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Chapter 40: Animal Form and Function Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Form and function are closely correlated Figure 40.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Natural selections select for what works best among the available variations in a population Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Evolutionary convergence – Independent adaptation to a similar environmental challenge (a) Tuna (b) Shark (c) Penguin (d) Dolphin Figure 40.2a–e (e) Seal Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Exchange with the Environment • Occurs as substances dissolved in the aqueous medium transported across membranes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Single-celled protist has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Diffusion Figure 40.3a Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (a) Single cell • Multicellular organisms with body walls that are only two cells thick facilitate diffusion Mouth Gastrovascular cavity Diffusion Diffusion Figure 40.3b (b) Two cell layers Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Organisms with complex body plans – highly folded internal surfaces (lg. surface area) specialized for exchanging materials Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings External environment Mouth Food CO2 O2 Respiratory system 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 50 µm Animal body Circulatory system 10 µm Interstitial fluid Digestive system Excretory system The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM). Anus Unabsorbed matter (feces) Figure 40.4 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Metabolic waste products (urine) Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). • Animal form and function are correlated at all levels of organization – cells – tissues – organs – organ systems Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tissue Structure and Function • 4 main categories – Epithelial, connective, muscle, and nervous Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial Tissue • Covers the outside of the body and lines organs and cavities within the body – cells are closely joined Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Epithelial tissue A simple columnar epithelium A stratified columnar A pseudostratified epithelium ciliated columnar epithelium Stratified squamous epithelia Cuboidal epithelia Simple squamous epithelia Basement membrane Figure 40.5 40 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Connective Tissue • Bind and supports other tissues – sparsely packed cells scattered throughout an extracellular matrix Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CONNECTIVE TISSUE • Connective tissue 100 µm Chondrocytes Chondroitin sulfate Loose connective tissue 100 µm Collagenous fiber Elastic fiber Cartilage Adipose tissue Fibrous connective tissue Fat droplets 150 µm Nuclei 30 µm Blood Bone Central canal Red blood cells White blood cell Osteon Figure 40.5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 700 µm Plasma 55 µm Muscle Tissue • Composed of long cells called muscle fibers, contract in response to nerve signals – 3 types: skeletal, cardiac, and smooth Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nervous Tissue • Senses stimuli and transmits signals throughout the animal Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Muscle and nervous tissue MUSCLE TISSUE 100 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere Cardiac muscle Nucleus Intercalated disk Smooth muscle 50 µm Nucleus Muscle fibers 25 µm NERVOUS TISSUE Process Neurons Cell body Nucleus Figure 40.5 50 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Neurons Dendrites Cell body Nucleus Synapse Signal Axon direction Axon hillock Presynaptic cell Postsynaptic cell Myelin sheath Figure 48.5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Synaptic terminals • In some organs tissues are arranged in layers 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 consists mainly of smooth muscle tissue. Serosa. External to the muscularis is the serosa, a thin layer of connective and epithelial tissue. Figure 40.6 0.2 mm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Organ systems in mammals Table 40.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Organisms require chemical energy for – Growth, repair, physiological processes, regulation, and reproduction Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Bioenergetics • Flow of energy through an animal – Limits the animal’s behavior, growth, and reproduction, how much food it needs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Energy Sources and Allocation • Chemical energy from food food digested molecules generate ATP powers cellular work Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Metabolic needs and biosynthesis Organic molecules in food External environment Animal body Digestion and absorption Heat Nutrient molecules in body cells Carbon skeletons Cellular respiration Energy lost in feces Energy lost in urine Heat ATP Biosynthesis: growth, storage, and reproduction Figure 40.7 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heat Cellular work Heat • Measuring metabolic rate by amount of oxygen consumed or carbon dioxide produced (a) Figure 40.8a, b This photograph shows a ghost crab in a respirometer. Temperature is held constant in the chamber, with air of known O2 concentration flowing through. The crab’s metabolic rate is calculated from the difference between the amount of O2 entering and the amount of O2 leaving the respirometer. This crab is on a treadmill, running at a constant speed as measurements are made. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he works out on a stationary bike. • Birds and mammals are endothermic – bodies warmed by heat generated by metabolism – high metabolic rates Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Amphibians, reptiles other than birds, and ………..Daphnia are ectothermic – gain their heat from external sources – lower metabolic rates – Q 10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Size and Metabolic Rate • Metabolic rate inversely related to body size among similar animals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Activity and Metabolic Rate • Basal metabolic rate (BMR) – Metabolic rate of an endotherm at rest • Standard metabolic rate (SMR) – Metabolic rate of an ectotherm at rest Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Animal’s maximum possible metabolic rate is inversely related to the duration of the activity 500 A 100 H A (kcal/min; log scale) Maximum metabolic rate A = 60-kg alligator H H = 60-kg human 50 H 10 H H 5 A 1 A A 0.5 0.1 1 second 1 minute 1 hour Time interval Key Figure 40.9 Existing intracellular ATP ATP from glycolysis ATP from aerobic respiration Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1 day 1 week Energy use Annual energy expenditure (kcal/yr) Endotherms Ectotherm Reproduction 800,000 Basal metabolic rate Temperature regulation costs Growth Activity costs 340,000 8,000 4,000 4-kg male Adélie penguin from Antarctica (brooding) 60-kg female human from temperate climate (b) 4-kg female python from Australia 438 Human 233 Deer mouse Python Adélie (kcal/kg•day) Energy expenditure per unit mass (a) Total annual energy expenditures 0.025-kg female deer mouse from temperate North America penguin 36.5 5.5 Energy expenditures per unit mass (kcal/kg•day) Figure 40.10a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Animals regulate their internal environment within relatively narrow limits • Homeostasis: balance between external changes and the animal’s internal control mechanisms that oppose the changes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Regulator – Uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation • Conformer – Allows its internal condition to vary with certain external changes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Homeostatic control system • 3 functional components – receptor, control center, and effector Response No heat produced Heater turned off Room temperature decreases Too hot Set point Too cold Set point Set point Control center: thermostat Room temperature increases Heater turned on Response Figure 40.11 Heat produced Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Homeostatic control systems function by negative feedback – buildup of the end product shuts the system off Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Positive feedback – change in some variable that amplify the change Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Thermoregulation – animals maintain an internal temperature within a tolerable range Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ectotherms • Tolerate greater variation in internal temperature 40 than endotherms Body temperature (°C) River otter (endotherm) 30 20 Largemouth bass (ectotherm) 10 0 Figure 40.12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 10 20 30 40 Ambient (environmental) temperature (°C) Endothermy • Energetically more expensive than ectothermy – Buffers animals’ internal temperatures against external fluctuations – High level of aerobic metabolism Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heat Exchange • Organisms exchange heat by four physical processes 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. Figure 40.13 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. Convection is the transfer of heat by the Conduction is the direct transfer of thermal motion (heat) 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. between molecules of objects in direct contact with each other, as when a lizard sits on a hot rock. