Digestion & Nutrition

Transcription

1 Digestion & Nutrition Ch. 41 Lecture

2 Animal Nutrition

3 Big Ideas (Unity and Diversity of Life) 1.B.1: Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today. Metabolic pathways are similar among all animals 2011 Pearson Education, Inc.

4 Big Ideas (Dynamic Homeostasis) 2.A.1.a: Life requires a highly ordered system. Carbohydrates, O 2 & Free energy Coupling of free energy and endergonic reactions Glycolysis, Krebs cycle, ETC 2.A.3: Organisms must exchange matter with the environment to grow, reproduce and maintain organization. Ingestion, absorption of nutrition Cell SA:V relationship and villi of intestinal tract 2011 Pearson Education, Inc.

5 Big Ideas (Dynamic Homeostasis) 2.B.2: Growth and dynamic homeostasis are maintained by the constant movement of molecules across the cell membrane. Carbohydrates, O 2 & Free energy Coupling of free energy and endergonic reactions Glucose transport into cell and insulin (neg. feedback) 2011 Pearson Education, Inc.

6 Big Ideas (Dynamic Homeostasis) 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. brain tissue sensors, hyperventilation, breathing rates/depth Diabetes mellitus is the consequence of improper feedback control 2.C.2: Organisms respond to changes in their external environments Hibernation and migration due to insufficient food resources 2011 Pearson Education, Inc.

7 Big Ideas (Dynamic Homeostasis) 2.D.1: All biological systems from cells ecosystems are affected by complex abiotic and biotic interactions. Predator/prey relationships Availability of nutrients (and water) Population density 2.D.2: Organisms have various ways for obtaining nutrients and eliminating wastes. Ingestion, absorption, diffusion and active transport 2.D.2: Homeostatic control systems support common ancestry. Digestive mechanisms in animals (food vacuoles, GV cavities, one-way digestive systems (aka alimentary canals) 2011 Pearson Education, Inc.

8 Big Ideas (Dynamic Homeostasis) 3.D.1: Cell communication process share common features that reflect a shared evolutionary history. Epinephrine stimulation of glycogen breakdown in mammals 2011 Pearson Education, Inc.

9 Big Ideas (Dynamic Homeostasis) 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. Endocrine signals insulin production 2011 Pearson Education, Inc.

10 Big Ideas (Dynamic Homeostasis) 3.D.4: Changes in signal transduction pathways can alter cellular response. Diabetes 2011 Pearson Education, Inc.

11 Big Ideas (Dynamic Homeostasis) 3.E.1: Individuals can act on information and communicate it to others. Bees communicating source of pollen, nectar Migration patterns (caribou seeking grasslands in spring) Predator warning 2011 Pearson Education, Inc.

12 Big Ideas (Complex Properties) 4.A.4 a): Organisms exhibit complex properties due to interactions between their constituent parts Stomach and small intestines 4.A.4 b): Interactions and coordination between systems provide essential biological activities Digestive and circulatory systems 4.B.2 a.2): Within multicellular organisms, specialization of organs contributes to the overall functioning of the organism Nervous system, digestive, circulatory, respiratory digestion of food 2011 Pearson Education, Inc.

13 Big Ideas (Complex Properties) 4.B.3) Interactions between and within populations influence patterns of species distribution and abundance. Predation, mutualism, competition, commensalism 2011 Pearson Education, Inc.

14 Big Picture Animal nutrition is defined by obtaining food, taking it apart, and taking it in (to cells). This process involves ingestion, digestion, absorption & elimination. Animals, unlike plants, must consume food for both energy and organic matter to build new molecules, cells, and tissues. Lipids Proteins Water Nucleic Acids Vitamins Carbohydrates Absorption Diffusion 2011 Pearson Education, Inc.

15 FRQ 2011 (#2) F

16 Mix and Match Autotroph Glycogen Liver Storage Vegetarian Eliminate Ingestion Diffusion Carnivore Bulk feeding Hydra Amino acids Extracellular Intracellular Caprophagy Colon

17 Testing Your Understanding 1. All 20 amino acids are needed to make animal proteins. Why aren t they all essential to animal diets? 2. In what sense are nutrients from a recently ingested meal not really inside your body prior to the absorption stage of food processing? 3. How does swallowed food reach the stomach of a weightless astronaut in orbit? 4. What features of a mammal s digestive tract make an attractive habitat for mutualistic microorganisms? 5. Explain how people can become obese even if their intake of dietary fat is relatively low compared to their carb intake.

18 Testing for Understanding: Answers 1. The only essential amino acids are those that an animal cannot make on their own from other molecules. 2. As long as the food is in the alimentary canal (esophagus anus), it is continuously connected to the outside. 3. By peristalsis, which can squeeze food through the esophagus even without the help of gravity. 4. A mammal s digestive system provides microbes with a warm, protective environment stocked with nutrients. 5. Over the long term, the body stores excess calories as fat, regardless of where the calories came from originally (sugar, fat, protein, etc.)

19 mouth stomach liver small intestines pancreas large intestines

20 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with their diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.

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22 What do animals need to live? Animals make energy using: food oxygen Animals build bodies using: food for raw materials amino acids, sugars, fats, nucleotides food O 2 ATP energy for synthesis ATP

23 Nutritional requirements Animals are heterotrophs need to take in food Why? fulfills 3 needs fuel = chemical energy for production of ATP raw materials = carbon source for synthesis essential nutrients = animals cannot make elements (N, P, K, Fe, Na, K, Ca...), NAD, FAD, etc.

24 Energy budget food intake ATP production { synthesis { storage { basal (resting) metabolism temperature regulation activity repair growth reproduction glycogen fat

25 Energy storage In humans glycogen storage glucose polymer in liver & muscle cells If glycogen stores are full & caloric intake still exceeds caloric expenditure excess stored as fat synthesis pathway from acetyl coa Why is glycogen highly branched?

26 Balancing calorie needs with intake When fewer calories are taken in than are expended, fuel is taken out of storage deposits & oxidized (digested) breakdown (digest) glycogen from liver & muscle cells metabolize (digest) fat Just do it!

27 Vegetarian diets Need to make sure you get enough protein 20 amino acids to make protein humans can synthesize 12 of the amino acids 8 have to be eaten = essential amino acids Grains (like corn) have 6 (missing 2) Beans (like soybean & red beans) have 6 (missing different 2) mix beans & grains for complete group of amino acids rice & beans taco/tortilla & beans tofu & rice peanut butter & bread

28 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with their diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.

29 Figure 41.5a

30 Figure 41.5 Mechanical digestion Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Undigested material 1 Ingestion 2 Digestion 3 Absorption 4 Elimination

31 Getting, Using Food: Process 1. Ingest 2. Digest 3. Absorb taking in food mechanical digestion breaking up food into smaller pieces chemical digestion breaking down food into molecules small enough to be absorbed into cells enzymes (hydrolysis) absorb across cell membrane diffusion active transport 4. Eliminate undigested extracellular material passes out of digestive system intracellular digestion extracellular digestion

32 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with its diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.

33 Digestive systems Everybody s got one!

34 Common processes & structures Movement & Control peristalsis push food along by rhythmic waves of smooth muscle contraction in walls of digestive system sphincters muscular ring-like valves, regulate the passage of material between sections of digestive system

35 Figure 41.9b Accessory glands Salivary glands Pancreas Liver Gall bladder secrete digestive juices (enzymes & fluid) Mouth Esophagus Gallbladder Liver Pancreas Salivary glands Stomach Small intestine Large intestine Rectum Anus Schematic diagram

36 Figure 41.9 Tongue Oral cavity Salivary glands Pharynx Esophagus Mouth Esophagus Salivary glands Liver Sphincter Gallbladder Stomach Gallbladder Pancreas Small intestine Large intestine Rectum Anus Sphincter Stomach Duodenum of small intestine Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

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38 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

39 Human digestive system Alimentary Canal

40 Swallowing (& not choking) When a person is not swallowing, the esophageal sphincter muscle is contracted, epiglottis is up, and the glottis is open. Air can flow through trachea to the lungs.

41 Swallowing (& not choking) The swallowing reflex is triggered when a bolus (mass) of food reaches the pharynx (throat).

42 Swallowing (& not choking) The larynx moves upward and the epiglottis tips over the glottis. Food cannot enter trachea.

43 Swallowing (& not choking) After swallowing, larynx pushes down, opens trachea. Esophageal muscles rhythmically contract, move food to stomach.

