44 Structure of the urinary system including bladder

Question 1

What is the kidney encapsulated and protected by?

Answer 1

1. Perirenal/ perinephric fat
2. Renal fascia (derived from extraperitoneal fascia)
3. Pararenal/ paranephric fat

Question 2

What does the nephron consist of?

Answer 2

1. Renal corpuscle
2. Proximal convoluted tubule
3. Loop of Henlé
4. Distal collecting tubule
5. Collecting duct

Question 3

What is the function of nephron?

Answer 3

• Ultrafiltration

- Reabsorption

Question 4

Hilum (anterior to posterior)

Answer 4

• Renal vien
• Renal artery
• Renal pelvis

Question 5

Kidney: blood supply,
venous,
lymphatic drainage

Answer 5

1. Renal arteries
   - from aorta at L1
   - posterior to renal veins
   - divide at hilum
2. Renal veins
   - inferior vena cava
3. Lymph to lumbar lymph nodes

Question 6

Kidney: segmental,

lobal and interlobar arteries

Answer 6

• Each renal artery divides into 5 segmental arteries that enter kidney at its hilum
• Lobar arteries arise form each segmental artery (1 for each renal pyramid)
• Before entering the renal substance, each lobar artery gives off 2 or 3 interlobular arteries
• Interlobular arteries run towards the cortex on each side of the pyramids
• At junction of cortex and medulla the interloper artier give off the arcuate arteries that arch over the bases of the pyramids
• Arcuate arteries give off several interlobular arteries that ascend in the cortex
• The afferent glomerular arterioles (give blood directly into the renal corpuscle) arise as branches of the interlobular arteries

Question 7

Kidney: nerve supply

Answer 7

• Derived from T12 and L1
• Referred pain to back and lumbar region as well as loin to groin
• Afferents in vagus nerve (CN X) may cause nausea and vomiting associated with such pain

Question 8

What levels are kidneys located?

Answer 8

• Right lower than left
• Right L1-L4
• Left T12-L3

Question 9

What overlies the hilum of right kidney!

Answer 9

2nd (descending) part of duodenum

Question 10

Ureter function

Answer 10

Muscular tube that transports urine from kidney to bladder

Question 11

How long and wide is the ureter?

Answer 11

25-30 cm long

3mm wide

with narrowings

Question 12

Ureter narrowings?

Answer 12

1. Pelvi-Ureteric junction
2. Crossing the pelvic brim/ inlet
3. Passing through the bladder wall

Question 13

Relations of ureter?

Answer 13

Anterior to psoas major, branches of lumbar plexus

Cross bifurcation of common iliac artery

Medial to sacroiliac joints and iliac spines

Question 14

Difference between pelvic relations of the ureter in males and females?

Answer 14

Male: between vas/ ductus deferens and seminal vesicle

Female: posterior to ovary, inferior to uterine artery, passing cervix and lateral fornix of vagina

Question 15

Relations of ureter in pelvis?

Answer 15

Lateral to:

• Internal iliac vessels and branches
• Lumbosacral trunk

Question 16

Ureter: blood, nerve supply and lymphatic drainage?

Answer 16

Lymph to lumbar and iliac nodes

Good longitudinal anastomosis

Nerve supply:

• supply more at lower end of ureters
• derived segmentally: T10, T11, T12, L1, S2, S3, S4 from aortic, renal and pelvic plexuses
• referred pain: T11 to L2 from loin to groin and scrotum or labia

Question 17

What is the relevance of the ureters oblique entry into the bladder?

Answer 17

Creating a flap valve -prevents urine in bladder from backing up & returning into ureter (ureteric reflux)

Question 18

What does pressure of urine in full bladder do?

Answer 18

Forcing ureters to close

Question 19

Walls of ureters and bladder?

Answer 19

Muscular

Question 20

How is urine propelled down ureter? What pain does it cause of ureteric calculi?

Answer 20

Peristaltic waves

Colicky pain

Question 21

How does bladder fill?

Answer 21

Relaxation of detrusor muscle

Question 22

How is bladder emptied?

Answer 22

Contraction of detrusor muscle

Aided by raised intra-abdominal pressure

Internal urethral sphincter at proximal urethra opening

Question 23

What is the epithelial lining of bladder?

Answer 23

Transitional epithelium or urothelium

Urine-rpoof and allows distension

Question 24

Detrusor muscle nerve supply?

Answer 24

Mainly under control of parasympathetic nerves derived from S2, S3, S4

Question 25

External urethral sphincter

Answer 25

Around distal urethra Striated Under voluntary control

Question 26

Anatomically, how do men prevent semen back flow into bladder?

Answer 26

Preprostatic smooth muscle (involuntary) internal urethral sphincter (sympathetic) at the bladder neck that contracts during ejaculation to prevent semen backflowing into the bladder that is known as retrograde ejaculation

Question 27

How does female anatomy relate to urinary continence

Answer 27

Bladder neck is above the pelvic floor so that the pressure of pelvic organs as well as the levator ani contribute

Question 28

Female urethra

Answer 28

- Internal urethral sphincter (bladder neck and proximal urethra) - External urethral sphincter (striated muscle - voluntary at distal urethra) - 4cm long and 6mm wide - Embedded in anterior vaginal wall - Opens in vulva

Question 29

4 parts of male urethra?

Answer 29

1. Preprostatic at bladder neck (position of smooth muscle internal urethral sphincter) 2. Prostatic 3. Membranous - surrounded by striated muscle external urethral sphincter 4. Spongy or penile

Question 30

Arterial supply of bladder and urethra?

Answer 30

Internal iliac artery branches (superior and inferior vesicle, middle rectal) Branches from arteries to adjacent structures (e.g. vaginal) Internal pudendal

Question 31

Venous drainage of bladder and urethra?

Answer 31

Vesical (& prostatic) plexuses converging on internal iliac veins Internal pudendal

Question 32

Lymph drainage of bladder and urethra?

Answer 32

Internal & external iliac nodes

Question 33

From the prostate there are communications (Batson venous plexus) with the internal vertebral venous plexus that may facilitate ______ _______

Answer 33

Tumour spread

Question 34

Nerve supply of bladder and urethra

Answer 34

- Somatic motor for control of striated muscle (external urethral sphincter) - Autonomic sensory & motor for both sympathetic (male internal urethral sphincter contraction) & parasympathetic (detrusor muscle contraction) - Somatic motor from S2, S3, S4 pudendal nerve & its branches - Sympathetic & parasympathetic in pelvic plexus (inferior hypogastric)

Question 35

What are the 3 stages of micturition? Simultaneous relaxation/contraction

Answer 35

1. Storage: - Parasympathetic to detrusor “switched off” in spinal cord to allow bladder to relax & fill - Usual volume (male) about 400ml; if reach 500ml, pain in lower abdomen & perineum 2. "Full" causes desire to micturate/ urinate: - Afferents (sensory) to spinal cord, then “M” Centre in pons: stimulates preganglionic, parasympathetic neurones at S2, S3, S4 3. Void: - 1y neurons stimulate 2y neurons in bladder wall ganglia causing detrusor contraction - Simultaneous relaxation of external urethral sphincter (striated muscle) – pudendal nerve (S2, S3, S4) & contraction of abdominal wall; sensation of urine in urethra maintains the reflex