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

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

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 Hypoosmotic: lower solute conc, higher water Hyperosmotic: higher solute conc, lower water

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

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

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) excrete uric acid Desert kangaroo rat – excretes very concentrated urine

Which excretory system produces the most concentrated excretion product? 1.protonephridia 2.malpighian tubules 3.metanephridia 4.kidneys

12 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

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

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

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

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

17 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

18 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

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

20 Human Urinary System - Kidneys Reabsorption In proximal tubule, most water along with bicarbonate, K+, and NaCl are reabsorbed into blood.

21 Human Urinary System - Kidneys Loop of Henle –increasing osmolarity from cortex to the medulla –due to active transport of Na +, & Cl – at ascending loop –reabsorption of water from descending loop and collecting duct

22 Human Urinary System - Kidneys Secretion In distal tubule, additional wastes (like H+ and K+) are actively secreted into the tubule from the blood

23 Human Urinary System - Kidneys Concentration At collecting duct, additional water (and NaCl) leaves, thus urine more concentrated than blood.

24 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

If a drug blocked Na+/Cl- cotransporters, what effect would this have on urine volume? 1.Increase volume, water would be retained 2.Decrease volume, water would be retained 3.Decrease volume, water would be excreted 4.Increase volume, water would be excreted

26 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

What effect would blocking ADH have? 1.Lots of dilute urine produced 2.Lots of concentrated urine produced 3.Minimal dilute urine produced 4.Minimal concentrated urine produced

28 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

Things To Do After Lecture 12… Reading and Preparation: 1.Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms. 2.Ch. 44 Self-Quiz: #1, 3, 4, 6(correct answers in back of book) 3.Read chapter 44, focus on material covered in lecture (terms, concepts, and figures!) 4.Skim next lecture. “HOMEWORK” (NOT COLLECTED – but things to think about for studying): 1.Compare and contrast the four different types of excretory systems. 2.Diagram the nephron, labeling regions and describing uptake/excretion at each region. 3.Explain the parts of the human urinary system. 4.Discuss the role of ADH – location of secretion and effect.