1. 1 An albatross can drink salt water – how can they do this without getting sick?!

2. 2 If you eat a lot of salt, what happens to your urine? Thought Questions: If you do not drink enough water, what happens to your urine? If you drink excess water, what happens to your urine?

3. 3 Lecture 15 Outline (Ch. 44) I.Homeostasis II.Water Balance III. Animal Excretory Systems IV.Human Urinary System I.Bladder II.Kidneys V.Water Control VI.Lecture Concepts

4. 4 Maintains homeostasis of body fluids via water balance aka ‘Excretory System’ Urinary System Osmolarity, (solute concentration of solution), determines movement of water across selectively permeable membranes

5. 5 Excrete salt ions from gills Gain water, salt ions from food Osmotic water loss from gills, body surface Uptake water, ions in food Uptake salt ions by gills Osmotic water gain from gills, body surface Excretion of large amounts of dilute urine Excrete salt ions & little water in scanty urine from kidneys Gain water, salt ions from seawater (a) Osmoregulation in a saltwater fish (b) Osmoregulation in a freshwater fish Water Balance

6. 6 Water gain (mL) Water loss (mL) Urine (0.45) Urine (1,500) Evaporation (1.46) Evaporation (900) Feces (0.09)Feces (100) Derived from metabolism (1.8) Derived from metabolism (250) Ingested in food (750) Ingested in food (0.2) Ingested in liquid (1,500) Water balance in a kangaroo rat (2 mL/day) Water balance in a human (2,500 mL/day) Water Balance

7. 7 Flatworms use protonephridia Animal Excretory Systems Simplest system Wastes stored in excretory pore, drawn out by water environment Tubule Tubules of protonephridia Cilia Interstitial fluid flow Opening in body wall Nucleus of cap cell Flame bulb Tubule cell

8. 8 Insects use malpighian tubules Animal Excretory Systems Actively pump waste, extra salt and water into tubules Rectum Digestive tract Hindgut Intestine Malpighian tubules Rectum Feces and urine HEMOLYMPH Reabsorption Midgut (stomach) Salt, water, and nitrogenous wastes

9. 9 Worms use nephridia Animal Excretory Systems Collect body waste Remaining waste excreted Capillary network Components of a metanephridium: External opening Coelom Collecting tubule Internal opening Bladder

10. 10 Most urinary waste nitrogenous – from digesting protein Vertebrate Urinary System Blood filtered by kidneys Fish excrete ammonia Land vertebrates convert to urea – add to urine To reduce water-loss, desert animals (reptiles, snakes, birds, and the Kangaroo Rat) excrete uric acid

11. 11 urethra left renal artery left kidney left renal vein left ureter urinary bladder Human Urinary System 1) Kidneys Blood w wastes brought by renal artery to kidney Filtered blood carried away by renal vein 2) Ureters Transport urine away from kidney 3) Bladder Stores urine Max capacity ~ 1 L 4) Urethra Transport urine from bladder to outside body

12. 12 Micturition (urination) Human Urinary System Ureter Bladder Gotta pee? Stretch stimulates contractions Sphincters control release

13. 13 Bladder Ureter Urogenital diaphragm Internal urethral sphincter (involuntary) External urethral sphincter (voluntary) Human Urinary System - Bladder

14. 14 Human Urinary System - Bladder Sensory Input (spinal cord) (-) Stretch (~200 ml) (-) Brain

15. 15 Urinary Disasters Tycho Brahe: GO when you need to The infamous candiru: DON’T GO when in water?

16. 16 renal artery renal vein ureter (cut away to show path of urine) urine to bladder renal cortex renal medulla collecting duct renal cortex Bowman’s capsule renal medulla loop of Henle Human Urinary System - Kidneys Urine forms in the nephron, ~1 million/kidney

17. 17 collecting duct branch of renal artery branch of renal vein Bowman’s capsule glomerulus Each nephron is a filter: Glomerulus- network of capillaries Bowman’s capsule- cup around glomerulus Collecting duct- carries fluid from nephron Human Urinary System - Kidneys

18. 18 Human Urinary System - Kidneys Filtration Water, nutrients, and wastes - filtered from glomerulus into Bowman’s capsule 1. FILTRATION

19. 19 Human Urinary System - Kidneys Reabsorption In proximal tubule, most water and nutrients are reabsorbed into blood. 2. TUBULAR REABSORPTION

20. 20 Human Urinary System - Kidneys Secretion In distal tubule, additional wastes actively secreted into the tubule from the blood 3. TUBULAR SECRETION

21. 21 Human Urinary System - Kidneys Concentration At collecting duct, additional water leaves, thus urine more concentrated than blood. 4. CONCENTRATION

22. 22 capillaries loop of Henle proximal tubule distal tubule Human Urinary System - Kidneys Fluid travels a loop in the nephron Proximal tubule Loop of Henle Distal tubule

23. 23 Body detects dehydration. Signal from hypothalamus to posterior pituitary. Posterior pituitary releases ADH into the bloodstream. ADH (antidiuretic hormone) allows more water reabsorbed into the blood. Concentrated urine produced Water Balance

24. 24 Urine: Waste and remaining water from nephron 95% water / 5% solutes (ions, urea) Water Balance Alcohol interferes with ADH Production of dilute urine – Dehydration Headache Fatigue Nausea

25. 25 Homeostatic Functions of Kidney: (1) Eliminate waste (2) Balance salts (3) Filter toxins Water Balance Dialysis – artificial filtration

26. 26 Lecture 15 concepts - Why do water-dwelling animals (fish) have a challenge that land animals do not? - Describe animal systems besides the kidney for filtering out waste. - Know the relative locations of: kidneys, ureters, bladder, urethra. - What is a nephron? How many are in a kidney? - Describe the process of filtration in a nephron using correct terminology. How is ADH involved? - List any new terminology and definitions.