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Basic Principles of Animal Form and Function • Anatomy: the study of the biological form (STRUCTURE) of an organism• Physiology: the study of the biological FUNCTIONS an organism performs• Structure dictates function! 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 Hierarchical Organization of Body Plans:• Cells à Tissues à Organs à Organ Systems Four main types of tissues:Epithelial: covers the outside of the body and lines the organs and cavities within the bodyConnective: 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) 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 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 Negative Feedback: more stimulus gets you less of something THE POINT: return changing conditions back to a set point Examples: temperature, blood glucose levels, blood pH Ex: plants response to waterlimitations Positive feedback: more stimulus gets you more of something THE POINT: response moves variable further away from a set point As in, the STIMULUS AMPLIFIES THE RESPONSE Examples: lactation in mammals, Onset of labor in childbirth Ex: in plants, the 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?Balancing heat loss and gain:• Organisms exchange heat by four physical processes: radiation, evaporation, convection, and conductionFive 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”) 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 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
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