General Biology II Lecture 2-1 Chapter 40 Basic Principles of Animal Form and Function 林 翰 佳 老師 hanjia@ntou.edu.tw

Before the class… What is an animal body made of (made from)? How many kinds of tissue we have? What is homeostasis? What is energy budget? What is the relationship between energy and animal size?

Overview Part 1: Animal form and function Part 2: Feedback control and Homeostatic processes for thermoregulation Part 3: Energy requirements of animals

Diverse Forms, Common Challenges The comparative study of animals Reveals that form and function are closely correlated Natural selection can fit structure, anatomy, to function, physiology By selecting, over many generations, what works best among the available variations in a population

Concept 40.1 Physical laws constrain strength, diffusion, movement, and heat exchange As animals increase in size, their skeletons must be proportionately larger to support their mass

Evolutionary convergence Reflects different species’ independent adaptation to a similar environmental challenge Osteichthye Chondrichthye (a) Tuna All in Fusiform! (b) Shark Bird Mammal (c) Penguin (d) Dolphin Figure 40.2a–e (e) Seal

Exchange with the Environment An animal’s size and shape Have a direct effect on how the animal exchanges energy and materials with its surroundings Exchange with the environment 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 Diffusion (a) Single cell Figure 40.3a

Multicellular organisms with a sac (囊狀) body plan Have body walls that are only two cells thick, facilitating diffusion of materials Diffusion rate is related to surface region size With more cells, the surface… Mouth Gastrovascular cavity Diffusion Saclike: hydra Flat shape: Tapeworm Diffusion Figure 40.3b

Organisms with more complex body plans Have highly folded internal surfaces specialized for exchanging materials Digestive system Respiratory Excretory Circulatory Extensively folded and branched internal!

Benefits for complex body form Specialized outer covering provides extra protection. Internal digestive organs improve energy absorption. Internal body fluid provides relatively stable internal environment. Complex body form is especially well suited for animals living on land.

Concept 40.1 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

Tissue Structure and Function Different types of tissues Have different structures that are suited to their functions Tissues are classified into four main categories Epithelial, connective, muscle, and nervous

Epithelial Tissue Epithelial tissue Covers the outside of the body and lines organs and cavities within the body Contains cells that are closely joined Function: a barrier against mechanical injury… Types: Simple epithelium, stratified, psudostratified.. Cuboidal, columnar, squamous… Glandular epithelia, mucous membrane..

Types of epithelial tissue Cuboidal epithelium Simple columnar Simple squamous Pseudostratified columnar Stratified squamous Epithelial Tissue Figure 40.5aa Apical surface Basal surface Basal lamina 40 m Polarity of epithelia

Connective Tissue Connective tissue Functions mainly to bind and support other tissues Contains sparsely packed cells scattered throughout an extracellular matrix (ECM) 6 types: loose connective tissue, adipose tissue, fibrous connective tissue, cartilage, bone and blood ECM fibers: collagenous, elastic and reticular fiber

Types of connective tissue Figure 40.5ba Blood Connective Tissue Plasma White blood cells 55 m Red blood cells Cartilage Chondrocytes Chondroitin sulfate 100 m Adipose tissue Fat droplets 150 m Bone Central canal Osteon 700 m Nuclei Fibrous connective tissue Elastic fiber 30 m 120 m Collagenous fiber Loose connective tissue

Muscle Tissue Muscle tissue Is composed of long cells called muscle fibers capable of contracting in response to nerve signals Contracting unit: myofibril: actin + myosin Most abundant tissue in most animals 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

Types of muscle tissue

Nervous Tissue Nervous tissue Neurons, or nerve cells, senses stimuli and transmits signals throughout the animal Glial cells, or glia, that help nourish, insulate, and replenish neurons Nervous Tissue Neurons Glia Glia 15 m Neuron: Dendrites Cell body Axons of neurons Axon Blood vessel 40 m (Fluorescent LM) (Confocal LM)

Organs and Organ Systems In all but the simplest animals Different tissues are organized into organs The tissues are arranged in layers Lumen of stomach Mucosa. The mucosa is an epithelial layer that lines the lumen. Submucosa. The submucosa is a matrix of connective tissue that contains blood vessels and nerves. Muscularis. The muscularis consists mainly of smooth muscle tissue. 0.2 mm Serosa. External to the muscularis is the serosa, a thin layer of connective and epithelial tissue. 4 layers in stomach

Organ Systems Representing a level of organization higher than organs Organ systems carry out the major body functions of most animals

Coordination and Control Control and coordination within a body 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

The effect of neurons The nervous system transmits information between specific locations The information conveyed depends on a signal’s pathway, not the type of signal Nerve signal transmission is very fast Nerve impulses can be received by neurons, muscle cells, endocrine cells, and exocrine cells

Stimulation by hormones or neurons Figure 40.6 Signaling in the endocrine and nervous systems 25

Responses of hormones or neurons Figure 40.6 Signaling in the endocrine and nervous systems 26

End of Part 1 Ask your self….. What laws constrain the size and shape of animals? What are the four main categories of animal tissues? And what are the sub-categories?

Concept 40.2 Feedback control loops maintain the internal environment in many animals 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

Regulating and Conforming Are two extremes in how animals cope with environmental fluctuations An animal is said to be a regulator If it uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation An animal is said to be a conformer If it allows its internal condition to vary with certain external changes (spider crab)

Mechanisms of Homeostasis Response No heat produced Room temperature decreases Heater turned off Set point Too hot Set point Control center: thermostat increases on cold Heat Moderate changes in the internal environment A homeostatic control system has three functional components A receptor, a control center, and an effector

How a body controls homeostasis Most homeostatic control systems function by negative feedback (負回饋) Where buildup of the end product of the system shuts the system off A second type of homeostatic control system is positive feedback (正回饋) Which involves a change in some variable that triggers mechanisms that amplify the change Ex. Childbirth

Concept 40.3 Homeostatic processes for thermoregulation involve form, function, and behavior Thermoregulation Is the process by which animals maintain an internal temperature within a tolerable range

Ectotherms and Endotherms Include most invertebrates, fishes, amphibians, and non-bird reptiles Endotherms (內溫動物) Include birds and mammals Animals are not classified as ectotherms or endotherms based on whether they have variable or constant body temperature. Poikilotherm (變溫動物) and homeotherm (恆溫動物) Cold-blooded and warm-blooded

Ectotherms Tolerate greater variation in internal temperature than endotherms River otter (endotherm) Largemouth bass (ectotherm) Ambient (environmental) temperature (°C) Body temperature (°C) 40 30 20 10 Figure 40.7

Endotherm 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 Advantages: perform vigorous activity for much longer and solves certain thermal problem of living on extreme environment!

Variation in Body Temperature The body temperature of a poikilotherm varies with its environment The body temperature of a homeotherm is relatively constant The relationship between heat source and body temperature is not fixed (that is, not all poikilotherms are ectotherms)

Are we homeotherm? Circadian clock 生理時鐘 Melatonin 褪黑激素

Modes of Heat Exchange Organisms exchange heat by four physical processes Radiation is 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. Evaporation is 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. Convection is the transfer of heat by the movement 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. Conduction is 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. Figure 40.10

Balancing Heat Loss and Gain Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss. General adaptations are: Insulation Circulatory adaptation Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production

#1 Insulation (隔熱) Insulation, which is a major thermoregulatory adaptation in mammals and birds Reduces the flow of heat between an animal and its environment May include feathers, fur, or blubber

The integumentary system (皮膚系統) In mammals, the integumentary system acts as insulating material How many kinds of tissue here? Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Figure 40.11 Hair follicle

#2 Circulatory Adaptations Many endotherms and some ectotherms Can alter the amount of blood flowing between the body core and the skin In vasodilation (血管舒張) Blood flow in the skin increases, facilitating heat loss In vasoconstriction (血管收縮) Blood flow in the skin decreases, lowering heat loss

Another circulatory adaptation Many marine mammals and birds Have arrangements of blood vessels called countercurrent heat exchangers that are important for reducing heat loss In the flippers of a dolphin, each artery is surrounded by several veins in a countercurrent arrangement, allowing efficient heat exchange between arterial and venous blood. Canada goose Artery Vein 35°C Blood flow 30º 20º 10º 33° 27º 18º 9º Pacific bottlenose dolphin 2 1 3 Arteries carrying warm blood down the legs of a goose or the flippers of a dolphin are in close contact with veins conveying cool blood in the opposite direction, back toward the trunk of the body. This arrangement facilitates heat transfer from arteries to veins (black arrows) along the entire length of the blood vessels. Near the end of the leg or flipper, where arterial blood has been cooled to far below the animal’s core temperature, the artery can still transfer heat to the even colder blood of an adjacent vein. The venous blood continues to absorb heat as it passes warmer and warmer arterial blood traveling in the opposite direction. As the venous blood approaches the center of the body, it is almost as warm as the body core, minimizing the heat lost as a result of supplying blood to body parts immersed in cold water. 1 3 Figure 40.12

Specialized endothermic bony fishes Some specialized bony fishes and sharks Also possess countercurrent heat exchangers 21º 25º 23º 27º 29º 31º Body cavity Skin Artery Vein Capillary network within muscle Dorsal aorta Artery and vein under the skin Heart Blood vessels in gills (a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintains temperatures in its main swimming muscles that are much higher than the surrounding water. (b) Great white shark. Like the bluefin tuna, the great white shark has a countercurrent heat exchanger in its swimming muscles that reduces the loss of metabolic heat. All bony fishes and sharks lose heat to the surrounding water when their blood passes through the gills. However, endothermic sharks have a small dorsal aorta, and as a result, relatively little cold blood from the gills goes directly to the core of the body. Instead, most of the blood leaving the gills is conveyed via large arteries just under the skin, keeping cool blood away from the body core.

Endothermic insects Have countercurrent heat exchangers that help maintain a high temperature in the thorax Q: How animals produce heat?

#3 Cooling by Evaporative Heat Loss Many types of animals Lose heat through the evaporation of water in sweat Use panting to cool their bodies Bathing moistens the skin

#4 Behavioral Responses 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 “Obelisk”

#5 Adjusting Metabolic Heat Production 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 PREFLIGHT WARMUP FLIGHT Thorax Abdomen Temperature (°C) Time from onset of warmup (min) 40 35 30 25 2 4

Feedback Mechanisms in Thermoregulation Thermostat in hypothalamus activates cooling mechanisms. Sweat glands secrete sweat that evaporates, cooling the body. Blood vessels in skin dilate: capillaries fill with warm blood; heat radiates from skin surface. Body temperature decreases; thermostat shuts off cooling Increased body temperature (such as when exercising or in hot surroundings) Homeostasis: Internal body temperature of approximately 36–38C 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 Figure 40.16 Mammals regulate their body temperature By 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

Adjustment to Changing Temperatures 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

End of Part 2 Ask yourself… What is negative and positive feedback? Could you illustrate some examples? How to categorize animals by their thermoregulation mechanism? What are the general adaptations of animals’ thermoregulation? What is countercurrent exchanger?

Concept 40.4 Energy requirements are related to animal size, activity, and environment 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, its bioenergetics Ultimately limits the animal’s behavior, growth, and reproduction Determines how much food it needs Studying an animal’s bioenergetics Tells us a great deal about the animal’s adaptations

Energy Sources and Allocation Animals harvest chemical energy From the food they eat Once food has been digested, the energy- containing molecules Are usually used to make ATP, which powers cellular work

Bioenergetic overview After the energetic needs of staying alive are met Any remaining molecules from food can be used in biosynthesis 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 Figure 40.17 Heat

Quantifying Energy Use An animal’s metabolic rate Is the amount of energy an animal uses in a unit of time One way to measure metabolic rate Is to determine the amount of oxygen consumed or carbon dioxide produced by an organism This photograph shows a ghost crab in a respirometer. (a) (b) Similarly, the metabolic rate of a man fitted with a breathing apparatus is being monitored while he works out on a stationary bike.

Bioenergetic Strategies An animal’s metabolic rate is closely related to its bioenergetic strategy There are two basic strategies: Ectothermic Endothermic

Endothermic Birds and mammals are mainly endothermic, meaning that Their bodies are warmed mostly by heat generated by metabolism They typically have higher metabolic rates

Ectothermic Amphibians and reptiles other than birds are ectothermic, meaning that They gain their heat mostly from external sources They have lower metabolic rates

Influences on Metabolic Rate The metabolic rates of animals Are affected by many factors Size: Metabolic rate per gram is inversely related to body size among similar animals. Activity Energy budgets

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 For both endotherms and ectotherms Activity has a large effect on metabolic rate

Maximum possible metabolic rate Is inversely related to the duration of the activity Endotherm is more capable of long-duration activities. Average daily energy consumption is 2~4 BMR or SMR Maximum metabolic rate (kcal/min; log scale) 500 100 50 10 5 1 0.5 0.1 A H A = 60-kg alligator H = 60-kg human second minute hour Time interval day week Key Existing intracellular ATP ATP from glycolysis ATP from aerobic respiration Figure 40.9

Size and metabolism Bigger animals  larger BMR Smaller animals  larger BMR per body mass

Energy Budgets Different species of animals Use the energy and materials in food in different ways, depending on their environment For most animal: majority of food is devoted to ATP production (metabolism)

An animal’s use of energy Is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction Keep warm Cont. Growth Endotherms Ectotherm Annual energy expenditure (kcal/yr) 800,000 Basal metabolic rate Reproduction Temperature regulation costs Growth Activity costs 60-kg female human from temperate climate Total annual energy expenditures (a) 340,000 4-kg male Adélie penguin from Antarctica (brooding) 4,000 0.025-kg female deer mouse from temperate North America 8,000 4-kg female python from Australia Energy expenditure per unit mass (kcal/kg•day) 438 Deer mouse 233 Adélie penguin 36.5 Human 5.5 Python Energy expenditures per unit mass (kcal/kg•day) (b) Figure 40.20

Torpor and Energy Conservation Is an adaptation that enables animals to save energy while avoiding difficult and dangerous conditions Is a physiological state in which activity is low and metabolism decreases

Hibernation (冬眠) Hibernation is long-term torpor That is an adaptation to winter cold and food scarcity during which the animal’s body temperature declines Additional metabolism that would be necessary to stay active in winter 200 Actual metabolism 100 Figure 40.21 Metabolic rate (kcal per day) Arousals 35 Body temperature 30 25 20 Temperature (°C) 15 10 5 Outside temperature -5 Burrow temperature -10 -15 June August October December February April

Estivation and Daily torpor Estivation, or summer torpor (夏眠) Enables animals to survive long periods of high temperatures and scarce water supplies Daily torpor (日眠) Is exhibited by many small mammals and birds and seems to be adapted to their feeding patterns

End of Part 3 Ask yourself… What is BMR and SMR? Why bioenergentic strategy affects the maximum metabolic rate? What is energy budgets? Why the energy budget is different in different animals? What is torpor? How many kinds of torpor? Why some animals need torpor?

End of the class The key concepts which you have learned in Part 1