Excretory Systems Ch. 44

1. Excretory SystemsCh. 44 Regulating Water Loss and Solute Concentrations

2. Ch. 44 & 45 - Digestion & Fluid Balance • What organism is used by Dr. Carol Beuchat to illustrate how fluid is regulated and the role played by the urinary tract in maintaining homeostasis? (1st segment) • How is a complete digestive system different from an incomplete one? What function does each segment (region) of the digestive system have? • Name two enzymes mentioned by Dr. Sokolowski that play a role in the digestive system. How is the diet of a dog different from a cat? What are the nutritional needs for a cat and dog? What is the name of the café mentioned in the video? 4. The final segment discusses the role the kidneys play in maintaining homeostasis. What kind of machine is the patient connected to? **Write the title for each segment and FIVE statements for each segment.

3. Introductory Questions #7 • How is an osmoconformer different from an osmoregulator? • Name a fish that is able to adjust to salt concentrations ranging from freshwater to 2,000mosm/L (twice that of sea water). • How do marine fishes (hyperosmotic to the water) adjust and balance their water loss? • Name the three types of nitrogenous waste products that are released fish, mammals, and reptiles. Which one is most toxic? Which one is a semi-solid form? Which one is made by combining ammonia and carbon dioxide? • Name the key excretory structures found in Flatworms (Platyhelminthes), Earthworms (annelids), and Insects (Arthropodds). • Name the two distinct regions of the mammalian kidney. Name the three regions of nephron starting from the Bowman’s capsule.

4. Animals must dispose of nitrogenous wastes • Nitrogen-containing wastes are toxic by-products of protein and nucleic acid breakdown • Ammonia is poisonous but soluble and easily disposed of • Urea is less toxic and easy to store and excrete • Some land animals save water by excreting a virtually dry waste

5. Land animals gain water by drinking and eating • They lose water and solutes by evaporation and waste disposal • Their kidneys, behavior, and waterproof skin conserve water

6. Sweating can produce serious water loss • Water lost in thermoregulation can cause osmoregulatory problems • Drinking water is the best way to prevent dehydration during exercise Figure 25.6

7. Some animals face seasonal dehydration • Many small invertebrates can dehydrate and become dormant when their environment dries up Figure 25.7

8. Water Balance and waste disposal • Osmoregulation: • management of the body’s water content and solute composition (hyper, iso, hypo tonic soln’s) • Humans fluid is 1/3 as salty as seawater • Nitrogenous wastes: • breakdown products of proteins and nucleic acids; ammonia-very toxic • Deamination • Ammonia: most aquatic animals, many fish • Urea: mammals, most amphibians, sharks, bony fish (in liver; combo of 2NH3 and CO2) • Uric acid: birds, insects, many reptiles, land snails

9. Water Balance and waste disposal

10. Osmoregulators • Osmoconformer: no active adjustment of internal osmolarity (marine animals-sand dollars,sea stars, jellyfish); iso-osmotic to environment • Osmoregulator: adjusts to maintain a constant internal osmolarity (freshwater, marine, terrestrial) • Freshwater fishes (hyperosmotic)- gains water, loses; excretes large amounts of dilute urine salt • Marine fishes (hypo-osmotic)- loses water, gains salt; drinks large amount of saltwater pumps out extra solutes out of gills

11. Osmoregulators

12. Protonephridia ~ flatworms “flame-bulb”systems

13. Metanephridia ~ annelids • ciliated funnel system

14. Malpighian tubules ~ insects • tubes in digestive tract

15. Kidneys ~ vertebrates (outer region) (inner region) kidney blood flow urine excretory duct

16. The key functions of the excretory system are filtration, reabsorption, secretion, and excretion • Filtration • Blood pressure forces water and many solutes from the blood into the nephron • Reabsorption • The nephron tubule reclaims valuable solutes

17. The nephron removes substances and adds them to the filtrate • The product of all of the above processes is urine, which is excreted • Secretion Nephron tubule FILTRATION REABSORPTION EXCRETION SECRETION H2O, other small molecules Urine Capillary Figure 25.10

