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Chapter 44

Chapter 44. Regulating the Internal Environment. Homeostasis : regulation of internal environment. Thermoregulation internal temperature Osmoregulation solute and water balance Excretion nitrogen containing waste. Regulation of body temperature.

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Chapter 44

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  1. Chapter 44 • Regulating the Internal Environment

  2. Homeostasis: regulation of internal environment • Thermoregulation internal temperature • Osmoregulation solute and water balance • Excretion nitrogen containing waste

  3. Regulation of body temperature • Thermoregulation • 4 physical processes: • Conduction: transfer of heat between molecules of body and environment • Convection: transfer of heat as water/air move across body surface • Radiation: transfer of heat produced by organisms • Evaporation: loss of heat from liquid to gas • Sources of body heat: • Ectothermic: determined by environment • Endothermic: high metabolic rate generates high body heat

  4. Regulation during environmental extremes • Torpor: physiological state of low activity; decrease in metabolic rate • 1- Hibernation: long term or winter torpor (winter cold and food scarcity); bears, squirrels • 2- Estivation: short term or summer torpor (high temperatures and water scarcity); fish, amphibians, reptiles • Both often triggered by length of daylight

  5. Water balance and waste disposal • Osmoregulation: management of the body’s water content and solute composition • Nitrogenous wastes: breakdown products of proteins and nucleic acids; ammonia-very toxic • 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

  6. Low toxicity, so lots of water is not needed, Liver combines amonia with CO2 Disadvantage, energy is needed Low toxicity, insoluble in water, semi-solid so little water loss, more energy needed Very Toxic, need access to lots of water to keep concentration low

  7. 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 (hypoosmotic)- loses water, gains salt; drinks large amount of saltwater

  8. Takes in salt with the water, needs to keep the water and get rid of the salt, keep the water, result less urine I’m hypoosmotic (I get rid of less water)

  9. Takes in fresh water and ions, needs to keep the ions and get rid of excess, result lots of urine I’m hyperosmotic (I get rid of more water)

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

  11. Flatworm: Phylum Platyhelminthes Dead-end tube Draws water and solutes in from the interstitial fluid, filters it, moves urine outward through the tubule, exits through openings

  12. Earthworm: Annelids Metanephridium: excretory and osmoregulatory

  13. Insects and other terrestrial Arthropods Immersed in hemolymph: (circulatory fluid) Key adaptation that contributed to the success of these animals on land

  14. 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%)

  15. Nephron Structure http://www.lakemichigancollege.edu/liberal/bio/anat/urin.html • 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

  16. Basic Nephron Function http://www.biologymad.com/resources/kidney.swf http://www.getbodysmart.com/ap/urinarysystem/kidney/externalanatomy/tutorial.html

  17. Nephron Function, I • Proximal tubule: secretion and reabsorption http://www.sumanasinc.com/webcontent/animations/content/kidney.html

  18. Nephron Function, II • Loop of Henle: reabsorption of water and salt • Distal tubule: secretion and reabsorption http://www.physiology.ubc.ca/undergrad_files/urine.swf

  19. Nephron Function, III • Collecting duct: reabsorbs water, salt, some urea http://www.physiology.ubc.ca/undergrad_files/transport.swf

  20. Kidney regulation: hormones http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter20/animation__hormonal_communication.html • 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 http://www.health.bcu.ac.uk/physiology/renalsystem.htm#top http://www.wisc-online.com/objects/AP2204/AP2204.swf

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