BIOL 152 1st Edition Lecture 23 Outline of Last Lecture Circulation Outline of Current Lecture Osmoregulation Current Lecture Osmoregulation Osmoregulation and Excretion Homeostasis o Concentrations of blood solutes maintained within narrow limits o Threats posed to o Freshwater fish environment diluting body fluids o Marine desert animals environment depleting body fluids Two key homeostatic processes 1 Osmoregulation controlled movement of solutes between external environment and internal fluids Water follows solutes via osmosis 2 Excretion disposal of N containing wastes Why osmoregulation o Electrolyte balance is essential for cellular processes and life itself o NaCl compound that dissociates into ions when dissolved in water o Cells require precise concentrations of electrolytes to function normally Osmolarity mosm L Isotonic isosmotic water balance Hypertonic hyperosmotic water goes out Hypotonic hypoosmotic water goes in Osmoconformer isosmotic to the environment These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Osmoregulation internally regulate isosmotic conditions independent of its environment 5 of our BMR 30 for brine shrimp in Salt Lake Stenohaline cannot tolerate changes in environment Euryhaline can survive large fluctuations in environment o Saltwater fish o Freshwater fish Osmoregulation in Terrestrial animals o Lose water Gas exchange excretion and through skin o Adaptations to minimize water loss o Waxy outer layers shells layers of dead keratinized cells nocturnal habit internal gas exchange kidneys o Gain water water intake metabolism food Nitrogenous Wastes o Metabolic wastes from proteins and nucleic acids o Must be dissolved in water o Ammonia remove nitrogen in this form need a lot of water for intake so mainly done by aquatic species o Urea mammals sharks adult amphibians product of combining ammonia and carbon dioxide produced in liver o Uric acid birds reptiles snails Mix of feces and water Release of nitrogenous waste For little access to water Evolution and Nitrogenous Wastes 1 Mode of Reproduction solubility of waste 2 Habitat aquatic versus terrestrial and dry versus wet conditions Key steps in excretion of filtrate 1 Excretory tubule collects filtrate from blood 2 Transport epithelium reabsorbs substances from filtrate 3 Toxins and other wastes are extracted from body fluid into excretory tubule 4 The filtrate leaves the body Kidneys make up 5 of body weight yet receive 25 of cardiac output EVERY DAY o 1100 2000 L of blood moves through kidneys o 180 L of filtrate is collected o 99 of water sugars vitamins organic nutrients are reabsorbed o Leaving 1 5 L of urine
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