Basic principles of animal form & function

1. Chapter 40 Basic principles of animal form & function

2. 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

3. 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

4. 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.

5. 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)

6. 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

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

9. 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.

10. 40.2 • Animal form and function are correlated at all levels of organization. • Tissues are classified into 4 main categories – pg. 824-826

11. 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.

13. 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.

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

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

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

19. Types? • Skeletal – attaches to bones – voluntary movement • Cardiac – striated – involuntary • Smooth – lacks striations - involuntary

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

23. 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.

24. Fig. 40.7 – 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)

26. 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.

27. 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

28. Endo or Ectothermic?

29. Endo or Ectothermic?

30. Endo or ectothermic?

31. 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)

33. 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

34. 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

35. Energy budgets – pg. 831 Fig. 40.10

36. 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

37. 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

38. 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.

39. Mechanisms of Homeostasis • Negative feedback – thermostat in your house pg. 832 Fig. 40.1 • Positive feedback – amplify rather than reverse the change (child birth)

41. 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)

42. 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”

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

44. 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

45. Modes of heat exchange • Conduction • Convection • Radiation • Evaporation

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

48. Insulation • Skin, hair, nails, fur • Skin houses nerves, sweat glands, blood vessels, and hair follicles

49. Insulation

50. 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