin: Extensions of the cortex around pyramids
3) Renal sinus, filled with perirenal fat
4) Hilum (A to P: VAAAPA)
• Renal vein
• Renal arteries
• Renal pelvis
Identify the main differences between the renal cortex and medulla.
1) Renal cortex
• Outer
• Made up of nephrons + Numerous capillaries
2) Renal medulla
• Inner
• Contains collecting tubules + Arteries and veins
What are the main functions of nephrons ?
Ultrafiltration and re-absorption
What is the functional unit of the kidney ? What are the main components of this unit ?
Nephron
• Renal corpuscle
- Glomerulus
- Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henlé
- Distal convoluted tubule
- Collecting duct
What are the main functions of the nephron ?
Ultrafiltration and re-absorption
Describe the components of the juxtaglomurular apparatus, and its function.
Components of the juxtaglomerular apparatus: Distal convoluted tubule and the glomerular afferent arteriole
Function: Regulate blood pressure and the filtration rate of the glomerulus.
Describe the response of the juxtaglomerular apparatus to elevated sodium.
The macula densa is a collection of specialized epithelial cells in the distal convoluted tubule that detect sodium concentration of the fluid in the tubule. In response to elevated sodium, the macula densa cells trigger contraction of the afferent arteriole, reducing flow of blood to the glomerulus and the glomerular filtration rate. The juxtaglomerular cells, derived from smooth muscle cells, of the afferent arteriole secrete renin when blood pressure in the arteriole falls. Renin increases blood pressure via the renin-angiotensin-aldosterone system.
Describe the main anatomical relations of the kidney.
- The upper pole of the kidney is covered by the suprarenal gland.
- Anteriorly, the right kidney is related to the liver, duodenum, ascending colon or right colic flexure, and small intestine. The left is related to the spleen, stomach, pancreas, descending colon or left colic flexure, and small intestine.
- Posteriorly, the kidneys are related to rib 12 and the diaphragm, psoas major, quadratus lumborum, and transversus abdominis
-The upper part of the kidney is usually separated by the diaphragm from the pleura and lung. In the vertebrocostal trigone, however, the kidney and pleura may be separated only by connective tissue
Distinguish between the main structures on slide 13 of lecture slides.
Refer to lecture slide 13.
Describe the path of renal arteries.
From abdominal aorta (at L1/2)
Posterior to renal veins
Divide at hilum
Where do renal veins drain ?
IVC
Define nutcracker syndrome.
“Vascular compression disorder and refers to the compression of the left renal vein between the superior mesenteric artery (SMA) and aorta. This can lead to renal venous hypertension, resulting in rupture of thin-walled veins into the collecting system with resultant hematuria.”
What is the arterial supply of the kidneys ?
Renal arteries, from the abdominal aorta
What is the veinous supply of the kidneys ?
Renal veins, into IVC
Describe the main divisions of the renal arteries.
• Each renal artery usually divides into 5 segmental arteries that enter the kidney at its hilum
• Lobar arteries arise from each segmental artery (1 for each renal pyramid)
• Before entering the renal substance, each lobar artery gives off 2 or 3
interlobar arteries
• The interlobar arteries run towards the cortex on each side of the pyramids
• At the junction of the cortex & medulla the interlobar arteries give off the arcuate arteries that arch over the bases of the pyramids
• The arcuate arteries give off several interlobular arteries that ascend in the cortex
• The afferent glomerular arterioles (that give blood directly into the renal corpuscle) arise as branches of the interlobular arteries
Describe the lymphatic drainage of the kidneys.
Lymph drainage to lateral aortic (lumbar) lymph nodes
Describe the nerve supply of the kidneys, including where referred pain takes place and any associated symptoms with this pain.
- Sympathetics from T11-L1
- Referred pain to the back & lumbar region (costovertebral angle) as well as loin to groin
- Afferents in the vagus nerve (CN X) may cause the nausea and vomiting associated with such pain
Define glomerular filtrate.
The fluid that passes from the blood through the capillary walls of the glomeruli of the kidney
Describe the path of the filtrate.
