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Chapter 40 Basic Principles of Animal Form and Function PowerPoint® Lecture Presentations for Overview: Diverse Forms, Common Challenges • 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 Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-1 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 40.1: Animal form and function are correlated at all levels of organization • Size and shape affect the way an animal interacts with its environment • 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 Physical Constraints on Animal Size and Shape • The ability to perform certain actions depends on an animal’s shape, size, and environment • Evolutionary convergence reflects different species’ adaptations to a similar environmental challenge (a) Tuna • Physical laws impose constraints on animal size and shape (b) Penguin Video: Shark Eating Seal Video: Galá Galápagos Sea Lion (c) Seal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 1 Fig. 40-3 Exchange with the Environment Mouth • An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings Gastrovascular cavity Exchange Exchange • Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells’ plasma membranes Exchange • A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm 0.15 mm 1.5 mm (a) Single cell Video: Hydra Eating Daphnia (b) Two layers of cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials • More complex organisms have highly folded internal surfaces for exchanging materials Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-4 Fig. 40-4a External environment CO2 O Food 2 External environment CO2 Food O2 Mouth Mouth Animal body Animal body 0.5 cm Respiratory system 50 µm Respiratory system Nutrients Lung tissue Nutrients Heart Circulatory system Interstitial fluid Digestive system Excretory system Lining of small intestine Excretory system Kidney tubules Anus Unabsorbed matter (feces) Cells Circulatory system 10 µm Interstitial fluid Digestive system Heart Cells Metabolic waste products (nitrogenous waste) Anus Unabsorbed Metabolic waste products matter (feces) (nitrogenous waste) 2 Fig. 40-4b Fig. 40-4c 50 µm 0.5 cm Lung tissue Lining of small intestine Fig. 40-4d 10 µm • 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 Kidney tubules Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hierarchical Organization of Body Plans Table 40-1 • Most animals are composed of specialized cells organized into tissues that have different functions • Tissues make up organs, which together make up organ systems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 3 Tissue Structure and Function Epithelial Tissue • Different tissues have different structures that are suited to their functions • Epithelial tissue covers the outside of the body and lines the organs and cavities within the body • Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • It contains cells that are closely joined • The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-5a • The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length) Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-5b Connective Tissue Apical surface Basal surface Basal lamina • Connective tissue mainly binds and supports other tissues • It contains sparsely packed cells scattered throughout an extracellular matrix • The matrix consists of fibers in a liquid, jellylike, or solid foundation 40 µm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 4 • Connective tissue contains cells, including • There are three types of connective tissue fiber, all made of protein: – Fibroblasts that secrete the protein of extracellular fibers – Collagenous fibers provide strength and flexibility – Macrophages that are involved in the immune system – Elastic fibers stretch and snap back to their original length – Reticular fibers join connective tissue to adjacent tissues Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • In vertebrates, the fibers and foundation combine to form six major types of connective tissue: – Loose connective tissue binds epithelia to underlying tissues and holds organs in place – Adipose tissue stores fat for insulation and fuel – Blood is composed of blood cells and cell fragments in blood plasma – Bone is mineralized and forms the skeleton – Cartilage is a strong and flexible support material – Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-5c Fig. 40-5d Connective Tissue Loose connective tissue Chondrocytes Collagenous fiber Cartilage Elastic fiber Chondroitin sulfate Nuclei Osteon 150 µm Adipose tissue White blood cells Blood 55 µm 700 µm Bone Central canal Plasma 120 µm Fat droplets Fibrous connective tissue 30 µm 100 µm 120 µm Collagenous fiber Elastic fiber Loose connective tissue Red blood cells 5 Fig. 40-5e Fig. 40-5f Osteon 30 µm 700 µm Nuclei Central canal Fibrous connective tissue Bone Fig. 40-5g Fig. 40-5h Chondrocytes 150 µm 100 µm Fat droplets Chondroitin sulfate Adipose tissue Cartilage Fig. 40-5i Muscle Tissue White blood cells 55 µm • Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals Plasma Blood Red blood cells • It is divided in the vertebrate body into three types: – Skeletal muscle, or striated muscle, is responsible for voluntary movement – Smooth muscle is responsible for involuntary body activities – Cardiac muscle is responsible for contraction of the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 6 Fig. 40-5j Fig. 40-5k Muscle Tissue Multiple nuclei Multiple nuclei Muscle fiber Sarcomere Skeletal muscle Nucleus 100 µm Intercalated disk Muscle fiber 50 µm Cardiac muscle Sarcomere Nucleus Smooth muscle 100 µm Muscle fibers Skeletal muscle 25 µm Fig. 40-5l Fig. 40-5m Nucleus Muscle fibers Nucleus 25 µm Smooth muscle Nervous Tissue Intercalated disk 50 µm Cardiac muscle Fig. 40-5n Nervous Tissue 40 µm • Nervous tissue senses stimuli and transmits signals throughout the animal • Nervous tissue contains: Dendrites Cell body Glial cells Axon – Neurons, or nerve cells, that transmit nerve impulses Neuron – Glial cells, or glia, that help nourish, insulate, and replenish neurons Axons Blood vessel 15 µm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 7 Fig. 40-5o 40 µm Fig. 40-5p Glial cells Dendrites Cell body Axon Axons Blood vessel Glial cells and axons 15 µm Neuron Fig. 40-6 Coordination and Control Stimulus Stimulus Endocrine cell Neuron • Control and coordination within a body 