1. Urinary System What are the functions of the urinary system?
**Osmoregulation – water and salts
Waste excretion metabolic wastes (N)
If water is plentiful then NH3
If water is limited then Urea
If water is scarce then Uric acid
Hormone production – blood cell formation as a result of erythropoeitin secretion.

2. Urinary System
What are the “rules of thumb” regarding water and salts for different classes of vertebrates?
Fresh water organisms – excrete water and conserve salt
Salt water organisms – excrete salt and conserve water
Terrestrial organisms – modify salt and water loss appropriately

3. Urinary System What is the basic pattern and what is an archinephros?
Nephron – functional unit of kidneys
Renal corpuscle:
1) Glomerulus
2) Renal tubules
3) Excretory ducts

4. Urinary System What is the basic pattern and what is an archinephros?
Nephron – functional unit of kidneys
Renal corpuscle –

5. Urinary System
What are the 3 basic processes involved with urine formation?
1) Filtration – glomerulus
2) Reabsorption – renal tubules
3) Secretion – renal tubules
Other processes include:
4) Concentration – renal tubules and collecting ducts
5) Storage – bladder
6) Micturition – bladder, sphincters & urethra

6. Urinary System Where does filtration take place?
Renal corpuscle = glomerulus & Bowman’s capsule
Bowman’s capsule = parietal and visceral layers

7. Urinary System What is involved with producing filtrate?
Filtration Pressure…
Flow depends on pressure
Fluids and solutes move from > press. to < press.
Why is there a difference in pressure?
GCP = Glomerular capillary pressure
CP = Capsule pressure
COP = Colloidal osmotic pressure

8. Urinary System
What is the route of blood flow through the kidney and how does this fit with REABSORPTION?
Afferent arteriole to glomerulus to Efferent arteriole to peritubular capillaries to vasa recta, then back out

9. Urinary System What is the role of secretion in urine production?
Moving wastes into nephron both passive and active
Passive (NH3)
Active / countertransport (ex. H+, K+, Penicillin)

10. Urinary System
How is urine concentrated?

11. Urinary System How do kidneys form embryologically?
Nephrogenic mesoderm – lateral to mesodermal somites
Where are the kidneys in Necturus?
Tubules appear at cephalic end
Paired ducts develop and form caudad until they reach posterior and form opening
Posterior tubules

12. Urinary System What is an archinephros?
Hypothetical “kidney”– Believed to be the prototype from a segmented ancestor

13. Urinary System

14. Urinary System
Why would glomeruli be larger in freshwater fish and aquatic amphibians… and smaller in marine fishes and tetrapods (especially in tetrapods of arid environments)?

15. Urinary System
How are kidneys organized?

16. Urinary System Where can one find a kidney?
Location: Small of your back
Size: fist-sized
Surrounded by connective tissue (renal capsule)
Protected by renal fat pad (perirenal fat)

17. Urinary System
Gross anatomy!
retroperitoneal
peritoneal cavity

18. Urinary System
What is extrarenal salt excretion and how does it occur?
Gills – actively transport across lamellar membranes
Salt glands – can empty into nasal canals or mouth

19. What other anatomy is significant?
Transitional epithelium lines the ureters & urinary bladder
Stratified & Stretchy
Contract = peristaltic movements

20. What other anatomy is significant?
Transitional epithelium lines the ureters & urinary bladder
Stratified & Stretchy
Contract = peristaltic movements