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20-1 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Chapter 20: Animal and human.

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Presentation on theme: "20-1 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Chapter 20: Animal and human."— Presentation transcript:

1 20-1 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Chapter 20: Animal and human nutrition

2 20-2 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Nutrients Animals are heterotrophs –cannot synthesise organic compounds from inorganic molecules –rely on other organisms for nutrients Nutrients –organic compounds  carbohydrates, lipids –chemical compounds  amino acids, fatty acids  vitamins, minerals

3 20-3 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Plants as food Plant tissues –mostly carbohydrate  monosaccharides, disaccharides, starches  cellulose, pectin –some lipid (mostly unsaturated fatty acids) –little protein –minerals depend on soil Composition may change seasonally and with locality

4 20-4 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Animals as food Animal tissues –mostly protein –some lipid (saturated fatty acids, unsaturated fatty acids in fish) –little carbohydrate Carnivores can produce glucose from proteins and other materials –gluconeogenesis

5 20-5 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.2: Composition of some foods

6 20-6 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Metabolic rate Nutrient requirements depend on –age –reproductive state –metabolic rate Metabolic rate varies with –level of activity –body mass –environmental conditions

7 20-7 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Basal metabolic rate Endotherms –metabolic rate in inactive animal in thermoneutral environment (within thermal comfort zone) Ectotherms –metabolic rate in inactive animal is temperature dependent

8 20-8 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Metabolic rate and body mass Relationship between metabolic rate and body mass –mass-specific metabolic rate  metabolic rate per unit body mass –small animals require more energy per unit body mass than do large animals Relationship between body mass and quality of food –small animals eat higher quality (more energy-rich) food than do large animals

9 20-9 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.5: Mass-specific metabolic rate

10 20-10 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Digestive process Food must be broken down into molecules small enough to enter cells –digestion Process of digestion –physical  mechanical activity of teeth or gizzard –enzymatic  chemical action of enzymes

11 20-11 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Enzymes Digestive enzymes usually have low specificity –act on types of substrates (e.g. proteins) rather than on specific bonds Sequential breakdown –complex molecules are broken down into successively simpler ones as they pass through the gut

12 20-12 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Control of enzyme secretion Nervous control –saliva: is under nervous control and contains salivary enzymes Hormonal control –gastrin: stimulates release of hydrochloric acid and pepsinogen in stomach –secretin: stimulates release of bile from gall bladder –cholecystokinin: stimulates release of trypsinogen from pancreas

13 20-13 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Intra- and extracellular digestion Intracellular digestion –food taken into the cell for digestion is exposed to enzymes while enclosed in a vacuole Extracellular digestion –food digested externally is exposed to mechanical and chemical (enzyme) digestion outside the cells –breakdown products are taken into the cells after digestion

14 20-14 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Digestive systems Single-celled organisms and sponge cells engulf food that they digest in intracellular vacuoles –phagocytosis Multicelled organisms have specialised organs and tissue for digestion –vary in complexity from blind-ending digestive cavities to digestive systems with associated secretory organs

15 20-15 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Simple digestive cavities A simple sac-like gut with specialised digestive tissue is found in cnidarians (corals, sea anemones and allies) –waste expelled through mouth –water dilutes action of enzymes A similar gut is found in platyhelminthes (flatworms) –convoluted gut increases surface area for absorption –decreases distance travelled by diffusing nutrients

16 20-16 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.12: Gastrovascular cavity of Hydra

17 20-17 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint One-way digestive tract Food passes through gut in one direction –waste is eliminated at terminal anus Regional specialisation of gut, allowing sequential secretion of enzymes Food moved along gut by –body movements –ingestion of more food –peristalsis in animals with muscular gut wall

18 20-18 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Hard mouthparts Chitinous paired mouthparts in arthropods –specialisation in diet In insects, modification of the basic pattern of mouthparts allows a range of diets including liquid feeders –nectar –plant sap –fruit –blood –tears

19 20-19 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Vertebrate teeth Teeth covered with hard enamel Fish –teeth and jaws specialised for different diets  needle-like teeth in predators  flattened teeth in herbivores –specialist feeders  molluscivores  polyp predators Teeth-bearing bones in upper and lower jaws can be moved –kinesis (cont.)

20 20-20 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Vertebrate teeth (cont.) Reptiles –undifferentiated peg-like teeth –no lateral movement in jaw for chewing –snakes can disarticulate lower jaw and move elements independently Birds –consume easily-digestible food –teeth lost to reduce weight for flight –mechanical processing by muscular gizzard

21 20-21 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Mammals Teeth differentiated –specialised for different functions Incisors grasp and hold Canines stab and grip Premolars shear Molars grind (cont.)

22 20-22 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Mammals (cont.) Teeth differentiated –specialised for different diets Herbivores: crushing and grinding teeth for tough plant fibres Carnivores: tearing and shearing teeth for animal flesh Insectivores: crushing and puncturing teeth for invertebrate exoskeletons

23 20-23 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Filter feeding Animals extract small organisms or other particles by filtering large volumes of water Examples –invertebrates  sponges, bivalves, tunicates –vertebrates  whale sharks, fish, flamingos, baleen whales

24 20-24 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Digesting plants Structural materials in cell walls are difficult to digest –structural carbohydrates inaccessible to most herbivores Cellulose broken down by enzyme cellulase –few animals produce cellulase –many have colonies of symbiotic bacteria and protists in gut  these produce cellulase  microbial fermentation

25 20-25 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Microbial fermentation Symbiotic bacteria and protists –hydrolyse cellulose into glucose –use glucose –produce short-chain fatty acids as wastes  acetic acid  propionic acid  butyric acid –also ferment proteins Host –uses fatty acids as energy source –digests microbes for essential amino acids

26 20-26 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Site of microbial fermentation Foregut –food held in anterior part of stomach –foregut fermenters  example: kangaroos –ruminant foregut fermenters  example: sheep Hindgut –food held in caecum and colon  example: koala

27 20-27 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.24a: Foregut fermentation

28 20-28 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.24b: Foregut fermentation

29 20-29 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Ruminants Ruminants regurgitate contents of anterior stomach (rumen, reticulum) and chew it again –cannot pass through to omasum unless particles are small enough Food retained for prolonged period –extends time for fermentation High fibre/low quality foods must be chewed for longer than low fibre/high quality food –limits amount of food that can pass through gut per unit of time

30 20-30 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Fig. 20.27b: Hindgut fermentation

31 20-31 Copyright  2005 McGraw-Hill Australia Pty Ltd PPTs t/a Biology: An Australian focus 3e by Knox, Ladiges, Evans and Saint Hindgut fermentation Sugars and proteins in cell contents hydrolysed by herbivore’s digestive enzymes Undigested cell walls pass through to hindgut –site of microbial fermentation Microbes not digested (as they are in foregut fermenters) –pass out in faeces, so source of amino acids lost Microbial protein recovered by caecotrophy (coprophagy)


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