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Why do we crave pizza so?
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Why do we crave pizza so? How does a pizza help you make brain cells?
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Or a lean fish help a bear make fat?
Figure 41.1 How does a lean fish help a bear make fat?
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Chapter 41 Animal Nutrition
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Video: Lobster Mouth Parts
© 2011 Pearson Education, Inc.
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Video: Shark Eating a Seal
© 2011 Pearson Education, Inc.
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Concept 41.1: An animal’s diet must supply chemical energy, organic molecules, and essential nutrients An animal’s diet provides: Chemical energy, which is converted into ATP to power cellular processes Organic building blocks, such as organic carbon and organic nitrogen, to synthesize a variety of organic molecules Essential nutrients, which are required by cells and must be obtained from dietary sources © 2011 Pearson Education, Inc.
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Essential Nutrients There are four classes of essential nutrients:
Essential amino acids Essential fatty acids Vitamins - organic Minerals - inorganic © 2011 Pearson Education, Inc.
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What is the problem with a vegan diet?
© 2011 Pearson Education, Inc.
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What is the problem with a vegan diet?
Animals require 20 amino acids and can synthesize about half from molecules in their diet The remaining amino acids, the essential amino acids, must be obtained from food in preassembled form © 2011 Pearson Education, Inc.
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Table 41.1 Table 41.1 Vitamin Requirements of Humans
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Table 41.2 Table 4.2 Mineral Requirements of Humans
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Why is this fella licking the ground?
Figure 41.3 Why is this fella licking the ground? Figure 41.3 Obtaining essential nutrients.
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Assessing Nutritional Needs
What is the difference between malnourishment and undernourishment? Insights into human nutrition have come from epidemiology, the study of human health and disease in populations Example: neural tube defects were found to be the result of a deficiency in folic acid in pregnant mothers © 2011 Pearson Education, Inc.
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Can diet influence the frequency of birth defects?
RESULTS Number of infants/fetuses studied Infants/fetuses with a neural tube defect Group Vitamin supplements (experimental group) 141 1 (0.7%) No vitamin supplements (control group) Figure 41.4 Inquiry: Can diet influence the frequency of birth defects? 204 12 (5.9%)
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Concept 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination Nutrient molecules enter body cells Mechanical digestion Chemical digestion (enzymatic hydrolysis) Undigested material Figure 41.5 The four stages of food processing. 1 Ingestion 2 Digestion 3 Absorption 4 Elimination
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Suspension Feeders and Filter Feeders
Figure 41.6 Suspension Feeders and Filter Feeders Baleen Substrate Feeders Fluid Feeders Caterpillar Feces Bulk Feeders Figure 41.6 Exploring: Four Main Feeding Mechanisms of Animals
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Video: Hydra Eating Daphnia
© 2011 Pearson Education, Inc.
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Mouth Tentacles Food Digestive enzymes released 1 Food
Figure 41.7 Mouth Tentacles Food Digestive enzymes released 1 Food particles broken down 2 Figure 41.7 Digestion in a hydra. Food particles engulfed and digested 3 Epidermis Gastrodermis
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Variation in alimentary canals.
Crop Esophagus Gizzard Pharynx Intestine Variation in alimentary canals. Anus Mouth (a) Earthworm Foregut Midgut Hindgut Esophagus Crop Esophagus Rectum Stomach Anus Gizzard Figure 41.8 Variation in alimentary canals. Intestine Mouth Anus Crop Gastric cecae Mouth (b) Grasshopper (c) Bird
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Consistent layout of most mammals
Tongue Oral cavity Salivary glands Mouth Pharynx Salivary glands Esophagus Esophagus Liver Gall- bladder Stomach Sphincter Small intestine Gall- bladder Liver Sphincter Pancreas Large intestine Pancreas Stomach Figure 41.9 The human digestive system. Small intestine Rectum Anus Large intestine Schematic diagram Duodenum of small intestine Rectum Anus
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peristalsis Bolus of food Tongue Epiglottis up Pharynx Glottis
Esophageal sphincter contracted Larynx Trachea Esophagus To lungs To stomach Figure From mouth to stomach: the swallowing reflex and esophageal peristalsis.
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peristalsis Bolus of food Tongue Epiglottis up Pharynx Glottis
Esophageal sphincter contracted Larynx Trachea Esophagus To lungs To stomach Figure From mouth to stomach: the swallowing reflex and esophageal peristalsis.
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peristalsis Bolus of food Tongue Epiglottis up Pharynx Glottis
Esophageal sphincter contracted Larynx Trachea Esophagus Relaxed muscles To lungs To stomach Contracted muscles Figure From mouth to stomach: the swallowing reflex and esophageal peristalsis. Sphincter relaxed Stomach
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Digestion in the Stomach
The stomach stores food and secretes gastric juice, which converts a bolus to acid chyme © 2011 Pearson Education, Inc.
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Chemical Digestion in the Stomach
Gastric juice has a low pH of about 2, which kills bacteria and denatures proteins Gastric juice is made up of hydrochloric acid (HCl) and pepsin Pepsin is a protease, or protein-digesting enzyme, that cleaves proteins into smaller peptides © 2011 Pearson Education, Inc.
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Why doesn’t the stomach digest itself?
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Esophagus Sphincter Stomach Sphincter Small intestine Folds of
Figure 41.11 Esophagus Sphincter Stomach Sphincter Small intestine 10 m Folds of epithelial tissue Epithelium Gastric pits on interior surface of stomach 3 Pepsinogen Pepsin 2 Gastric gland HCl Chief cell 1 Figure The stomach and its secretions. Mucous cell H Cl Parietal cell Chief cell Parietal cell
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Chemical digestion in the human digestive system.
Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Salivary amylase Smaller polysaccharides Maltose Figure Chemical digestion in the human digestive system.
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Figure 41.12 Chemical digestion in the human digestive system.
Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Salivary amylase Smaller polysaccharides Maltose Protein digestion Stomach Proteins Pepsin Small polypeptides Figure Chemical digestion in the human digestive system.
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Figure 41.12 Chemical digestion in the human digestive system.
Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Salivary amylase Smaller polysaccharides Maltose Protein digestion Stomach Proteins Pepsin Small polypeptides Nucleic acid digestion Fat digestion Small intestine (enzymes from pancreas) DNA, RNA Fat (triglycerides) Pancreatic amylases Pancreatic trypsin and chymotrypsin Pancreatic nucleases Disaccharides Smaller polypeptides Nucleotides Pancreatic lipase Pancreatic carboxypeptidase Glycerol, fatty acids, monoglycerides Figure Chemical digestion in the human digestive system. Small peptides
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Figure 41.12 Chemical digestion in the human digestive system.
Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Disaccharides Salivary amylase Smaller polysaccharides Maltose Protein digestion Stomach Proteins Pepsin Small polypeptides Nucleic acid digestion Fat digestion Small intestine (enzymes from pancreas) DNA, RNA Fat (triglycerides) Pancreatic amylases Pancreatic trypsin and chymotrypsin Pancreatic nucleases Disaccharides Smaller polypeptides Nucleotides Pancreatic lipase Pancreatic carboxypeptidase Glycerol, fatty acids, monoglycerides Figure Chemical digestion in the human digestive system. Small peptides Small intestine (enzymes from epithelium) Nucleotidases Dipeptidases, carboxy- peptidase, and aminopeptidase Nucleosides Disaccharidases Nucleosidases and phosphatases Nitrogenous bases, sugars, phosphates Monosaccharides Amino acids
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Most of absorption happens in the small intestine
15 – 32 feet in humans The first portion of the small intestine is the duodenum, where chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself Most of nutrient digestion here Jejunum and ilium mostly extract water Some nutrients diffuse through membranes, most are pumped against gradient © 2011 Pearson Education, Inc.
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Pancreatic Secretions
The pancreas produces proteases trypsin and chymotrypsin that are activated in the lumen of the duodenum Its solution is alkaline…Why? © 2011 Pearson Education, Inc.
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Bile Production by the Liver
In the small intestine, bile aids in digestion and absorption of fats Bile is made in the liver and stored in the gallbladder Bile also destroys nonfunctional red blood cells © 2011 Pearson Education, Inc.
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Figure 41.13 Nutrient absorption in the small intestine.
Microvilli (brush border) at apical (lumenal) surface Villi Vein carrying blood to liver Lumen Epithelial cells Blood capillaries Epithelial cells Basal surface Muscle layers Villi Large circular folds Intestinal wall Lacteal Figure Nutrient absorption in the small intestine. Key Lymph vessel Nutrient absorption membrane transport review bioflix
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The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules © 2011 Pearson Education, Inc.
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The colon’s primary purpose is to absorb water from chyme.
Figure 41.15 The colon’s primary purpose is to absorb water from chyme. Ascending portion of colon Small intestine Figure Junction of the small and large intestines. Cecum Appendix 90% of water consumed is reabsorbed. What happens if too much is absorbed? Too little?
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Symbiotic bacteria and digestion
There are approximately 500 species of bacteria comprising the gut flora (part of the “human microbiome”) that aid in digestion 100 trillion cells compared to 10 trillion actual body cells Why don’t we eat feces? © 2011 Pearson Education, Inc.
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Symbiotic bacteria and digestion
There are approximately 500 species of bacteria comprising the gut flora (part of the “human microbiome”) that aid in digestion 100 trillion cells compared to 10 trillion actual body cells Why don’t we eat feces? 30% of dry weight of feces is bacteria. Dogs and gorillas practice coprophagia for different reasons. Why? proof © 2011 Pearson Education, Inc.
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Feces are stored in the rectum until they can be eliminated through the anus
Two sphincters between the rectum and anus control bowel movements, the top being involuntary, the bottom (anus) being voluntary © 2011 Pearson Education, Inc.
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Stomach and Intestinal Adaptations
Many carnivores have large, expandable stomachs Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation © 2011 Pearson Education, Inc.
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Small intestine Small intestine Stomach Cecum Colon (large intestine)
Figure 41.17 Small intestine Small intestine Stomach Cecum Figure The alimentary canals of a carnivore (coyote) and herbivore (koala). Colon (large intestine) Carnivore Herbivore
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Rumen Reticulum Esophagus Intestine Abomasum Omasum 1 2 4 3
Figure 41.18 1 Rumen 2 Reticulum Esophagus Intestine Figure Ruminant digestion. 4 Abomasum 3 Omasum
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Concept 41.5: Feedback circuits regulate digestion, energy storage, and appetite
Each step in the digestive system is activated as needed The enteric division of the nervous system helps to regulate the digestive process The endocrine system also regulates digestion through the release and transport of hormones © 2011 Pearson Education, Inc.
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Hormonal control of digestion.
1 2 3 Food Bile Liver Stomach Secretin and CCK Chyme Gastric juices Gastrin Gastric juices Gallbladder CCK Pancreas HCO3, enzymes Duodenum of small intestine Secretin CCK Key Figure Hormonal control of digestion. Stimulation Inhibition
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Regulation of Energy Storage
The body stores energy-rich molecules that are not needed right away for metabolism In humans, energy is stored first in the liver and muscle cells in the polymer glycogen Excess energy is stored in adipose tissue, the most space-efficient storage tissue © 2011 Pearson Education, Inc.
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Glucose Homeostasis Oxidation of glucose generates ATP to fuel cellular processes The hormones insulin and glucagon regulate the breakdown of glycogen into glucose The liver is the site for glucose homeostasis A carbohydrate-rich meal raises insulin levels, which triggers the synthesis of glycogen Low blood sugar causes glucagon to stimulate the breakdown of glycogen and release glucose Blood sugar regulation bioflix © 2011 Pearson Education, Inc.
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Pancreas secretes insulin. Transport of glucose into body cells
Figure 41.20 Pancreas secretes insulin. Transport of glucose into body cells and storage of glucose as glycogen Stimulus: Blood glucose level rises after eating. Homeostasis: 70–110 mg glucose/ 100 mL blood Stimulus: Blood glucose level drops below set point. Figure Homeostatic regulation of cellular fuel. Breakdown of glycogen and release of glucose into blood Pancreas secretes glucagon.
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Faulty appetite-regulating hormones can lead to obesity
Satiety center Faulty appetite-regulating hormones can lead to obesity Ghrelin Insulin Figure A few of the appetite-regulating hormones. Leptin PYY
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Obese mouse with mutant ob gene (left) next to wild-type mouse
Figure 41.22 EXPERIMENT Obese mouse with mutant ob gene (left) next to wild-type mouse RESULTS Genotype pairing (red type indicates mutant genes) Average change in body mass (g) of subject Subject Paired with Figure Inquiry: What are the roles of the ob and db genes in appetite regulation? obob , dbdb obob , dbdb 8.3 ob ob, dbdb ob ob, dbdb 38.7 ob ob, dbdb obob, dbdb 8.2 ob ob, dbdb obob, db db 14.9* *Due to pronounced weight loss and weakening, subjects in this pairing were reweighed after less than eight weeks.
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What is the point, evolutionarily, of binge eating?
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Carnivore Herbivore Omnivore Key Incisors Canines Premolars Molars
Dentition and diet. Carnivore Herbivore Omnivore Figure Dentition and diet. Key Incisors Canines Premolars Molars
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See 10-1, and also 10-2
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FRQ du jour Homeostatic maintenance of optimal blood glucose levels has been intensively studied in vertebrate organisms. Pancreatic hormones regulate blood glucose levels. Identify TWO pancreatic hormones and describe the effect of each hormone on blood glucose levels. For ONE of the hormones you identified in (a), identify ONE target cell and discuss the mechanism by which the hormone can alter activity in that target cell. Include in your discussion a description of reception, cellular transduction, and response. Compare the cell-signaling mechanisms of steroid hormones and protein hormones.
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