Nutrition. Why do humans need food? How do some animals get their food? ROUGHAGE NUTRIENTS. Animals make energy available using:

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1 Nutrition the activities by which organisms Why do humans need food? Animals make energy available using: obtain and process material needed for energy, growth, repair, and to maintain homeostasis humans are they have to get their food from somewhere, they cannot make it on their own. humans need food; which can be described as either or How do some animals get their food? filter feeding living in your food food (glucose) oxygen food Animals build bodies using: amino acids, sugars, fats, nucleotides ATP food for raw materials O2 ATP energy for synthesis mitochondria NUTRIENTS ROUGHAGE * * * complex carbos that cannot be broken down but is necessary for the digestive system to work; found in *carbos, lipids, and proteins MUST be first; vitamins minerals and water can be absorbed without digestion fluid feeding bulk feeding vitamins, minerals, and water are not used for energy or building structures, but are needed!

2 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 humans evolved as hunters, scavengers & gatherers The human digestive system is responsible for: 1. Ingestion: 2. Digestion: mechanically (physically) and chemically (enzymatic hydrolysis) 3. Absorption: 4. Elimination: the human digestive system (also called alimentary canal) is a one-way gastrointestinal tract with two openings Other gastrointestinal tracts Human digestive system Everybody s got one! food is moved in the correct direction by slow muscle contractions called

3 Ingestion 1) oral cavity (mouth) of food occurs here contains teeth, tongue and openings of the salivary glands A. teeth used to break down food physically ( ) to increase surface area for digestive enzymes ( ) Ingestion B. tongue moves food around mouth so that the teeth work more effectively helps mix food with saliva, and moves food to the back of the mouth for swallowing C. salivary glands secretes into digestive system which contains the hydrolytic enzyme which digests starch Swallowing (& not choking) Swallowing (& not choking) 2) esophagus when you swallow, food goes into this tube then to the stomach mucus is secreted here to lubricate the food to slide down easier A. epiglottis when you swallow, this (trachea) so that food will not go into the lungs this momentarily stops breathing!

4 3) stomach a thick-walled, muscular sac (organ) whose main job is to liquify the food ingested the lining of the stomach contains gastric glands which secrete gastric juices which contain: a) gastric protease b) hydrochloric acid c) mucus d) water 3) stomach gastric protease an enzyme which begins the digestion of the hydrochloric acid (HCl) lowers the ph of the stomach not to break down food, but to provide the! reaction rate stomach pepsin (protease) 7 ph 3) stomach the protects the stomach walls from being eaten away the water is used for chemical digestion ( ) Digestion/Absorption 4) small intestine partially digested food then enters the small intestine is a long tube (over 20 feet!) where intestinal glands line the intestinal walls and secrete lipase, maltase, and intestinal protease to food is digested along with the help of accessory organs

5 Accessory Digestive Organs A. liver produces ; however it does break down fats big globs to little globblets called Accessory Digestive Organs B. gall bladder C. pancreas secretes enzymes into the small intestine such as intestinal amylase, intestinal protease, and lipase bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes feces brown the pancreas also produces insulin and glucagon to regulate blood sugar levels Absorption/Egestion 5) large intestine takes the undigested food and solidifies the liquid wastes into solid feces (includes undigested and indigestible material roughage, bacteria, bile, mucus, worn out cells) You ve got company! Living in the large intestine is a community of helpful bacteria Escherichia coli (E. coli) produce vitamins vitamin K; B vitamins generate gases by-product of bacterial metabolism methane, hydrogen sulfide

6 A. appendix Vestigial organ has no known function in modern humans, however, if inflammed, can be life threatening! Different diets; different bodies Adaptations of herbivore vs. carnivore teeth length of digestive system B. rectum where solid wastes are temporarily stored C. anus opening in the alimentary canal where feces are removed (egested) Teeth Carnivore sharp ripping teeth canines Herbivore wide grinding teeth molars Omnivore both kinds of teeth

7 Length of digestive system Carnivores short digestive systems protein easier to digest than cellulose Herbivores & omnivores long digestive systems harder to digest cellulose (cell walls) bacteria in intestines help REVIEW OF CHEMICAL DIGESTION H 2 O + REVIEW OF CHEMICAL DIGESTION in organisms, this process is regulated by hydrolytic enzymes a protease a protease Digesting important polymers Carbohydrates = digested to glucose glucose glucose glucose glucose Proteins = digested to amino amino amino amino acid acid acid acid amino acid amino acid remember, the first part of the enzyme s name tells you what the enzyme works on ( )! Lipids = digested to

8 ABSORPTION OF DIGESTED MATERIALS the intestinal wall is lined with millions of which ABSORPTION OF DIGESTED MATERIALS in each individual villi (shown below with their microvilli) there are capillaries (small blood vessels) and other small ducts (pipes) of the lymphatic system called lacteals ABSORPTION OF DIGESTED MATERIALS I. CARBOHYDRATES: glucose (a ) is absorbed into the bloodstream by the capillaries it there can be sent to the liver to be stored temporarily as when the body needs energy (more glucose) the glycogen can be broken back down and released into the bloodstream ABSORPTION OF DIGESTED MATERIALS II. PROTEINS: amino acids can be stored in the liver until they are needed there are 20 different amino acids that humans need to make up proteins

9 Vegetarian Diets! Need to make sure you get enough protein 20 amino acids to make protein 12 amino acids humans can produce 8 we have to eat = 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 ABSORPTION OF DIGESTED MATERIALS III. LIPIDS: the building blocks of lipids fatty acids and glycerol are absorbed into the and are passed along to the lymph (other transport fluid besides the blood) they through this other set of pipes Saturated fats ( butter, grease) lots of hydrogen atoms too much in the diet can be linked to Unsaturated fats (oils) less hydrogen atoms than saturated fats does not appear to be linked to cardiovascular disease

10 Saturated vs. unsaturated saturated unsaturated MALFUNCTIONS OF THE HUMAN DIGESTIVE SYSTEM 1) Ulcers: used to think ulcers were caused by stress now know ulcers caused by bacterial infection of stomach H. pylori now cure with antibiotics 2) Appendicitis: ( = inflammation) can be life threatening if it ruptures 3) Gallstones: affects secretion of bile into small intestine 4) Constipation: a condition in which the large intestine is emptied with great difficulty due to: 5) Diarrhea: a gastrointestinal disturbance which results in: can result in severe dehydration!