The Urinary System

Question 1

What are the main functions of the urinary system?

Answer 1

• Stabilization of blood pH,
• Regulates fluid balance,
• Regulates electrolyte balance,
• Blood pressure control,
• Metabolism of toxic waste products and drugs,
• Stimulates RBC production,
• Required for absorption of calcium

Question 2

Describe the epithelium of the urinary system

Answer 2

• The ureter and upper urethra are lined by urothelium which are capable of stretching.
• Distal urethra is lined by a protective stratified squamous epithelium.

Question 3

Where are the locations of the kidneys?

Answer 3

• Retroperitoneum.
• Left Kidney is found in the left hypochondrium, epigastric, left lumbar and umbilical.
• Right kidney is found in right hypochondriac, epigastric, right lumbar and umbilical.

Question 4

Explain the layers of tissue that surround the kidneys

Answer 4

Renal capsule, perinephric fact, renal fascia, paranephric fat, parietal peritoneum and the anterolateral abdominal wall muscles

Question 5

Explain the structure of the kidneys

Answer 5

It consists of an outer cortex and an inner medulla (renal pyramids and renal columns which are extensions of the cortex around pyramids) The apex of the pyramids (renal papillae) empty into the minor calyces which empty into major calyces, these then empty into the renal pelvis which continues as the ureter

Question 6

Describe the structure of a nephron

Answer 6

• Renal corpuscle (bowmen’s capsule and glomerulus) - RC,
• Proximal convoluted tubule (RC)
• Loop of henle (RM)
• Distal convoluted tubule (RC)
• Collecting duct (RM)

Question 7

What is Nutcracker syndrome?

Answer 7

Compression of the left renal vein by the SMA. In males this results in varicocele in left spermatic cord

Question 8

Name the branches of the renal artery

Answer 8

• Segmental artery,
• Interlobar artery,
• Arcuate artery (anastomosis between interlobar arteries),
• Interlobular artery,
• Afferent arterioles then to glomerulus.

Question 9

Explain the abdominal path of the ureter

Answer 9

In passes anterior to psoaj major and the branches of the lumbar plexus. It has a close relationship to gonadal vessels and crosses common iliac artery at its bifercation

Question 10

Explain the pelvic cource of the ureter

Answer 10

Females - Crosses umbilical artery, obturator neurovascular. Forms the posterior boarder of ovarian fossa. Crossed superiorly by uterine artery.
Males - Crosses umbilical artery, obturator neurovascular. Cross the ductus deferences

Question 11

Explain features of intramural ureter

Answer 11

It passes into the bladder obliquely creating a valve flap. The pressure of urine in the full bladder forces the valve closed which prevents ureteric reflux

Question 12

name the three ureteric constrictions

Answer 12

1) Pelvi-ureteric junction,
2) Ureter crossing the iliac vessels at the pelvic inlet,
3) Uretic orifice as it passes through the bladder wall

Question 13

Explain the innervation of the ureter

Answer 13

• Nerve supply is derived from the renal, abdominal aortic and superior hypogastric plexuses.
• Visceral afferent fibres to T11 to L2 so referred pain is mainly to loin, groin and scrotum/labia. Afferents in vagus can cause N/V

Question 14

Describe the blood supply to the ureter

Answer 14

It receives multiple arterial branches from;

• Renal arteries,
• Gonadal arteries,
• Aorta,
• Common iliac arteries

Question 15

What is the lymphatic drainage of the kidneys and ureter

Answer 15

Kidneys - Lateral aortic (lumbar) LNs,

Ureter - Lateral aortic, common and internal iliac LNs

Question 16

In males what sits between the bladder and rectum?

Answer 16

Seminal vesicles and the retrovesical septum

Question 17

Describe the clinical correlations of catheters and child birth with the bladder

Answer 17

Catheters can be places urethrally or suprapubically.

Repeated childbirth may weaken pelvic floor allowing for bladder drop which affects uriniary continence

Question 18

Describe features of the detrusor muscle

Answer 18

It is 3 layered smooth muscle which is internally lined by mucosa, it is involuntary (PSNS)

Question 19

Describe internal features of the bladder

Answer 19

Trigone - area between ureteric orifices and urethral orifice.
Urothelium - Urine proof and allows distention
Internal urethral sphincter (males) - involuntary and contracts to prevent passage of semen into the bladder

Question 20

Name the supportive structures of the bladder

Answer 20

Fascial condensations - eg, puboprostatic and pubovesical ligaments

Question 21

Name the different parts of the male urethra

Answer 21

• Pre-prostatic urethra,
• Prostatic urethra,
• Membranous urethra,
• Spongy (penile) urethra

Question 22

Describe the vasculature of the bladder and urethra

Answer 22

Arterial supply - Branches of internal iliac artery and internal pudendal.
Venous - Vesical (and prostatic) plexuses converging on internal iliac veins.
Lymph - Internal and external iliac nodes

Question 23

Describe the innervation of the bladder and urethra

Answer 23

From the inferior hypogastric (pelvic) plexus.
PSNS from S2-4 via pelvic splanchnic nerves (contracts detrusor muscle and relaxes internal urethral sphincter in males)
Sympathetics from T11-L2 (contract internal urethral sphincter in males)
Somatic motor from pudendal nerve (control of external urethral sphincter)

Question 24

Explain the first stage of micturition

Answer 24

Storage phase;

1) PSNS supply to detrusor muscle ‘off’ to allow for relaxation and filling.
2) When urine volume reaches {400-500m} then stretch receptors are activated.
3) afferents sent to S2-4) Inhibition lifted
5) Preganglionic OSNS fibres synapse with postganglionic fibres in walls of bladder = contraction of detrusor muscle

Question 25

Describe the second stage of micturition

Answer 25

Voiding;

1) Contraction of detrusor muscle by PSNS,
2) Relaxation of external urethral sphincter by pudendal nerve,
3) Contraction of abdominal wall,
4) Sensation of urine in urethra maintains the reflex