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1 Define ‘homeostasis’ What things to animals do to maintain homeostasis?

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1 1 Define ‘homeostasis’ What things to animals do to maintain homeostasis?

2 2 Lecture 12 Outline (Ch. 40) I.Animal Size/Shape and the Environment II.Tissues III. Feedback control and Heat Balance IV.Bioenergetics and Energy Use V.Lecture Concepts

3 3 Overview: Diverse Forms, Common Challenges Anatomy: study of biological form of an organism Physiology: study of biological functions of an organism

4 4 (a) Tuna (b) Penguin (c) Seal Physical Constraints on Animal Size and Shape Evolutionary convergence reflects different species’ adaptations to similar environmental challenge

5 5 Exchange 0.15 mm (a) Single cell 1.5 mm (b) Two layers of cells Exchange Mouth Gastrovascular cavity Animals sizes and shapes directly affect how they exchange energy and materials with surroundings Exchange with the Environment

6 6 0.5 cm Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO 2 O2O2 Circulatory system Heart Respiratory system Cells Interstitial fluid Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 µm 50 µm Lung tissue More complex organisms have highly folded internal surfaces Exchange with the Environment

7 7 Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems Hierarchical Organization of Body Plans Table 40.1

8 8 Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Tissue Structure and Function

9 9 Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Note differences in cell shape and type of layering Tissue Structure and Function

10 10 Apical surface Basal surface Basal lamina 40 µm Tissue Structure and Function

11 11 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

12 12 Connective Tissue Collagenous fiber Loose connective tissue Elastic fiber 120 µm Cartilage Chondrocytes 100 µm Chondroitin sulfate Adipose tissue Fat droplets 150 µm White blood cells 55 µm Plasma Red blood cells Blood Nuclei Fibrous connective tissue 30 µm Osteon Bone Central canal 700 µm Tissue Structure and Function

13 13 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

14 14 Muscle Tissue 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth muscle Cardiac muscle Nucleus Muscle fibers 25 µm Nucleus Intercalated disk Tissue Structure and Function

15 15 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

16 16 Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm Tissue Structure and Function

17 17 Self-Check Tissue CategoryTissues/Cells Included; Functions Epithelial Connective Muscle Nervous

18 18 Feedback control loops maintain the internal environment in many animals Animals manage their internal environment by regulating or conforming to the external environment Homeostasis Stimulus: Perturbation/stress Response/effector Control center Sensor/receptor

19 19 Response: Heater turned off Stimulus: Control center (thermostat) reads too hot Room temperature decreases Set point: 20ºC Room temperature increases Stimulus: Control center (thermostat) reads too cold Response: Heater turned on Feedback control loops maintain the internal environment in many animals

20 20 Feedback control loops maintain the internal environment in many animals Thermoregulation: process by which animals maintain an internal temperature (a) A walrus, an endotherm (b) A lizard, an ectotherm Endothermic animals generate heat by metabolism (birds and mammals) Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and non- avian reptiles)

21 21 Balancing Heat Loss and Gain Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation RadiationEvaporation ConvectionConduction

22 22 Epidermis Dermis Hypodermis Adipose tissue Blood vessels Hair Sweat pore Muscle Nerve Sweat gland Oil gland Hair follicle Balancing Heat Loss and Gain Balancing temperature usually involves the integumentary system

23 23 Five general adaptations help animals thermoregulate: –Insulation –Circulatory adaptations –Cooling by evaporative heat loss –Behavioral responses –Adjusting metabolic heat production Balancing Heat Loss and Gain

24 24 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 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 Heat Biosynthesis Heat Cellular work Energy Allocation and Use

25 25 Metabolic rate is the amount of energy an animal uses in a unit of time Energy Use Measured by determining the amount of oxygen consumed or carbon dioxide produced

26 26 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 Energy Use

27 27 Shrew Harvest mouse Mouse Ground squirrel Rat Cat Dog Sheep Human Horse Elephant Body mass (kg) (log scale) BMR (L O 2 /hr) (log scale) (a) Relationship of BMR to body size 10 –3 10 –2 10 – Energy Use

28 –1 10 –2 10 – Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size BMR (L O2/hr) (per kg) Shrew Harvest mouse Mouse Rat Ground squirrel Cat Sheep Dog Human Horse Elephant Energy Use

29 29 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, kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake EndothermsEctotherm Energy Use Different animals budget their energy differently.

30 30 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 Energy Use

31 31 Additional metabolism that would be necessary to stay active in winter Actual metabolism Arousals Body temperature Outside temperature Burrow temperature Metabolic rate (kcal per day) Temperature (°C) JuneAugustOctoberDecemberFebruaryApril –15 –10 – Energy Use

32 32 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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