AP Biology Unit Four Maintaining Homeostasis

1. AP Biology Unit FourMaintaining Homeostasis 2/11 – 3/29

2. Just bear with me……

3. 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.

4. 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 • Plants – homeostatic`mechanisms and how they respond

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

6. 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

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

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

9. HOMEOSTASIS

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

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

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

14. 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

15. Negative Feedback Loops RECEPTOR STIMULUS EFFECTOR RESPONSE

18. 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.

19. 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

21. 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

22. 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.

23. Negative feedback: control of sugar in the blood

24. Islets of Langerhans

25. Positive feedback:oxytocin to induce childbirth

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

27. Biological Examples of Negative Feedback Loops Thermoregulation Blood Sugar Levels Blood volume Respiratory Rate

28. Negative Feedback Loops RECEPTOR STIMULUS EFFECTOR RESPONSE

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

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

31. Freshwater: 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.

33. 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

35. Excretory system in flatworms

36. Excretory system in earthworms

37. Inhumans

38. 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.

39. 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.

40. 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.

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

42. 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.

44. Development of respiratory systems

45. 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.

46. Fish respiratory system

47. Countercurrent exchange

48. How are lungs perfected for terrestrial living?

49. lungfish

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