Presentation on theme: "Animal Form and Function"— Presentation transcript:
1Animal Form and Function Ch 40Animal Form and Function
2Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organismPhysiology is the study of biological functions an organism performsThe comparative study of animals reveals that form and function are closely related.
3Animal form and function are correlated at all levels of organization Evolution of Animal Size and ShapeDifferent body plans have arisen during the course of evolution but these variations fall within certain boundsPhysical laws constrain strength, diffusion, movement, and heat exchangeEx. As animals increase in size, their skeletons must be proportionately larger to support their massEvolutionary convergence reflects different species’ adaptations to a similar environmental challenge
4Example: Seal, Penguin, Tuna Water is 1000x denser than air and also more viscous. Any bump on animal may cause drag and slow them down.Natural selection often results in similar adaptations when diverse organisms face the same environmental challenges (convergent evolution)
5Exchange with the Environment An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings (may limit body plan)Animal cells must have access to aqueous medium (substances dissolved diffuse and are transported across the cells’ plasma membranes)Interstitial fluid
6Exchange with the Environment A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasmTwo celled sacs and flat shape maximize exposure to surrounding medium (facilitate diffusion)
8Exchange with the Environment Complex body plans have highly folded internal membrane to maximize surface area.
9External environment CO2 Food O2 Mouth Animal body Respiratory system Blood50 µm0.5 cmA 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).CellsHeartNutrientsCirculatorysystem10 µmDigestivesystemInterstitialfluidExcretorysystemThe lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM).AnusInside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).Unabsorbedmatter (feces)Metabolic wasteproducts (urine)
10Benefits of complex body plans over simple ones External skeleton protects against predatorsSensory organs can provide detailed information about animal’s surroundingsInternal digestive organs can break food down gradually controlling release of stored energySpecialized filtration systems can adjust the composition of the internal fluid that baths animal cells helps maintain stable environment in a changeable external environmentDespite the challenges of exchange with the environment, complex body plans have distinct benefits over simple ones.Complex body plan is especially advantageous for land animals where the environment is highly variable.
11Hierarchical Organization of Body Plans Most animals are composed of specialized cells organized into tissues that have different functionsTissues make up organs, which together make up organ systemsSome organs, such as the pancreas, belong to more than one organ systemPancreas – digestive system and endocrine system
13Exploring Structure and Function in Animal Tissues Different tissues have different structures that are suited to their functionsTissues are classified into four main categories: epithelial, connective, muscle, and nervous
14Epithelial Tissues Sheets of cells Cover outside of body and line organs and cavities.Closely packed (tight junctions)BarrierPolar: apical faces out, basal faces in.
15Epithelial Tissue Stratified squamous epithelium Pseudostratified Figure 40.5aaEpithelial TissueStratified squamousepitheliumThe 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)PseudostratifiedcolumnarepitheliumCuboidalepitheliumSimple columnarepitheliumSimple squamousepithelium15
16Connective TissuesSparse cells scattered throughout extracellular matrix.Holds tissues and organs in place.Matrix + Fibroblasts + macrophagesFibroblasts: secrete fiber proteinsMacrophages: phagocytosis.
18Muscle Tissues Responsible for movement Consist of filaments (actin and myosin)Three types:Skeletal (voluntary)Smooth (involuntary)Cardiac (interconnected to relay signals)
19Muscle Tissue Skeletal muscle Smooth muscle Cardiac muscle Nuclei Figure 40.5caMuscle TissueSkeletal muscleNucleiMusclefiberSarcomere100 mSmooth muscleCardiac muscleSkeletal muscle, or striated muscle, is responsible for voluntary movementSmooth muscle is responsible for involuntary body activitiesCardiac muscle is responsible for contraction of the heartNucleusMuscle fibers25 mNucleusIntercalated disk50 m19
20Nervous Tissue Neurons Glia Glia Neuron: Dendrites Cell body Axons of Figure 40.5daNervous TissueNeuronsGliaGlia15 mNeuron:DendritesCell bodyAxons ofneuronsAxonBloodvessel40 mNeurons, or nerve cells, that transmit nerve impulsesGlial cells, or glia, that help nourish, insulate, and replenish neurons(Fluorescent LM)(Confocal LM)20
21Nervous Tissue Receipt, processing, and transmission of info Neurons + GliaNeurons: transmit nerve impulsesGlia: support cells
22Coordination and Control Animal tissues, organs, organ systems must act in concert together.Coordinating activity across an animals body in this way requires communication (BIG IDEA!) between different body locations.