18. Kidney Functional Units Nephron: functional unit of kidney urine storage urine elimination tube In medulla; 20% supplies blood to nephron from renal artery In cortex; 80% blood from glomerulus

19. 1 Proximal tubule Bowman’s capsule Glomerulus Arteriolefrom renalartery Capillaries • Each nephron consists of a folded tubule and associated blood vessels 3 Arteriolefrom glomerulus Distaltubule Branch ofrenal vein Fromanothernephron • The nephrons extract a filtrate from the blood • They refine the filtrate into a much smaller amount of urine Collectingduct 2 Loop of Henlewith capillary network D. DETAILED STRUCTURE OF A NEPHRON Figure 25.9D

20. From blood to filtrate to urine: A closer look • The proximal tubule reabsorbs • nutrients • salts • water • Antidiuretic hormone and other hormones regulate the amount of salt and water the kidneys excrete

21. Controlled secretion of H+ and reabsorption of bicarbonate ions help regulate blood pH • Secretion also includes the active transport of drugs and poisons • Reabsorption of salts and urea promote the osmotic reabsorption of water

22. Nephron Structure • Glomerulus: ball of capillaries (filtration) • Bowman’s capsule: surrounds glomerulus directs filtrate to tubules • Proximal tubule: secretion & reabsorption • Peritubular capillaries: from efferent arteriole; surround proximal & distal tubules • Loop of Henle: water & salt balance • Distal tubule: secretion & reabsorption • Collecting duct: carries filtrate to renal pelvis

23. Overview of Mammalian Nephron Function

24. Proximal tubule Distal tubule Bowman’scapsule NaCl H2O Glucose andamino acids H2O HCO3– NaCl HCO3– Blood Somedrugsand poisons K+ NH3 H+ H+ Filtrate Collectingduct H2O CORTEX Salts (NaCl, etc.) MEDULLA HCO3– H+ Loop ofHenle Urea NaCl Glucose Amino acids NaCl Some drugs H2O Reabsorption Urea Active transport NaCl H2O Passive transport Secretion (active transport) Urine (to renal pelvis) Figure 25.11

25. The Human Kidney & Nephron

26. Kidney regulation: hormones • Antidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); [urine]; inhibited by alcohol and coffee • Juxtaglomerular apparatus (JGA) ~ reduced salt intake--->enzyme renin initiates conversion of angiotension (plasma protein) to angiotension II (peptide); increase blood pressure and blood volume by constricting capillaries • Angiotension II also stimulates adrenal glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-angiotension-aldosterone system; RAAS) • Atrial natriuretic factor (ANF) ~ walls of atria; inhibits release of renin, salt reabsorption, and aldosterone release

28. Kidney dialysis can be a lifesaver • A dialysis machine compensates for kidney failure • It performs the function of the nephrons by removing wastes from the blood and maintaining its solute concentration

29. Line from arteryto apparatus Pump Tubing made of aselectively permeablemembrane Dialyzingsolution Line fromapparatusto vein Fresh dialyzingsolution Used dialyzingsolution (with urea and excess salts) Figure 25.12

30. Maintaining Core Temperature • Endotherm - Regulates heat using metabolic activities • Ectotherm • Slow metabolism • Gains energy from environment

31. Behavior often affects body temperature • Basking in the sun • Sitting in the shade • Bathing • Burrowing or huddling • Migrating Figure 25.3

32. Reducing the metabolic rate saves energy • Torpor is a state of reduced activity and lowered metabolic rate • Hibernation in cold weather • Estivation in warm weather Figure 25.4

33. The liver is vital in homeostasis • It assists the kidneys by • making urea from ammonia • breaking down toxic chemicals

34. Blood from the intestines flows through the liver before distribution to the rest of the body Inferiorvena cava Hepatic vein Liver • This allows the liver to adjust the blood’s chemical content Hepaticportal vessel Intestines Figure 25.13