Animal Form and Function

1. Animal Form and Function Ch 40

2. Diffusion (a) Single cell Organisms must exchange matter and energy with the environment. Multicellular organisms with a sac body plan A single-celled animal living in water Mouth Gastrovascular cavity Diffusion Diffusion Figure 40.3a Figure 40.3b (b) Two cell layers

3. Animal body External environment Food O2 CO2 Mouth Respiratory system 50 µm 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 Blood 0.5 cm Heart Circulatory system Nutrients Digestive system 10 µm Interstitial fluid Metabolic waste products (urine) Excretory system The lining of the small intestine, a diges- tive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM). Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). Anus Unabsorbed matter (feces) Figure 40.4

4. Energy intake is used for maintaining homeostasis • Energy is used for maintenance and homeostasis first • Any excess energy can go towards growth or reproduction Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in urine Cellular respiration Carbon skeletons Heat ATP Biosynthesis: growth, storage, and reproduction Cellular work Heat Figure 40.7 Heat

5. Endotherms Ectotherm Reproduction 800,000 Temperature regulation costs Basal metabolic rate Growth 340,000 Activity costs Annual energy expenditure (kcal/yr) 8,000 4,000 0.025-kg female deer mouse from temperate North America 4-kg male Adélie penguin from Antarctica (brooding) 60-kg female human from temperate climate 4-kg female python from Australia (a) Total annual energy expenditures 438 Human Energy expenditure per unit mass (kcal/kg•day) 233 Python Deer mouse Adélie penguin 36.5 5.5 Energy expenditures per unit mass (kcal/kg•day) (b) Body Size and Metabolic Efficiency • Large animals require more energy overall, but have a lower energy expenditure per unit mass. • Why? Surface area to volume ratio helps them conserve energy • Ectotherms use less energy overall and per unit body mass • Why? Do not waste energy heating body Figure 40.10a, b

6. Response No heat produced Heater turned off Room temperature decreases Set point Too hot Set point Too cold Set point Control center: thermostat Room temperature increases Heater turned on Response Heat produced A homeostatic control system has three functional components • A receptor • Control center • An effector Positive vs negative regulation: see pogil Figure 40.11

7. Maintaining Homeostasis Regulators and Conformers • Regulators use physiological responses to maintain constant internal conditions • Conformers are able to tolerate a range of a particular environmental condition • In this example the Crab can tolerate a range of salt concentrations in the environment. Too low or too high leads to death

8. 40 River otter (endotherm) 30 Body temperature (°C) 20 Largemouth bass (ectotherm) 10 0 10 20 30 40 Ambient (environmental) temperature (°C) Ectotherms and Endotherms an example of regulators vs. conformers • Ectotherms • Include most invertebrates, fishes, amphibians, and non-bird reptiles • Endotherms • Include birds and mammals Figure 40.12

9. Homeostatic control mechanisms support common ancestry • Countercurrent Exchange systems help animalsmaintain higher core temperatures in the cold- see diagrams for explanation of how. • Countercurrent exchange systems are evolutionarily conserved-seen in terrestrial and aquatic animals Systems reach equilibrium and no further exchange takes place Systems do not reach equilibrium and exchange takes place along the entire length. More of the exchanged substance is transferred than in the previous example

10. Reproductive strategies reflect energy availability in the environment • When is the most energy available • Which season is best to reproduce/ support young?

11. Type 1: relatively few young, more parental investment/ care, most survive past infancy and die after adulthood Type 2: young are as likely to die as adults. Intermediate number of offspring and parental care. Type 3: have many young, young are small in size, few survive infancy, once adult or mature stage is reached most survive.

12. Responses to the environment can be behavioral or physiological • Behavioral responses: behaviors that maximize organisms chances of survival • Seasonal Migration • Nocturnal or crepuscular activity • Reptiles (thermo-conformers) “sunning” when cold and seeking shade when hot This kangaroo is licking its forearms to cool itself by evaporation

13. Responses to the environment can be behavioral or physiological • Physiological Responses • Vasodilatation when hot, vasoconstriction when cold • Insulation layer of body fat in marine mammals • Torpor/ Hibernation during extended periods of energy deprivation • Counter current exchange to reduce loss of heat • Shivering in the cold/ sweating when hot

14. Hibernation is long term torpor • Torpor- Is a physiological state in which activity is low and metabolism decreases • The body cools to near freezing temperatures • Shivering warms body for brief intervals • Saves energy during winter when food is not available Additional metabolism that would be necessary to stay active in winter Metabolic rate (kcal per day) 200 Actual metabolism 100 0 Arousals Body temperature 35 30 25 20 15 Temperature (°C) 10 5 Outside temperature 0 Burrow temperature -5 -10 -15 June August October December February April Figure 40.22

15. Circulation and Gas Exchange- a model of specialization, coordination, and adaptation • Animals have specialized organs and organ systems for gas exchange and circulation • The respiratory and circulatory systems reflect common ancestry and divergence due to different environments. • Interaction and coordination between circulatory and respiratory systems allow the organism obtain nutrients and eliminate wastes

16. Circularcanal Heart Heart Hemolymph in sinusessurrounding ograns Interstitialfluid Small branch vessels in each organ Ostia Anterior vessel Lateral vessels Dorsal vessel(main heart) Radial canal Mouth Ventral vessels Auxiliary hearts Tubular heart Figure 42.2 (a) An open circulatory system (b) A closed circulatory system Figure 42.3a Circulatory systems in animals • Gastrovascular cavity- open with the water • Open circulatory systems in insects- fluid bathes internal organs and tissues • Closed circulatory systems- blood is circulated, materials exchange by diffusion

17. Gill capillaries Lung and skin capillaries Lung capillaries Lung capillaries AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS FISHES Right systemicaorta Pulmonarycircuit Artery Pulmocutaneouscircuit Pulmonarycircuit Gillcirculation Heart:ventricle (V) Left Systemicaorta A A A A A A Atrium (A) V V V V V Left Right Left Left Right Right Systemiccirculation Systemic circuit Systemic circuit Vein Systemic capillaries Systemic capillaries Systemic capillaries Systemic capillaries Figure 42.4 Vertebrate Circulatory Systems: Common Ancestry and Divergence in different environments

18. Homeostatic Mechanisms represent common ancestry and divergence in different environments • The heart is just one example of a structure that has diverged in organisms Here is a phylogeny based on a heart structure. • Source: Emergence of Xin Demarcates a Key Innovation in Heart Evolution. DOI: 10.1371/journal.pone.0002857

19. Gas exchange systems all have large surface areas to maximize diffusion Alveoli in Lungs Salmon Gills Gills in marine worms Figure 42.20b

20. Oxygen-poorblood Gill arch Oxygen-richblood Lamella 15% 40% Water flow 70% 5% 30% 100% 60% 90% Blood flowthrough capillariesin lamellaeshowing % O2 O2 Water flowover lamellaeshowing % O2 Figure 42.21 Gillfilaments Countercurrent exchange!!! Interaction and coordination between circulatory and respiratory systems allow the organism obtain nutrients and eliminate wastes

21. Branch from thepulmonary artery(oxygen-poor blood) Branch from the pulmonary vein (oxygen-rich blood) Alveoli 50 µm 50 µm Colorized SEM SEM Heart Mammalian Respiratory Systems