How does a jackrabbit keep from overheating? Figure 40.1 How does a jackrabbit keep from overheating? For the Discovery Video Human Body, go to Animation and Video Files.

Convergent evolution in fast swimmers (a) Tuna Figure 40.2 Convergent evolution in fast swimmers (b) Penguin (c) Seal

Contact with the environment Mouth Gastrovascular cavity Exchange Exchange Exchange Figure 40.3 Contact with the environment 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells

Internal exchange surfaces of complex animals External environment CO2 Food O2 Mouth Animal body Respiratory system Blood 50 µm 0.5 cm Lung tissue Nutrients Cells Heart Circulatory system 10 µm Interstitial fluid Digestive system Figure 40.4 Internal exchange surfaces of complex animals Lining of small intestine Excretory system Kidney tubules Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste)

Organ Systems

Structure and function in animal tissues Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Figure 40.5 Structure and function in animal tissues Simple squamous epithelium

Connective Tissue Loose connective tissue Cartilage Fibrous connective Collagenous fiber Loose connective tissue Chondrocytes Cartilage 120 µm 100 µm Elastic fiber Chondroitin sulfate Nuclei Fat droplets Fibrous connective tissue Adipose tissue 30 µm 150 µm Figure 40.5 Structure and function in animal tissues Osteon White blood cells Bone Blood 700 µm 55 µm Central canal Plasma Red blood cells

Muscle Tissue Skeletal muscle Cardiac muscle Smooth muscle Multiple nuclei Muscle fiber Sarcomere Skeletal muscle Nucleus 100 µm Intercalated disk 50 µm Cardiac muscle Figure 40.5 Structure and function in animal tissues Smooth muscle Nucleus Muscle fibers 25 µm

Nervous Tissue Neuron 40 µm Axons Blood vessel Dendrites Cell body Glial cells Neuron Figure 40.5 Structure and function in animal tissues Axons Blood vessel 15 µm

Neuron 40 µm Dendrites Cell body Axon Figure 40.5 Structure and function in animal tissues Neuron

Signaling Stimulus Stimulus Endocrine cell Neuron Axon Signal Hormone Signal travels along axon to a specific location. Signal travels everywhere via the bloodstream. Blood vessel Signal Axons Figure 40.6 Signaling in the endocrine and nervous systems Response Response (a) Signaling by hormones (b) Signaling by neurons

Stimulus Neuron Axon Signal Signal travels along axon to a specific location. Signal Axons Figure 40.6b Signaling in the endocrine and nervous systems Response Signaling by neurons

(temperature conformer) 40 River otter (temperature regulator) 30 Body temperature (°C) 20 Largemouth bass (temperature conformer) 10 Figure 40.7 The relationship between body and environmental temperatures in an aquatic temperature regulator and an aquatic temperature conformer 10 20 30 40 Ambient (environmental) temperature (ºC)

negative feedback Response: Heater turned off Room temperature decreases Stimulus: Control center (thermostat) reads too hot Set point: 20ºC Figure 40.8 A nonliving example of negative feedback: control of room temperature Stimulus: Control center (thermostat) reads too cold Room temperature increases Response: Heater turned on

(a) A walrus, an endotherm Figure 40.9 Endothermy and ectothermy (b) A lizard, an ectotherm

Heat exchange between an organism and its environment Radiation Evaporation Figure 40.10 Heat exchange between an organism and its environment Convection Conduction

Mammalian integumentary system Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Figure 40.11 Mammalian integumentary system Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle

Countercurrent heat exchangers Canada goose Bottlenose dolphin Blood flow Artery Vein Vein Artery 35ºC 33º Figure 40.12 Countercurrent heat exchangers 30º 27º 20º 18º 10º 9º Countercurrent heat exchangers

O2 consumption (mL O2/hr) per kg RESULTS A Burmese python generates heat while incubating eggs. 120 100 80 O2 consumption (mL O2/hr) per kg 60 40 Figure 40.14 How does a Burmese python generate heat while incubating eggs? 20 5 10 15 20 25 30 35 Contractions per minute

Hypothalamus: thermoregulation Sweat glands secrete sweat, which evaporates, cooling the body. Thermostat in hypothalamus activates cooling mechanisms. Hypothalamus: thermoregulation Blood vessels in skin dilate: capillaries fill; heat radiates from skin. Body temperature decreases; thermostat shuts off cooling mechanisms. Increased body temperature Homeostasis: Internal temperature of 36–38°C Body temperature increases; thermostat shuts off warming mechanisms. Decreased body temperature Figure 40.16 The thermostatic function of the hypothalamus in human thermoregulation Blood vessels in skin constrict, reducing heat loss. Thermostat in hypothalamus activates warming mechanisms. Skeletal muscles contract; shivering generates heat.

Bioenergetics of an animal Organic molecules in food Bioenergetics of an animal External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in nitrogenous waste Carbon skeletons Cellular respiration Heat Figure 40.17 Bioenergetics of an animal: an overview ATP Biosynthesis Cellular work Heat Heat

Relationship of Metabolic Rate to Body Size 103 Elephant 102 Horse Human 10 Sheep BMR (L O2/hr) (Iog scale) Cat Dog 1 Rat 10–1 Ground squirrel 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 8 Shrew 7 6 Figure 40.19 The relationship of metabolic rate to body size 5 BMR (L O2/hr) (per kg) 4 3 Harvest mouse 2 Mouse Sheep Rat Human Elephant 1 Cat Dog Ground squirrel Horse 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

from temperate climate Energy budgets for four animals Endotherms Ectotherm 800,000 Reproduction Basal (standard) metabolism Thermoregulation Growth Activity Annual energy expenditure (kcal/hr) 340,000 8,000 4,000 Figure 40.20 Energy budgets for four animals 60-kg female human from temperate climate 4-kg male Adélie penguin from Antarctica (brooding) 0.025-kg female deer mouse from temperate North America 4-kg female eastern indigo snake

Body temperature and metabolism during hibernation in ground squirrels 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 10 Figure 40.21 Body temperature and metabolism during hibernation in Belding’s ground squirrels 5 Outside temperature –5 Burrow temperature –10 –15 June August October December February April

Stimulus: Perturbation/stress Review Homeostasis Response/effector Stimulus: Perturbation/stress Control center Sensor/receptor

You should now be able to: 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. 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

Compare and contrast the nervous and endocrine systems. Define thermoregulation and explain how endotherms and ectotherms manage their heat budgets. Describe how a countercurrent heat exchanger may function to retain heat within an animal body. Define bioenergetics and biosynthesis. Define metabolic rate and explain how it can be determined for animals. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings