Animal Form and Function Animal challenges Obtain oxygen

Animal Form and Function

Animal challenges • • • Obtain oxygen Nourishment Hydration Excrete waste Move Reproduce

The solution • Natural Selection and adaptation!!!!

The Study of Form and Function • Anatomy – structure • Physiology – function

Animal forms • Evolution is limited by physical laws – Gravity – hydrodynamics

Exchange with the Environment – All cells must be surrounded by water – Surface area: volume ratio (lung, intestine) – Access to outside (flatworm, hydra)

Levels of Organization • Form and function are correlated on all levels – Organs – Tissue – Cell

Homeostasis • Interstitial fluid – p. H • ~7. 4 – Blood sugar • 90 mg/100 ml – Temperature • ~98. 6

To Regulate or to Conform? • Regulator – Moderate internal conditions in response to external change • Salmon, mammal • Conformer – Allow internal conditions to vary with external • Shark, lizard

Regulation • Negative feedback – Change in variable limits further change – Thermostat keeps room temperature within a narrow range • Positive feedback – Change in variable increases variable – Ethylene production 1 ripe fruit leads to more ripe fruit

Bioenergetics • Energy limits behavior, growth, reproduction • Food macromolecules glucose ATP • Metabolic rate=energy/time – How can you measure metabolism? – Calories – Oxygen – CO 2

Endothermic – “warm blooded” – Body warmed by metabolic heat – Benefits • Wide range of environments • Intense activity – Limitations • High energy cost

Ectothermic – “cold blooded” – Get heat from environment – Benefits • Low energy requirement (less food) – Limitations • Environment • Slower moving

Size and Metabolic Rate

• Activity – Inversely related to duration of activity – Energy requirements depend on: • • Temperature Age Body size gender

• Size Metabolic rate – Inverse relationship between size and metabolic rate – Why? – Maintaining body temp, surface area: volume

Thermoregulation Review • Ectotherms-invertebrates, most fish, most reptiles, amphibians – Narrow range – Regulate with behavior • Endotherms-mammals, most birds, some fish and reptiles – Tolerate wider range of temperatures – Regulate with metabolic rate – Change in response to environment • Fever

• Insulation – Fat – Fur – Organs in core • Circulation – Vasodilation/ Vasoconstriction – Core shunt – Countercurrent heat exchange

Cooling • Evaporative cooling • Behavioral responses – Shivering – Torpor

Feedback mechanisms • Require multiple systems – Coordinated by brain – Activates muscles to adjust temperature • Shivering • Vasoconstriction – Affects behavior • Fanning hive • location

Acclimatization • Seasonal variation • Organism – More fur, fat, hibernation, etc • Cellular – Membrane fats – Enzyme production – Cryoprotectants – Heat shock proteins

Torpor • Activity slows, metabolism decreases • Hibernation – Energy consumption is 100 x lower – Cool body temp • Estivation- summer torpor