44 Ingestion Mouth mechanical digestion teeth breaking up food chemical digestion saliva amylase enzyme digests starch mucin slippery protein (mucus) protects soft lining of digestive system lubricates food for easier swallowing buffers neutralizes acid to prevent tooth decay anti-bacterial chemicals kill bacteria that enter mouth with food

45 mouth break up food moisten food digest starch kill germs

46 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

47 Stomach Functions food storage can stretch to fit ~2L food disinfect food HCl = ph 2 kills bacteria breaks apart cells chemical digestion pepsin enzyme breaks down proteins secreted as pepsinogen activated by HCl Ooooooh! Zymogen! But the stomach is made out of protein! What stops the stomach from digesting itself? mucus secreted by stomach cells protects stomach lining & regenerative mitosis (q 3 d)

48 Positive Feedback Once activated by HCl, more Pepsin makes more Pepsinogen, which makes more Pepsin

49 mouth break up food moisten food digest starch kill germs stomach kills germs store food break up food digest proteins cardiac sphincter pyloric sphincter

50 Digestive enzymes

51 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

52 Pancreas Digestive enzymes peptidases trypsin trypsinogen chymotrypsin chimotrypsinogen carboxypeptidase procarboxypeptidase pancreatic amylase Buffers reduces acidity alkaline solution rich in bicarbonate (HCO 3 -) buffers acidity of material from stomach What stops pancreas Ooooooh! from Zymogen! digesting itself small intestines Explain how this is a molecular example of structure-function theme.

53 mouth break up food moisten food digest starch kill germs stomach kills germs break up food digest proteins store food pancreas produces enzymes to digest proteins & starch

54 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

55 Liver Digestive System Functions produces bile stored in gallbladder until needed breaks up fats act like detergents to breakup fats Circulatory System Connection bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes feces brown

56 mouth break up food moisten food digest starch kill germs stomach kills germs break up food digest proteins store food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & starch

57 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Large intestine Rectum Anus Schematic diagram Small Intestine= 20 feet! Structure-function?

58 Small intestine Function major organ of digestion & absorption chemical digestion digestive enzymes absorption through lining over 6 meters! small intestine has huge surface area = 300m 2 (~size of tennis court) Structure 3 sections duodenum = most digestion jejunum = absorption of nutrients & water ileum = absorption of nutrients & water

59 Duodenum 1st section of small intestines acid food from stomach mixes with digestive juices from accessory glands: pancreas liver gall bladder

60 Absorption by Small Intestines Absorption through villi & microvilli finger-like projections increase surface area for absorption

61 Absorption of Nutrients Passive transport fructose Active (protein pumps) transport pump amino acids, vitamins & glucose against concentration gradients across intestinal cell membranes allows intestine to absorb much higher proportion of nutrients in the intestine than would be possible with passive diffusion worth the cost of ATP! nutrients are valuable grab all you can get!

62 mouth break up food moisten food digest starch kill germs liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & starch stomach kills germs break up food digest proteins store food small intestines breakdown all foods - proteins - starch - fats - nucleic acids absorb nutrients

63 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

64 Large intestines (colon) Function re-absorb water use ~9 liters of water every day in digestive juices > 90% of water reabsorbed not enough water absorbed back to body diarrhea too much water absorbed back to body constipation

65 Flora of large intestines You ve got company! Living in the large intestine is a rich flora of harmless, helpful bacteria Escherichia coli (E. coli) a favorite research organism bacteria produce vitamins vitamin K; biotin, folic acid & other B vitamins generate gases by-product of bacterial metabolism methane, hydrogen sulfide

66 Appendix Vestigial organ

67 mouth break up food moisten food digest starch kill germs liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & carbs stomach kills germs break up food digest proteins store food small intestines breakdown food - proteins - starch - fats absorb nutrients large intestines absorb water

68 Mouth Esophagus Salivary glands Gallbladder Stomach Liver Pancreas Small intestine Large intestine Rectum Anus Schematic diagram

69 Rectum Last section of colon (large intestines) eliminate feces undigested materials extracellular waste salts mainly cellulose from plants roughage or fiber masses of bacteria

70 Geez, Thumper. Really? Mechanical digestion Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Undigested material 1 Ingestion 2 Digestion 3 Absorption 4 Elimination

71 Mix and Match Autotroph Glycogen Liver Storage Vegetarian Eliminate Ingestion Diffusion Carnivore Bulk feeding Hydra Amino acids Extracellular Intracellular Caprophagy Colon

72 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with its diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.

