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Chapter 40: Basic Principles of Animal Form and Function 40.1 Form and Function • Anatomy is the study of the biological form of an organism • Physiology is the study of the biological functions an organism performs • The comparative study of animals reveals that form and function are closely correlated • Many different animal body plans have evolved and are determined by the genome Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-2 The ability to perform certain actions depends on an animal’s shape, size, and environment (a) Tuna (b) Penguin Physical laws impose constraints on animal size and shape (c) Seal • Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells’ plasma membranes • A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Video: Hydra Eating Daphnia Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-3 An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings Exchange Mouth Gastrovascular cavity Exchange Exchange 0.15 mm Exchange with the Environment1.5 mm (a) Single cell (b) Two layers of cells Fig. 40-4 0.5 cm External environment CO2 Food O2 Mouth Animal body Respiratory system 50 µm More complex organisms have highly folded internal surfaces for exchanging materials Lung tissue Nutrients Heart Cells Circulatory system 10 µm Interstitial fluid Digestive system Excretory system Lining of small intestine Kidney tubules Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Hierarchical Organization of Body Plans • Most animals are composed of specialized cells organized into tissues that have different functions • Tissues make up organs, which together make up organ systems • In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells • A complex body plan helps an animal in a variable environment to maintain a relatively stable internal environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings I. Animal Tissues A. Epithelial tissue: provides outer covering of the body and lines the organs and cavities within the body 1. Bottom layer attaches to the noncellular basement 2. types are classified by shape and layers 3. Some specialized to absorb/secrete. Some have cilia. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-5a Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Fig. 40-5b Apical surface Basal surface Basal lamina 40 µm Fig. 40-5c B. Connective Tissue : live cells are scattered in a nonliving matrix Loose connective tissue Chondrocytes Cartilage Elastic fiber Chondroitin sulfate Nuclei Fat droplets Adipose tissue Osteon 150 µm Fibrous connective tissue 30 µm 100 µm 120 µm Collagenous fiber White blood cells Blood 55 µm 700 µm Bone Central canal Plasma Red blood cells Fig. 40-5d Collagenous fiber 1. Loose connective tissue: binds epithelia to other tissues, holds organs in place. 120 µm a. Collagen fibers: strong (skin) b. Elastic fibers: retractable property c. Reticular fibers: join Elastic fiber connective tissue to adjacent tissues (lattice) Loose connective tissue Fig. 40-5h 2. Adipose tissue stores fat for insulation and fuel 150 µm Fat droplets Adipose tissue Fig. 40-5e 3. Fibrous connective tissue: dense collagen fibers a. tendons: muscles to bones (little flexibility) b. ligaments: bone to bones at joints (more flexible) 30 µm Nuclei Fibrous connective tissue Fig. 40-5g 4. Cartilage is a strong and flexible support material (chondrocytes embedded in chondrin and collagen fibers) 100 µm Chondrocytes Chondroitin sulfate Cartilage Fig. 40-5f 5. Bone: osteocytes embedded in collagen and mineral deposits: Haversian systems 700 µm Osteon Central canal Bone Fig. 40-5i 6. Blood is composed of blood cells and cell fragments in blood plasma 55 µm White blood cells Plasma Blood Red blood cells Fig. 40-5j C. Muscle Tissue: long cells capable of contraction Multiple nuclei Muscle fiber Sarcomere Skeletal muscle Nucleus 100 µm Intercalated disk 50 µm Cardiac muscle Nucleus Smooth muscle Muscle fibers 25 µm Fig. 40-5k Multiple nuclei Muscle fiber Sarcomere 100 µm 1. Skeletal (striated) muscle: voluntary movement Fig. 40-5m Nucleus Intercalated disk 50 µm 2. Cardiac muscle: branched striated muscle of the heart Fig. 40-5l Nucleus Muscle fibers 25 µm 3. Smooth muscle: slower, involuntary movement D. Nervous Tissue • Nervous tissue senses stimuli and transmits signals throughout the animal • Nervous tissue contains: – Neurons, or nerve cells, that transmit nerve impulses – Glial cells, or glia, that help nourish, insulate, and replenish neurons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-5n Nervous Tissue 40 µm Dendrites Cell body Glial cells Axon Neuron Axons Blood vessel 15 µm 40.2 Coordination and Control: depend on the endocrine system and the nervous system • The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood • A hormone may affect one or more regions throughout the body • Hormones are relatively slow acting, but can have long-lasting effects Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coordination and Control • The nervous system transmits information between specific locations (depends on a signal’s pathway) • Nerve signal transmission is very fast • Nerve impulses can be received by neurons, muscle cells, and endocrine cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Homeostasis • Animals manage their internal environment by regulating or conforming to the external environment • Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment • In humans: – body temperature, – blood pH, and – glucose