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Controlling the Internal Environment

Controlling the Internal Environment. Thermoregulation Osmoregulation Excretion. Ectothermic Endothermic. Poikilothermic Homeothermic. Thermoregulation. Heat Exchange. Heat Exchange. Conduction - direct transfer of heat

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Controlling the Internal Environment

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  1. Controlling the Internal Environment Thermoregulation Osmoregulation Excretion

  2. Ectothermic Endothermic Poikilothermic Homeothermic Thermoregulation

  3. Heat Exchange

  4. Heat Exchange • Conduction - direct transfer of heat • Convection - transfer of heat by the movement of air or water across a surface • Radiation - emission of electromagnetic waves • Evaporation - loss of heat from changing a liquid into a gas

  5. Body Temp vs. Ambient Temp

  6. Thermoregulation Adjustments • Adjusting the rate of heat exchange • vasodilation/vasoconstiction • countercurrent heat exchange • Cooling by evaporation • Behavioral responses • Changing the rate of metabolic heat production

  7. Endothermic Animals • Invertebrates • Large flying insects • Honeybees

  8. Endothermic Animals • Fish • Bluefin tuna • Swordfish • Great white shark • Countercurrent heat exchange

  9. Amphibians and Reptiles • Most are ectothermic • regulate temperature by behavior

  10. Mammals and Birds • Contraction of muscles • moving • shivering • Nonshivering thermogenesis • triggered by hormones

  11. High body temperature hypothalamus activates skin blood vessels to dilate and the sweat glands to produce sweat Low body temperature hypothalamus activates skin blood vessels to constrict and the skeletal muscles to shiver Feedback Mechanisms

  12. Temperature Range Adjustments • Slow changes • acclimatization (enzymes and membranes) • Fast changes • heat-shock proteins

  13. Metabolic Cycles • Torpor • Hibernation • Aestivation

  14. Osmoregulation • Osmoconformers vs. Osmoregulators

  15. Osmoregulation • Marine Fish • hypoosmotic • lose water to environment • must excrete salt • small amounts of urine • Freshwater Fish • hyperosmotic • gain water from environment • must take in salt • large amounts of urine

  16. Functions of the Excretory System • Filtration • Reabsorption • Secretion • Excretion

  17. Excretion of Nitrogenous Waste • Ammonia • Urea • Uric Acid

  18. Invertebrate Structures • Protonephridia (flame cells) • network of closed tubules • used mostly for osmoregulation • found in platyhelminthes, some annelids, mollusk larvae

  19. Invertebrate Structures • Open tubules surrounded by a nephrostome • Osmoregulation and excretion • Found in annelids

  20. Invertebrate Structures • Malpighian Tubules • Open into the digestive tract • Osmoregulation and excretion • Insects and terrestrial arthropods

  21. Excretory SystemsOrigins in Vertebrates • Pronephros, Mesonephros, Metanephros

  22. Vertebrate Excretory Systems • Pronephros • adult hagfish, embryonic fish, amphibians, reptiles, birds, mammals • Mesonephros • adult lamprey, fish, amphibians, embryonic reptiles, birds, mammals • Metanephros • adult reptiles, birds, mammals

  23. The Human Excretory System • Kidneys • Ureters • Urinary Bladder • Urethra

  24. Blood Filtrate to Urine • Bowman’s Capsule and the Glomerulus • (filters the blood) • Proximal tubule • reabsorbed (NaCl, Potassium, Water, Nutrients) • secretes ( ammonia) • regulates (pH)

  25. Blood Filtrate to Urine • Loop of Henle • Descending loop • reabsorbed (water) • Ascending loop • reabsorbed (NaCl)

  26. Blood Filtrate to Urine • Distal tubule • reabsorbed (NaCl, Water) • secrete (potassium) • regulate (pH) • Collecting duct • reabsorbed (NaCl, Water, Urea)

  27. Control of the Kidney • Antidiuretic hormone (ADH) • water reabsorption • Renin-angiotensin-aldosterone system (RAAS) • water reabsorption • Atrialnatiuretic Factor (ANF) • inhibits the release of renin

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