73 How do animals get their food? filter (suspension) feeding substrate feeding fluid feeding bulk feeding

74 Suspension Feeders Many aquatic animals are suspension feeders, which sift small food particles from the water Baleen 2011 Pearson Education, Inc.

75 Figure 41.6b Substrate Feeders Substrate feeders are animals that live in or on their food source Substrate Feeders 2011 Pearson Education, Inc. Caterpillar Feces

76 Fluid Feeders Fluid feeders suck nutrient-rich fluid from a living host Fluid Feeders 2011 Pearson Education, Inc.

77 Bulk Feeders Bulk feeders eat relatively large pieces of food 2011 Pearson Education, Inc.

78 Different diets; different lives All animals eat other organisms Herbivores eat mainly plants gorillas, cows, rabbits, snails Carnivores eat other animals sharks, hawks, spiders, snakes Omnivores eat animals & plants cockroaches, bears, raccoons, humans

79 Different diets; different bodies Adaptations of herbivore vs. carnivore specialization in teeth length of digestive system number & size of stomachs

80 Teeth Carnivore sharp ripping teeth canines Herbivore wide grinding teeth molars Omnivore both kinds of teeth

81 Length of digestive system Carnivores short digestive system protein easier to digest than cellulose Herbivores & omnivores long digestive system more time to digest cellulose symbiotic bacteria in gut

82 Symbiotic organisms How can cows digest cellulose efficiently? Ruminants additional mechanical digestion by chewing food multiple times after mixing it with enzymes symbiotic bacteria in stomachs help digest cellulose-rich meals coprophagy ruminant rabbit vs. cow adaptation: eat feces vs. chew cud

83 starch Digesting cellulose How well you digest cellulose governs life strategy of herbivores cellulose bond between the sugars governs digestibility

84 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with its diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.

85 Regulation of Energy Storage The body stores energy-rich molecules that are not needed right away for metabolism In humans, energy is stored in this order: 1 liver & muscle cells as glycogen (polymer) 2 adipose tissue; most space-efficient storage tissue 2011 Pearson Education, Inc.

86 Evaluating Fat Levels

87 Glucose Homeostasis The hormones insulin and glucagon regulate the breakdown of glycogen into glucose The liver is the site for glucose homeostasis carbohydrate-rich meal insulin levels glycogen Low blood sugar glucagon stimulates breakdown of glycogen and release glucose 2011 Pearson Education, Inc.

88 Figure Transport of glucose into body cells and storage of glucose as glycogen Homeostasis: mg glucose/ 100 ml blood Stimulus: Blood glucose level rises after eating. Pancreas secretes insulin. Breakdown of glycogen and release of glucose into blood Stimulus: Blood glucose level drops below set point. Pancreas secretes glucagon.

89 Regulation of Appetite and Consumption Overnourishment: causes obesity obesity contributes to diabetes (type 2) cancer of the colon and breasts heart attacks, and strokes Researchers have discovered several of the mechanisms that help regulate body weight 2011 Pearson Education, Inc.

90 Gain fat Leptin levels rise Lose fat Leptin levels fall Therefore Leptin controls appetite

91 Figure Satiety center I Ghrelin Leptin Insulin PYY

92 Hormones regulate long-term and short-term appetite by affecting a satiety center in the brain Studies on mice revealed that the hormone leptin plays an important role in regulating obesity Leptin is produced by adipose tissue and can help to suppress appetite 2011 Pearson Education, Inc.

93 Figure 41.22a Obese mouse with mutant ob gene (left) next to wild-type mouse

94 Figure 41.22b RESULTS Genotype pairing (red type indicates mutant genes) Subject ob ob, db db ob ob, db db Paired with ob ob, db db ob ob, db db Average change in body mass (g) of subject ob ob, db db ob ob, db db ob ob, db db ob ob, db db * *Due to pronounced weight loss and weakening, subjects in this pairing were reweighed after less than eight weeks.

95 Key Points 1) An animal s diet must supply chemical energy, organic molecules, and essential nutrients. 2) The main stages of food processing are ingestion, digestion, absorption, and elimination. 3) The mammalian digestive system has organs specialized for processing food in sequential. 4) A vertebrate s digestive system correlates with its diet. 5) Feedback circuits regulate digestion, energy storage, & appetite.