Lecture 26: Urinary System

Question 1

Urinary system

Answer 1

Filter blood and dispose of waste byproducts
Helps with fluid and electrolyte balance
Includes kidneys, ureters, urinary bladder, urethra

Question 2

Kidneys

Answer 2

2 bean shaped organs against posterior abdomen at TXII-LIII
R kidney is slightly than L kidney due to liver
Has 2 surfaces (posterior/anterior), 2 borders (lateral/medial), 2 poles (superior/inferior)

Question 3

Surroundings of kidney

Answer 3

Superior pole: super-renal gland/adrenal gland
Posterior: quadratus lumborum, psoas major, transversus abdominus, diaphragm; between kidney and posterior abdominal wall are 2 branches of lumbar plexus: ilioinguinal and iliohypogastric
Anterior: R - liver, R colic flexure, duodenum; L - L colic flexure, spleen, pancreas, stomach
Medial (concave): hilum containing renal artery, branches of abdominal aorta, renal vein, ureter

Question 4

Kidney relation to ribs

Answer 4

R kidney associated with rib 12

L kidney associated with rib 11 and

Question 5

Coverings of kidney

Answer 5

Fibrous capsule: first layer of connective tissue tightly bound to surface, goes inside kidney creating renal space/sinus
Peri-renal fat: surrounds kidney outside fibrous capsule
Renal fascia: layer of connective tissue; surrounds kidney and adrenal gland and continues with connective tissue around deep blood vessels
Para-renal fat: surrounds renal fascia
Layers mechanically support and warm kidney

Question 6

Internal structures of kidney

Answer 6

Renal cortex: outer internal feature
Renal medulla: C shaped feature
Renal pyramid: pyramidal structures inside renal medulla
Nephrons: inside renal pyramid; smallest functional and structural unit of kidney
Renal papilla: tip of each renal pyramid
Renal column: extension of cortex between pyramids
Renal lobe: internal fissure made up of renal pyramid and half a renal column on each side
Renal sinus: contains renal pelvis, minor/major calyx, branches of renal arteries, renal vein, adipose tissue

Question 7

Pathway of urine

Answer 7

Urine comes from renal papilla to minor calyx (cup - shaped structure)
Tips of minor calyx join to form larger cup structure = major calyx (1-3 per kidney)
This drains urine into the renal pelvis which continues as the ureter outside the kidney

Question 8

Ureter

Answer 8

25cm muscular tube starting at renal hilum, through posterior abdominal wall, to pelvis and joins at urinary bladder
Sits on anterior surface of psoas major

Question 9

Constrictors in ureter

Answer 9

3 constrictions
Level at junction of ureter and renal pelvis
Level which ureter passes over ring of pelvis (over common iliac artery)
Level where ureter enters bladder
If there is a kidney stone, it will be stuck at one of these constrictions

Question 10

Urinary bladder

Answer 10

Pyramidal hollow structure that sits in true pelvis when empty, but goes up to abdomen when full
Has base/fundus, apex, neck, superior surface, 2 inferior lateral surfaces

Question 11

Surroundings of urinary bladder

Answer 11

Apex: behind pubic symphysis; connected to umbilicus via medius umbilical ligament
2 inferior lateral surfaces (L/R): on pelvic floor associated with pelvic wall and pelvic diaphragm
Fundus: associated with ductus deference, seminal vesicles, rectum in males, uterus and vagina in females
Neck: on prostate in males, and external urethral sphincter in females
Superior surface: associated with sigmoid colon in males, uterus in females, ileum in both

Question 12

Peritoneum reflections in urinary system

Answer 12

Rectovesical pouch: peritoneum covers anterior abdominal wall and reflects to cover rectum; where fluid accumulates when sitting down (males)
Uterovesical pouch: peritoneum coves superior surface of bladder and reflects on uterus (females)
Rectouterine pouch/pouch of Douglas: peritoneum between uterus and anterior surface of rectum; deepest pouch, lipids accumulate here and can be reached through the rectum (females)

Question 13

Internal features of bladder

Answer 13

Trigone: smooth posterior wall containing mucous membrane; inverted triangle
Angles made by ureter on top (2) and internal urethral sphincter at the bottom

Question 14

Urethra in males

Answer 14

20 cm long
Has 4 parts
Preprostatic urethra: above prostate
Prostatic urethra: through prostate; widest part; prostatic and ejaculatory ducts open here
Membranous urethra: narrowest part; passes pelvic floor
Penile/spongy urethra: passes through penis via external urethral orifice/opening

Question 15

Urethral sphincters in males

Answer 15

Internal urethral sphincter: surrounds preprostatic urethra; involuntary; prevents backflow of semen into the bladder
External urethral sphincter: surrounds membranous urethra; voluntary

Question 16

Urethra in females

Answer 16

4cm long
Passes through anterior pelvic floor through perineal muscles where it’s surrounded by external urethral sphincter (no internal sphincter)
Paraurethral glands drain secretion into urethra
Urinary infections are more common in females - urethra and rectum are close

Question 17

Blood supply of urinary system

Answer 17

Renal arteries supply kidneys

Branches of internal iliac arteries supply bladder and urethra

Question 18

Nerve supply of urinary system

Answer 18

Parasympathetic: vagus nerve for kidney and ureter; pelvic splanchnic nerves (S2-S4) for bladder and urethra
Sympathetic: lesser, least, lumbar splanchnic nerves for kidney and ureter; lumbar and sacral splanchnic nerves for bladder and urethra