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The Digestive System Today you will be able to: Explain what a nutrient is Explain the difference between energy and non-energy nutrients Define a calorie List the energy nutrients and how many calories each provides List non energy nutrients and foods that supply them as well as some of their functions.

The Digestive System

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The Digestive System. Today you will be able to: Explain what a nutrient is Explain the difference between energy and non-energy nutrients Define a calorie List the energy nutrients and how many calories each provides - PowerPoint PPT Presentation

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Nutrients

The Digestive SystemToday you will be able to:Explain what a nutrient isExplain the difference between energy and non-energy nutrientsDefine a calorieList the energy nutrients and how many calories each providesList non energy nutrients and foods that supply them as well as some of their functions.

Nutrients What is in the food you eat?NutrientsSubstances your body needs to function properly and maintain homeostasis.Energy nutrientsEnergy nutrients provide fuel for the body. This is measured in calories. Carbohydrates 55-60% of diet should come from carbohydrates4 calories per gramPrimary food sources are grains, fruits, vegetables.

Proteins10-15% of calories should come from Protein4 calories per gramBest sources are meats and dairy, but plants (beans, nuts, etc.) have some of the amino acids that make up proteinsFatsShould comprise 25-30% of your diet9 calories per gramGood sources; red meats, butter, oils, cheese, etc.Needed for skin health, hormone production, and cell membrane integrity. Non-energy nutrients (no calories)Water, vitamins, and minerals- provide no fuel for energy, but are necessary in the chemical reactions needed to release energy and build tissues.Water.Makes up approximately 65% of your body weight.Needed to perform the chemical reactions and regulate body temperature.Most importantVitamins A- meats, milk, carrotsB- (B1, B2, B12, riboflavin, niacin, etc) vegetables, fruit, grainsC- citrus fruitsD-fortified milk, sunlightE- fish K- made by bacteria in your intestinesMinerals- plants absorb from soilIron- red meat, plants (for blood cells) Calcium and phosphorus milk (bone health)Sodium- saltsPotassium bananasChloride- saltsMany more trace minerals (only need a small amount) Read and fill out summary sheet for nutrientsCalorie needsThe average adult needs about 2,000 calories per day to supply the energy needs and provide adequate amounts of vitamins and minerals for proper functioning.The food guide pyramid amounts and categories insure that all necessary nutrients will be consumed.

Pg 512Exceptions Caloric needs vary depending on the size of the person and their activity levels. Larger persons need more caloriesVery active persons need more caloriesRegardless of the calories, you must maintain the proper balance of nutrients.RDA (recommended daily allowance)The United States Food and Drug Administration sets the minimum amount of each nutrient that a person should get each day to maintain their optimal health. This is called the recommended daily allowance. Read and fill out summary sheet for healthy eatingWeight gain or lossWeight is a tricky word. We should be less concerned about weight and more concerned about body composition. What we want to do is keep body Fat levels at the proper percentage. See chart on next slide for Proper body fat levels.

Weight factsMuscle weighs more than fat1 pound of body fat is 3,500 caloriesHealthy weight (fat) loss is 1-2 pounds per week.If you are losing more than 2 pounds per week, you are probably losing water weight, not fat.To lose 1 pound of body fat per week, either increase activity to burn 500 more calories per day or eat 500 less calories per day.

Basal Metabolic rate (BMR) Basal metabolic rate (BMR) is the amount of calories needed each day just to keep you alive (all autonomic functioning). To calculate your BMR find your mass in Kg (weight /2.2) X 24. It takes approximately 1 calorie (measure of energy) per Kg of body mass per hour just for BMR. (this is the minimum # of calories you need each day)Calculating calories used / day

Eating disordersBulimia- a person eats a normal amount, but then throws it back up before it completes digestion.Anorexia Nervosa- a person starves themselves to the point that their body starts to consume their own muscle tissue (from skeletal, cardiac, and smooth) to supply the brain with its energy needs.Show digestive you-tube videoThe digestive process beginsThe process of digestion occurs in stages and at different locations throughout the alimentary canal. You should be able to trace the process from start to finish and explain the role of each part during the process. Mouth (5-30 seconds) Mechanical digestion- chewing breaks the food down into smaller particles that does not change the substance of the food. This makes greater surface area for the enzymes to work on.Chemical digestion- food mixes with saliva, which contains enzymes that chemically changes carbohydrates into sugars.Mechanical digestionMechanical digestion begins in the mouth where the food is chewed into smaller pieces without changing the substance.

Chemical digestionChemical digestion of carbohydrates begins in the mouth when enzymes in saliva start to change the food into base substances (sugars)

Pharynx (throat)When you swallow food, the tongue moves the food to the back of the Pharynx. The epiglottis covers the trachea (windpipe) to keep the food out of the lungs and directs the food into the esophagus. To the Stomach Esophagus (10 seconds) Swallowed food passes the trachea as the epiglotis covers the top of the trachea and directs food into the esophagus. Muscle contractions, called peristalsis, carry the food to the stomach. This takes about 10 seconds.

Stomach (3 hours) The stomach is a J shaped organ lined with mucosal cells. It receives the food, mixes it with stomach acids and mashes the food into a paste called chyme. Then it pushes the food into the small intestine.Mashing and soaking in the stomachFood is further broken down by strong acids (chemical) and enzymes as it is mashed (mechanical) into a paste in the stomach.

Mucosal cellsProduce mucous inside the stomach to protect the stomach lining from damage by the strong stomach acids.

Chemicals / enzymes /acidThe process of chemical digestion requires chemicals that break down the bonds of foods. Different chemicals work on different nutrient types. (some work on all) Examples:Hydrochloric acid in the stomach allBile in liver stored in gall bladder fatsSaliva salivary glands carbohydratesPancreatic enzymes pancreas proteins, fats

Final digestionOnce the food has been dissolved and mashed it is time to absorb the nutrients into the blood to deliver to cells and to eliminate the waste material.Small Intestine (10-12 hours)Upper part- mix food paste (chyme) with pancreatic enzymes to break lipids and proteins into small, absorbable particlesFood moves through the 23 feet of the small intestine while the villi absorb the broken down nutrientsIndigestible & unabsorbable material (such as fiber) is moved into the large intestineSmall intestine

Villi

Large intestine

Large intestine

Once the food enters the large intestine: water is reabsorbedVitamins are produced (K)Waste is formed and expelled.Large Intestine (3-4 hours)Rectum stores the prepared waste materialAnus opening through which waste is eliminated

Accessory organsFood does not enter these organs. They produce or secrete chemicals into the system to help in the chemical digestion process.Liver Food does not enter the liver, gall bladder, or the pancreas, but they each play an important roll in the process of digestion.Produces bile for the breakdown of fatAlso acts to filter toxins and neutralize them

Gall bladderStores bile until it is secreted into the intestine

Pancreas Produces enzymes that complete the breakdown of fats and proteins into individual lipid and amino acid molecules.Also functions as an endocrine gland producing insulin and other hormones. (double gland)

Appendix Composed primarily of lymphatic tissue that helps development of the immune response.