1) The filtrate coming from the collecting tubules empty through the renal papillae into minor calyces
2) Minor calyces empty, in turn, into two or three major calyces
3) Renal pelvis is the upper dilated portion of the ureter where major calyces empty into
4) Renal pelvis fills most of the renal sinus and continues as the ureter
5) Ureter empties into bladder
6) Urethra
State the dimensions (width, length) of ureters.
- 25-30 cm long
- 1-10 mm wide
- Right ureter is 1 cm shorter than left
Define ureter.
Muscular tube that transports urine from kidney to bladder
Describe the anatomical path of ureters.
- Commence at the hilum
• Abdominal course:
- Anterior to psoas major and branches of the lumbar plexus
- Cross the common iliac artery or its bifurcation
• Pelvic course (in males):
- Cross the umbilical artery, obturator vessels and nerve
- Cross the ductus deferens
• Pelvic course (in females):
- Cross the umbilical artery, obturator vessels and nerve
- Form the posterior border of ovarian fossa
- Crossed by uterine artery near cervix
Are ureters retro, intra or secondary retroperitoneal ? The bladder ?
Ureters are retroperitoneal
Bladder is retroperitoneal
Describe any mechanism preventing urine from returning to the ureter from the urinary bladder.
♦ The ureters pass through the bladder wall obliquely (intramural ureter) creating a flap valve
− Pressure of urine in the full bladder force the “valve” to close
− prevents urine returning into the ureter (ureteric reflux)
Identify the main constrictions of the ureters. What is their significance ?
- At renal pelvis-ureter junction
- When it crosses the iliac vessels at the pelvic inlet
- When it passes through the bladder wall
Significant because if calculus, likely to lodge in one of these.
How wide are the ureter constrictions ?
1-10 mm wide
Identify the arterial supply and veinous drainage of ureters.
- Multiple sources of arterial blood (incl. renal arteries, gonadal arteries, abdominal aorta), with longitudinal anastomosis
- Veins form a network around the ureter, mirror the arteries
Identify the lymphatic drainage and nerve supply of ureters.
LYMPHATICS
Lymphatics drain to lateral aortic (lumbar), common and internal iliac lymph nodes
NERVE SUPPLY
Sympathetics from T10-L1, parasympathetics from S2-4 (from aortic, renal and pelvic plexuses)
Where does pain to ureters refer ?
Referred pain is mainly to loin, groin and scrotum or labia
Where are ureters usually located relative to transverse processes of vertebrae ?
Ureters are anterior to transverse processes of vertebrae
State what IVP/IVU stands for in the context of imaging, and define it.
Intravenous Pyelogram/Urography, an x-ray of the renal pelvises and the urinary tract made with a radiopaque contrast medium that is injected intravenously and excreted by the kidneys.
What is a normal course of the radiopaque agent in an IVP/IVU ? What is a possible abnormality ?
Contrast medium will be drained by the kidneys, filtrated, into collecting tubes, minor/major calyces, renal pelvic, ureters, urinary bladder.
Blockages or enlargements
What is the function of the bladder ?
Temporary urine reservoir
How much urine can the bladder hold ?
300-600 mL (max ~1 L)
Describe the anatomical position of the urinary bladder.
♦ Retroperitoneal
♦ Rests on the pelvic floor
− Neck is held in position by puboprostatic ligament in males and the pubovesical ligament in females
♦ Posterior to the pubis when empty (in adults)
− Descends to true pelvis after ~6 yr of age
− Rises above pubis when full
Is the position and shape of the urinary bladder fixed, or variable ?
Shape and position variable
What are the main anatomical parts of the bladder ?
- Apex (median umbilical fold extends from it to the umbilicus)
- Fundus (posteriorly)
- Body
- Neck
Describe the anatomical relations of the urinary bladder, in males and females.
MALES
- Between fundus and rectum in males are rectovesical septum [fascia], seminal vesicle and ampulla of ductus deferens
- Recto-vesical pouch (pocket that lies between the rectum and the urinary bladder)
- Retropubic (prevesical) space of Retzius (between the pubic symphysis and the urinary bladder)
FEMALES
- Related posteriorly to vagina and cervix
- Related superiorly to body of the uterus
- Vesico-uterine pouch
- Retropubic (prevesical) space
Identify the main components of the walls of the urinary bladder.
