1. A CQUISITION OF NUTRIENTS IN ANIMALS Biology ATA Unit 2 Chapter 11 Pages 278-284

2. Mechanical digestion Mastication Bolus Peristalsis Chemical digestion Enzymes Gastrovascular cavity Alimentary canal Herbivore Cellulose Ruminants Non-ruminants Carnivore Omnivore Heterotrophic multicellular organisms need to eat food to survive. This food needs to be broken down into its molecular components so nutrients can be absorbed into the blood. This process is called digestion. KeywordsMaking connections

3. D EFINITIONS KeywordMeaning IngestionThe taking in of nutrients DigestionThe breakdown of complex organic molecules into smaller components by mechanical and chemical means AbsorptionThe taking up of digested molecules into the internal environment of the cells of the digestive tract EgestionThe removal of waste materials from the body

4. D IGESTIVE SYSTEMS The function of the digestive system is to provide cells with nutrients in a form that can be absorbed and used by them Digestion changes nutrients: 1. Large to small 2. Insoluble to soluble Different organisms require different nutrients Different organisms have different types of digestive systems

5. N UTRIENTS All organisms need 6 types of nutrients 1. Water 2. Carbohydrates 3. Fats 4. Protein 5. Minerals 6. Vitamins The proportion of each type of nutrient in the diet varies between species. Nutrients are broken down through: Mechanical digestion  Breaks food down into smaller pieces increased surface area increased efficiency of chemical digestion Chemical digestion  Enzymes break down food into molecules that can be absorbed into the blood

6. D IGESTION OF NUTRIENTS MECHANICAL DIGESTION Mastication Teeth  Incisors  Canines  Premolars  Molars Tongue  Helps to form a bolus which is swallowed and is forced down into the stomach by peristalsis Stomach churns food by muscular contractions

7. D IGESTION OF NUTRIENTS CHEMICAL DIGESTION Enzymes break down food further through chemical digestion Each nutrient has specific enzymes that work to break it down into its most basic unit Carbohydrates into glucose Fats into fatty acids and glycerol Proteins into amino acids

8. T YPES OF DIGESTIVE SYSTEMS Gastrovascular cavity with one opening Specialised alimentary canal with two openings Herbivores Carnivores Omnivores

9. G ASTROVASCULAR CAVITY Cnidarians Platyhelminthes (flatworms) A gastrovascular cavity is a single opening through which food enters and wastes leave. It is found in less complex animals

10. S PECIALISED ALIMENTARY CANAL Most animals have a specialised alimentary canal with two openings One opening is the mouth – food in The other opening is the anus – waste out

11. S PECIALISED ALIMENTARY CANALS : O RGANS Mouth Tongue Teeth Pharynx Epiglottis Oesophagus Stomach Liver Gall bladder Pancreas Small intestine Caecum Appendix Large intestine Ascending colon Transverse colon Descending colon Rectum Anus

12. S PECIALISED ALIMENTARY CANALS : E NZYMES & CHEMICAL DIGESTION Digestion Mouth Amylase (carbohydrates) Stomach Acid Pepsin (protein) Small intestine Proteases(protein) Amylase Lipases (fats) Bile (fats) Absorption Small intestines Glucose Fatty acids Glycerol Amino acids Vitamins Minerals Large intestine Water

13. S PECIALISED ALIMENTARY CANALS : A BSORPTION The small intestine absorbs most of the nutrients. It has a rich supply of capillaries The lining of the small intestine is highly convoluted with many villae These greatly increase the surface area for absorption

14. S TRUCTURE OF THE ALIMENTARY TUBE Mucosa Longitudinal muscle layer Circular muscle layer Peritoneu m Villus Submucosa Thin muscle layer

15. S PECIALISED ALIMENTARY CANALS : T HE HUMAN DIGESTIVE SYSTEM US Govt NIH

16. H ERBIVORES Herbivores are plant eaters They obtain most of their energy from carbohydrates They have specialised microflora (gut bacteria) to help with the digestion of cellulose and lignin

17. H ERBIVORES : RUMINANTS & NON - RUMINANTS RUMINANTS Have a stomach divided into a number of chambers (2-4) The first chamber (the rumen) ferments food Regurgitate their food from the first chamber for further mechanical digestion Microflora to aid the digestion of cellulose are found in the rumen and in the caecum Example: cows, sheep NON-RUMINANTS Do not regurgitate their ingested food Microflora to aid the digestion of cellulose is found in the caecum Example: kangaroos,horses

18. C ARNIVORES The digestive system of carnivores does not have to cope with digesting large amounts of cellulose. The main difference is that the caecum is much reduced in size and the large intestine is shorter Some consider the appendix to be the reduced caecum and thus a vestigial organ. However, evidence suggests that the appendix is actually a part of the immune system. It is filled with lymphatic tissue and white blood cells.