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Define ‘homeostasis’ What things to animals do to maintain homeostasis?
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Lecture 12 Outline (Ch. 40) I. Animal Size/Shape and the Environment
II. Tissues III. Feedback control and Heat Balance Bioenergetics and Energy Use Lecture Concepts
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Overview: Diverse Forms, Common Challenges
Anatomy: study of biological form of an organism Physiology: study of biological functions of an organism
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Physical Constraints on Animal Size and Shape
Evolutionary convergence reflects different species’ adaptations to similar environmental challenge (a) Tuna Figure 40.2 Convergent evolution in fast swimmers (b) Penguin (c) Seal
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Exchange with the Environment
Animals sizes and shapes directly affect how they exchange energy and materials with surroundings Mouth Gastrovascular cavity Exchange Exchange Figure 40.3 Contact with the environment Exchange 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells
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Exchange with the Environment
More complex organisms have highly folded internal surfaces 0.5 cm Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO2 O2 Circulatory Heart Respiratory Cells Interstitial fluid Excretory Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 µm 50 µm Lung tissue Blood Figure 40.4 Internal exchange surfaces of complex animals
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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 Table 40.1
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Tissue Structure and Function
Tissues are classified into four main categories: epithelial, connective, muscle, and nervous
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Tissue Structure and Function
Epithelial Tissue Cuboidal epithelium Simple columnar Pseudostratified ciliated Stratified squamous Figure 40.5 Structure and function in animal tissues Note differences in cell shape and type of layering
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Tissue Structure and Function
Apical surface Basal surface Basal lamina Figure 40.5 Structure and function in animal tissues 40 µm
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Connective Tissue 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
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Tissue Structure and Function
Connective Tissue Collagenous fiber Loose connective tissue Elastic fiber 120 µm Cartilage Chondrocytes 100 µm Chondroitin sulfate Adipose Fat droplets 150 µm White blood cells 55 µm Plasma Red blood cells Blood Nuclei Fibrous 30 µm Osteon Bone Central canal 700 µm Figure 40.5 Structure and function in animal tissues
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Muscle Tissue Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals 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
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Tissue Structure and Function
Muscle Tissue 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth Cardiac muscle Nucleus Muscle fibers 25 µm Intercalated disk Figure 40.5 Structure and function in animal tissues
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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
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Tissue Structure and Function
Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm Figure 40.5 Structure and function in animal tissues
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Tissues/Cells Included; Functions
Self-Check Tissue Category Tissues/Cells Included; Functions Epithelial Connective Muscle Nervous
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Feedback control loops maintain the internal environment in many animals
Animals manage their internal environment by regulating or conforming to the external environment Homeostasis Response/effector Stimulus: Perturbation/stress Control center Sensor/receptor
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Feedback control loops maintain the internal environment in many animals
Response: Heater turned off Stimulus: Control center (thermostat) reads too hot Room temperature decreases Set point: 20ºC increases reads too cold on Figure 40.8 A nonliving example of negative feedback: control of room temperature
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Feedback control loops maintain the internal environment in many animals
(a) A walrus, an endotherm (b) A lizard, an ectotherm Thermoregulation: process by which animals maintain an internal temperature Endothermic animals generate heat by metabolism (birds and mammals) Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and non-avian reptiles)
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Balancing Heat Loss and Gain
Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation Radiation Evaporation Convection Conduction
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Balancing Heat Loss and Gain
Balancing temperature usually involves the integumentary system Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Figure Mammalian integumentary system Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle
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Balancing Heat Loss and Gain
Five general adaptations help animals thermoregulate: Insulation Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production
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Energy Allocation and Use
Organic molecules in food External environment Animal body Digestion and absorption Nutrient molecules in body cells Carbon skeletons Cellular respiration ATP Heat Energy lost in feces Energy lost in nitrogenous waste Biosynthesis work 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
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Energy Use Metabolic rate is the amount of energy an animal uses in a unit of time Measured by determining the amount of oxygen consumed or carbon dioxide produced
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Energy Use Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Ectotherms have much lower metabolic rates than endotherms of a comparable size
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Energy Use 103 Elephant 102 Horse Human Sheep 10
BMR (L O2/hr) (log scale) Cat Dog 1 Rat 10–1 Ground squirrel Figure The relationship of metabolic rate to body size Shrew Mouse Harvest mouse 10–2 10–3 10–2 10–1 1 10 102 103 Body mass (kg) (log scale) (a) Relationship of BMR to body size
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Energy Use 8 Shrew 7 6 5 BMR (L O2/hr) (per kg) 4 Harvest mouse 3 2
Sheep Figure The relationship of metabolic rate to body size Rat Human Elephant Cat 1 Dog Horse Ground squirrel 10–3 10–2 10–1 1 10 102 103 Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size
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from temperate climate
Energy Use Different animals budget their energy differently. Annual energy expenditure (kcal/hr) 60-kg female human from temperate climate 800,000 Basal (standard) metabolism Reproduction Thermoregulation Growth Activity 340,000 4-kg male Adélie penguin from Antarctica (brooding) 4,000 0.025-kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake Endotherms Ectotherm Figure Energy budgets for four animals
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Energy Use Torpor is a physiological state in which activity is low and metabolism decreases – allows 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
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Energy Use Additional metabolism that would be
necessary to stay active in winter 200 Actual metabolism Metabolic rate (kcal per day) 100 Arousals 35 Body temperature 30 25 20 Temperature (°C) 15 Figure Body temperature and metabolism during hibernation in Belding’s ground squirrels 10 5 Outside temperature –5 Burrow temperature –10 –15 June August October December February April
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Lecture 12 concepts Distinguish among the following sets of terms: ectotherms and endotherms, positive and negative feedback; basal and standard metabolic rates; torpor and hibernation. Identify and describe the function of the following animal tissues: epithelial, connective tissue (six types), muscle tissue (three types), and nervous tissue (two types). Define metabolic rate and explain how it can be determined for animals Describe how an animals size affects its interaction with the environment, and metabolic rate. Discuss bioenergetics. Make a list of new vocabulary with definitions.
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