concentration are each maintained at a constant level Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mechanisms of Homeostasis (think thermostat) • Mechanisms of homeostasis moderate changes in the internal environment • For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response • The response returns the variable to the set point Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Feedback Loops in Homeostasis • Negative feedback- a change triggers a control mechanism that counteracts the effect of the change (ex. body temperature) – Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off • Positive feedback-a change triggers a mechanism that amplifies the response (ex. childbirth) – do not usually contribute to homeostasis Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 40.3 Example of Homeostasis: • Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range – Endothermic animals generate heat by metabolism; birds and mammals are endotherms – Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and nonavian reptiles Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperatures • Endothermy is more energetically expensive than ectothermy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-10 Radiation Evaporation Balancing Heat Loss and Gain Convection Conduction Five general adaptations help animals thermoregulate: 1. Insulation 2. Circulatory adaptations: • arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange. Transfer heat between fluids flowing in opposite directions 3. Cooling by evaporative heat loss 4. Behavioral responses 5. Adjusting metabolic heat production Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-12 Canada goose Bottlenose dolphin Blood flow Artery Vein Vein Artery 35ºC 33º 30º 27º 20º 18º 10º 9º Fig. 40-16 Sweat glands secrete sweat, which evaporates, cooling the body. Body temperature decreases; thermostat shuts off cooling mechanisms. Thermostat in hypothalamus activates cooling mechanisms. Blood vessels in skin dilate: capillaries fill; heat radiates from skin. Increased body temperature Homeostasis: Internal temperature of 36–38°C Body temperature increases; thermostat shuts off warming mechanisms. Decreased body temperature Blood vessels in skin constrict, reducing heat loss. Skeletal muscles contract; shivering generates heat. Thermostat in hypothalamus activates warming mechanisms. 40.4 Bioenergetics: The study of how organisms manage their resources • It determines how much food an animal needs and relates to an animal’s size, activity, and environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Quantifying Energy Use • Metabolic rate is the amount of energy an animal uses in a unit of time • Energy is measured in calories (cal) or kilocalories (Kcal = 1000 calories) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Measuring Metabolic Rate 1. Measure heat loss per unit of time (ex. placing a bird in a calorimeter) 2. Determine the amount of oxygen consumed by cellular respiration – Minimal rate: necessary to support basic functions (breathing, heart rate) – Maximal rate: occurs during peak activity (sprinting, high level aerobics) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Influences on Metabolic Rate • Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm • These factors are: Age body temperature surrounding temperature amount of available O2 Hormone balance Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings gender time of day food intake Rate Types: Both rates assume a nongrowing, fasting, and nonstressed animal • Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature – Human avg.: 1600-1880 Kcal/day: adult male 1300-1500 Kcal/day: adult female • Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Size and Metabolic Rate • Metabolic rate per gram of body weight is inversely related to body size among similar animals – may be due to surface area to volume ratio but does not explain the relationship in ectotherms • The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-19a 103 BMR (L O2/hr) (log scale) Elephant Horse 102 Human Sheep 10 Cat Dog 1 10–1 Rat Ground squirrel Shrew Mouse Harvest mouse 10–2 10–3 10–2 102 1 10–1 10 Body mass (kg) (log scale) (a) Relationship of BMR to body size 103 Fig. 40-19b 8 7 BMR (L O2/hr) (per kg) Each gram of a mouse requires about 20X’s more calories as a gram of an elephant Shrew 6 5 4 Harvest mouse 3 Mouse 2 Rat 1 Ground squirrel 0 10–3 10–2 Sheep Human Elephant Cat Dog Horse 1 10 102 10–1 Body mass (kg) (log scale) 103 (b) Relationship of BMR per kilogram of body mass to body size Annual energy expenditure (kcal/hr) Fig. 40-20a Reproduction 800,000 Thermoregulation Basal (standard) metabolism Growth Activity 60-kg female human from temperate climate Annual energy expenditure (kcal/yr) Fig. 40-20b Basal (standard) metabolism Reproduction Thermoregulation Activity 340,000 4-kg male Adélie penguin from Antarctica (brooding) Annual energy expenditure (kcal/yr) Fig. 40-20c Basal (standard) metabolism Reproduction Thermoregulation Activity 4,000 0.025-kg female deer mouse from temperate North America Annual energy expenditure (kcal/yr) Fig. 40-20d Basal (standard) metabolism Reproduction Growth Activity 8,000 4-kg female eastern indigo snake Torpor and Energy Conservation • Torpor is a physiological state in which activity is low and metabolism decreases • Torpor enables animals to save energy while avoiding difficult and dangerous conditions • Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings