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Chapter 40 Basic Principals of animal form and function (Compressed)


Michael Giroux

on 9 March 2012

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Transcript of Chapter 40 Basic Principals of animal form and function (Compressed)

Basic Principles of Animal Form and Function Overview: Diverse Forms, Common Challenges Despite their enormous amount of diversity, all animals have a similar set of problems. Form and Function are closely related Natural selection can fit structure and anatomy to function and physiology. By selecting what works best among the variations of a population. Concept 40.1: Physical laws and the environment constrain animal size and shape Physical laws and the need to exchange materials with the environment
places certain limits on the range of animal forms The ability to perform certain actions and exchange materials with the environment depends on an animal’s shape and size.
–Reflects different species’ independent adaptation to a similar environmental challenge Evolutionary convergence (Same challenge, different solutions) With single-celled organisms, exchange with the environment occurs as substances dissolve in the aqueous medium, diffuse, and are then transported across the cell's plasma membranes. Has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm. It serves the cell well, but differentiating growth dimensions prevent it from becoming exceedingly huge. Chapter 40 Let me sing you the song of my people (A single-celled protist living in water) Multicellular organisms with a sac body plan have body walls that are only two cells thick, which facilitate the diffusion of materials.
Organisms with more complex body plans have highly folded internal surfaces specialized for exchanging materials Concept 40.2: Animal form and function are correlated at all levels of organization Animals are composed of cells Groups of cells with a common structure and function make up tissues Different tissues make up organs, which together make up organ systems Tissues are classified into four main categories:
–> Epithelial, connective, muscle, and nervous. Epithelial tissue
–Covers the outside of the body and lines organs and cavities within the body, it contains cells that are closely joined. Connective tissue -Functions mainly to bind and support other tissues, it contains sparsely packed cells scattered throughout an extracellular matrix. Muscle tissue Is composed of long cells called "muscle fibers" capable of contracting in response to nerve signals.
In the vertebrate body they are divided into three types: skeletal, cardiac, and smooth. Nervous tissue -Senses stimuli and transmits signals throughout the animal. Muscle Tissue Nervous Tissue (Only the simplest of animals have tissues that are not organized into organs) In some organs, The tissues are arranged in layers Organ systems carry out the major body functions of most animals. FYI: Concept 40.3: Animals use the chemical energy in food to sustain form and function All organisms require chemical energy for growth, repair, physiological processes, regulation, and reproduction. Bioenergetics "The flow of energy through an animal" -Ultimately limits the animal’s behavior, growth, and reproduction, and determines how much food it needs. Studying an animal's bioenergetics can reveal much about its adaptations. Animals harvest chemical energy from the food they eat. Once digested, energy-containing molecules are usually used to make ATP, which powers cellular work. After the energetic needs of staying alive are met, any remaining molecules from food can be used in biosynthesis. An animal’s metabolic rate is the amount of energy an animal uses in a unit of time, and can be measured in a variety of ways An animal’s metabolic rate Is closely related to its bioenergetic strategy. Birds and mammals are mainly endothermic, meaning that their bodies are warmed mostly by heat generated by metabolism They typically have higher metabolic rates Amphibians and reptiles other than birds are ectothermic, meaning that they gain their heat mostly from external sources. They typically have lower metabolic rates The metabolic rates of animals are affected by many factors. Metabolic rate per gram is inversely related to body size among similar animals. The larger the animal the smaller the metabolic rate per gram. The smaller the animal, the larger the metabolic rate per gram. The Basal Metabolic Rate (BMR) -Is the metabolic rate of an endotherm at rest. The Standard Metabolic Rate (SMR) -Is the metabolic rate of an ectotherm at rest. For both endotherms and ectotherms, activity has a large effect on metabolic rate. In general, an animal’s maximum possible metabolic rate is inversely related to the duration of the activity. Different species of animals use the energy and materials in food in different ways, depending on their environment. An animal’s use of energy is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction. Concept 40.4: Animals regulate their internal environment within relatively narrow limits This is where I ruin everything forever. (The internal environment of vertebrates is called the interstitial fluid, and is very different from the external environment.) -A balance between external changesnd the animal’s internal control mechanisms that oppose the changes Homeostasis Regulating and conforming are two extremes in how animals cope with environmental fluctuations. –If it uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation. An animal is said to be a regulator An animal is said to be a conformer -If it allows its internal condition to vary with certain external changes. Mechanisms of homeostasis moderate changes in the internal environment
Control center
Effector A homeostatic control system has three functional components: Most homeostatic control systems function by negative feedback; where buildup of the end product of the system shuts the system off. A second type of homeostatic control system is positive feedback; which involves a change in some variable that triggers mechanisms that amplify the change.

Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior Thermoregulation -The process by which animals maintain an internal temperature within a tolerable range. In general, ectotherms tolerate greater variation in internal temperature than endotherms. Endothermy is more energetically expensive than ectothermy: But buffers animals’ internal temperatures against external fluctuations.
And enables the animals to maintain a high level of aerobic metabolism. Organisms exchange heat by four physical processes. -The emission of electromagnetic waves by all objects warmer than absolute zero. Radiation can transfer heat between objects that are not in direct contact, as when a lizard absorbs heat radiating from the sun. Radiation -The removal of heat from the surface of a liquid that is losing some of its molecules as gas. evaporation of water from a lizard’s moist surfaces that are exposed to the environment has a strong cooling effect. Evaporation -The transfer of heat by themovement of air or liquid past a surface, as when a breeze contributes to heat loss from a lizard’s dry skin, or blood moves heat from the body core to the extremities. Convection -The direct transfer of thermal motion (heat) between molecules of objects in direct contact with each other, as when a lizard sits on a hot rock. Conduction Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss -A major thermoregulatory adaptation in mammals and birds that reduces the flow of heat between an animal and its environment Insulation (may include feathers, fur, or blubber) In mammals, the integumentary system acts as insulating material. Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin. Vasodilation -Blood flow in the skin increases, facilitating heat loss. Vasoconstriction -Blood flow in the skin decreases, lowering heat loss. Many marine mammals and birds have arrangements of blood vessels called Countercurrent Heat Exchangers that are important for reducing heat loss Some specialized bony fishes and sharks also possess countercurrent heat exchangers. Many endothermic insects have countercurrent heat exchangers that help maintain a high temperature in the thorax. Many types of animals:
Lose heat through the evaporation of water in sweat.
Use panting to cool their bodies Bathing moistens the skin which helps to cool an animal down. Both endotherms and ectotherms use a variety of behavioral responses to control body temperature. -Some terrestrial invertebrates have certain postures that enable them to minimize or maximize their absorption of heat from the sun. Some animals can regulate body temperature by adjusting their rate of metabolic heat production. Many species of flying insects use shivering to warm up before taking flight. Mammals regulate their body temperature through a complex negative feedback system that involves several organ systems. In humans, a specific part of the brain, the hypothalamus, contains a group of nerve cells that function as a thermostat. In a process known as acclimatization
–Many animals can adjust to a new range of environmental temperatures over a period of days or weeks. Acclimatization may involve cellular adjustments, or in the case of birds and mammals, adjustments of insulation and metabolic heat production. Torpor -an adaptation that enables animals to save energy while avoiding difficult and dangerous conditions it is a physiological state in which activity is low and metabolism decreases.
–It is an adaptation to winter cold and food scarcity during which the animal’s body temperature declines. Estivation, or Summer Torpor Hibernation is long-term torpor –Enables animals to survive long periods of high temperatures and scarce water supplies. Daily torpor –Is exhibited by many small mammals and birds and seems to be adapted to their feeding patterns -The study of the transformation of energy in living organisms.
Bioenergetics Heat acquired from dead stuff.
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