1. Ch 26: Urinary System Objectives
Identify and describe the components of the urinary system and their function
Describe the (histological) organization of the nephron
Identify the blood vessels that supply blood to the nephrons
Describe the blood flow through and around the nephron

2. Functions of Urinary System (Kidneys):
Excretion of organic waste products
Regulation of blood
Volume pH
Ion concentration

3. Kidney Location
Lateral to vertebral column in retro-peritoneal position

4. Surface Anatomy Hilus Three layers Renal fascia Adipose capsule
Renal capsule

5. Sectional Anatomy
Cortex: light reddish brow and granular (due to many capillaries)
Medulla: darker striped appearance (due to tubules) Subdivided into distinct renal pyramids. Separated by renal columns from the cortex.
Fig 26-3

6. Urine collection: Ducts within each renal papilla release urine
into minor calyx
major calyx
renal pelvis
ureter

7. Functional unit: Nephron
(>mio/kidney)
Renal corpuscle:
Glomerulus
Bowman’s capsule
Tubular passageways:
PCT
LOH
DCT CD
Fig 26-5
Fig 26-4

8. Filtration: Passage across Three Barriers
Capillary endothelium
Fenestrated
What gets through?
Basement membrane
Glomerular epithelium (= visceral layer of Bowman’s capsule)
slit pores between pedicels
Fig 26-5

9. Juxtaglomerular Apparatus
Macula densa +
Juxtaglomerular cells (smooth muscle fibers from afferent arteriole)
= Juxtaglomerular Apparatus
= Endocrine system structure (renin and EPO)

10. Cortical vs Juxtamedullary Nephrons
Cortical nephrons (85%)
Juxtamedullary nephrons (15%), play keyrole in concentrating urine.

11. Renal Circulation Renal Artery Segmental arteries Renal Vein
Fig 26-7
Renal Artery
Segmental arteries
Interlobar arteries
Arcuate arteries
Interlobular arteries
Afferent arterioles
Glomerulus
Efferent arterioles
Peritubular capillaries
Renal Vein
Segmental veins
Interlobar veins
Arcuate veins
Interlobular veins
Venules

12. Urine Transport, Storage, and Elimination
Trace drop of urine from kidneys to outside world
Lining of these parts?
Nephroptosis (= floating kidneys)
Nephrolithiasis

13. Transitional Epithelium
from renal pelvis to
neck of urethra.
full bladder
empty bladder

14. Nephroptosis Upright position: 1st degree nephroptosis:
Supine position

15. Nephrolithiasis
occurs when urine becomes too concentrated and substances crystalize. Symptoms arise when stones begin to move down ureter causing intense pain.
Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.

16. Anatomy of Urinary Bladder
max.
holding
capacity: 1l
Detrusor
muscle:
• inner longitudinal
• middle circular
• outer longitudinal

17. Male versus Female
UTIs (esp. E.coli)

18. The End
Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!!
2-4 % of population only have 1 kidney!
Manneken Pis
Fountain
Brussels, 1619