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

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 Critical Thinking Most animals (even many aquatic animals) urinate. Why??? Do plants pee???

15 Critical Thinking Most animals (even many aquatic animals) urinate. Why??? Most animals circulate metabolic waste products through a filtering system (such as our kidneys) and eliminate a liquid waste Do plants pee???

16 Critical Thinking Most animals (even many aquatic animals) urinate. Why??? Most animals circulate metabolic waste products through a filtering system (such as our kidneys) and eliminate a liquid waste Do plants pee??? Plants don’t produce as much metabolic waste (they use more nitrogen) and they mostly either die back and recycle, or store the waste in isolated vacuoles or wood

17 Images - convergent evolution of spindle- shaped swimmers 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

Hands On Think of some other adaptations to habitat, food source or 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? 18

19 Diagram - 2 tissue layers in Cnidarians 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

20 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 m 2 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

21 Critical Thinking How on earth do such large surface areas fit into our bodies???

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

23 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

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

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

26 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???

27 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”

28 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

29 Indirect exchange between organ systems occurs via the interstitial fluid one big exception: the Malpighian excretory tubules in insects are directly connected to the digestive tract

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

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

32 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

33 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!!!

34 Diagram – tissue types Four major tissue types – read more in text

35 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….

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

37 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

38 Critical Thinking What makes the “bones” of plants???

39 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

40 Critical Thinking How about the blood???

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

42 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

43 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!

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

45 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

46 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

47 Diagram – body cavities 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)

48 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)

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

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

51 Respiratory Immune

52 Excretory Nervous

53 Reproductive Endocrine

54 Skeletal and Integumentary Muscular

55 Diagram – summary of organ systems Organ systems are integrated in both structure and function to produce the whole organism

56 Bioenergetic Principles Regulate Organism Activity Bioenergetics: the flow of energy through the animal  Controlled by energy sources vs. energy uses (food intake vs. metabolism) Metabolic rates vary based on size, activity levels, homeostasis strategy and thermoregulation strategy  Important selection pressures include the physical environment and interactions with other organisms

57 Diagram – bioenergetics in an organism Energy management: food supplies energy to fund metabolism, maintain homeostasis, and support activity

58 Influences on Metabolic Rate Body size  Inverse relationship between size and metabolic rate per unit mass  Evidence is clear; explanation is unclear Activity level Homeostasis strategy  It “costs” more to regulate Thermoregulation strategy

59 Influences on Metabolic Rate Body size  Inverse relationship between size and metabolic rate per unit mass  Evidence is clear; explanation is unclear Activity level Homeostasis strategy  It “costs” more to regulate Thermoregulation strategy

60 Homeostasis Maintenance of constant internal conditions (actually, within a range of tolerance) Various control systems regulate temperature, salt concentrations, water content, pH, blood sugar, etc Most control systems rely on negative feedback loops = the results of a process inhibit that process  process is self limiting

61 Diagram – homeostasis Most organisms regulate at least some components of their internal environment

62 Diagram – homeostasis Homeostasis mechanisms primarily control the interstitial fluid – the inside of the cell is very dynamic, depending on metabolic activity Freeman is not completely accurate on this issue…..

63 Homeostasis Maintenance of constant internal conditions (actually, within a range of tolerance) Various control systems regulate temperature, salt concentrations, water content, pH, blood sugar, etc Most control systems rely on negative feedback loops = the results of a process inhibit that process  Process is self limiting

64 Diagram – a mechanical representation of a negative feedback loop Feedback Loops: thermostats and furnaces are a non-living example

65 Diagrams – representations of biological negative feedback loops Many similar strategies for regulation of blood chemistry, blood sugar, body temperature, etc etc etc

Homeostasis is dynamic…. All feedback loops are constantly monitored and levels are fluctuating within range Not all animals maintain stable internal conditions  Regulators expend metabolic energy to maintain stability  Conformers don’t – internal values vary with external conditions  Some animals regulate some conditions, conform to others 66

67 Influences on Metabolic Rate Body size  Inverse relationship between size and metabolic rate per unit mass  Evidence is clear; explanation is unclear Activity level Homeostasis strategy  It “costs” more to regulate Thermoregulation strategy

68 Thermoregulation All biochemical processes are sensitive to temperature Extreme temperatures can denature proteins or alter membrane function Animals regulate their internal temperature to maintain metabolic function Two main strategies have emerged  Ecothermy  Endothermy

69 Thermoregulation Ectothermic animals gain heat from the surrounding environment Most invertebrates, fishes, amphibians and reptiles  Low metabolic rate when cold  Not always able to be active  Behavior is often used to regulate body temperature

70 Critical Thinking Are ectothermic animals cold blooded???

71 Graph – body temp vs. environmental temp in ectotherms vs. endotherms Critical Thinking Are ectothermic animals cold blooded??? NO!!! An ectotherm’s body temperature reflects its environment (with some exceptions)

72 Critical Thinking What are the costs and benefits of ectothermy???

73 Critical Thinking What are the costs and benefits of ectothermy??? Cost – limited activity and endurance  Animals must remain warm to maintain active cellular respiration  When their body is cold, they cannot produce enough ATP to be active  When cold, they can’t forage or escape! Benefits – low energy cost

74 Thermoregulation Endothermic animals use energy to maintain a constant body temperature Primarily mammals and birds  High metabolic rate generates waste heat that keeps the body warm  Most endotherms also gain some heat from their surroundings or behaviors  Some endotherms vary body temperature by season or time of day (hibernation, estivation, diurnation)

75 Critical Thinking What are the costs and benefits of endothermy???

76 Critical Thinking What are the costs and benefits of endothermy??? Cost – uses lots of energy  10-30x more than same size ectotherm Benefits – allows for constant activity  Always able to forage  Always able to escape

77 Most endotherms are terrestrial Moving on land requires more energy than moving in water (water supports) Land T fluctuates more than water T (high heat capacity of H 2 O) The development of endothermy was an important adaptation to the colonization of land Many terrestrial animals are ectothermic, but few aquatic animals are endothermic

78 Graph – body temp vs. environmental temp in ectotherms vs. endotherms Always active Slow when it’s cold

79 Both endo’s and ecto’s have many strategies to regulate body temperature Adjusting the rate of heat exchange with the environment Adjusting metabolic rate

80 Adjusting the rate of heat exchange with the environment Constriction or dilation of surface blood vessels Raising of fur or feathers Fat accumulation Countercurrent heat exchange Behaviors

81 Critical Thinking How would changing blood vessel diameter change the rate of heat exchange???

82 Critical Thinking How would changing blood vessel diameter change the rate of heat exchange??? Alters the amount of warm blood that reaches the surface of the skin  Constricting holds heat  Dilating releases heat

83 Adjusting the rate of heat exchange with the environment Constriction or dilation of surface blood vessels Raising of fur or feathers Fat accumulation Countercurrent heat exchange Behaviors

84 Critical Thinking How would raising the fur or feathers change the rate of heat exchange???

85 Critical Thinking Why would raising the fur or feathers change the rate of heat exchange??? Adds more of an insulating boundary layer around the skin

86 Adjusting the rate of heat exchange with the environment Constriction or dilation of surface blood vessels Raising of fur or feathers Fat accumulation Countercurrent heat exchange Behaviors

87 Diagram – adipose tissue as insulation

88 Adjusting the rate of heat exchange with the environment Constriction or dilation of surface blood vessels Raising of fur or feathers Fat accumulation Countercurrent heat exchange Behaviors

89 Diagram – countercurrent blood flow in bird’s leg and dolphin’s fin Countercurrent Exchange: arterial blood is warmer (comes from body core); warms adjacent venous blood in extremities

90 Diagram – countercurrent flow in deep muscles of fish Adjusting the rate of heat exchange with the environment Some ectotherm fishes maintain higher temperatures in their deep swimming muscles with a heat exchanging pattern of blood flow  Increases aerobic respiration (thus ATP production) in those muscles  Partial endotherms

91 Adjusting the rate of heat exchange with the environment Constriction or dilation of surface blood vessels Raising of fur or feathers Fat accumulation Countercurrent heat exchange Behaviors

92 Image – dragonflies positioned for max or min solar exposure Behavior Moving to shade/sun Moving into/out of water Restricting activity to night/day Regulating body posture to manage solar exposure Migrating Social behavior to share heat (bees)

93 Images – animals panting and spraying Sweating, panting, licking, spraying….often linked to behaviors….

94 Many strategies to regulate body temperature Adjusting the rate of heat exchange with the environment Adjusting metabolic rate

95 Adjusting metabolic rate Increases or decreases in muscular activity (shivering, active motion) Acclimation – many animals adjust to temperature changes throughout the seasons by changing enzyme type and quantity, altering lipids to keep membranes fluid Torpor – some animals react to predictable temperature and food supply fluctuations by entering a state of reduced metabolism (hibernation, etc)  Daylength is the likely trigger

96 Graph – change in a moth’s thorax temperature with pre-flight shivering

97 Adjusting metabolic rate Increases or decreases in muscular activity (shivering, active motion) Acclimation – many animals adjust to temperature changes throughout the seasons by changing enzyme type and quantity, altering lipids to keep membranes fluid Torpor – some animals react to predictable temperature and food supply fluctuations by entering a state of reduced metabolism (hibernation, etc)  Daylength is the likely trigger for seasonal torpor

98 REVIEW: 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