Basic Principles of Animal Form and Function Chapter 40 Basic Principles of Animal Form and Function

Anatomy is the study of the structure of an organism Physiology is the study of the functions an organism performs

Concept 40.2: Animal form and function are correlated at all levels of organization Most animals are composed of specialized cells organized into tissues that have different functions Tissues are classified into four main categories: epithelial, connective, muscle, and nervous

LE 40-5_1 Simple Stratified columnar columnar epithelium epithelium EPITHELIAL TISSUE Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function. Simple columnar epithelium Stratified columnar epithelium Pseudostratified ciliated columnar epithelium Cuboidal epithelia Stratified squamous epithelia Simple squamous epithelia Basement membrane 40 µm

LE 40-5_2 Chondrocytes Collagenous fiber Loose connective tissue 120 µm Chondrocytes Collagenous fiber Loose connective tissue Chondroitin sulfate Elastic fiber 100 µm Cartilage Fibrous connective tissue Adipose tissue Fat droplets Nuclei 150 µm 30 µm Blood Central canal Red blood cells Bone White blood cell Osteon Plasma 700 µm 55 µm

LE 40-5_3 Multiple nuclei Skeletal muscle Muscle fiber Sarcomere MUSCLE TISSUE 100 µm Multiple nuclei Skeletal muscle Muscle fiber Sarcomere Cardiac muscle Nucleus Intercalated disk 50 µm Nucleus Smooth muscle Muscle fibers 25 µm NERVOUS TISSUE Neuron Process Cell body Nucleus 50 µm

Organs and Organ Systems In all but the simplest animals, tissues are organized into organs In some organs, the tissues are arranged in layers

LE 40-6 Lumen of stomach Mucosa: an epithelial layer that lines the Submucosa: a matrix of connective tissue that contains blood vessels and nerves Muscularis: consists mainly of smooth muscle tissue Serosa: a thin layer of connective and epithelial tissue external to the muscularis 0.2 mm

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 reproduction

LE 40-7 Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in urine Carbon skeletons Cellular respiration Heat ATP Biosynthesis: growth, storage, and reproduction 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

LE 40-8 This photograph shows a ghost crab in a respirometer. Temperature is held constant in the chamber, with air of known O2 concentration flowing through. The crab’s metabolic rate is calculated from the difference between the amount of O2 entering and the amount of O2 leaving the respirometer. This crab is on a treadmill, running at a constant speed as measurements are made. Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he exercises on a stationary bike.

Bioenergetic Strategies An animal’s metabolic rate is closely related to its bioenergetic strategy Birds and mammals are mainly endothermic: Their bodies are warmed mostly by heat generated by metabolism Endotherms typically have higher metabolic rates

Amphibians and reptiles other than birds are ectothermic: They gain their heat mostly from external sources Ectotherms generally have lower metabolic rates

Activity and Metabolic Rate 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 Activity greatly affects metabolic rate

Maximum metabolic rate LE 40-9 500 A = 60-kg alligator A H 100 H A A = 60-kg human 50 H Maximum metabolic rate (kcal/min; log scale) 10 H 5 H A 1 A 0.5 A 0.1 1 second 1 minute 1 hour 1 day 1 week Time interval Key Existing intracellular ATP ATP from glycolysis ATP from aerobic respiration

Endotherms Ectotherm 800,000 340,000 8,000 4,000 438 Human 233 Python Annual energy expenditure (kcal/yr) Basal (standard) metabolism Reproduction Temperature regulation Growth Activity 60-kg female human from temperate climate 4-kg male Adélie penguin from Antarctica (brooding) 4,000 0.025-kg female deer mouse from temperate North America 4-kg female python from Australia 8,000 Ectotherm Total annual energy expenditures. The slices of the pie charts indicate energy expenditures for various functions. Energy expenditures per unit mass (kcal/kg•day). Comparing the daily energy expenditures per kg of body weight for the four animals reinforces two important concepts of bioenergetics. First, a small animal, such as a mouse, has a much greater energy demand per kg than does a large animal of the same taxonomic class, such as a human (both mammals). Second, note again that an ectotherm, such as a python, requires much less energy per kg than does an endotherm of equivalent size, such as a penguin. Energy expenditure per unit mass (kcal/kg•day) 438 233 36.5 5.5 Python Human Deer mouse Adélie penguin

