Chapter 41 Need to feed 3 Categories for animals 1 Herbivores 2 Carnivores 3 Omnivores Opportunistic feeders eat outside dies if dies isn t available Concept 41 1 An Animal s dies must supply chemical energy organic molecules and essential nutrients Essential nutrients 4 classes 1 Essential Amino Acids a 20 amino acid come from diet b E A A must be obtained in preassembled form c Meat Eggs and Cheese provide all the essential amino acids and this complete proteins d Most plant proteins are incomplete in amino acid composition i Individuals who only eat plant proteins need to eat specific combinations to get all E A A 1 Corn and Grains Beans and Legumes 2 Essential Fatty Acids a Animals synthesize most fatty acids b E F A must be obtained from diet and include certain unsaturated fats one or more double bonds on carbon 3 Vitamins a Vitamins organic molecules required in small amounts b Fat Soluble A D E K and Water Soluble B s C Biotin i A Vision ii B Coenzymes iii Niacin NAD iv Pantothenic CoA v D Bone formation vi K clotting 4 Minerals amounts a Minerals simple inorganic nutrients required in small i Calcium for bones and teeth ii Phosphorus for nucleotides phospholipids and bones Iron for hemoglobin iii iv To much is harmful too much iron damages liver too much NaCl causes hypertension Dietary Deficiencies Malnourishment long term absence of one or more nutrients from diet Undernourishment Diet not supplying enough chemical energy Use up stored fat and carbohydrates Concept 41 2 Main stages of food processing are ingestion digestion absorption and elimination 1 Ingestion Act of eating 2 Digestion break down of food Mechanical chewing Chemical Process of enzymatic hydrolysis use water to split 3 Absorption Uptake of nutrients by body cells 4 Elimination is the passage of undigested food out of the digestive bonds Anus compartment Digestive Compartments complex animals have a digestive tube with two openings Mouth and Complete Digestive Tract or Alimentary Canal Digestive tube Extracellular and Intercellular Digestion ECD breakdown of food is outside cell Gastrovascular Cavity In animals with simple body plans functions in both digestion and distribution of nutrients ICD food particles are engulfed though phagocytosis Food vacuoles fuse with lysosomes contain hydrolytic enzymes Concept 41 3 Organs specialized for sequential stages of food processing form the mammalian digestive system Mammalian digestive system contains alimentary canal and Accessory glands Accessory Glands 1 Salivary Glands 2 Pancreas 3 Liver 4 Gallbladder Food is pushed by peristalsis rhythmic contractions of muscles in the wall of the canal SPHINCTERS valve that regulates the movement of material between compartments Oral Cavity Pharynx and Esophagus First stage of digestion is mechanical takes place in oral cavity Salivary Glands deliver saliva to lube up food Teeth chew food into small particles that are exposed to Salivary amylase initiating breakdown of glucose polymers such as starch into maltose and glucose Chemical digestion of polysaccharides Saliva also contains mucus a viscous mixture of water salts cells and glycoproteins Mucin glycoprotein that lubes mouth and reduces abrasion Tongue shapes food into a bolus and provides help with swallowing Throat or pharynx is the junction that opens to both esophagus and trachea wind pipe to the stomach by peristalsis Esophagus Connects to the stomach and moves food from pharynx Epiglottis Block food from entering trachea Coughing is when food or liquid enters trachea Digestion in the Stomach acid chyme Stomach stores food and secretes gastric juice which converts a meal to Gastric Juice has a pH of 2 kills bacteria and denatures proteins Made up of HCl and pepsin Pepsin is a protease protein digesting enzyme cleaving proteins Parietal Cells secrete hydrogen and chloride ions separately into the lumen Chief cells secrete inactive pepsinogen turns to pepsin when mixed with Mucus protects stomach lining Gastric Ulcers Lesions in the lining are caused mainly by bacterium into smaller peptides of the stomach HCl Helicobacter Pylori Stomach Dynamics stomachs contents Coordinated contraction and relaxation of stomach muscle churn the Sphincters prevent Chyme from entering esophagus and regulate entry to small intestine Digestion in Small Intestine Small intestine largest part of alimentary canal Major organ in digestion and absorption Digestion is completed here First portion of small intestine is duodenum where acidic chyme mixes with digestive juices from pancreas liver gallbladder and small intestine Pancreatic Juices are alkaline basic which neutralize chyme Pancreatic Secretions Pancreas produces pancreatic juice containing Pancreatic Amylase completes starch digestion The proteases typsin and chymotrypsin protein digesting enzymes that are activated after the enter the lumen of the duodenum Lipases digests fats to glycerol and fatty acids Nucleases Digests DNA and RNA nucleotides Bile Production by liver In small intestine Bile aids in digestion and absorption of fats Made in liver stored in gallbladder Bile breaks fats into small particles emulsifies fats allows lipases to work Destroys non functional red blood cells Secretions of Small Intestines digestive enzymes Epithelial lining of the duodenum brush border produces several Disaccharidases Breaks down maltose to 2 glucose units Dipeptideases Breaks down dipeptides to 2 free amino acids The jejunum and ileum function for absorption of nutrients and water Absorption in small intestines Occurs mostly across wall of the small intestine and into nearby capillaries Small intestine has huge surface area due to villi and microvilli that are exposed to the intestinal lumen Creates brush border that greatly increase rate of absorption Each villus contains network of blood vessels and a small lymphatic vessel Epithelial cells absorb fatty acids and monoglycerides and recombine them Coated with phospholipids cholesterol and proteins to form water Chylomicrons are transported into a lacteal a lymphatic vessel in lacteal into triglycerides soluble chylomicrons each villus Lymphatic vessels deliver chylomicron containing lymph to large veins that return blood to the heart and enter the capillaries in the villus Amino acids and sugars pass through the epithelium of the small intestine the Heptic Portal Vein carries nutrient rich blood from the capillaries of the villi to the liver then to the heart allows for the liver
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