Ch. 40 Warm up Define and give an example of homeostasis. Sequence the organization of living things from cell to biome. Describe negative and positive feedback.

Basic Principles of Animal Form and Function Chapter 40 Basic Principles of Animal Form and Function

Overview: Diverse Forms, Common Challenges Anatomy: the study of the biological form (STRUCTURE) of an organism Physiology: the study of the biological FUNCTIONS an organism performs Structure dictates function! © 2011 Pearson Education, Inc.

Figure 40.1 Figure 40.1 How does a jackrabbit keep from overheating? 4

Animal form and function are correlated at all levels of organization Size and shape affect the way an animal interacts with its environment Many different animal body plans have evolved and are determined by the genome © 2011 Pearson Education, Inc.

Hierarchical Organization of Body Plans Cells  Tissues  Organs  Organ Systems © 2011 Pearson Education, Inc.

Four main types of tissues: Epithelial: covers the outside of the body and lines the organs and cavities within the body Connective: binds and supports other tissues (cartilage, tendons, ligaments, bone, blood, adipose) Muscle: controls body movement (skeletal, smooth, cardiac) Nervous: senses stimuli and transmits signals throughout the animal (neurons, glia) © 2011 Pearson Education, Inc.

Coordination and Control Within a Body Endocrine system: transmits chemical signals (hormones) to receptive cells throughout body via blood Slow acting, long-lasting effects Nervous system: neurons transmit info between specific locations Very fast! Info received by: neurons, muscle cells, endocrine cells © 2011 Pearson Education, Inc.

Homeostasis Maintain a “steady state” or internal balance regardless of external environment Fluctuations above/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 © 2011 Pearson Education, Inc.

Negative Feedback Positive Feedback “More gets you less.” Return changing conditions back to set point Examples: Temperature Blood glucose levels Blood pH Plants: response to water limitations “More gets you more.” Response moves variable further away from set point Stimulus amplifies a response Examples: Lactation in mammals Onset of labor in childbirth Plants: ripening of fruit

Thermoregulation Maintain an internal temperature within a tolerable range Endothermic animals generate heat by metabolism (birds and mammals) Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and nonavian reptiles) Q: Which is more active at greater temperature variations? Q: Which requires more energy? © 2011 Pearson Education, Inc.

Figure 40.10 Figure 40.10 Endothermy and ectothermy. 19

Balancing Heat Loss and Gain Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conduction © 2011 Pearson Education, Inc.

Five adaptations for thermoregulation: Insulation (skin, feather, fur, blubber) Circulatory adaptations (countercurrent exchange) Cooling by evaporative heat loss (sweat) Behavioral responses (shivering) Adjusting metabolic heat production (“antifreeze”) © 2011 Pearson Education, Inc.

Figure 40.12 Figure 40.12 Countercurrent heat exchangers. 22

Figure 40.16 Figure 40.16 The thermostatic function of the hypothalamus in human thermoregulation. 23

Energy Use Metabolic rate: amount of energy an animal uses in a unit of time Basal metabolic rate (BMR): endotherm at rest at a “comfortable” temperature Standard metabolic rate (SMR): ectotherm at rest at a specific temperature Ectotherms have much lower metabolic rates than endotherms of a comparable size © 2011 Pearson Education, Inc.

Figure 40.19 Figure 40.19 The relationship of metabolic rate to body size. 25

Torpor and Energy Conservation Torpor is a physiological state in which activity is low and metabolism decreases Save energy while avoiding difficult and dangerous conditions Hibernation: torpor during winter cold and food scarcity Estivation: summer torpor, survive long periods of high temperatures and scarce water © 2011 Pearson Education, Inc.