L25+form+_+function+water+preview+balance+02+apr+2010.ppt

Salmon fry just after hatching (left). The same constraints that influence structure and function in small vs large animals, influence structure and function in a single animal as it changes from small to large. Stream-resident parr (below) and seaward-migrating smolt (above). What is the relationship between body size and metabolic rate? As size increases, mass-specific M.R. must decrease, or SA available for exchange of materials would fail to keep up with metabolic demands generated in that volume The surface area to volume relationship explains the relationship between size and mass-specific metabolic rate in mammals. Regulation of internal environment Homeostatic mechanisms are specializations that contribute to maintaining specific aspects of the internal environment; mechanisms of physiological regulation Conformational homeostasis Regulatory homeostasis Homeostatic Mechanisms: Interactions between the three components of a generalized system for attaining homeostasis, applied to temperature regulation Sensor detects change in condition Integrator processes information from sensor and directs appropriate response by Effector Integrator detects error signal (difference between set point and actual value), directs effector to increase heat production Negative feedback system in that if counteracts the process that causes the error signal Water and Electrolyte Homeostasis, and Elimination of Nitrogenous Waste Lungs or gills The physiological systems of animals operate within a fluid intracellular and extracellular environment. Water in a multicellular animal's body is distributed between the intracellular and extracellular compartments. open or closed External environment: salt water, fresh water, or air (terrestrial) External environment: salt water, fresh water, or air (terrestrial) Lungs or gills open or closed Water enters and leaves cells by osmosis, a special case of diffusion Osmolarity of a solution is the total solute concentration, expressed as molarity, or moles of solute (osmotically active particles) per liter of solution (solvent) Diffusion (top); solutes move from areas of higher to lower concentration Osmosis (bottom); water moves from areas of higher to lower concentration OSMOSIS DIFFUSION Water enters and leaves cells by osmosis, a special case of diffusion Osmolarity of a solution is the total solute concentration, expressed as molarity, or moles of solute (osmotically active particles) per liter of solution (solvent) Osmolarity is expressed as milliosmoles per liter (mosm/L). 1 mosm/L is the equivalent to a total solute concentration of 10^-3 M. Osmolarity of seawater is ~ 1000 mosm/L Diffusion (top); solutes move from areas of higher to lower concentration Osmosis (bottom); water moves from areas of higher to lower concentration OSMOSIS DIFFUSION Lungs or gills External environment: salt water, fresh water, or air (terrestrial) The physiological systems of animals operate within a fluid intracellular and extracellular environment. Physiological function requires maintenance within fairly narrow limits, of total water concentration and total solute concentration (osmoregulation) and concentration of specific solutes (ionic regulation), often in the face of strong challenges from an animal's external environment. Lungs or gills External environment: salt water, fresh water, or air (terrestrial) The physiological systems of animals operate within a fluid intracellular and extracellular environment. In organisms with open circulatory systems, intracellular water and solute concentrations are regulated directly by the fluid that bathes the cells; hemolymph In organisms with closed circulatory systems intracellular composition is maintained indirectly, through maintenance of the blood composition Lungs or gills Most animals are osmotic regulators and ionic regulators Some animals, such as hagfish and brine shrimp, are osmoconformers, ionic regulators hagfish Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Lungs or gills freshwater marine terrestrial Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Freshwater animals live in an external environment that threatens to flood and dilute their body fluids and deplete solutes They show adaptations that reduce water uptake, conserve solutes, and take up solutes from their surroundings. freshwater Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Terrestrial and marine animals face dessicating environments with the potential to deplete the animal's body water and, for marine animals, take on excessive solutes They similarly show adaptations for maintaining water and solute homeostasis marine terrestrial Lungs or gills freshwater marine Metabolism requires mechanisms of waste disposal, including the elimination of nitrogen-containing waste (excretion) Ammonia, a toxic compound, is the primary waste product resulting from the breakdown of proteins and nucleic acids that can only be tolerated within certain physiological limits Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Excretion Lungs or gills freshwater marine Metabolism requires mechanisms of waste disposal, including the elimination of nitrogen-containing waste (excretion) Ammonia, a toxic compound, is the primary waste product resulting from the breakdown of proteins and nucleic acids that can only be tolerated within certain physiological limits Ammonia, or less toxic metabolites of ammonia, must be eliminated; structures and mechanisms of excretion are typically closely associated with osmotic and ionic regulation Lungs or gills External environment: salt water, fresh water, or air (terrestrial) Excretion Nitrogenous waste products in vertebrate animals Lungs or gills Homeostasis of water and electrolytes and excretion of nitrogenous waste involves passive exchange processes water barrier adaptations at body/environment interfaces - such as the integument, exoskeleton. behavioral adaptations energy-costing mechanisms of selective retention and removal of molecules across transport epithelia In most animals, one or more transport epithelia spend energy to regulate solute and water movements to affect osmotic and ionic regulation and the often related function of metabolic waste removal Homeostatic regulation of water and ionic concentrations fish gills vertebrate kidney Saltwater and Freshwater Fish Face Different Challenges in Maintaining Water & Ion Balance Freshwater Gain metabolic water Gill Lose water in urine formation Gain some electrolytes in food Freshwater (lower osmolarity) Gill tissue (higher osmolarity) Gain electrolytes through active transport in Lose some electrolytes in urine Gain water by osmosis Lose electrolytes by diffusion Freshwater fishes- large glomeruli Saltwater and Freshwater Fish Face Different Challenges in Maintaining Water & Ion Balance Seawater Gain some electrolytes in food and water Replace water by drinking Gill Gill tissue (lower osmolarity) Gain many electrolytes by diffusion Seawater (higher osmolarity) Lose large amounts of water by osmosis Lose electrolytes through active transport out Lose water in urine formation Gain metabolic water Lose some electrolytes in urine reduced glomeruli Terrestrial Animals Kangaroo Rat Camel (Skin, respiratory epithelia)