Basic Principles of Animal Form and Function Chapter 32 – Part I Basic Principles of Animal Form and Function

What you must know: How feedback systems function to maintain homeostasis One example of positive feedback and one example of negative feedback

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!

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  Tissues  Organs  Organ Systems

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)

Coordination and control within a body Endocrine System: transmits chemical signals (hormones) to all locations in the body through the bloodstream Slow acting, long-lasting effects Info received by: cells with specific receptors for released hormone 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 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

Temperature Regulation

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?

Energy Use Metabolic rate: total amount of energy an animal uses in a unit of time Ectotherms have much lower metabolic rates than endotherms of a comparable size

Metabolic rate is inversely related to body size among similar animals

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

Five adaptations for thermoregulation: Insulation (skin, feather, fur, blubber) Circulatory adaptations (countercurrent exchange) Cooling by evaporative heat loss (sweat) Behavioral responses (shivering) Cellular adjustments (“antifreeze” proteins, membrane lipids, enzyme variants)

Countercurrent heat exchange

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

Marine vs. Freshwater Fish Osmoregulation Marine vs. Freshwater Fish Nitrogenous wastes

Mammalian Excretory System Osmoregulation Mammalian Excretory System

Nephron: blood filtration and water concentration in the human kidney