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The Digestive Process Supplying Energy for all Life Processes What is Digestion? • Process by which large molecules are broken down to provide energy and raw materials for the organism Energy • Energy content in foods can be measured by burning them. (Release all of the energy at one time.) • Unit of energy - Calorie • Calorie - amount of energy to raise one ml of water one degree Celsius. • Calorie on packages - 1000 calories (1 kcal) • Avg. Teenager -> 1800-2800 kcal/day Nutrients • Raw materials the body needs • Water, Carbohydrates, Fats, Proteins, Vitamins, and Minerals Water • Most important of all nutrients • Needed by every cell, makes up the bulk of blood, lymph, and other body fluids, dissolves food, cools the body (sweat) • Need about 4-8 cups a day Carbohydrates • Major Source of Energy (used 1st) • Simple Sugars – Glucose, Sucrose, Fructose – Fruits, Honey, Sugar Cane, Sugar Beets • Complex – Starch / Cellulose Fats • Need a little fat in diet • Cell membranes and hormones • 60 grams (2 Tbs.)/day • Avg. American – 40% Calories come from fat. – High BP, heart disease, obesity, diabetes Proteins • Contain Amino Acids • Build new cells and tissues • 22 common Amino Acids – Body makes 14 – the rest (8) from diet Vitamins / Minerals • Vitamins needed in important chemical reactions – making hormones, metabolism, etc. • Minerals – Calcium - bones – Iron - hemoglobin – Iodine - Thyroxin (growth) Digestive Processes • We will examine the Digestive Processes of the following Organisms – – – – – Protozoa Hydra Earthworm Grasshopper Humans Protozoa • Single celled organisms • Live in water (FW/SW) • Obtain food via DIFFUSION • Some cases of Active Transport Hydra • 2 cells thick • stinging cells on tentacles • cousins of jellyfish • One digestive opening – Mouth/Anus Earthworm • Multi-cells thick • Specialized organs to help break down materials • Mouth / Anus – Sequential Digestion – Continuously remove food and nutrients Grasshopper • Multi-celled • Keeps many of the advancements of the Earthworm • Sequential Digestion Humans Mouth • Starts digestion • Teeth - cut, tear, crush food • Saliva - moistens food to make easier to chew • Enzyme - Amylase – breaks down sugars • Enzyme - lysozyme – breaks walls bacteria Esophagus • Food tube to the stomach • pushes food to stomach by muscle contractions – food moves to stomach whether you are sitting, lying down, upside down, or in space Stomach • Stores food so body can break it down at a slower pace • Gastric Glands – protect stomach lining – hydrochloric acid – Pepsin (enzyme) • breaks down proteins • needs acid environment Stomach Small Intestine • 23 feet long - small diameter • food / nutrients are absorbed • tiny projections called villi – increases surface area of the intestine to maximize absorption Accessory Organs • Pancreas – enzymes to break down carbohydrates, proteins, fats, and nucleic acids. – secretes sodium bicarbonate (baking soda) to neutralize stomach acids • Liver – secretes Bile - like a detergent • dissolves/disperses fat droplets for digestion Large Intestine • Primary Job Remove water from food • Undigested or unabsorbed material is released out the anus. Digestion Summary • Protozoa - Diffusion (1 cell) • Active Transport (bring things in and make food vacuoles) • Hydra - Diffusion (mouth, primitive gut) • Planaria - Multi-celled • Mouth/Anus, Intestine Digestion Summary (cont.) • Earthworm - multi-celled, non-flat • mouth, crop, gizzard, intestine, anus • Grasshopper - multi-celled, non-flat • mouth, crop, gizzard, intestine, accesary organs (Malpigian tubules), anus Digestion Summary (cont.) • Human – mouth, esophagus, stomach, accessory organs (liver, pancreas), small intestine, large intestine, anus