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The great Serengeti migration: A quest for minerals.

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Presentation on theme: "The great Serengeti migration: A quest for minerals."— Presentation transcript:

1 The great Serengeti migration: A quest for minerals

2 Digestive system Functions Organs

3 Figure 23.2 Organs of alimentary canal

4 Figure 23.1 Month Esophagus Stomach Small intestine Large intestine Accessory organs Salivary glands, liver, pancreas, gall bladder

5 Digestive tracts of various vertebrates

6 Digestive tracts of invertebrates and vertebrates

7 Figure 4.1 The composition of the adult human body

8 Nutrition Proteins Lipids Carbohydrates Vitamins and minerals

9 Figure 4.2 Amino acid chemistry (Part 1)

10 Figure 4.2 Amino acid chemistry (Part 2)

11 Figure 4.3 Fatty acids and triacylglycerols (Part 1)

12 Figure 4.3 Fatty acids and triacylglycerols (Part 2)

13 Figure 4.4 Carbohydrate chemistry

14 Figure 4.5 Vitamin structures

15 Feeding Examples of feeding adaptations Food chains

16 Figure 4.6 Some species feed by targeting and subduing individual food items (Part 1)

17 Figure 4.7 Specialization of a vertebrate feeding apparatus

18 Dentition

19 Figure 4.8 Specialization of an invertebrate feeding apparatus (Part 1)

20 Figure 4.8 Specialization of an invertebrate feeding apparatus (Part 2)

21 Figure 4.10 The feeding apparatus of a baleen whale

22 Figure 4.12 Reef-building corals of warm waters need light because they are symbiotic with algae (2)

23 Figure 4.9 Short food chains deplete energy less than long food chains do

24 Digestive systems of insects and crustaceans Crustaceans digestive system is separate from the excretory system Insects– the Malpighian tubules – excretory system is connected at the junction of the midgut and hindgut

25 Figure 4.16 The digestive systems of two types of arthropods: insects and crustaceans

26

27 Figure 23.1

28 Stomach (continued) Contractions of the stomach churn chyme. –Mix chyme with gastric secretions. –Push food into intestine. Insert fig. 18.5

29 Small Intestine Each villus is a fold in the mucosa. Covered with columnar epithelial cells interspersed with goblet cells. Epithelial cells at the tips of villi are exfoliated and replaced by mitosis in crypt of Lieberkuhn. Lamina propria contain lymphocytes, capillaries, and central lacteal. Insert fig

30 Histology of the Alimentary Canal Figure 23.6

31 Sensors of the GI tract– regulatory mechanisms Mechanoreceptors and chemoreceptors involved Located in the walls of the tract organs Sensors respond to –Stretching –Osmolarity –pH –Presence of substrates and end-products

32 Regulatory mechanisms (2) Receptors initiate reflexes Activate of inhibit glands that secrete digestive juices Stimulate smooth muscle of GI tract –Move food along the tract –Mix lumen content

33 Peristalsis and Segmentation Figure 23.3

34 Adaptation associated with animals diet Microbe-assisted digestion –animals in hydrothermal vents-trophosomes Dentition/mouth parts Length of digestive tract –Herbivores –Carnivores –Omnivores –Sharks –Birds

35 Microbe-dependent digestion Digestion assisted by microbes

36 Animals maintain symbiosis with three categories of microbes Heterotrophic microbes –Organic compounds of external origin Autotrophic microbes –Synthesize organic molecules from inorganic precursors Chemosynthetic Photosynthetic

37 Figure 4.13 Hydrothermal-vent worms are symbiotic with chemoautotrophic bacteria (Part 1)

38 Hydrothermal-vent worms Symbiotic with chemoautotrophic bacteria- trophosomes Worms have not mouth, gut, or anus Food comes from sulfur-oxidizing chemoautotrophic bacteria Organic molecules from bacteria meets nutritional needs Vents- source of H 2 S

39 Hydrothermal-vent worms Symbiotic with chemoautotrophic bacteria- trophosomes Worms have not mouth, gut, or anus Food comes from sulfur-oxidizing chemoautotrophic bacteria Organic molecules from bacteria meets nutritional needs Vents- source of H 2 S

