Lecture 22: The Urinary System

Question 1

Outline the flow of urine in the urinary system:

Answer 1

Urine is filtered out of blood in kidneys (water reabsorption also occurs) → Ureters, urinary bladder and urethra serve as passageways for storage and expulsion of urine

Question 2

What are the main functions of the kidney

Answer 2

• Excretion of waste products
• Regulation of blood pH, volume, ionic comp and glucose levels
• Production of hormones
  
  • Enzymatic blood pressure regulation (secretion of renin’)
    *

Question 3

Outline the anatomy of the kidney:

Answer 3

• RETROPERTONEAL ORGAN
• Posterior abdominal wall
• Renal hilum located on concave border
  
  • Surrounded by 3 layers of tissue → renal capsule, adipose capsule, renal fascia (ATTATCHES TO POSTERIOR ABDOMINAL WALL)

Question 4

What vessels enter/exit the renal hylum?

Answer 4

• Renal arteries
• Renal veins
  
  • Ureter

Question 5

What is the inner kidney composed of?

Answer 5

• Renal Cortex = Outer layer
• Renal medulla = made up of renal pyramids (base of pyramid is renal papilla)
• Renal Columns= areas of cortex btw pyramids
• Renal Lobe = pyramids + cortex with half columns on each side

Question 6

Identify the path of urine drainage:

Answer 6

Collection duct exiting nephron → Papillary duct in renal pyramid → minor calyx → Major calyx → Renal pelvis → Ureter → Urinary Bladder

Question 7

What is the cavity that houses the calyces, renal pelvis, blood vessels and nerves

Answer 7

Renal sinus!

Question 8

Describe the flow of blood that is being supplied to the kidneys

Answer 8

Renal Artery → segmental → interlobar → Arcuate → Interlobular → Afferent arterioles → glomerular capillaries → Efferent arterioles → Peritubular capillaries → Inter lobular vein → arcuate vein → Interlobar vein → Renal vein

Question 9

Identify all the arteries that supply the kidney and the veins that drain

Answer 9

Question 10

What is the functional unit of the kidney?

Answer 10

The nephron!

Question 11

Identify key features of the nephron?

Answer 11

• Renal Corpuscle = filters blood plasma
• → Glomerulus- Capillary network and Bowman’s Capusle

→ Filtered fluid enters Renal tubule for reabsorption and secretion

• Proximal convoluted tubule (most reabsorption occurs here)
• Enters decending limb → loop of henle (in medulla) → ascending limb
  
  • enters distal convoluted tubule → Drain into papillary ducts in medulla

Question 12

Label the nephron

Answer 12

Question 13

What are the 2 types of nephrons?

Answer 13

Cortical and Juxtamedullary nephrons

Question 14

What are the differences between the cortical and juxtomedullary nephrons?

Answer 14

Cortical Nephron:

→ Most common

→ Loop of henle only in outer region of medulla

Juxtomedullary Nephron

→ Least common

Loop of henle deep into medulla (PRODUCES MORE CONCENTRATED URINE)

Question 15

What is the visceral and parietal layer of the glomerular capsule made of?

Answer 15

Visceral layer: Modified simple squamous epithelium: PODOCYTES → have slits that allow water and small molecules to pass into the capsular space toward the proximal convoluted tubule.

Parietal Layer: Simple squamous epithelium:

Question 16

What is the juxtaglomerular complex composed of?

Answer 16

Macula Densa + Juxtaglomerular Cells

Question 17

Where is the juxtaglomerular complex located and what is the function of the juxtaglomerular complex?

Answer 17

Located at the ascending loop on Henle which makes contact with the afferent arteriole

• Macula Densa contains chemreceptors to monitor sodium concentration.
• When sodium levels too low JUXTAGLOMERULAR CELLS will secrete renin.

Question 18

What is the ureter and identify its function

Answer 18

• Retroperitoneal muscle duct
• Function: Carry urine from kidneys to the urinary bladder.

Question 19

Describe the histology of the ureter:

Answer 19

• Stellate Lumen
• 3 layered wall: → Mucosa → Muscularis→ adventitia

Question 20

Where is the urinary bladder located and what is it characterized by?

Answer 20

• Situated in the pelvic cavity, posterior to the pubic symphysis
• Hollow organ with strong muscular walls characterised by its DISTENSIBILITY.

Question 21

Describe the anatomy of the urinary bladder:

Answer 21

• Trigone- floor or urinary bladder
  
  • Apex - points to the pubic symphysis

Question 22

What is the 3 layered wall of the bladder?

Answer 22

mucosa → transitional epithelium

Muscularis → Detrusor muscle

Adventitia (posterior and inferior aspects) and Serosa (superior aspects)

Question 23

Where is the urethra located in a female

Answer 23

• Lies behind pubic symphyses
  
  • Ends in external urethral orifice between clitoris and vaginal orifice

Question 24

What are the parts of the urethra in the male?

Answer 24

• Prostatic : Ducts from prostate, seminal vesicles and ductus deferens
• Membranous
  
  • Spongy: Cowper’s Gland, urethral gland

Question 25

What is micturition?

Answer 25

Discharge of the urine from the urinary bladder

combination of voluntary and involuntary muscle contraction