Chapter 40

1. Chapter 40 Basic Principles of Animal Form and Function

2. Anatomy & Physiology • Anatomy – study of STRUCTURE • Physiology – study of FUNCTION

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

4. Convergent Evolution in Animals • 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

5. 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

6. Diffusion (a) Single cell Contact with the Environment • 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

7. Contact with the Environment • 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

8. Contact with the Environment 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

9. Function Correlates with Structure in Animal Tissues • 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

10. 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

11. 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

12. 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

13. 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

14. 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 Organs and Organ Systems • In all but the simplest animals different tissues are organized into organs • In some organs the tissues are arranged in layers Figure 40.6

15. Body Cavities in Mammals • Thoracic:houses lungs, heart • Abdominal: “guts” – stomach, liver, intestines, pancreas, reproductive organs of females, bladder • In higher animals, thoracic and abdominal cavities separated by diaphragm • Both cavities are lined by mesentery – connective tissue that binds and supports organs

16. Thoracic Cavity

17. Abdominal Cavity

18. Organ Systems in Mammals • Representing a level of organization higher than organs organ systems carry out the major body functions of most animals Table 40.1

19. Bioenergetics of Animals • 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 • The flow of energy through an animal, its bioenergetics, ultimately limits the animal’s behavior, growth, and reproduction – which determines how much food it needs • Studying an animal’s bioenergetics tells us a great deal about the animal’s adaptations

20. Overview: Bioenergetics of an Animal • 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. 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

21. 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 • An animal’s metabolic rate • Is closely related to its bioenergetic strategy

22. (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 Quantifying Energy Use • One way to measure metabolic rate is to determine the amount of oxygen consumed or carbon dioxide produced by an organism

23. Endothermic & Ectothermic Animals • Birds and mammals are mainly endothermic, meaning that • Their bodies are warmed mostly by heat generated by metabolism • They typically have higher metabolic rates • Amphibians and reptiles other than birds are ectothermic, meaning that • They gain their heat mostly from external sources • They have lower metabolic rates

24. Influences on Metabolic Rate • The metabolic rates of animals • Are affected by many factors • Metabolic rate per gram • Is inversely related to body size among similar animals

25. 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

26. 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 Maximum Metabolic Rate in Animals • In general, an animal’s maximum possible metabolic rate is inversely related to the duration of the activity Figure 40.9

27. 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) Energy Budgets • Different species of animals use the energy and materials in food in different ways, depending on their environment • An animal’s use of energy is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction Figure 40.10a, b

28. Regulating & Conforming: Homeostasis • 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

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

30. 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 Mechanisms of Homeostasis • Mechanisms of homeostasis moderate changes in the internal environment • A homeostatic control system has three functional components: a receptor, a control center, and an effector Figure 40.11

31. Positive/Negative Feedback and Homeostasis • Most homeostatic control systems function by negative feedback • Where buildup of the end product of the system shuts the system off • A second type of homeostatic control system is positive feedback • Which involves a change in some variable that triggers mechanisms that amplify the change

32. Control of Body Temperature – Negative Feedback

33. Thermoregulation • 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 • Ectotherms include most invertebrates, fishes, amphibians, and non-bird reptiles • Endotherms include birds and mammals

34. 40 River otter (endotherm) 30 Body temperature (°C) 20 Largemouth bass (ectotherm) 10 0 10 20 30 40 Ambient (environmental) temperature (°C) Ectotherms • In general, ectotherms tolerate greater variation in internal temperature than endotherms Figure 40.12

35. Endotherms • Endothermy is more energetically expensive than ectothermy • But buffers animals’ internal temperatures against external fluctuations • And enables the animals to maintain a high level of aerobic metabolism

36. Feedback Mechanisms in Thermoregulation • Mammals regulate their body temperature • By a complex negative feedback system that involves several organ systems