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 calories (1 kcal) Avg. Teenager -> 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