Chapter 40: Basic Principles of Animal Form and Function

40.1 Form and Function Anatomy is the study of the biological form of an organism Physiology is the study of the biological functions an organism performs The comparative study of animals reveals that form and function are closely correlated Many different animal body plans have evolved and are determined by the genome Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig (a) Tuna (b) Penguin (c) Seal The ability to perform certain actions depends on an animal’s shape, size, and environment Physical laws impose constraints on animal size and shape

Exchange occurs as substances dissolved in the aqueous medium diffuse and are transported across the cells’ plasma membranes A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Video: Hydra Eating Daphnia Video: Hydra Eating Daphnia

Fig Exchange 0.15 mm (a) Single cell 1.5 mm (b) Two layers of cells Exchange Mouth Gastrovascular cavity An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings Exchange with the Environment

Fig cm Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO 2 O2O2 Circulatory system Heart Respiratory system Cells Interstitial fluid Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 µm 50 µm Lung tissue More complex organisms have highly folded internal surfaces for exchanging materials

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

A. Epithelial tissue: provides outer covering of the body and lines the organs and cavities within the body 1. Bottom layer attaches to the noncellular basement 2. types are classified by shape and layers 3. Some specialized to absorb/secrete. Some have cilia. I. Animal Tissues Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 40-5a Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium

Fig. 40-5b Apical surface Basal surface Basal lamina 40 µm

Fig. 40-5c B. Connective Tissue : live cells are scattered in a nonliving matrix Collagenous fiber Loose connective tissue Elastic fiber 120 µm Cartilage Chondrocytes 100 µm Chondroitin sulfate Adipose tissue Fat droplets 150 µm White blood cells 55 µm Plasma Red blood cells Blood Nuclei Fibrous connective tissue 30 µm Osteon Bone Central canal 700 µm

Fig. 40-5d Collagenous fiber 120 µm Elastic fiber Loose connective tissue 1. Loose connective tissue: binds epithelia to other tissues, holds organs in place. a.Collagen fibers: strong (skin) b.Elastic fibers: retractable property c.Reticular fibers: join connective tissue to adjacent tissues (lattice)

Fig. 40-5h Fat droplets Adipose tissue 150 µm 2. Adipose tissue stores fat for insulation and fuel

Fig. 40-5e Nuclei Fibrous connective tissue 30 µm 3. Fibrous connective tissue: dense collagen fibers a. tendons: muscles to bones (little flexibility) b. ligaments: bone to bones at joints (more flexible)

Fig. 40-5g Chondrocytes Chondroitin sulfate Cartilage 100 µm 4. Cartilage is a strong and flexible support material (chondrocytes embedded in chondrin and collagen fibers)

Fig. 40-5f Osteon Central canal Bone 700 µm 5. Bone: osteocytes embedded in collagen and mineral deposits: Haversian systems

Fig. 40-5i White blood cells Plasma Red blood cells 55 µm Blood 6. Blood is composed of blood cells and cell fragments in blood plasma

Fig. 40-5j C. Muscle Tissue: long cells capable of contraction 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth muscle Cardiac muscle Nucleus Muscle fibers 25 µm Nucleus Intercalated disk

Fig. 40-5k 1.Skeletal (striated) muscle: voluntary movement Multiple nuclei Muscle fiber Sarcomere 100 µm

Fig. 40-5m NucleusIntercalated disk 2. Cardiac muscle: branched striated muscle of the heart 50 µm

Fig. 40-5l 3. Smooth muscle: slower, involuntary movement Nucleus Muscle fibers 25 µm

D. Nervous Tissue Nervous tissue senses stimuli and transmits signals throughout the animal Nervous tissue contains: – Neurons, or nerve cells, that transmit nerve impulses – Glial cells, or glia, that help nourish, insulate, and replenish neurons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 40-5n Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm

40.2 Coordination and Control: depend on the endocrine system and the nervous system The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood A hormone may affect one or more regions throughout the body Hormones are relatively slow acting, but can have long-lasting effects Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Coordination and Control The nervous system transmits information between specific locations (depends on a signal’s pathway) Nerve signal transmission is very fast Nerve impulses can be received by neurons, muscle cells, and endocrine cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Homeostasis Animals manage their internal environment by regulating or conforming to the external environment Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment In humans: – body temperature, – blood pH, and – glucose concentration are each maintained at a constant level Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Mechanisms of homeostasis moderate changes in the internal environment For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response The response returns the variable to the set point Mechanisms of Homeostasis (think thermostat) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Feedback Loops in Homeostasis Negative feedback- a change triggers a control mechanism that counteracts the effect of the change (ex. body temperature) – Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off Positive feedback-a change triggers a mechanism that amplifies the response (ex. childbirth) – do not usually contribute to homeostasis Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

40.3 Example of Homeostasis: Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range – Endothermic animals generate heat by metabolism; birds and mammals are endotherms – Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non- avian reptiles Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig RadiationEvaporation ConvectionConduction Balancing Heat Loss and Gain

Five general adaptations help animals thermoregulate: 1.Insulation 2.Circulatory adaptations: arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange. Transfer heat between fluids flowing in opposite directions 3.Cooling by evaporative heat loss 4.Behavioral responses 5.Adjusting metabolic heat production Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig Canada gooseBottlenose dolphin Artery Vein Blood flow 33º35ºC 27º 30º 18º 20º 10º9º

Fig Sweat glands secrete sweat, which evaporates, cooling the body. Thermostat in hypothalamus activates cooling mechanisms. Blood vessels in skin dilate: capillaries fill; heat radiates from skin. Increased body temperature Decreased body temperature Thermostat in hypothalamus activates warming mechanisms. Blood vessels in skin constrict, reducing heat loss. Skeletal muscles contract; shivering generates heat. Body temperature increases; thermostat shuts off warming mechanisms. Homeostasis: Internal temperature of 36–38°C Body temperature decreases; thermostat shuts off cooling mechanisms.

40.4 Bioenergetics: The study of how organisms manage their resources 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

Metabolic rate is the amount of energy an animal uses in a unit of time Energy is measured in calories (cal) or kilocalories (Kcal = 1000 calories) Quantifying Energy Use Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Measuring Metabolic Rate 1.Measure heat loss per unit of time (ex. placing a bird in a calorimeter) 2.Determine the amount of oxygen consumed by cellular respiration – Minimal rate: necessary to support basic functions (breathing, heart rate) – Maximal rate: occurs during peak activity (sprinting, high level aerobics) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm These factors are: Agegender body temperaturetime of day surrounding temperaturefood intake amount of available O 2 Hormone balance Influences on Metabolic Rate Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Rate Types: Both rates assume a nongrowing, fasting, and nonstressed animal Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature – Human avg.: Kcal/day: adult male Kcal/day: adult female Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature

Size and Metabolic Rate Metabolic rate per gram of body weight is inversely related to body size among similar animals – may be due to surface area to volume ratio but does not explain the relationship in ectotherms 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

Fig a Shrew Harvest mouse Mouse Ground squirrel Rat Cat Dog Sheep Human Horse Elephant Body mass (kg) (log scale) BMR (L O 2 /hr) (log scale) (a) Relationship of BMR to body size 10 –3 10 –2 10 –

Fig b –1 10 –2 10 – Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size BMR (L O2/hr) (per kg) Shrew Harvest mouse Mouse Rat Ground squirrel Cat Sheep Dog Human Horse Elephant Each gram of a mouse requires about 20X’s more calories as a gram of an elephant

Fig a Annual energy expenditure (kcal/hr) 60-kg female human from temperate climate 800,000 Basal (standard) metabolism Reproduction Thermoregulation Growth Activity

Fig b Reproduction Thermoregulation Activity Basal (standard) metabolism 4-kg male Adélie penguin from Antarctica (brooding) Annual energy expenditure (kcal/yr) 340,000

Fig c Reproduction Thermoregulation Basal (standard) metabolism Activity 4, kg female deer mouse from temperate North America Annual energy expenditure (kcal/yr)

Fig d Reproduction Growth Activity Basal (standard) metabolism 4-kg female eastern indigo snake 8,000 Annual energy expenditure (kcal/yr)

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