23Two major systems for coordinating and controlling responses to stimuli Endocrine (good for gradual changes such as growth, direction, etc.)Releases hormones via the blood streamOnly certain cells are responsive to each hormoneHormones tale second to act but can have long-lasting effectsNervous (good for rapid responses to environment)Use cellular circuits involving electrical and chemical signals to send information to specific locations.The information conveyed depends on a signal’s pathway, not the type of signalNerve signal transmission is very fastNerve impulses can be received by neurons, muscle cells, endocrine cells, and exocrine cells
24Response limited to cells that have the receptor for that signal. Figure 40.6Response limited to cells that have the receptor for that signal.Figure 40.6 Signaling in the endocrine and nervous systemsConveys information along a pathway.24
25Feedback control maintains the internal environment in many animals Animals manage their internal environment by regulating or conforming to the external environment
26Regulating and Conforming A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuationA conformer allows its internal condition to vary with certain external changesAnimals may regulate some environmental variables while conforming to others
27Figure 40.7Figure 40.7 The relationship between body and environmental temperatures in an aquatic temperature regulator and an aquatic temperature conformer.27
28HomeostasisOrganisms use homeostasis to maintain a “steady state” or internal balance regardless of external environmentIn humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level
29Mechanisms of Homeostasis Mechanisms of homeostasis moderate changes in the internal environmentFor 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.)Find videos of negative feedback animation
30Figure 40.8Figure 40.8 A nonliving example of temperature regulation: control of room temperature.30
31Feedback Control in Homeostasis The dynamic equilibrium of homeostasis is maintained by negative feedback, which helps to return a variable to a normal rangeMost homeostatic control systems function by negative feedback, where buildup of the end product shuts the system offPositive feedback amplifies a stimulus and does not usually contribute to homeostasis in animals (does not reverse the change but drives a process towards completion, i.e. childbirth/uterus contractions)
32Alterations in Homeostasis Set points and normal ranges can change with age or show cyclic variationIn animals and plants, a circadian rhythm governs physiological changes that occur roughly every 24 hours
35Homeostasis can adjust to changes in external environment, a process called acclimatization Acclimatization is a temporary change during an animal’s lifetime, not be confused with adaptation.Ex. Elk moves us into mountains from sea level. Less oxygen. Breathing deepens. More CO2 lost through exhalation therefore raising pH above norm. Over days kidney function excretes more alkaline urine. Blood returns to normal pH.Acclimatization is a temporary change during an animal’s lifetime, show not be confused with adaptation.
3640.3: Homeostatic processes for thermoregulation involve form, function, and behavior Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range
37Endothermy and Ectothermy Endothermic animals generate heat by metabolism; birds and mammals are endothermsEctothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and nonavian reptiles
38Endothermy is more energetically expensive than ectothermy In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperaturesEndothermy is more energetically expensive than ectothermyEcototherms need less food than endotherms of equivalent size – an advantage if food supplies are limitedEndothermy is more energetically expensive than ectothermyIt buffers the animal’s internal temperatures against external fluctuationsIt also enables the animal to maintain a high level of aerobic metabolism
40Variation in Body Temperature The body temperature of a poi kilo therm varies with its environmentThe body temperature of a homeotherm is relatively constantThe relationship between heat source and body temperature is not fixed (that is, not all poikilotherms are ectotherms)
41Balancing Heat Loss and Gain Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conduction
42Five adaptations help animals thermoregulate: Heat regulation in mammals often involves the integumentary system: skin, hair, and nailsFive adaptations help animals thermoregulate:InsulationCirculatory adaptationsCooling by evaporative heat lossBehavioral responsesAdjusting metabolic heat production
43InsulationInsulation is a major thermoregulatory adaptation in mammals and birdsSkin, feathers, fur, and blubber reduce heat flow between an animal and its environmentInsulation is especially important in marine mammals such as whales and walruses
44Circulatory Adaptations Regulation of blood flow near the body surface significantly affects thermoregulationMany endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skinIn vasodilation, blood flow in the skin increases, facilitating heat lossIn vasoconstriction, blood flow in the skin decreases, lowering heat loss
45The 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 and reduce heat lossArteries and veins flow in opposite directions.As warm blood moves from the body core in arteries, it transfers hear to the colder blood returning from the extremities in the veins.
46Figure 40.12 Countercurrent heat exchangers. Heat transfer is facilitated between the warm artery and the cool vein. This allows the animal to minimize heat loss. As the blood in the veins approaches the center of the body, it is almost as warm as the core.46
47Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water from their skinPanting increases the cooling effect in birds and many mammalsSweating or bathing moistens the skin, helping to cool an animal down
48Behavioral ResponsesBoth endotherms and ectotherms use behavioral responses to control body temperatureSome terrestrial invertebrates have postures that minimize or maximize absorption of solar heat
49Both endotherms and ectotherms use behavioral responses to control body temperature Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heatFigure Thermoregulatory behavior in a dragonfly.
