BASIC PRINCIPLES OF ANIMAL FORM AND FUNCTION CHAPTER 40 BASIC PRINCIPLES OF ANIMAL FORM AND FUNCTION

REVIEW: anatomy—study of an organism’s structure physiology—study of biological function You Must Know: Four types of tissues and their general functions The importance of homeostasis and examples How feedback systems control homeostasis, and one example of positive feedback and one example of negative feedback

I. Concept 40.1: 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 The ability to perform certain actions depends on an animal’s shape, size, and environment Evolutionary convergence reflects different species’ adaptations to a similar environmental challenge Physical laws impose constraints on animal size and shape

Mouth Gastrovascular cavity Exchange Exchange Exchange 0.15 mm 1.5 mm Fig. 40-3 Mouth Gastrovascular cavity Exchange Exchange Exchange Figure 40.3 Contact with the environment 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells

Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials More complex organisms have highly folded internal surfaces for exchanging materials Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Figure 40.4 Internal exchange surfaces of complex animals External environment CO2 Food O2 Mouth Animal body Respiratory system Blood 50 µm 0.5 cm Lung tissue Nutrients Cells Heart Circulatory system 10 µm Interstitial fluid Digestive system Figure 40.4 Internal exchange surfaces of complex animals Lining of small intestine Excretory system Kidney tubules Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste)

Metabolic waste products (nitrogenous waste) Fig. 40-4a External environment CO2 Food O2 Mouth Animal body Respiratory system Blood Nutrients Cells Heart Circulatory system Interstitial fluid Digestive system Figure 40.4 Internal exchange surfaces of complex animals Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste)

Lining of small intestine Fig. 40-4b 0.5 cm Figure 40.4 Internal exchange surfaces of complex animals Lining of small intestine

Fig. 40-4c 50 µm Lung tissue Figure 40.4 Internal exchange surfaces of complex animals

Kidney tubules 10 µm Fig. 40-4d Figure 40.4 Internal exchange surfaces of complex animals Kidney tubules

In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells A complex body plan helps an animal in a variable environment to maintain a relatively stable internal environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Hierarchical Organization of Body Plans Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Tissues 1. Are defined as groups of cell that have a common structure and function 2. Can be organized into functional units called organs 3. Groups of organs that work together make up organ systems (Ex: digestive, circulatory, and excretory systems)

B. Four types of tissue: 1. Epithelial Tissue Occurs in sheets of tightly packed cells Covers the body, lines the organs and acts as a protective barrier One side of the epithelium is always bound to an underlying surface called the basement membrane (basal surface) Always has one free surface facing either air or a fluid environment

It contains cells that are closely joined The shape of epithelial cells may be cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles) The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Connective Tissue Mainly supports and binds other tissues Consists of scattered cells within an extracellular matrix Ex: cartilage, tendons, ligaments, bone, adipose tissue, and blood

There are three types of connective tissue fiber, all made of protein: Collagenous fibers provide strength and flexibility Elastic fibers stretch and snap back to their original length Reticular fibers join connective tissue to adjacent tissues Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Connective tissue contains cells, including Fibroblasts that secrete the protein of extracellular fibers Macrophages that are involved in the immune system Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

In vertebrates, the fibers and foundation combine to form six major types of connective tissue: Loose connective tissue binds epithelia to underlying tissues and holds organs in place Cartilage is a strong and flexible support material Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Adipose tissue stores fat for insulation and fuel Blood is composed of blood cells and cell fragments in blood plasma Bone is mineralized and forms the skeleton Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. Muscle Tissue Responsible for nearly all types of body movement Muscle filaments are made of the proteins actin (thin) and myosin (thick) Muscle fibers contract when stimulated by a nerve impulse Most abundant tissue in most animals Three types of muscle: skeletal (voluntary), cardiac (involuntary—makes up heart), smooth (involuntary)

Muscle Tissue It is divided in the vertebrate body into three types: Skeletal muscle, or striated muscle, is responsible for voluntary movement Smooth muscle is responsible for involuntary body activities Cardiac muscle is responsible for contraction of the heart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4. Nervous Tissue Functional unit is the neuron (nerve cell) Senses stimuli and transmits signals from one part of the body to another part Includes other neurons, glands, muscles and the brain

C. For animal survival tissue, organs, and organ systems C. For animal survival tissue, organs, and organ systems must act in a coordinated manner 1. The Endocrine System Involves glands that produce chemicals called hormones that are released into the bloodstream and carried to specific glands A hormone may affect one or more regions throughout the body Hormones are relatively slow acting, but can have long-lasting effects

C. For animal survival tissue, organs, and organ systems C. For animal survival tissue, organs, and organ systems must act in a coordinated manner 2. The Nervous System Neurons transmit information between specific locations Only three type of cells receive nerve impulses: neuron, muscle cells, and endocrine cells

