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Chapter 40 Homeostasis

Chapter 40 Homeostasis. Animal Form and Function . Animals provide examples of biology’s major themes diversity & unity of life form & function are interwoven evolution is the thread that ties it all together

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Chapter 40 Homeostasis

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  1. Chapter 40 Homeostasis

  2. Animal Form and Function • Animals provide examples of biology’s major themes • diversity & unity of life • form & function are interwoven • evolution is the thread that ties it all together • adaptations observed in a comparative study of animals evolved by natural selection The cold-adapted rabbit has short ears and extremities to reduce heat lost, while the heat-adapted jackrabbit has longer ears that act as heat exchangers with ambient air.

  3. Big Idea #2 Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis.

  4. Conformers vs. Regulators • 2 evolutionary paths for organisms • regulate internal environment • maintain relatively constant internal conditions • conformto external environment • allow internal conditions to fluctuate along with external changes osmoregulation thermoregulation regulator regulator conformer conformer

  5. Remember that from regular bio? Hierarchy of Structure • cells  tissues  organs  organ systems • tissues = groups of cells with common structure and function • organs = composed of different tissue types • organ systems = organs working towards the same function

  6. Organ Systems cells tissues organs organ system organism

  7. aa O2 CH CHO CO2 aa NH3 CHO O2 CH O2 aa CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 NH3 O2 CO2 CO2 CO2 NH3 aa NH3 NH3 CHO CO2 CO2 aa CH Animal systems evolved to support multicellularlife… intracellular waste Diffusion too slow! extracellular waste

  8. Homeostasis • Keeping the balance • animal body needs to coordinate many systems all at once • temperature • blood sugar levels • energy production • water balance & intracellular waste disposal • nutrients • ion balance • cell growth • maintaining a “steady state” condition

  9. Homeostasis • systems work to maintain a balance • integrated open and closed systems • requires monitoring, feedback, and response

  10. Feedback Circuits • Negative feedback • stimulus triggers control mechanism counteracting further change • reverse effect • Postitive feedback • stimulus triggers control mechanism amplifying effect • much less common • Feedforward information • changing the set point at which the desired equilibrium should be

  11. high low Negative FeedbackModel Negative Feedback hormone 1 lowersbody condition gland specific body condition raisesbody condition gland hormone 2

  12. not that common in living systems Positive Feedback

  13. FeedforwardInformation • using feedback from senses, the driver regulates the speed of a car

  14. Q10 • the temperature sensitivity of a reaction or process • = RT/RT-10 • most biological Q10 values are between 2 and 3

  15. What -therm are you? • ectotherm • animals whose body temperature are determined by external heat sources • endotherm • regulate body temperature by producing metabolic heat or prevention of heat loss • heterotherm • can behave like either • hibernating mammals

  16. BMR (Basal Metabolic Rate) • measured when a resting animal is consuming just enough to carry out its minimal life functions within the thermoneutral zone • when the metabolic rate of endotherms is low and independent of temperature

  17. hypothalamus hypothalamus high low Controlling Body Temperature nerve signals sweat dilates surfaceblood vessels body temperature (37°C) constricts surfaceblood vessels shiver nerve signals

  18. Thermoregulation • Vasodilation & vasoconstriction • adjusts blood flow • evaporative cooling Vasoconstriction Vasodilation

  19. Osmoregulation • Water balance • freshwater • hypotonic • water flow into cells & salt loss • saltwater • hypertonic • water loss from cells • land • dry environment • need to conserve water • may need to conserve salt Why do all land animals have to conserve water? • always lose water (breathing & waste) • may lose life while searching for water

  20. Animalspoison themselvesfrom the insideby digestingproteins! H O | | | H –C– C–OH N | H R Waste Disposal • What waste products? • what do we digest our food into… • carbohydrates = CHO • lipids = CHO • proteins = CHON • nucleic acids = CHOPN • relatively small amount in cell  CO2 +H2O  CO2 +H2O  CO2 +H2O + N  CO2 +H2O + P + N cellular digestion…cellular waste CO2 + H2O NH2into ammonia

  21. Nitrogenous Waste Disposal • Ammonia (NH3) • very toxic • carcinogenic • very soluble • easily crosses membranes • must dilute it & get rid of it… fast! • How you get rid of nitrogenous wastes depends on: • who you are (evolutionary relationship) • where you live (habitat)

  22. Nitrogen Waste • Aquatic organisms • can afford to lose water • ammonia • most toxic • Terrestrial • need to conserve water • urea • less toxic • Terrestrial egglayers • need to conserve most water • uric acid • least toxic

  23. Any Questions?

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