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Insulation • Thermoregulatory adaptation in mammals and birds – Reduces the flow of heat between an animal and its environment – e.g. feathers, fur, or blubber Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Mammal integumentary system – Acts as insulating material Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Figure 40.14 Blood vessels Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oil gland Hair follicle Circulatory adaptations • Vasodilation – Blood flow in the skin increases, facilitating heat loss • Vasoconstriction – Blood flow in the skin decreases, lowering heat loss Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Countercurrent heat exchangers reduce heat loss 1 Arteries carrying warm blood down the legs of a goose or the flippers of a dolphin are in close contact with veins conveying cool blood in the opposite direction, back toward the trunk of the body. This arrangement facilitates heat transfer from arteries to veins (black arrows) along the entire length of the blood vessels. Canada goose Pacific bottlenose dolphin 2 Artery 35°C 33° 30º 1 27º 20º 18º 10º 9º 2 Figure 40.15 Vein Near the end of the leg or flipper, where arterial blood has been cooled to far below the animal’s core temperature, the artery can still transfer heat to the even colder blood of an adjacent vein. The venous blood continues to absorb heat as it passes warmer and warmer arterial blood traveling in the 3 direction. opposite 1 Blood flow Vein Artery 3 3 2 3 As the venous blood approaches the center of the body, it is almost as warm as the body core, minimizing the heat lost as a result of supplying blood to body parts immersed in cold water. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In the flippers of a dolphin, each artery is surrounded by several veins in a countercurrent arrangement, allowing efficient heat exchange between arterial and venous blood. • Some bony fishes and sharks also possess countercurrent heat exchangers 21º 25º 23º 27º (a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintains temperatures in its main swimming muscles that are much higher than the surrounding water (colors indicate swimming muscles cut in transverse section). These temperatures were recorded for a tuna in 19°C water. (b) Great white shark. Like the bluefin tuna, the great white shark has a countercurrent heat exchanger in its swimming muscles that reduces the loss of metabolic heat. All bony fishes and sharks lose heat to the surrounding water when their blood passes through the gills. However, endothermic sharks have a small dorsal aorta, and as a result, relatively little cold blood from the gills goes directly to the core of the body. Instead, most of the blood leaving the gills is conveyed via large arteries just under the skin, keeping cool blood away from the body core. As shown in the enlargement, small arteries carrying cool blood inward from the large arteries under the skin are paralleled by small veins carrying warm blood outward from the inner body. This countercurrent flow retains heat in the muscles. Figure 40.16a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 29º 31º Body cavity Skin Artery Vein Blood vessels in gills Heart Capillary network within muscle Artery and vein under Dorsal aorta the skin • Endothermic insects – countercurrent heat exchangers maintain a high temperature in the thorax Figure 40.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cooling by Evaporative Heat Loss • Lose heat through the evaporation of water in sweat • Panting cools bodies Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Bathing cools animal Figure 40.18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Certain postures enable animals to minimize or maximize their absorption of heat from the sun Figure 40.19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Flying insects use shivering to warm up before taking flight PREFLIGHT PREFLIGHT FLIGHT WARMUP Temperature (°C) 40 Thorax 35 30 Abdomen 25 0 2 Time from onset of warmup (min) Figure 40.20 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 4 Thermoregulation • The hypothalamus functions as a thermostat Sweat glands secrete sweat that evaporates, cooling the body. Thermostat in hypothalamus activates cooling mechanisms. Blood vessels in skin dilate: capillaries fill with warm blood; heat radiates from skin surface. Increased body temperature (such as when exercising or in hot surroundings) Body temperature decreases; thermostat shuts off cooling mechanisms. Homeostasis: Internal body temperature of approximately 36–38C Body temperature increases; thermostat shuts off warming mechanisms. Decreased body temperature (such as when in cold surroundings) Blood vessels in skin constrict, diverting blood from skin to deeper tissues and reducing heat loss from skin surface. Figure 40.21 Skeletal muscles rapidly contract, causing shivering, which generates heat. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Thermostat in hypothalamus activates warming mechanisms. Acclimatization • Animals can adjust to a new range of environmental temperatures over a period of days or weeks Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Torpor • Adaptation that enables animals to save energy while avoiding difficult and dangerous conditions – physiological state of low activity and metabolism Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Hibernation (long-term torpor) Additional metabolism that would be necessary to stay active in winter Figure 40.22 Metabolic rate (kcal per day) 200 Actual metabolism 100 0 Arousals 35 Body temperature Temperature (°C) 30 25 20 15 10 5 0 Outside temperature -5 Burrow temperature -10 -15 June Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings August October December February April • Estivation, or summer torpor – survive long periods of high temperatures and scarce water supplies Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings