Lecture #8 – Introduction to Animal Structure and Function

1. Lecture #8 – Introduction to Animal Structure and Function

2. Key Concepts • What separates animals from other organisms? • Introduction to structure and function relationships – the implications of being multicellular • Hierarchical organization in animals • Tissues • Organ systems • Bioenergetics and metabolic rates

3. What do all organisms have to do to make a living???

4. What do organisms have to do to make a living??? • Acquire resources (food, water) • Eliminate waste products • Exchange metabolic gasses • Control internal conditions (homeostasis) • Control function • Control development • Reproduce (optional for individuals, essential for evolutionary success)

5. What makes an animal an animal?

6. What makes an animal an animal? • All are eukaryotic, multi-cellular, aerobic, and heterotrophic • Most are mobile – exceptions??? • Most are highly complex with many specialized organs – exceptions??? • Cells divide by cleavage • Excess carbohydrate stored as glycogen or converted to fats • Most engage in sexual reproduction, some also have asexual reproduction processes

7. Structure and Function of Animal Systems • Focus on human biology, but will use comparative approach • Comparisons between animals of differing levels of complexity • We will correlate structure with function, at all levels of organization • Important theme in biology • Start with intro to basic principles • Then discussions of various organ systems

8. Critical Thinking • Life has been on this planet for 3½ billion years! • Until about 700 million years ago, all organisms were______________? Table - the geological time scale

9. It’s always fun to study the geological time scale – it reveals the history of life on earth What happened here???

10. Critical Thinking • Life has been on this planet for 3½ billion years! • Until about 700 million years ago, all organisms were single celled!!! • The emergence of multi-cellularity allowed for organisms to adapt in complex ways to their environment • The migration to land promoted even more diversification – about 450 million years ago

11. Multi-cellularity imposes limitations, too • In most multi-cellular organisms, not every cell is in contact with the external environment • Multi-cellular organisms develop complex morphologies that reflect their environment • Multi-cellular organisms develop complex mechanisms for resource/waste exchange with their environment • We saw these phenomena with plants – animals do the same thing

12. Critical Thinking • Terrestrial plants use a tight epidermis and a waxy cuticle to retain water • What is the analogous structure in terrestrial animals???

13. Critical Thinking • Terrestrial plants use a tight epidermis and a waxy cuticle to retain water • What is the analogous structure in terrestrial animals??? • The skin, and the oils that coat it • Structure and function are related, and are the product of each species’ long history of evolutionary adaptations

14. Constraints On Size And Shape:The physical environment affects animal evolution – as it does with all organisms • Simple physics • Flight, soil burrowing, swimming for speed… • The physical environment • Dense water or soil, thin air • Often leads to convergent evolution of shape Images - convergent evolution of spindle-shaped swimmers

15. Hands On • Think of some other adaptations to habitat, food sourceor predators • Name an animal – speculate on adaptive characteristics • What selection pressure might have resulted in a structure or function? • What structures or functions are phylogenetic?

16. Constraints On Size And Shape:The necessity of exchange with the environment affects animal evolution…. • Resource/waste exchange with the environment • Diffusion at the surface was characteristic of the earliest animals • Limits size • Limits shape to thin, flat, open • Limits complexity • Mostly quite simple animals Diagram - 2 tissue layers in Cnidarians

17. Most animals have much more complex exchange systems • Exchange occurs at internal epithelia • Huge surface area is characteristic • Fun factoids from humans: • Lungs have 100 m2 of surface area (about ½ as big as room) • Small intestine has surface area of a tennis court • 80 km of tubules in a single kidney • 100,000 km of blood vessels = almost 3x circumference of the earth

18. Critical Thinking • How on earth do such large surface areas fit into our bodies???

19. Critical Thinking • How on earth do such large surface areas fit into our bodies??? • Folding and branching! All these epithelial surfaces are highly convoluted Micrographs - lung and intestinal tissues Small Intestine Tissue

20. Exchange with environment is not direct for most animals • Body is covered with waterproof surface • Complex organ systems exchange materials • Organ systems are linked together, but not usually directly • Most organ systems are separated by interstitial fluid = a water-based solution that surrounds all cells in the animal body • Transport occurs through the interstitial fluid

21. Indirect exchange between organism and environment, and between organ systems Diagram - organization of organ systems showing indirect exchange through the interstitial fluid; same diagram on #29

22. Critical Thinking • Do nutrients leap from our breakfast cereal to our cells??? • Why do animals need nutrients anyways???

23. Critical Thinking • Do nutrients leap from our breakfast cereal to our cells??? • No – first they are extracted through digestion, then they diffuse to the cells through a fluid medium • Why do animals need nutrients anyways???

24. Critical Thinking • Do nutrients leap from our breakfast cereal to our cells??? • No – first they are extracted through digestion, then they diffuse to the cells through a fluid medium • Why do animals need nutrients anyways??? • Same as with plants – to build the macro-molecules that make the animal “work”

25. Exchange with environment is not direct for complex animals • Body is covered with waterproof surface • Complex organ systems exchange materials • Organ systems are linked together, but not usually directly • Organ systems are separated by interstitial fluid = a water-based solution that surrounds all cells in the animal body • Transport occurs through the interstitial fluid

26. Indirect exchange between organ systems occurs via the interstitial fluid one big exception: the Malpighianexcretory tubules in insects are directly connected to the digestive tract

27. All complex organisms have a hierarchical organization Diagram - cells - organism in a zebra • Cells • Tissues • Organs • Organ systems • Organism Form Reflects Function!!!

28. Critical Thinking • Think of your heart, or this zebra’s – how are structure and function related???

29. Critical Thinking • Think of your heart, or this zebra’s – how are structure and function related??? • Stretchy chambers to “store” blood • Muscular chambers to “pump” blood • Connected to vessels • Result = circulation!!! Yes, it really is often that simple and elegant

30. Form and function are correlated from cells  whole organism • We learned about cells in 111…. • Cells • Tissues • Organs • Organ systems • Organism Let’s talk about tissues!!!

31. Four major tissue types –read more in text Diagram – tissue types

32. Epithelial Tissues • Sheets of cells that cover the body surfaces and line many of the internal organs • Base of epithelial tissue is attached to a basement membrane • The free (exposed) surface has cells that are either cuboidal, columnar or squamous (tile shaped) • Shape reflects function! • Some epithelia waterproof, some leak, some secrete, some slough off….

33. Epithelial tissues Diagram – sub-types of epithelial tissues Which do you think are waterproof??? Which leaky??? Which secrete??? Which slough off???

34. Connective Tissues • Cells held in a fibrous or fluid extra-cellular matrix • Matrix generally secreted by the cells • Many types and sub-types of connective tissue • Loose – bind and shape • Adipose – store fat • Fibrous – strong connections • Cartilage – cushions • Bone – support system • Blood – connects tissues to resources

35. Critical Thinking • What makes the “bones” of plants???

36. Critical Thinking • What makes the “bones” of plants??? • Lignin gives rigid structure • Cellulose allows positive pressure to build to keep cells plump • Ground tissue gives additional structure to herbaceous plants

37. Critical Thinking • How about the blood???

38. Critical Thinking • What makes the “blood” of plants??? • Resources are transported in the vascular tissues • Some are “circulated” in phloem

39. Muscle Tissue • Composed of cells that can contract • Skeletal = enable movement, attached to bones by tendons • Voluntary = under conscious nervous system control • Cardiac = forms the heart • Involuntary • Smooth or visceral = surround the digestive tract, other organs • Involuntary

40. Nervous Tissue • Transmits messages from one part of body to another • Nerve cells have a central cell body + appendages that carry messages toward or away from the cell (dendrites/axons) • Appendages may be a meter long in humans!

41. Critical Thinking • Do all animal tissue types have directly analogous tissue types in plants??? • Epithelial??? • Connective??? • Muscle??? • Nervous???

42. Critical Thinking • Do all animal tissue types have directly analogous tissue types in plants??? • Epithelial – certainly, though not internal • Connective –sort of (vascular, ground) • Muscle – not really – remember plants “move” by growing, other motions are related to water potential changes • Nervous – no – plants respond primarily based on chemical signals

43. Organs • Composed of two or more types of tissues organized into a functional unit • Tissues are often in layers, or they may be integrated throughout the organ • Stomach has layers of epithelial, connective, muscle • Skin has layers of epithelial, connective, muscle • All tissues have blood vessels and nerve tissues integrated

44. Most animals have body cavities • These are fluid filled spaces that cushion and suspend organs • Sometimes they also give the body shape • In vertebrates, many organs are held in place in the body cavity by layers of connective tissues (mesenteries) and sheets of muscle (diaphragm) Diagram – body cavities

45. Organ Systems: groups of related organs that maintain various body functions • Complex organ systems are present in most animals • All organ systems are interdependent • Functions are coordinated (ex: digestive + vascular) • All systems work together to maintain homeostasis (~constant internal conditions, more on this later)

46. Organ Systems:most complex animals have 11 major organ systems – image search for a table like this one Table – all the organ systems found in a complex animal

47. Diagrams – closeups of the major organ systems; similar diagrams on next 4 slides Digestive Circulatory

48. Respiratory Immune

49. Nervous Excretory

50. Reproductive Endocrine