Concept 40.4: Animals regulate their internal environment within relatively narrow limits The internal environment of vertebrates is called the interstitial fluid and is very different from the external environment Homeostasis is a balance between external changes and the animal’s internal control mechanisms that oppose the changes

Mechanisms of Homeostasis A homeostatic control system has three functional components: a receptor a control center an effector Animation: Negative Feedback Animation: Positive Feedback

Negative Feedback Positive Feedback LE 40-11 Response No heat produced Room temperature decreases increases Set point Too hot Set point Heater turned off cold Control center: thermostat on Heat Negative Feedback Positive Feedback

Concept 40.5: Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range

Ectotherms and Endotherms Ectotherms include most invertebrates, fishes, amphibians, and non-bird reptiles Endotherms include birds and mammals In general, ectotherms tolerate greater variation in internal temperature than endotherms

River otter (endotherm) LE 40-12 40 River otter (endotherm) 30 Body temperature (°C) 20 Largemouth bass (ectotherm) 10 10 20 30 40 Ambient (environmental) temperature (°C)

Endothermy is more energetically expensive than ectothermy It buffers the animal’s internal temperatures against external fluctuations It also enables the animal to maintain a high level of aerobic metabolism

LE 40-13 Radiation Evaporation Convection Conduction

Balancing Heat Loss and Gain In thermoregulation, physiological and behavioral adjustments balance heat loss and gain Five general adaptations help animals thermoregulate: Insulation Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production

Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle

Circulatory Adaptations In vasodilation, blood flow in the skin increases, facilitating heat loss In vasoconstriction, blood flow in the skin decreases, lowering heat loss

Canada goose Pacific bottlenose dolphin Blood flow Artery Vein Vein 33° 30° 27° 20° 18° 10° 9°

LE 40-16a 21° 23° 25° 27° 29° 31° Body cavity Bluefin tuna

Skin Artery Vein Blood Capillary vessels network within in gills LE 40-16b Skin Artery Vein Blood vessels in gills Capillary network within muscle Heart Artery and vein under the skin Dorsal aorta Great white shark

Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water in sweat Panting augments the cooling effect in birds and many mammals Bathing moistens the skin, helping to cool an animal down

Adjusting Metabolic Heat Production Many species of flying insects use shivering to warm up before taking flight PREFLIGHT WARMUP FLIGHT Abdomen Thorax Time from onset of warmup (min) 4 2 40 35 30 25 Temperature (°C)

Feedback Mechanisms in Thermoregulation Mammals regulate body temperature by negative feedback involving several organ systems In humans, the hypothalamus (a part of the brain) contains nerve cells that function as a thermostat

Internal body temperature LE 40-21 Thermostat in hypothalamus activates cooling mechanisms. Increased body temperature (such as when exercising or in hot surroundings) Body temperature decreases; thermostat shuts off cooling Sweat glands secrete sweat that evaporates, cooling the body. Blood vessels in skin dilate: capillaries fill with warm blood; heat radiates from skin surface. increases; shuts off warming Decreased body temperature (such as when in cold Blood vessels in skin constrict, diverting blood from skin to deeper tissues and reducing heat loss from skin surface. Skeletal muscles rapidly contract, causing shivering, which generates heat. activates warming Homeostasis: Internal body temperature of approximately 36–38°C

Adjustment to Changing Temperatures In acclimatization, many animals adjust to a new range of environmental temperatures over a period of days or weeks

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

LE 40-22 Additional metabolism that would be necessary to stay active in winter 200 Actual metabolism Metabolic rate (kcal per day) 100 Arousals 35 Body temperature 30 25 20 Temperature (°C) 15 10 5 –5 Outside temperature Burrow temperature –10 –15 June August October December February April

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