Chapter 40

1. Chapter 40 Basic Principles of Animal Form and Function

2. Overview: Diverse Forms, Common Challenges • Animals inhabit almost every part of the biosphere • Despite their amazing diversity, • All animals face a similar set of problems, including how to nourish themselves

3. Figure 40.1 The comparative study of animals • Reveals that form and function are closely correlated

4. Natural selection can fit structure, i.e. anatomy, to function, i.e. physiology • By selecting, over many generations, what works best among the available variations in a population Narural Selection and Adaptation

5. Concept 40.1: Physical laws and the environment constrain animal size and shape • Physical laws and the need to exchange materials with the environment • Place certain limits on the range of animal forms • Must be multicellular

6. Physical Laws and Animal Form • The ability to perform certain actions • Depends on an animal’s shape and size

7. Evolutionary convergence • Reflects different species’ independent adaptation to a similar environmental challenge (a) Tuna (b) Shark (c) Penguin (d) Dolphin Figure 40.2a–e (e) Seal

8. Exchange with the Environment • An animal’s size and shape • Have a direct effect on how the animal exchanges energy and materials with its surroundings • Exchange with the environment occurs as substances dissolved in the aqueous medium • Diffuse and are transported across the cells’ plasma membranes

9. Diffusion (a) Single cell • A single-celled protist living in water • Has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Figure 40.3a

10. Multicellular organisms with a sac body plan • Have body walls that are only two cells thick, facilitating diffusion of materials Mouth Gastrovascular cavity Diffusion Diffusion Figure 40.3b (b) Two cell layers

11. Organisms with more complex body plans • Have highly folded internal surfaces specialized for exchanging materials

12. External environment Food CO2 O2 Mouth Animal body Respiratory system Blood 50 µm 0.5 cm A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM). Cells Heart Nutrients Circulatory system 10 µm Interstitial fluid Digestive system Excretory system The lining of the small intestine, a diges- tive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM). Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). Anus Unabsorbed matter (feces) Metabolic waste products (urine) Figure 40.4

13. Concept 40.2: Animal form and function are correlated at all levels of organization • Animals are composed of cells • Groups of cells with a common structure and function • Make up tissues • Different tissues make up organs • Which together make up organ systems

14. Tissue Structure and Function • Different types of tissues • Have different structures that are suited to their functions • Tissues are classified into four main categories • Epithelial, connective, muscle, and nervous

15. 1. Epithelial Tissue • Epithelial tissue • Covers the outside of the body and lines organs and cavities within the body • Contains cells that are closely joined

16. Epithelial tissue EPITHELIAL TISSUE Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function. A simple columnar epithelium A stratified columnar epithelium A pseudostratified ciliated columnar epithelium Stratified squamous epithelia Cuboidal epithelia Simple squamous epithelia Basement membrane Figure 40.5 40 µm

17. 2. Connective Tissue • Connective tissue • Functions mainly to bind and support other tissues • Contains sparsely packed cells scattered throughout an extracellular matrix

18. CONNECTIVE TISSUE • Connective tissue 100 µm Chondrocytes Collagenous fiber Chondroitin sulfate Elastic fiber 100 µm Cartilage Loose connective tissue Adipose tissue Fibrous connective tissue Fat droplets Nuclei 150 µm 30 µm Blood Bone Central canal Red blood cells White blood cell Osteon Plasma Figure 40.5 700 µm 55 µm

19. 3. Muscle Tissue • Muscle tissue • Is composed of long cells called muscle fibers capable of contracting in response to nerve signals • Is divided in the vertebrate body into three types: skeletal, cardiac, and smooth

20. 4. Nervous Tissue • Nervous tissue • Senses stimuli and transmits signals throughout the animal

21. Muscle and nervous tissue MUSCLE TISSUE 100 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere Cardiac muscle 50 µm Nucleus Intercalated disk Smooth muscle Nucleus Muscle fibers 25 µm NERVOUS TISSUE Process Neurons Cell body Nucleus Figure 40.5 50 µm

22. Organs and Organ Systems • In all but the simplest animals • Different tissues are organized into organs

23. Lumen of stomach Mucosa. The mucosa is an epithelial layer that lines the lumen. Submucosa. The submucosa is a matrix of connective tissue that contains blood vessels and nerves. Muscularis. The muscularis consistsmainly of smooth muscle tissue. Serosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue. 0.2 mm • In some organs • The tissues are arranged in layers Figure 40.6

24. Representing a level of organization higher than organs • Organ systems carry out the major body functions of most animals

25. 11 Organ systems in mammals Table 40.1

26. Concept 40.3: Animals use the chemical energy in food to sustain form and function • All organisms require chemical energy for • Growth, repair, physiological processes, regulation, and reproduction

27. Bioenergetics • The flow of energy through an animal = its bioenergetics • Ultimately limits the animal’s behavior, growth, and reproduction • Determines how much food it needs • Studying an animal’s bioenergetics • Tells us a great deal about the animal’s adaptations

