Chapter 40: Basic Principles of Animal Form and Function

1. Chapter 40:Basic Principles of AnimalForm and Function

2. 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. The comparative study of animals reveals that form and function are closely correlated

4. Natural selection can fit structure, anatomy, to function, physiology by selecting, over many generations, what works best among the available variations in a population

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

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 Tuna Shark Penguin Dolphin 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

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 (b) Two cell layers

11. Organisms with more complex body plans have highly folded internal surfaces specialized for exchanging materials Respiratory system Circulatory system Digestive system Excretory system

12. 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

13. 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

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

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

16. 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

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

18. 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

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

20. Organ systems in mammals:

21. 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

22. Bioenergetics --The flow of energy through an animal • 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

23. 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

24. After the energetic needs of staying alive are met by 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 Heat

25. 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

26. (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. • One way to measure metabolic rate isto determine the amount of oxygen consumed or carbon dioxide produced by an organism

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

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

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

30. Influences on Metabolic Rate • The metabolic rates of animals are affected by many factors

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

32. 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

33. 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

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

35. 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

36. 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

37. Regulating and Conforming • Regulating and conforming are two extremes in how animals cope with environmental fluctuations

38. 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 (endotherms) • An animal is said to be a conformer if it allows its internal condition to vary with certain external changes (ectotherms)

39. Mechanisms of Homeostasis • Mechanisms of homeostasis moderate changes in the internal environment

40. 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

41. Most homeostatic control systems function by negative feedback where buildup of the end product of the system shuts the system off

42. A second type of homeostatic control system is positive feedback, which involves a change in some variable that triggers mechanisms that amplify the change Positive Feedback and Global Warming

43. 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

44. Ectotherms and Endotherms • Ectotherms • Include most invertebrates, fishes, amphibians, and non-bird reptiles • Endotherms • Include birds and mammals

45. 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

46. 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

47. Radiation is the emission of electromagnetic waves by all objects warmer than absolute zero. Radiation can transfer heat between objects that are not in direct contact, as when a lizard absorbs heat radiating from the sun. Evaporation is the removal of heat from the surface of a liquid that is losing some of its molecules as gas. Evaporation of water from a lizard’s moist surfaces that are exposed to the environment has a strong cooling effect. Conduction is the direct transfer of thermal motion (heat) between molecules of objects in direct contact with each other, as when a lizard sits on a hot rock. Convection is the transfer of heat by the movement of air or liquid past a surface, as when a breeze contributes to heat loss from a lizard’s dry skin, or blood moves heat from the body core to the extremities. Modes of Heat Exchange • Organisms exchange heat by four physical processes Figure 40.13

48. Balancing Heat Loss and Gain • Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss

49. Insulation • Insulation, which is a major thermoregulatory adaptation in mammals and birds • Reduces the flow of heat between an animal and its environment • May include feathers, fur, or blubber

50. In mammals, the integumentary system acts as insulating material Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle