1. ANATOMY OF URINARY SYSTEM

2. Anatomy of the Urinary System
Kidneys
(urine formation)
Lower Urinary Tract
Ureters (2)
Bladder (1)
Urethra (1)
(urine collection, storage, excretion)

3. (with calyces forming the medulary pyramids)
Cortex
Glomeruli
Medulla
Renal tubules
(with calyces forming the medulary pyramids)
Ureter
Takes urine to bladder
Blood carried to the kidney by the renal artery and taken away by the renal vein.
Cortex
Medulla
Renal hilum
Renal artery
Renal vein
Renal pelvis
Ureter

4. Each KIDNEY consists of 1 million NEPHRONS
Each nephron consists of a:
GLOMERULUS (found in cortex)
forms a protein-free filtrate from blood
TUBULE (found in medulla)
processes the filtrate to form urine
Each TUBULE consists of several segments:
Proximal tubule
Loop of Henle
Distal Tubule
Collecting Ducts.

5. Functional Unit of the Kidney is the NEPHRON
Glomerulus
Proximal Tubule
Loop of Henle
Distal Tubule
Collecting Duct

6. Kidney Functions Regulation of water, electrolyte balance, pH.
Removal of waste from blood and excretion of urine.
Secretion of hormones
Erythropoietin
Renin
Vitamin D3

7. COVERINGS FIBROUS CAPSULE:
Outer capsule. Protects from trauma & infections
PERIRENAL FAT:
Covers fibrous capsule
RENAL FASCIA:
Encloses kidneys and suprarenal gland
PARARENAL FAT:
External most forms large quantity of retroperitoneal fat

9. Gross anatomy
Renal sinus
Renal parenchyma

10. Renal sinus
Surrounded by renal parenchyma
Contains blood & lymph vessels, nerves, urine-collecting structures

11. Renal parenchyma Glandular tissue Forms urine Two zones Outer cortex
Inner medulla

12. Renal parenchyma Renal pyramids
Extensions of cortex (renal columns) divide medulla into 6 – 10 renal pyramids
Pyramid + overlying cortex = Lobe
Point of pyramid = Papilla
Papilla nested in cup (minor calyx)
2 – 3 minor calices  Major calyx
2 – 3 major calices  Renal pelvis
Renal pelvis  Ureter

14. Functional units of kidney ~1.2 million per kidney Three main parts
Nephrons
Functional units of kidney
~1.2 million per kidney
Three main parts
Blood vessels
Renal corpuscle
Renal tubule

15. Blood vessels servicing kidney Supplied by renal artery
~21% or cardiac output
(Mass in only ~ 0.4%)
Afferent arterioles
Capillary cluster (glomerulus)

16. Blood vessels servicing kidney Glomerulus
Fenestrated capillaries
Capillary filtration in glomerulus initiates urine production
Filtrate lacks cells & proteins
Drained by efferent arteriole
Peritubular capillaries
 Renal vein

20. NEPHRON Renal corpuscle Glomerulus plus capsule
Glomerulus enclosed in two-layered glomerular capsule
“Bowman’s capsule”
Fluid filters from glomerular capillaries
“Glomerular filtrate”
Fluid collects in capsular space
Fluid flows into renal tubule

22. NEPHRON Renal tubule Leads from glomerular capsule
Ends at tip of medullary pyramid
~3 cm long
Four major regions
Proximal convoluted tubule
Nephron loop
Distal convoluted tubule
Collecting duct

24. LYMPH SUPPLY: lateral aortic lymph nodes NERVE SUPPLY: Renal sympathetic plexus. Afferent fibers travel through 10th 11th 12th thoracic nerves to spinal cord.

25. URINE FORMATION Overview Blood plasma  Urine Four steps
Glomerular filtration
Tubular reabsorption
Tubular secretion
Water conservation

28. URINE STORAGE
Ureters
Carry urine from kidneys to urinary bladder via peristalsis
Rhythmic contraction of smooth muscle
Enter bladder from below
Pressure from full bladder compresses ureters and prevents backflow

29. Ureters
Small diameter
Easily obstructed or injured by kidney stones (renal calculi)
3 constrictions: 1) renal pelvis joins the ureter 2) where it crosses the pelvic brim 3) enter into the urinary bladder

30. BLOOD SUPPLY
UPPER END: Renal artery
MIDDLE PORTION: testicular artery or Ovarian
LOWER END: In pelvis, sup. Vesical artery
VENOUS Blood drains into the veins corresponding arteries

31. Lymph : lateral aortic lymph nodes and iliac nodes
NERVE SUPPLY: Renal, testicular or ovarian and hypogastric plexuses.
Afferent fibers travel with the sympathetic fibers and enter the 1st and 2nd lumber segments in the spinal cord.

32. Urinary bladder
Muscular sac
Wrinkles termed rugae
Openings of ureters common site for bladder infection

33. URINE ELIMINATION Urethra Conveys urine from body
Internal urethral sphincter
Retains urine in bladder
Smooth muscle, involuntary
External urethral sphincter
Provides voluntary control over voiding of urine

34. Urethra 3 – 4 cm long in females
Bound by connective tissue to anterior wall of vagina
Urethral orifice exits body between vaginal orifice and clitoris

36. Urethra ~18 cm long in males Prostatic urethra Membranous urethra
~2.5 cm long, urinary bladder  prostate
Membranous urethra
~0.5 cm, passes through floor of pelvic cavity
Penile urethra
~15 cm long, passes through penis

38. URINE ELIMINATION Urination (micturition) ~200 ml of urine held
Distension initiates desire to void
Internal sphincter relaxes involuntarily
Smooth muscle
External sphincter voluntarily relaxes
Skeletal muscle
Poor control in infants
Bladder muscle contracts
Urine forces through urethra