28. Energy Sources and Allocation • Animals harvest chemical energy • From the food they eat • Once food has been digested, the energy-containing molecules • Are usually used to make ATP, which powers cellular work

29. After the energetic needs of staying alive are met • Any remaining molecules from food can be used in biosynthesis Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in urine Cellular respiration Carbon skeletons Heat ATP Biosynthesis: growth, storage, and reproduction Cellular work Heat Figure 40.7 Heat

30. Quantifying Energy Use • An animal’s metabolic rate • Is the amount of energy an animal uses in a unit of time • Can be measured in a variety of ways

31. (a) This photograph shows a ghost crab in arespirometer. Temperature is held constant in thechamber, with air of known O2 concentration flow-ing through. The crab’s metabolic rate is calculatedfrom the difference between the amount of O2entering and the amount of O2 leaving therespirometer. This crab is on a treadmill, runningat a constant speed as measurements are made. (b) Similarly, the metabolic rate of a manfitted with a breathing apparatus isbeing monitored while he works outon a stationary bike. Figure 40.8a, b • One way to measure metabolic rate • Is to determine the amount of oxygen consumed or carbon dioxide produced by an organism

32. Bioenergetic Strategies • An animal’s metabolic rate • Is closely related to its bioenergetic strategy

33. Birds and mammals are mainly endothermic, meaning that • Their bodies are warmed mostly by heat generated by metabolism • They typically have higher metabolic rates

34. Amphibians and reptiles (other than birds) are ectothermic, meaning that • They gain their heat mostly from external sources • They have lower metabolic rates

35. Influences on Metabolic Rate • The metabolic rates of animals • Are affected by many factors

36. Size and Metabolic Rate • Metabolic rate per gram • Is inversely related to body size among similar animals

37. Activity and Metabolic Rate • The basal metabolic rate (BMR) • Is the metabolic rate of an endotherm at rest • The standard metabolic rate (SMR) • Is the metabolic rate of an ectotherm at rest • For both endotherms and ectotherms • Activity has a large effect on metabolic rate

38. 500 A = 60-kg alligator A H 100 H A H = 60-kg human 50 H Maximum metabolic rate (kcal/min; log scale) 10 H H 5 A 1 A A 0.5 0.1 1 minute 1 second 1 hour 1 day 1 week Time interval Key Existing intracellular ATP ATP from glycolysis ATP from aerobic respiration • In general, an animal’s maximum possible metabolic rate • Is inversely related to the duration of the activity Figure 40.9

39. Energy Budgets • Different species of animals • Use the energy and materials in food in different ways, depending on their environment

40. Endotherms Ectotherm Reproduction 800,000 Temperature regulation costs Basal metabolic rate Growth 340,000 Activity costs Annual energy expenditure (kcal/yr) 8,000 4,000 0.025-kg female deer mouse from temperate North America 4-kg male Adélie penguin from Antarctica (brooding) 60-kg female human from temperate climate 4-kg female python from Australia (a) Total annual energy expenditures 438 Human 233 Energy expenditure per unit mass (kcal/kg•day) Python Deer mouse Adélie penguin 36.5 5.5 Energy expenditures per unit mass (kcal/kg•day) (b) • An animal’s use of energy • Is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction Figure 40.10a, b

41. Concept 40.4: Animals regulate their internal environment within relatively narrow limits • The internal environment of vertebrates • Is called the interstitial fluid, and is very different from the external environment • Homeostasis is a balance between external changes • And the animal’s internal control mechanisms that oppose the changes

42. Regulating and Conforming • Regulating and conforming • Are two extremes in how animals cope with environmental fluctuations

43. An animal is said to be a regulator • If it uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation • An animal is said to be a conformer • If it allows its internal condition to vary with certain external changes

44. Mechanisms of Homeostasis • Mechanisms of homeostasis • Moderate changes in the internal environment

45. Response No heat produced Heater turned off Room temperature decreases Set point Too hot Set point Too cold Set point Control center: thermostat Room temperature increases Heater turned on Response Heat produced • A homeostatic control system has three functional components • A receptor, a control center, and an effector Figure 40.11

46. Most homeostatic control systems function by negative feedback • Where buildup of the end product of the system shuts the system off

47. A second type of homeostatic control system is positive feedback • Which involves a change in some variable that triggers mechanisms that amplify the change • Often disadvantageous: autoimmune disease

48. Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior • Thermoregulation • Is the process by which animals maintain an internal temperature within a tolerable range

49. Ectotherms and Endotherms • Ectotherms (conformer) • Include most invertebrates, fishes, amphibians, and non-bird reptiles • Endotherms (regulator) • Include birds and mammals

50. 40 River otter (endotherm) 30 Body temperature (°C) 20 Largemouth bass (ectotherm) 10 0 10 20 30 40 Ambient (environmental) temperature (°C) • In general, ectotherms • Tolerate greater variation in internal temperature than endotherms Figure 40.12