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 Axon Signal Hormone Signal travels along axon to a specific location. Signal travels everywhere via the bloodstream. Blood vessel Signal Axons • A hormone may affect one or more regions throughout the body • Hormones are relatively slow acting, but can have long-lasting effects Response (a) Signaling by hormones Response (b) Signaling by neurons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-6a Stimulus Endocrine cell • The nervous system transmits information between specific locations Hormone Signal travels everywhere • The information conveyed depends on a signal’s pathway, not the type of signal via the bloodstream. Blood vessel • Nerve signal transmission is very fast • Nerve impulses can be received by neurons, muscle cells, and endocrine cells Response (a) Signaling by hormones Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 8 Fig. 40-6b Stimulus Neuron Axon Signal Signal travels along axon to a specific location. Concept 40.2: Feedback control loops maintain the internal environment in many animals • Animals manage their internal environment by regulating or conforming to the external environment Signal Axons Response (b) Signaling by neurons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Regulating and Conforming Fig. 40-7 40 • A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation • A conformer allows its internal condition to vary with certain external changes Body temperature (°C) River otter (temperature regulator) 30 20 Largemouth bass (temperature conformer) 10 0 10 20 30 40 Ambient (environmental) temperature (ºC) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Homeostasis Mechanisms of Homeostasis • Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment • Mechanisms of homeostasis moderate changes in the internal environment • In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level • 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 Animation: Negative Feedback Animation: Positive Feedback Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 9 Fig. 40-8 Response: Heater turned off Room temperature decreases Feedback Loops in Homeostasis Stimulus: Control center (thermostat) reads too hot Set point: 20ºC Stimulus: Control center (thermostat) reads too cold Room temperature increases Response: Heater turned on • The dynamic equilibrium of homeostasis is maintained by negative feedback, which helps to return a variable to either a normal range or a set point • Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off • Positive feedback loops occur in animals, but do not usually contribute to homeostasis Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Alterations in Homeostasis • Set points and normal ranges can change with age or show cyclic variation • Homeostasis can adjust to changes in external environment, a process called acclimatization Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 40.3: Homeostatic processes for thermoregulation involve form, function, and behavior • Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Endothermy and Ectothermy • 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 10 Fig. 40-9 Variation in Body Temperature • The body temperature of a poikilotherm varies with its environment, while that of a homeotherm is relatively constant (a) A walrus, an endotherm (b) A lizard, an ectotherm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Balancing Heat Loss and Gain Fig. 40-10 Radiation Evaporation • Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation Convection Conduction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-11 • Heat regulation in mammals often involves the integumentary system: skin, hair, and nails Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 11 Insulation • Insulation is a major thermoregulatory adaptation in mammals and birds • Five general adaptations help animals thermoregulate: • Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment – Insulation – Circulatory adaptations – Cooling by evaporative heat loss – Behavioral responses – Adjusting metabolic heat production Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Circulatory Adaptations • Regulation of blood flow near the body surface significantly affects thermoregulation • Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin • In vasodilation, blood flow in the skin increases, facilitating heat loss • The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange • Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions • Countercurrent heat exchangers are an important mechanism for reducing heat loss • In vasoconstriction, blood flow in the skin decreases, lowering heat loss Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-12 Canada goose Bottlenose dolphin • Some bony fishes and sharks also use countercurrent heat exchanges Blood flow Artery Vein Vein Artery 35ºC 33º 30º 27º 20º 18º 10º 9º • Many endothermic insects have countercurrent heat exchangers that help maintain a high temperature in the thorax Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 12 Cooling by Evaporative Heat Loss Behavioral Responses • Many types of animals lose heat through evaporation of water in sweat • Both endotherms and ectotherms use behavioral responses to control body temperature • Panting increases the cooling effect in birds and many mammals • Sweating or bathing moistens the skin, helping to cool an animal down Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-13 Adjusting Metabolic Heat Production • Some animals can regulate body temperature by adjusting their rate of metabolic heat production • Heat production is increased by muscle activity such as moving or shivering • Some ectotherms can also shiver to increase body temperature Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-14 Fig. 40-15 PREFLIGHT 120 40 100 Temperature (ºC) O2 consumption (mL O2/hr) per kg RESULTS 80 60 PREFLIGHT WARM-UP FLIGHT Thorax 35 30 Abdomen 40 20 25 0 0 5 10 15 20 30 25 Contractions per minute 35 0 2 Time from onset of warm-up (min) 4 13 Acclimatization in Thermoregulation Physiological Thermostats and Fever • Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes • Thermoregulation is controlled by a region of the brain called the hypothalamus • When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells • The hypothalamus triggers heat loss or heat generating mechanisms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 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. • Fever is the result of a change to the set point for a biological thermostat Concept 40.4: Energy requirements are related to animal size, activity, and environment • Bioenergetics is the overall flow and transformation of energy in an animal • It determines how much food an animal needs and relates to an animal’s size, activity, and environment Decreased body temperature Blood vessels in skin constrict, reducing heat loss. Skeletal muscles contract; shivering generates heat. Thermostat in hypothalamus activates warming mechanisms. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Energy Allocation and Use • Animals harvest chemical energy from food • Energy-containing molecules from food are usually used to make ATP, which powers cellular work • After the needs of staying alive are met, remaining food molecules can be used in biosynthesis • Biosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes Fig. 40-17 External environment Animal body Organic molecules in food Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Carbon skeletons Cellular respiration Energy lost in nitrogenous waste Heat ATP Biosynthesis Cellular work Heat Heat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 14 Quantifying Energy Use Fig. 40-18 • Metabolic rate is the amount of energy an animal uses in a unit of time • One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Minimum Metabolic Rate and Thermoregulation Influences on Metabolic Rate • Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature • Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm • Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature • Two of these factors are size and activity • Both rates assume a nongrowing, fasting, and nonstressed animal • Ectotherms have much lower metabolic rates than endotherms of a comparable size Size and Metabolic Rate • Metabolic rate per gram is inversely related to body size among similar animals • Researchers continue to search for the causes of this relationship Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-19 103 Elephant BMR (L O2/hr) (Iog scale) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Horse 102 Human Sheep 10 Cat Dog 1 10–1 Rat Ground squirrel Shrew Mouse Harvest mouse 10–2 10–3 10–2 1 10 10–1 102 Body mass (kg) (log scale) 103 (a) Relationship of BMR to body size 8 7 BMR (L O2/hr) (per kg) • 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 Shrew 6 5 4 3 Harvest mouse Mouse Sheep Rat Cat Human Elephant Dog Horse Ground squirrel 0 10–3 10–2 10–1 102 103 1 10 Body mass (kg) (log scale) 2 1 (b) Relationship of BMR per kilogram of body mass to body size Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 15 Fig. 40-19a Fig. 40-19b 103 8 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) Shrew 7 Horse 102 BMR (L O2/hr) (per kg) BMR (L O2/hr) (log scale) Elephant 6 5 4 Harvest mouse 3 Mouse 2 Rat 1 Sheep Cat Ground squirrel 0 10–3 103 10–2 Human Dog 1 10 10–1 102 Body mass (kg) (log scale) Elephant Horse 103 (b) Relationship of BMR per kilogram of body mass to body size (a) Relationship of BMR to body size Activity and Metabolic Rate Energy Budgets • Activity greatly affects metabolic rate for endotherms and ectotherms • Different species use energy and materials in food in different ways, depending on their environment • In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity • Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 40-20 Fig. 40-20a Annual energy expenditure (kcal/hr) Endotherms Ectotherm 800,000 Reproduction Thermoregulation Basal (standard) Growth metabolism Activity 340,000 4,000 60-kg female human from temperate climate 4-kg male Adélie penguin from Antarctica (brooding) 8,000 0.025-kg female deer mouse 4-kg female eastern from temperate indigo snake North America Annual energy expenditure (kcal/hr) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Reproduction 800,000 Thermoregulation Basal (standard) metabolism Growth Activity 60-kg female human from temperate climate 16 Fig. 40-20c Basal (standard) metabolism Reproduction Thermoregulation Activity 340,000 Fig. 40-20d Annual energy expenditure (kcal/yr) Basal (standard) metabolism Reproduction Thermoregulation Activity 4,000 0.025-kg female deer mouse from temperate North America 4-kg male Adélie penguin from Antarctica (brooding) Basal (standard) metabolism Annual energy expenditure (kcal/yr) Annual energy expenditure (kcal/yr) Fig. 40-20b Torpor and Energy Conservation Reproduction • Torpor is a physiological state in which activity is low and metabolism decreases Growth • Torpor enables animals to save energy while avoiding difficult and dangerous conditions Activity • Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity 8,000 4-kg female eastern indigo snake Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Metabolic rate (kcal per day) Fig. 40-21 200 Actual metabolism • Estivation, or summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies 100 0 35 30 Temperature (°C) Additional metabolism that would be necessary to stay active in winter Arousals Body temperature • Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns 25 20 15 10 5 0 –5 Outside temperature Burrow temperature –10 –15 June August October December February April Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 17 Fig. 40-UN1 Fig. 40-UN2 Homeostasis Response/effector Stimulus: Perturbation/stress Control center Sensor/receptor You should now be able to: 1. Distinguish among the following sets of terms: collagenous, elastic, and reticular fibers; regulator and conformer; positive and negative feedback; basal and standard metabolic rates; torpor, hibernation, estivation, and daily torpor 2. Relate structure with function and identify diagrams of the following animal tissues: epithelial, connective tissue (six types), muscle tissue (three types), and nervous tissue Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 3. Compare and contrast the nervous and endocrine systems 4. Define thermoregulation and explain how endotherms and ectotherms manage their heat budgets 5. Describe how a countercurrent heat exchanger may function to retain heat within an animal body 6. Define bioenergetics and biosynthesis 7. Define metabolic rate and explain how it can be determined for animals Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 18