50Adjusting Metabolic Heat Production Thermogenesis is the adjustment of metabolic heat production to maintain body temperatureIncreased by muscle activity (moving or shivering)Nonshivering thermogenesis takes place when hormones cause mitochondria to increase their metabolic activity (can produce heat instead of ATP)
51Results: The python’s oxygen consumption increased when the temperature of the chamber decreased. Her oxygen consumption also increased with the rate of muscle contraction.Figure Inquiry: How does a Burmese python generate heat while incubating eggs?Figure 40.14Conclusion: Because oxygen consumption, which generates heat through cellular respiration, increased linearly with the rate of muscle contraction, the researchers concluded that the muscle contractions, a form of shivering, were the source of the Burmese python’s elevated body temperature.51
52Hawkmoth uses a shivering-like mechanism for preflight warm up. Figure 40.15Figure Preflight warm-up in the hawkmoth.Uses a shivering-like mechanism for preflight warm upHawkmoth uses a shivering-like mechanism for preflight warm up.52
53Acclimatization in Thermoregulation Birds and mammals can vary their insulation to acclimatize to seasonal temperature changesWhen temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells
54Physiological Thermostats and Fever Thermoregulation is controlled by a region of the brain called the hypothalamusGroup of nerve cells within hypothalamus functions as a thermostat.The hypothalamus triggers heat loss or heat generating mechanismsFever is the result of a change to the set point for a biological thermostatHypothalmus, the brain region that also control circadian clock.
55Figure 40.16Figure The thermostatic function of the hypothalamus in human thermoregulation.55
56Concept 40.4: Energy requirements are related to animal size, activity, and environment Bioenergetics is the overall flow and transformation of energy in an animalIt determines how much food an animal needs and it relates to an animals size, activity, and environment
57Energy Allocation and Use Animals harvest chemical energy from foodEnergy-containing molecules from food are usually used to make ATP, which powers cellular workAfter the needs of staying alive are met, remaining food molecules can be used in biosynthesisBiosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes
58Figure 40.17 Bioenergetics of an animal: an overview. 58
59Quantifying Energy Use Metabolic rate is the amount of energy an animal uses in a unit of timeMetabolic rate can be determined byAn animal’s heat lossThe amount of oxygen consumed or carbon dioxide produced
60Figure 40.18Figure Measuring the rate of oxygen consumption by a swimming shark.60
61Minimum Metabolic Rate and Thermoregulation Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperatureStandard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperatureBoth rates assume a nongrowing, fasting, and nonstressed animalEctotherms have much lower metabolic rates than endotherms of a comparable size
62Influences on Metabolic Rate Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectothermTwo of these factors are size and activity
63Size and Metabolic Rate Metabolic rate is proportional to body mass to the power of three quarters (m3/4)Smaller animals have higher metabolic rates per gram than larger animalsThe 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
64Figure 40.19 The relationship of metabolic rate to body size. 64
65Figure 40.19 The relationship of metabolic rate to body size. Figure 40.19aFigure The relationship of metabolic rate to body size.65
66Figure 40.19 The relationship of metabolic rate to body size. Figure 40.19bFigure The relationship of metabolic rate to body size.66
67Activity and Metabolic Rate Activity greatly affects metabolic rate for endotherms and ectothermsIn general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity
68Energy BudgetsDifferent species use energy and materials in food in different ways, depending on their environmentUse of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction
69Figure 40.20 Energy budgets for four animals. 69
70Figure 40.20 Energy budgets for four animals. Figure 40.20aFigure Energy budgets for four animals.70
71Figure 40.20 Energy budgets for four animals. Figure 40.20bFigure Energy budgets for four animals.71
72Torpor and Energy Conservation Torpor is a physiological state in which activity is low and metabolism decreasesTorpor enables animals to save energy while avoiding difficult and dangerous conditionsHibernation is long-term torpor that is an adaptation to winter cold and food scarcitySmall mammals an birds exhibit a daily torpor that seems to be adapted to feeding patterns.EX. Some bats feed at night and go into torpor in daylightChickadees and hummingbirds feed during the day and often go into torpor on cold nights. The body temp of chickadees drops as much as 10 degrees Celcius (18F) at night. Hummingbirds can fall 25C (45F) or more.
73Figure 40.21Figure Inquiry: What happens to the circadian clock during hibernation?73
74Summer torpor, called estivation, enables animals to survive long periods of high temperatures and scarce waterDaily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns