Chapter 40

Problem Solving  Animals must solve basic challenges of life:  Obtain oxygen  Nourish themselves  Excrete waste products  Move  These questions will be addressed throughout our next unit.  Unifying themes that will be introduced here:  Form & function are closely related

Vocabulary  Anatomy – is the study of the structure of an organism  Physiology – is the study of the functions an organism performs  Bioenergetics – how organisms obtain, process, and use their energy resources.  Homeostasis – regulating internal temperature

40.1  Physical laws and the environment constrain animal size and shape.  An animal’s size and shape (body plan or design) affect the way it interacts with its environment.

Physical Laws  Physical laws and the need to exchange materials with the environment place certain limits on the range of animals forms.  Examples: Aquatic animals (sleek streamlined body forms) and flying animals (bones that allow for the organism to generate enough lift to become air born)

Exchange with the environment  Living cells must be bathed in a aqueous medium to keep the plasma membrane intact  Single celled organisms – Surface-to-volume ratio Fig. 40.3a

Multicellular organisms  Composed of numerous cells which also must be in water  Saclike body plan  Hydra Fig. 40.3b  Flat body plan – tapeworm

 Both of these put a large surface area in contact with the environment but do NOT allow for complexity in internal organization  Complex body forms allow for: outer coverings to protect against predators, large muscles for fast movement internal digestive organs to break down food gradually, maintaining relatively stable internal environment, and for living on land.

40.2  Animal form and function are correlated at all levels of organization.  Tissues are classified into 4 main categories – pg

Epithelial  Sheets of tightly packed cells  Where is it found? Epithelial tissue covers the outside of the body and lines organs and cavities within the body  Form & function? Closely joined (tight junctions between them) so epithelium functions as a barrier against mechanical injury, microbes, and fluid loss.

 Types?  Stratified columnar  Simple columnar  Pseudostratified ciliated columnar  Stratified squamous  Simple squamous  Cuboidal  All have slightly different volumes of cytoplasm which allow them to perform different functions.

Connective Tissue  Sparse population of cells scattered through an extracellular matrix.  Where is it found? Everywhere  Form & function? Bind and support other tissues

 Types?  Loose connective tissue – holds organs in place  Fibrous connective tissue – tendons & ligaments  Cartilage  Bone – mineralized connective tissue  Blood  Adipose tissue – stores fat

Muscles tissue  Long cells called muscle fibers  Where is it found? Everywhere!! Most abundant tissue in most animals  Form & function? Contraction brings about movement

 Types?  Skeletal – attaches to bones – voluntary movement  Cardiac – striated – involuntary  Smooth – lacks striations - involuntary

Nervous Tissue  Nerve cells  Organs & organ systems – see table 40.1 pg. 827

40.3  Animals use the chemical energy in food to sustain form and function  Bioenergetics – limits the animal’s behavior, growth, and reproduction and determines how much food it needs.

 Fig – After the energetic needs of staying alive are met any remaining molecules from food can be used in biosynthesis (body growth & repair, storage material such as fat and production of gametes)

 Metabolic rate – the sum of all the energy- requiring biochemical reactions occurring over a given time interval.  Energy measured in Calories (cal) or kilocalories (kcal)  Unit Calorie with a capital C is actually a kilocalorie  Energy appears as heat so metabolic rate can be determined by measuring heat.

2 Bioenergetic Strategies  Endothermic – bodies are warmed mostly by heat generated by matabolism and body temperature is maintained within a relatively narrow range.  Ectothermic – meaning that they gain their heat mostly from external sources

Endo or Ectothermic?

Endo or ectothermic?

Influences on metabolic rate  Size and metabolic rate: amount of energy it takes to maintain each gram of body weight is inversely related to body size. (Example – each gram of a mouse requires about 20 times more calories than a gram of an elephant)

 Activity and metabolic rate: every animal experiences a range of metabolic rates. Basal Metabolic rate (BMR) – metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing stress.  1,600-1,800 kcal per day for adult male  1,300-1,500 kcal per day for adult female

 Standard Metabolic rate (SMR) – metabolic rate of a resting, fasting, nonstressed ectotherm at a particular temperature.  Maximum potential metabolic rates and ATP sources – pg. 830 fig. 40.9

 Energy budgets – pg. 831 Fig

40.4  Many animals regulate their internal environment within relatively narrow limits  Interstitial fluid (Bernard more than a century ago) – internal environment of vertebrates – today homeostasis – steady state

Regulators vs. Conformers  Regulators – animal is a regulator for a particular environmental variable is it uses internal control mechanisms to moderate internal change in the face of external fluctuation

 Conformer – an animal is said to be a conformer for a particular environmental variable if it allows its internal condition to vary with certain external changes  Regulators and conformers are extremes and no animal is a perfect regulator or conformer  Some animals may regulate some internal conditions and conform to external conditions for others.

Mechanisms of Homeostasis  Negative feedback – thermostat in your house pg. 832 Fig  Positive feedback – amplify rather than reverse the change (child birth)

40.5  Thermoregulation – process by which animals maintain an internal temperature within a tolerable range. Critical because most biological processes work best at optimal conditions (plasma membrane)

Ectotherms vs. Endotherms  Ectotherms include invertebrates, fishes, amphibians, lizards, snakes, and turtles  The amount of heat they generate has little effect on body temperature  Bask in the sun to warm  Seek shade to cool  Can tolerate greater variation in internal temperature than endotherms  Not “cold-blooded”

 Endotherms include mammals, birds, some fish, and numerous insect species  Can use metabolic heat to regulate body temperature  Sweating to cool  Not “warm-blooded”

Advantages & Disadvantages  Advantages – able to generate a large amount of heat metabolically – can perform vigorous activity for much longer than is possible for most ectotherms, can tolerate extreme temperatures  Disadvantages – energetically expensive – requires more food

Modes of heat exchange  Conduction  Convection  Radiation  Evaporation

Balancing heat loss & gain  Insulation  Circulatory adaptations  Cooling by evaporative heat loss  Behavioral responses  Adjusting metabolic heat production

Insulation  Skin, hair, nails, fur  Skin houses nerves, sweat glands, blood vessels, and hair follicles

Insulation

Circulatory adaptations  Vasodilation (warms skin) – increases in diameter of superficial blood vessels  Vasoconstriction (cools skin) – reduces blood flow and heat transfer by decreasing the diameter of superficial blood vessels  Countercurrent heat exchanger – important for reducing heat loss in many endotherms

Cooling by evaporative heat loss  Water absorbs considerable heat when it evaporates  Panting  Sweat glands  Spreading saliva on body surface

Roxy panting!!

Behavioral responses  Both ecto and endotherms  Hibernation  Migration  Huddling in cold weather

Adjusting metabolic heat production  Endotherms must counteract constant heat loss  Heat production is increased by shivering  NST – nonshivering thermogenesis (produce heat instead of ATP)

 Feedback mechanisms controlled by hypothalamus in the brain

 Acclimatization – both ectotherms and endotherms can adjust to new range of environmental temperatures.  Shedding, growing a thicker coat  Heat shock proteins – help maintain integrity of cell’s proteins when exposed to extreme heat so they don’t denature

Torpor & energy conservation  Torpor – a physiological state in which activity is low and metabolism decreases  Hibernation – long term torpor to winter cold and food scarcity  Estivation – summer torpor  Daily torpor – adapted to feeding patterns