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AP Biology Unit Four Maintaining Homeostasis

AP Biology Unit Four Maintaining Homeostasis. BIG IDEA 2: Biological systems utilize energy and molecular building blocks to grow, to reproduce, and to maintain homeostasis. BIG IDEA 3: Living systems store, retrieve, transmit, and respond to information essential to life processes.

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AP Biology Unit Four Maintaining Homeostasis

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  1. AP Biology Unit FourMaintaining Homeostasis

  2. BIG IDEA 2: Biological systems utilize energy and molecular building blocks to grow, to reproduce, and to maintain homeostasis. BIG IDEA 3: Living systems store, retrieve, transmit, and respond to information essential to life processes. BIG IDEA 4:Biological systems interact, and these interactions possess complex properties.

  3. We will cover….. • Feedback control AGAIN! • Evolutionary development of animal organ systems to control homeostasis with the environment • Cellular signaling • Specific systems: endocrine, nervous, immune • Developmental stages and timing • Plants – homeostatic mechanisms and how they respond

  4. Organism Organization • Cells • Tissues • Organs • Organ Systems (not technically in plants) • Organism The structure of a component of an organism underlies its function.

  5. Homeostasis • occurs in ALL organisms • Involves all levels (except unicellular organisms): cells, organs, organisms • Reflects continuity and change • Shaped by evolution • Affected by disruptions • Defenses evolved to maintain

  6. Remember…. • Body systems coordinate their activities to maintain homeostasis.

  7. http://www.youtube.com/watch?v=TeSKSPPZ6Ik Boseman videos are helpful! bit.ly/homeoprezi

  8. HOMEOSTASIS

  9. behavior Timingand control control disruption Feedback loops response environment Shaped by evolution HOMEOSTASIS physiological abiotic biotic defenses development

  10. Regulator or conformer? • Regulators – control internal fluctuations (us) • Conformers – allow internal conditions to vary with environmental changes (temp in ectotherms)

  11. acclimatization • An animal’s normal range of homeostasis may change as the animal adjusts to external environmental changes

  12. Video on Feedback Loops • As you watch, take notes on the basic diagram of a negative feedback loop • What are the component parts • Use two biological examples http://www.youtube.com/watch?v=q_e6tNCW-uk

  13. Negative Feedback Loops RECEPTOR Most feed back loops are STIMULUS EFFECTOR RESPONSE

  14. In mammals, a group of neurons in the hypothalamus functions as a thermostat Fever as a response to infection can reset the hypothalamus set point.

  15. Other circulatory adjustments:Countercurrent exchange in temp regulation • Common in marine mammals and birds • the heat in the arterial blood leaving the body core is transferred to the venous blood

  16. Other thermoregulatory mechanisms • Insulation • Evaporative heat loss • Behavioral responses • Regulation of metabolic heat - endotherms use metabolic heat to maintain their body temp - ectotherm gain heat mostly from environment

  17. Raising temp metabolically • Mammals and birds regulate rate of metabolic heat production through activity and shivering. • Some mammals generate heat through nonshivering thermogenesis, rise in metabolic rate produces heat instead of ATP. • Some mammals have brown fat for rapid heat production.

  18. Negative feedback: control of sugar in the blood

  19. Islets of Langerhans

  20. Positive feedback:oxytocin to induce childbirth

  21. Ethylene in fruit ripening Has anyone told you to put a banana in the bag with your apples or pears to help them ripen?

  22. Biological Examples of Negative Feedback Loops • Thermoregulation • Blood Sugar Levels • Osmoregulation • Respiratory Rate • Blood Pressure

  23. Homeostatic mechanisms and organ systems are shaped by evolution. • Excretory systems deal with osmoregulation (water balance) and excretion of nitrogenous wastes

  24. osmoregulation Prokaryotes respond via altered gene expression to changes in the osmotic environment Protists: Many have contractile vacuoles

  25. In Fish • Freshwater Fish: Water will diffuse into the fish, so it excretes a very hypotonic (dilute) urine to expel all the excess water. Gills uptake lost salt. • A marine fish has an internal osmotic concentration lower than that of the surrounding seawater, so it tends to lose water and gain salt. It actively excretes salt out from the gills.

  26. dealing with nitrogenous wastes The excretory system in vertebrates: - maintains water, salt, and pH balance - removes nitrogenous wastes (from breakdown of protein and nucleic acids) by filtering the blood - nitrogenous waste type depends on environment

  27. Excretory system in flatworms

  28. Excretory system in earthworms

  29. Inhumans

  30. The kidney works closely with the circulatory system in that the salt content, pH, and water balance of the blood is controlled by the kidneys.

  31. Within the kidney, fluid and dissolved substances are filtered from the blood and pass through nephrons where some of the water and dissolved substances (nutrients) are reabsorbed. The remaining liquid (including toxins) and wastes form urine. Increasing salt concentration draws water out of tubule.

  32. What homeostatic mechanisms work here? Concentrated blood (too much salt, too little water) signal receptors in the hypothalamus to stimulate release of ADH (AntiDiuretic Hormone) by the pituitary gland which influences kidney to reabsorbs water, making blood more dilute.

  33. Alcohol inhibits the release of ADH, causing the kidneys to produce dilute urine.

  34. If, on the other hand, a person drinks an excess of water, the sodium in the blood becomes more dilute and the release of ADH is inhibited. The lack of ADH causes the nephrons to become practically impermeable to water, and little or no water is reabsorbed from them back into the blood. Consequently, the kidneys excrete more watery urine until the water concentration of the body fluids returns to normal.

  35. It’s really a salt thing!

  36. Osmoregulation RECEPTOR STIMULUS EFFECTOR RESPONSE

  37. Development of respiratory systems

  38. The Respiratory System • The respiratory system: • - delivers oxygen to and removes CO2 from the circulatory system and eventually the tissues • - in humans, this occurs in the alveoli of the lungs which are covered in capillaries • The respiratory system works closely with the circulatory system.

  39. Aquatic organisms such as fish: respiratory system Less Oxygen in water…. Design of gills important….

  40. Countercurrent exchange

  41. How are lungs perfected for terrestrial living?

  42. lungfish Transition…..both.

  43. How does structure correlate with the function of the parts?

  44. What homeostatic mechanisms are at work here? • Breathing is controlled by the medulla of the brainstem. It repeatedly triggers contraction of the diaphragm initiating inspiration. • The rate of breathing changes with activity level in response to carbon dioxide levels, and to a lesser extent, oxygen levels, in the blood. Carbon dioxide lowers the pH of the blood (water and CO2 make carbonic acid H2CO3). • Hemoglobin carries oxygen and also can carry bicarbonate ions (form of CO2)..

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