what are the functions of the urinary system? **osmoregulation – water and salts waste excretion...
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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.
Urinary System
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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
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
Urinary System
What is the basic pattern and what is an archinephros?
Nephron – functional unit of kidneys
Renal corpuscle –
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
Urinary System
Renal corpuscle =glomerulus & Bowman’s capsule
Bowman’s capsule =parietal and visceral layers
Where does filtration take place?
Urinary System
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
What is involved with producing filtrate?
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
Urinary System
Moving wastes into nephron both passive and active
Passive (NH3)
Active / countertransport
(ex. H+, K+, Penicillin)
What is the role of secretion in urine production?
Urinary System
How is urine concentrated?
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
Urinary System
What is an archinephros?
Hypothetical “kidney”– Believed to be the prototype from a segmented ancestor
Urinary System
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)?
Urinary System
How are kidneys organized?
Urinary System
Location:Small of your back
Size:fist-sized
Surrounded byconnective tissue (renal capsule)
Protected byrenal fat pad (perirenal fat)
Where can one find a kidney?
Urinary System
retroperitoneal
peritoneal cavity
Gross anatomy!
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
Urinary System
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Stratified &Stretchy
Contract = peristaltic movements
What other anatomy is significant?Transitional epithelium lines the ureters & urinary bladder
Stratified &Stretchy
Contract = peristaltic movements
What other anatomy is significant?Transitional epithelium lines the ureters & urinary bladder