40 Figure 4.13 Hydrothermal-vent worms are symbiotic with chemoautotrophic bacteria (Part 2)

41 Comparison of the digestive tracts of carnivores and herbivores Carnivores- foregut digestion Herbivores –Hindgut –Foregut

42 Figure 4.14 The digestive tract of ruminants (Part 1)

43 Stomach of ruminants Several chambers Rumen – first chamber/fermentation occurs Regurgitate fermenting materials from the rumen into mouth Further grinding and reswallow From rumen reticulum omasum abomasum (true stomach)

44 Functions of microbes in ruminants Synthesize B vitamins, essential amino acids Fermentative breakdown of compounds that animals cannot digest– cellulose Recycle waste nitrogen from animal metabolism Make ammonia so other microbes can use it as nitrogen source

45 Figure 4.14 The digestive tract of ruminants (Part 2)

46 Figure 4.15 The digestive tracts of two hindgut fermenters

47 Hind and midgut fermenters Enlarged cecum/colon –Rabbits, horses, zebras, rhinos, apes, elephants Break down of cellulose and carbohydrates Forms short-chain fatty acid B vitamins- not utilized, lost in feces Coprophagy– rabbits eat special soft feces

48 A comparison of the digestive tracts of a carnivore (coyote) and a herbivore (koala)

49 Digestion and absorption Digestive enzymes in 3 spatial contexts Intraluminal enzymes Membrane-associated enzymes Intracellular enzymes

50 Intracellular and extracellular digestion Intraluminal and membrane-associated enzymes are responsible for extracellular digestion Intracellular enzymes are responsible for intracellular digestion Advantages and disadvantages of intra- and extracellular digestions?

51 Figure 4.17 The stomach of a clam (Part 2)

52 Carbohydrate digestion OrganSubstrateEnzymeEnd product(s) Oral cavityStarchSal1vary amylaseMaltose Stomach Amylase denatured Lumen of intestine Undigested polysaccharides Pancreatic amylase Maltose Brush border of small intestine Disaacharides: maltose Sucrose Lactose Maltase Sucrase Lactase Monosaccharides

53 Figure 4.19 Absorption of monosaccharides in the vertebrate midgut (Part 2)

54 Protein digestion OrganSubstrateEnzymeEnd product(s) Stomach PolypeptidesPepsinogen +HCl = pepsin Smaller peptides Lumen of intestine PolypeptidesTrypsinogen, chymotrypsinogen (inactive enzymes released from the pancreas, transported to duodenum via pancreatic duct. These enzymes are activated by enterokinase from small intestine to trypsin and chymotrypsin Smaller peptides Smaller polypeptides Aminopeptidase, carboxypeptidase Amino acids Brush border of small intestine Dipeptides DipeptidaseAmino acids

55 Figure 4.18 The digestion of a short protein by three pancreatic peptidases

56 Fat digestion OrganSubstrateEnzymeEnd product(s) Oral cavity No enzyme to digest fat Stomach No enzyme to digest fat Lumen of intestineFat globules Fat globules Bile salt from gallbladder lipase Emulsified fat Glycerol, fatty acids Brush border of small intestine

57 Chemical Digestion: Fats Figure 23.35

58 Figure 4.19 Absorption of monosaccharides in the vertebrate midgut (Part 1)

59 Chemical Digestion: Carbohydrates Carbohydrates absorption: via cotransport with Na +, and facilitated diffusion –Enter the capillary bed in the villi –Transported to the liver via the hepatic portal vein

60 Chemical Digestion: Proteins Absorption: similar to carbohydrates Enzymes used: pepsin in the stomach Enzymes acting in the small intestine

61 Chemical Digestion: Fats Absorption: Diffusion into intestinal cells where they: –Combine with proteins and extrude chylomicrons –Enter lacteals and are transported to systemic circulation via lymph

62 Coordination of digestion– neural and endocrine control Controls of digestive activity Extrinsic –Central nervous system and autonomic nervous system Intrinsic –Hormone-producing cells in stomach and small intestine –Distributed via blood and interstitial fluid to target cells

63

64 Endocrine control Gastrin Secretin CCK GIP –Where? –When? –Why? –How?

65 Figure 4.20 GI function after a meal is coordinated in part by hormones secreted by cells in the gut


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