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Excretory Systems Ch. 44

Excretory Systems Ch. 44. Regulating Water Loss and Solute Concentrations. 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)

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Excretory Systems Ch. 44

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  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 #1 • 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. Water Balance and waste disposal • Osmoregulation: • management of the body’s water content and solute composition (hyper, iso, hypo tonic soln’s) • 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 NH3 and CO2) • Uric acid: birds, insects, many reptiles, land snails

  5. Water Balance and waste disposal

  6. Osmoregulators • Osmoconformer: no active adjustment of internal osmolarity (marine animals); isoosmotic to environment • Osmoregulator: adjust internal osmolarity (freshwater, marine, terrestrial) • Freshwater fishes (hyperosmotic)- gains water, loses; excretes large amounts of urine salt vs. marine fishes (hypo-osmotic)- loses water, gains salt; drinks large amount of saltwater

  7. Osmoregulators

  8. Excretory Systems • Production of urine by 2 steps: -Filtration (non-selective) -Reabsorption (secretion of solutes) • Protonephridia ~ flatworms (“flame-bulb” systems) • Metanephridia ~ annelids (ciliated funnel system) • Malpighian tubules ~ insects (tubes in digestive tract) • Kidneys ~ vertebrates

  9. Excretory Systems

  10. Kidney Functional Units • Renal artery/vein: kidney blood flow • Ureter: urine excretory duct • Urinary bladder: urine storage • Urethra: urine elimination tube • Renal cortex (outer region) • Renal medulla (inner region) • Nephron: functional unit of kidney • Cortical nephrons (cortex; 80%) • Juxtamedullary nephrons (medulla; 20%)

  11. Nephron Structure • Afferent arteriole: supplies blood to nephron from renal artery • Glomerulus: ball of capillaries • Efferent arteriole: blood from glomerulus • Bowman’s capsule: surrounds glomerulus • 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

  12. Overview of Mammalian Nephron Function

  13. The Human Kidney & Nephron

  14. Kidney regulation: hormones • Antidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); 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

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