Animal Form and Function ch 40

1. Animal Form and Functionch 40

2. What problems do all three share? Differences?

3. Animals come in a variety of sizes and shapes yet all share similar problems • obtain oxygen, food, get rid of waste (exchange with environment) • fight infection • reproduce • homeostasis

4. I. Correlation between Animal Form and Function • Form fits function at all the levels of life, from molecules to organisms. • What limits animal form? • Physical laws that affect strength, movement, heat exchange, diffusion

5. A. Exchange with the Environment • Exchange of nutrients, waste, gases occurs at the cell membrane of all cells • Cell membrane MUST be bathed in aqueous environment for diffusion • What constrains this diffusion? • Surface area to volume ratio of cells

6. 1. Single celled organisms • Enough surface area in contact with environment to service cytoplasm

7. 2. simple animals with gastrovascular cavity (cnidarians, flatworms) • body walls only 2 cell layers thick so enough surface area in contact with environment

8. 3. more complex and larger animals have organ systems for exchange • respiratory • digestive • excretory • have highly folded internal surfaces for exchange • these are evolutionary adaptations for increased size and help animals in variable environments maintain steady internal conditions

10. II. Coordination and Control • organ system activity is under control of nervous and endocrine systems • these involve cell communication and help keep an organism in homeostasis

11. What do these 2 have in common?

12. III. Feedback Control Maintains Homeostasis A. Regulators and Conformers • Regulators • Use internal mechanisms to maintain homeostasis • Conformers • Internal conditions change along with external environment

13. Explain the graph:

14. Animals can be regulators for one stimulus and conformers for another • (fish and water)

15. B. Homeostasis • ability of an organism to maintain constant internal conditions • body temp, blood pH, blood glucose etc in humans • involves feedback loops

17. 1. Negative feedback loop • Most homeostatic control mechanisms • Control mechanism that moves AWAY from the stimulus • Ex: body temp • Explain:

18. 2. Positive feedback loop • Only stressful situations • Control mechanism that moves TOWARDS the stimulus • Ex: childbirth

19. IV. Homeostatic control of thermoregulation involves form, function and behavior • Thermoregulation = process by which animals maintain an internal body temp within a specific range • All enzymatic and physiological processes are sensitive to changes in temp

20. How do these animals regulate body temp?

21. A. Endothermyand Ectothermy • Endotherms: gain heat thru metabolism • Ectotherms: gain body heat externally • Endotherms must consume more food than ectotherms • Ectotherms can tolerate greater fluctuations in body temp than endotherms

22. Graph body temp as a function of external temp for endotherms and exotherms

23. B. Poikilothermsvs Homeotherms • Poikilotherms body temp changes with environment • Homeotherms body temp is relatively constant

24. Is an angelfish that inhabits the waters of the Caribbean a poikilotherm or homeotherm? Endotherm or ectotherm?

25. Is a hibernating chipmunk a poikilotherm or homeotherm? Endotherm or ectotherm?

26. C. Exchanging Heat with the Environment • In order to thermoregulate, organisms must gain or lose heat with the environment • Which way does heat move?

27. Which mechanisms result in heat loss? Which mechanisms result in heat gain?

28. What must occur in order to maintain constant body temp? • In order to maintain body temp, heat loss to environment and heat gain from environment must be balanced

29. B. Mechanisms that Regulate Body Temp 1. Insulation (endotherms) • Hair, fur, feathers, fat layers • Raised fur and feathers traps heat near skin • Excess fat near surface prevents core body heat loss in marine mammals • Oily secretions in many birds and mammals that spend time in water prevents heat loss

31. 2. dilating or constricting blood vessels (endotherms and a few ectotherms): • Vasodilation increases the diameter of the blood vessels. This increases vessel surface area and allows excess heat to be lost • Vasoconstriction constricts the diameter of blood vessels. This decreases vessel surface area and prevents heat from being lost

33. What do they have in common?

34. 3. evaporative cooling (endotherms): • Humans lose excess heat thru their skin (sweating) • Furry mammals lose excess heat thru panting. • This is due to the excess heat absorbed to evaporate water . Why?

35. 4. Adjusting metabolic heat production (endotherms and a few ectotherms) • Thermogenesis: adjustment of metabolic heat production to maintain body temp • Shivering thermogenesis: increased muscle contraction due to increased metabolic activity • Nonshivering thermogenesis: hormonal increase in metabolism in brown fat cells with the production of heat vs ATP

37. Graph O2 consumption as a function of external temp for endotherms and exotherms. What does O2 consumption measure?

38. 5. Behavioral changes • Ectotherms change locations • Hibernation/migration

39. V. Hormonal Control of Thermoregulation • Under control of hypothalamus

40. VI. Energy requirements are related to size, activity, and environment • Bioenergetics = flow and transformation of energy in an animal • determines how much food is needed and relates to animal’s size, activity, and environment

42. metabolic rate: amount of NRG animal uses in a given time • how can metabolic rate be measured? • basal metabolic rate: minimum metabolic rate of endotherm in fasting, nonstressed, nongrowing, constant temp conditions • standard metabolic rate: minimum metabolic rate of ectotherm in fasting, nonstressed, nongrowing, constant temp conditions

43. 1. Thermoregulation and metabolic rate • Who has a higher minimum metabolic rate, endotherm or ectotherm? Why?

44. 2. Size and metabolic rate What is this graph telling?

45. What is this graph telling?

46. Smaller mammals have a higher metabolic rate per gram of body and therefore a higher breathing rate, heart rate • Who consumes more food per unit body mass?