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

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

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

3. Lecture 12 Outline (Ch. 44) I. Homeostasis II. Water Balance III. Animal Excretory Systems • Human Urinary System • Bladder • Kidneys • Water Control • Preparation for next lecture

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

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

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

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

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

9. Vertebrate Urinary System Most urinary waste nitrogenous – from digesting protein Desert kangaroo rat – excretes very concentrated urine Blood filtered by kidneys Fish excrete ammonia (toxic at high levels) Land vertebrates convert to urea – add to urine To reduce water-loss, desert animals (reptiles, snakes, birds) excrete uric acid (non-toxic, hydrophobic)

10. left renal artery left kidney left renal vein left ureter urinary bladder urethra 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

11. Internal urethral sphincter (involuntary) External urethral sphincter (voluntary) Human Urinary System - Bladder Micturition (urination) Ureter Gotta pee? Stretch stimulates contractions Bladder Sphincters control release Urogenital diaphragm

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

13. Urinary Disasters Tycho Brahe: When you SHOULD go The infamous candiru: When NOT TO go

14. Human Urinary System - Kidneys Kidney Structure Urine forms in the nephron, ~1 million/kidney Renalcortex nephron Renalmedulla Renal artery Renal vein Renalcortex Ureter Renalmedulla Renal pelvis

15. Human Urinary System - Kidneys Afferent arteriolefrom renal artery Glomerulus Each nephron is a filter: Glomerulus- network of capillaries Bowman’s capsule- cup around glomerulus Loop of Henle- Tubule network for adjusting water, salt, and waste levels Collecting duct- carries fluid from nephron Bowman’s capsule Proximaltubule Peritubularcapillaries Distaltubule Efferentarteriolefrom glomerulus Branch ofrenal vein Descendinglimb LoopofHenle Collectingduct Ascendinglimb

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

17. Human Urinary System - Kidneys Distal tubule Proximal tubule NaCl Nutrients H2O Reabsorption H2O HCO3 K HCO3 NaCl In proximal tubule, most water along with bicarbonate, K+, and NaCl are reabsorbed into blood. H NH3 H K Filtrate CORTEX Loop ofHenle NaCl H2O OUTERMEDULLA NaCl Collectingduct Key Urea Active transport NaCl H2O Passive transport INNERMEDULLA

18. Human Urinary System - Kidneys Distal tubule Proximal tubule NaCl Nutrients H2O H2O HCO3 K HCO3 NaCl • Loop of Henle • increasing osmolarity cortex to medulla • active transport of Na+ & Cl– at ascending loop H NH3 H K Filtrate CORTEX Loop ofHenle NaCl H2O OUTERMEDULLA NaCl Collectingduct Key Urea Active transport NaCl H2O Passive transport INNERMEDULLA

19. Human Urinary System - Kidneys Distal tubule Proximal tubule NaCl Nutrients H2O H2O HCO3 K HCO3 NaCl Secretion H NH3 H K In distal tubule, additional wastes (like H+ and K+) are actively secreted into the tubule from the blood Filtrate CORTEX Loop ofHenle NaCl H2O OUTERMEDULLA NaCl Collectingduct Key Urea Active transport NaCl H2O Passive transport INNERMEDULLA

20. Human Urinary System - Kidneys Distal tubule Proximal tubule NaCl Nutrients H2O H2O HCO3 K HCO3 NaCl Concentration H NH3 H K Filtrate At collecting duct, additional water (and NaCl) leaves; urine more concentrated than blood. CORTEX Loop ofHenle NaCl H2O OUTERMEDULLA NaCl Collectingduct Key Urea Active transport NaCl H2O Passive transport INNERMEDULLA

21. Human Urinary System - Kidneys Two-solute model: NaCl and Urea are moved into the kidney medulla The filtrate in the nephron passes into this area three times Osmolarityof interstitialfluid(mOsm/L) 300 300 100 300 100 300 300 H2O NaCl H2O CORTEX 400 200 400 400 H2O NaCl H2O NaCl H2O H2O NaCl NaCl NaCl H2O H2O OUTERMEDULLA 600 600 600 400 H2O NaCl H2O Urea H2O H2O NaCl 900 700 900 Urea Key H2O NaCl H2O INNERMEDULLA Urea Activetransport 1,200 1,200 1,200 Passivetransport

22. Posterior pituitary releases ADH into the bloodstream. ADH (antidiuretic hormone) allows more water reabsorbed into the blood. Concentrated urine produced Water Balance Osmoreceptors inhypothalamus triggerrelease of ADH. Thirst Body detects dehydration. Signal from hypothalamus to posterior pituitary. Hypothalamus Drinking reducesblood osmolarityto set point. ADH Pituitarygland Increasedpermeability Distaltubule STIMULUS:Increase in bloodosmolarity (forinstance, aftersweating profusely) H2O reab-sorption helpsprevent furtherosmolarityincrease. Collecting duct Homeostasis:Blood osmolarity(300 mOsm/L)

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

24. Things To Do After Lecture 12… Reading and Preparation: • Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms. • Ch. 44 Self-Quiz: #1, 3, 4, 6(correct answers in back of book) • Read chapter 44, focus on material covered in lecture (terms, concepts, and figures!) • Skim next lecture. “HOMEWORK” (NOT COLLECTED – but things to think about for studying): • Compare and contrast the four different types of excretory systems. • Diagram the nephron, labeling regions and describing uptake/excretion at each region. • Explain the parts of the human urinary system. • Discuss the role of ADH – location of secretion and effect.