II. Concept 40.2 Homeostasis Process by which animals maintain a relatively constant internal environment, even when the external environment changes significantly “steady state” B. Homeostatic control systems function by having a set point (body temperature), sensors to detect any stimulus above or below the set point, and a physiological response that helps return the body to its set point

C. Negative Feedback Animal response to the stimulus in a way that reduces the stimulus Ex: in response to exercise, the body temperature rises, which initiates sweating to cool the body Positive Feedback Involves a change in some variable that triggers mechanisms that amplify rather than reverse the change Very unstable Ex: uterine contractions

Alterations in Homeostasis Set points and normal ranges can change with age or show cyclic variation Homeostasis can adjust to changes in external environment, a process called acclimatization Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

III. Concept 40.3 Thermoregulation—refers to how animals maintain their internal temperature within a tolerable range Endotherms (warm blooded) Ex: mammals and birds Are warmed mostly by heat generated by metabolism Ectotherms (cold blooded) Ex: most invertebrates, fishes, amphibians, reptiles Generate relatively little metabolic heat, gaining most of their heat from external sources

Endothermy is more energetically expensive than ectothermy In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperatures Endothermy is more energetically expensive than ectothermy The body temperature of a poikilotherm varies with its environment, while that of a homeotherm is relatively constant Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Balancing Heat Loss and Gain Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Radiation Evaporation Convection Conduction Fig. 40-10 Figure 40.10 Heat exchange between an organism and its environment Convection Conduction

Heat regulation in mammals often involves the integumentary system: skin, hair, and nails Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Hypodermis Fig. 40-11 Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Figure 40.11 Mammalian integumentary system Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle

Five general adaptations help animals thermoregulate: Insulation Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Insulation Insulation is a major thermoregulatory adaptation in mammals and birds Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Circulatory Adaptations Regulation of blood flow near the body surface significantly affects thermoregulation Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin In vasodilation, blood flow in the skin increases, facilitating heat loss In vasoconstriction, blood flow in the skin decreases, lowering heat loss Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

D. Countercurrent Exchange This is the method by which many birds and mammals reduce heat loss Heat transfer involves antiparallel arrangement of blood vessels such that warm blood from the core of the animal, en route to the extremities, transfers heart to colder blood returning form the extremities. Heat that would have been lost to the environment is conserved in the blood returning to the core of the animals

Countercurrent Exchange

Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water in sweat Panting increases the cooling effect in birds and many mammals Sweating or bathing moistens the skin, helping to cool an animal down Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Behavioral Responses Both endotherms and ectotherms use behavioral responses to control body temperature Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 40-13 Figure 40.13 Thermoregulatory behavior in a dragonfly

Adjusting Metabolic Heat Production Some animals can regulate body temperature by adjusting their rate of metabolic heat production Heat production is increased by muscle activity such as moving or shivering Some ectotherms can also shiver to increase body temperature Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Concept 40.4: Energy requirements are related to animal size, activity, and environment Bioenergetics is the overall flow and transformation of energy in an animal It determines how much food an animal needs and relates to an animal’s size, activity, and environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Energy Allocation and Use Animals harvest chemical energy from food Energy-containing molecules from food are usually used to make ATP, which powers cellular work After the needs of staying alive are met, remaining food molecules can be used in biosynthesis Biosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Organic molecules in food External environment Animal body Fig. 40-17 Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in nitrogenous waste Carbon skeletons Cellular respiration Heat Figure 40.17 Bioenergetics of an animal: an overview ATP Biosynthesis Cellular work Heat Heat

Quantifying Energy Use Metabolic rate is the amount of energy an animal uses in a unit of time One way to measure it is to determine the amount of oxygen consumed or carbon dioxide produced Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 40-18 Figure 40.18 Measuring rate of oxygen consumption in a running pronghorn

Minimum Metabolic Rate and Thermoregulation Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Both rates assume a nongrowing, fasting, and nonstressed animal Ectotherms have much lower metabolic rates than endotherms of a comparable size Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Influences on Metabolic Rate Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm Two of these factors are size and activity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Size and Metabolic Rate Metabolic rate per gram is inversely related to body size among similar animals Researchers continue to search for the causes of this relationship The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Activity and Metabolic Rate Activity greatly affects metabolic rate for endotherms and ectotherms In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Energy Budgets Different species use energy and materials in food in different ways, depending on their environment Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Torpor and Energy Conservation Torpor is a physiological state in which activity is low and metabolism decreases Torpor enables animals to save energy while avoiding difficult and dangerous conditions Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Estivation, or summer 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 adapted to feeding patterns Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Stimulus: Perturbation/stress Fig. 40-UN1 Homeostasis Response/effector Stimulus: Perturbation/stress Control center Sensor/receptor