Basic Principles of Animal Form and Function Taught by Dhruv, Tommy, Zach, and Butch

Physical Constraints on Size  Physical laws govern strength, diffusion, movement, and heat exchange limit the range of animal forms.  Ex. Streamlined body, maximum body sizes  Physical laws govern strength, diffusion, movement, and heat exchange limit the range of animal forms.  Ex. Streamlined body, maximum body sizes

Exchange with the Environment  Rate of exchange proportional to surface area, amount proportional to volume.  Multicellular organization only works if every cell has access to a suitable aqueous environment, either inside or outside.  Ex. Inner, outer layers, flat body shape, extensively branched or folded exchange surfaces)  Rate of exchange proportional to surface area, amount proportional to volume.  Multicellular organization only works if every cell has access to a suitable aqueous environment, either inside or outside.  Ex. Inner, outer layers, flat body shape, extensively branched or folded exchange surfaces)

Hierarchical Organization of Body Plans  Tissues  Organs  Organ Systems  Tissues  Organs  Organ Systems

Tissue Structure and Function  Four types of tissues:  Epithelial Tissue  Connective Tissue  Muscle Tissue  Nervous Tissue  Four types of tissues:  Epithelial Tissue  Connective Tissue  Muscle Tissue  Nervous Tissue

Epithelial Tissue  Covers the outside of the body and lines organs and cavities within the body.  Close packing allows enables it to function as barrier against mechanical injury, pathogens, and fluid loss.  Epithelium (the cells) form active interfaces with the environment.  Covers the outside of the body and lines organs and cavities within the body.  Close packing allows enables it to function as barrier against mechanical injury, pathogens, and fluid loss.  Epithelium (the cells) form active interfaces with the environment.

Connective Tissue  functions to bind and support other tissues.  Sparse population of cells scattered through an extra cellular matrix.  Two types of connective tissue cells: Fibroblasts (secrete the protein ingredients of extracellular fibers) and Macrophages (cells that roam the maze of fibers, engulfing debris)  Three types of connective tissue fibers: collagenous (provide strength with flexibility, made of collagen, are nonelastic and do not tear easily), elastic (easily stretched but are also resilient, made of elastin), and reticular (very thin and branched, form tightly woven fabric that joins connective tissue to adjacent tissue.  functions to bind and support other tissues.  Sparse population of cells scattered through an extra cellular matrix.  Two types of connective tissue cells: Fibroblasts (secrete the protein ingredients of extracellular fibers) and Macrophages (cells that roam the maze of fibers, engulfing debris)  Three types of connective tissue fibers: collagenous (provide strength with flexibility, made of collagen, are nonelastic and do not tear easily), elastic (easily stretched but are also resilient, made of elastin), and reticular (very thin and branched, form tightly woven fabric that joins connective tissue to adjacent tissue.

Muscle Tissue  The most abundant tissue in animals  All muscle cells consist of filaments containing actin and myosin, which together enable contraction.  Types: Skeletal, Cardiac, Smooth  The most abundant tissue in animals  All muscle cells consist of filaments containing actin and myosin, which together enable contraction.  Types: Skeletal, Cardiac, Smooth

Nervous Tissue  Sense stimuli and transmit signals in the form of nerve impulses from one part of animal to another.

 A regu lator uses mechanisms to regulate the internal environment in face of external change.  A conformer allows its internal environment to conform to external changes.  A regu lator uses mechanisms to regulate the internal environment in face of external change.  A conformer allows its internal environment to conform to external changes. Regulators vs. Conformers

Regulator vs Conformer

Homeostasis  Homeostasis: means “ steady state ” or internal balance.

Feedback

Thermoregulation: process by which animal maintains an internal temperature within a tolerable range

Endothermy and Ectothermy  Endotherm: Warmed mostly by heat generated by metabolism. Commom Examples: Mammals, birds and insects.  Ectotherms: Gain heat mostly from external sources. Common examples: Lizards, amphibians, snakes, many fish and invertabrates  Endotherm: Warmed mostly by heat generated by metabolism. Commom Examples: Mammals, birds and insects.  Ectotherms: Gain heat mostly from external sources. Common examples: Lizards, amphibians, snakes, many fish and invertabrates

Poikilotherm vs. Homeotherm  Poikilotherm: Body temperature varies with the temperature of the environment  Homeotherm: Body temperature relatively constant despite temperature changes in the environment.  Poikilotherm: Body temperature varies with the temperature of the environment  Homeotherm: Body temperature relatively constant despite temperature changes in the environment.

Type of heat loss to the Environment

 Insulation reduces Heat Loss to the Environment. Seen in birds in the form of feathers, in marine mammals in the form of blubber and land mammals in the form of fur

Countercurrent Exchange

 Countercurrent exchange is flow of adjacent fluids in opposing directions in order to maximize transfer rates of heat or solutes.  Antiparallel arrangement so that heat transfer occurs along entire exchanger  Countercurrent exchange is flow of adjacent fluids in opposing directions in order to maximize transfer rates of heat or solutes.  Antiparallel arrangement so that heat transfer occurs along entire exchanger

Cooling  Some animals sweat; as the water evaporates, it absorbs heat and cools the animal  Panting is important in many birds and mammals (birds have a pouch): water evaporates from the pouch or tongue  Some animals, like honeybees, flap their wings to improve evaporation and convection  Some animals sweat; as the water evaporates, it absorbs heat and cools the animal  Panting is important in many birds and mammals (birds have a pouch): water evaporates from the pouch or tongue  Some animals, like honeybees, flap their wings to improve evaporation and convection

Thermoregulatory Behavioral Responses  Move to warm or cool areas, move into or out of wind  Some animals, like honeybees, huddle together to better retain heat  Move to warm or cool areas, move into or out of wind  Some animals, like honeybees, huddle together to better retain heat

Metabolic Heat Production  Shivering raises body temperature  Some mammals can cause mitochondria to produce heat instead of ATP  Some reptiles become endothermic and produce heat through shivering under special conditions, such as when incubating eggs  In insects, wing muscles are very important for heat production.  Shivering raises body temperature  Some mammals can cause mitochondria to produce heat instead of ATP  Some reptiles become endothermic and produce heat through shivering under special conditions, such as when incubating eggs  In insects, wing muscles are very important for heat production.

Acclimatization  Adjust to seasons by growing or shedding fur or feathers  Ectotherms are better at acclimatization and often produce variants of enzymes that have the same function but different optimal temperatures  Change amount of saturated lipids in membrane; saturated lipids decrease fluidity and unsaturated lipids increase fluidity  Adjust to seasons by growing or shedding fur or feathers  Ectotherms are better at acclimatization and often produce variants of enzymes that have the same function but different optimal temperatures  Change amount of saturated lipids in membrane; saturated lipids decrease fluidity and unsaturated lipids increase fluidity

Hypothalamus and Fever  Hypothalamus: region of the brain that functions as the thermostat  Some endotherms develop fever to kill off a bacteria infection; some ectotherms seeks warmer environmental temperatures to kill off a bacteria infection  Hypothalamus: region of the brain that functions as the thermostat  Some endotherms develop fever to kill off a bacteria infection; some ectotherms seeks warmer environmental temperatures to kill off a bacteria infection

Metabolic Rate  A bigger organism has a higher metabolic rate than a smaller organism  For some unknown reason, bigger animals have a smaller metabolic rate per kg than smaller animals, despite the fact that a greater percentage of their body mass is devoted to locomotion. This is all true for both ectotherms and endotherms.  Metabolic rate is roughly proportional to body mass to the three-quarter power  Animals typically have an average daily metabolic rate that is 2 to 4 times their BMR or SMR. Humans ’ average daily metabolic rate is 1.5 times their BMR- indicating their sedentary lifestyles  A bigger organism has a higher metabolic rate than a smaller organism  For some unknown reason, bigger animals have a smaller metabolic rate per kg than smaller animals, despite the fact that a greater percentage of their body mass is devoted to locomotion. This is all true for both ectotherms and endotherms.  Metabolic rate is roughly proportional to body mass to the three-quarter power  Animals typically have an average daily metabolic rate that is 2 to 4 times their BMR or SMR. Humans ’ average daily metabolic rate is 1.5 times their BMR- indicating their sedentary lifestyles

Energy budgets  Ectotherms have smaller average daily metabolic rates than endotherms of similar size because they do not spend energy on thermoregulation  Smaller organisms must spend more energy on thermoregulation because they have a high surface to volume ratio, causing them to lose or gain heat more easily  Animals, such as penguins, that have to swim to catch their food spend a large fraction of their energy on movement, because water has more resistance to movement than air  Ectotherms have smaller average daily metabolic rates than endotherms of similar size because they do not spend energy on thermoregulation  Smaller organisms must spend more energy on thermoregulation because they have a high surface to volume ratio, causing them to lose or gain heat more easily  Animals, such as penguins, that have to swim to catch their food spend a large fraction of their energy on movement, because water has more resistance to movement than air

Energy Conservation  Torpor: a physiological state in which activity is low and metabolism decreases  Hibernation: during the winter; Estivation: during the summer  Torpor: a physiological state in which activity is low and metabolism decreases  Hibernation: during the winter; Estivation: during the summer

Diseases/Disorders  Amyotrophic Lateral Sclerosis  Ross Syndrome  Parkinson’s Disease  Schizophrenia  Lymphocyte Homeostasis Syndrome  Amyotrophic Lateral Sclerosis  Ross Syndrome  Parkinson’s Disease  Schizophrenia  Lymphocyte Homeostasis Syndrome