Walls composed of 3 layers of smooth muscle (detrusor muscle) + mucosa
Toward the neck of the male bladder, middle layer of muscle condenses and forms the internal urethral sphincter
Describe the function of the internal urethral sphincter.
Involuntary, contracts during ejaculation
to prevent passage of semen into the bladder.
What feature of the urinary bladder permit its distention ?
Folds of the mucosa can be seen when the urinary bladder is empty
− Permit distension of bladder
Define the trigone of the bladder.
Trigone of the bladder is the ~triangular area on the mucosa. Contains:
− (2) openings of the ureters
− Urethral opening
Identify the main parts of the urethra in the male. State any specificity to each of these.
1) Pre-prostatic (intramural) urethra
− surrounded by involuntary internal urethral sphincter
2) Prostatic urethra
3) Membranous urethra
− surrounded by voluntary external urethral sphincter
4) Spongy urethra
− Openings of the ducts of mucus-secreting urethral glands (glands of Littré), which “contribute mucus to the seminal fluid”
What is the average urethral length in males ? females ?
Males: 20 cm long and “10.5 mm wide”
Females: 4cm long and 6mm wide
Identify any sphincters presents in or around the female urethra.
Internal urethral sphincter (bladder neck & proximal urethra) that is functional & not a distinct anatomical feature
External urethral sphincter of striated muscle (voluntary) at distal urethra
Identify any anatomical relations of the female urethra.
Related to the anterior vaginal wall
Where does the female urethra open ?
Opens in vulva (external female genitalia) between vagina and the clitoris
Identify any glands present in or around the female urethra.
The ducts of the para-urethral glands (Skene’s glands) open on each side of the lateral margins of the urethra.
Describe the arterial supply of the bladder and urethra.
- Branches of internal iliac artery (superior & inferior vesical, middle rectal)
- Branches from arteries to adjacent structures (e.g. vaginal)
- Internal pudendal
Describe the veinous drainage of the bladder and urethra.
- Vesical (and prostatic) plexuses converging on internal iliac veins
- Internal pudendal
From the prostate there are valveless venous communications (Batson venous plexus) with the internal vertebral venous plexus that may facilitate tumour spread
Describe the lymphatic drainage of the bladder and urethra.
Internal and external iliac nodes
Describe the nerve supply of the bladder and urethra.
From inferior hypogastric (pelvic) plexus:
♦ Parasympathetics from S2-4 via pelvic
splanchnic nerves
• Contract detrusor muscle
• Relax internal urethral sphincter in males
♦ Sympathetics from T11-L2
• Contract internal urethral sphincter in
males
♦ Somatic motor from pudendal nerve (S2-4 and its branches
• Controls external urethral sphincter
Describe the main muscle actions required for the storage phase of micturition, and the NS innervation required for these.
STORAGE PHASE
1) Parasympathetic supply to detrusor muscle “switched off” in spinal cord to allow bladder to relax and fill
2) When the volume of urine reaches ~400-500ml
• Stretch receptors are activated
• Pain in lower abdomen and perineum
3) Afferents to the S2-4 spinal cord (Reflex micturition centre) → “M” Centre in pons →
Inhibition is lifted → Preganglionic, parasympathetic neurones at S2-4 are stimulated → Preganglionic fibres synapse with postganglionic fibres
Describe the main muscle actions required for the voiding phase of micturition, and the NS innervation required for these.
1) Contraction of detrusor muscle by parasympathetics
2) Relaxation of external urethral sphincter by pudendal nerve (S2-4)
3) Contraction of abdominal wall
4) Sensation of urine in urethra maintains the reflex
How does urine move in the ureter ?
Peristaltic waves propel urine down the ureter (hence the colicky pain of ureteric calculi)
What kind of epithelium is present in the urinary tract ? Why is this significant ?
The epithelial lining is transitional epithelium or urothelium that is urine-proof and allows distension
What portions of the NS control detrusor muscle ?
The detrusor muscle is smooth and involuntary controlled by the autonomic and particularly the parasympathetic system
Is the external urethral sphincter smooth or striated ? voluntary or involuntary ?
External urethral sphincter around the distal urethra is striated & under voluntary control
