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Chapter 18 The Digestive System.

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Presentation on theme: "Chapter 18 The Digestive System."— Presentation transcript:

1 Chapter 18 The Digestive System

2 Ch 18.1 - Nutrition A. Your body needs nutrients found in foods
1. Nutrients provide energy and materials for cell development 2. You need energy for every activity and to maintain a steady internal temperature

3 B. Classes of Nutrients 1. Proteins a) Used for replacement and repair of body cells and for growth b) Made up of amino acids c) Essential amino acids supplied by food d) Found in eggs, milk, cheese and meat

4 2. Carbohydrates a) Main source of energy for your body b) Made of carbon, hydrogen and oxygen c) Sugars are simple; starch & fiber complex - Sugars found in fruits, honey, milk - Starches found in potatoes and pasta - Fiber found in whole-grains and veggies

5 b) Stores excess energy c) Helps body absorb vitamins
3. Fats a) Also called lipids b) Stores excess energy c) Helps body absorb vitamins d) Classified as saturated & unsaturated - Saturated solid at room temp, clog blood vessels and associated with high cholesterol - Unsaturated liquid at room temp, and not associated with health risks

6 a) Needed for growth, regulating body functions and preventing disease
4. Vitamins a) Needed for growth, regulating body functions and preventing disease b) A well-balanced diet usually gives your body all the vitamins it needs c) Two groups: water soluble & fat soluble - Water: Vitamins B & C - Fat: Vitamins A, D, E & K B – growth, nervous system health, RBC production; eggs, dairy, vegetables C – healthy bones, teeth, immune system, wound recovery; fruits & vegetables A – eyesight, healthy skin; dairy, meat, fruits, vegetables (carrots) D – absorption of calcium for teeth and bones; dairy & fish E – formation of cell membranes; eggs, nuts, oils K – blood clotting; vegetables


8 5. Minerals a) Inorganic nutrients needed in small amounts b) Regulate many chemical reactions in the body c) Calcium and Phosphorus used most


10 6. Water a) Required for survival b) Cells need water to carry out their work c) Dissolves other nutrients d) Human body is about 60% water e) Lost each day when you perspire, exhale, and get rid of wastes

11 C. Food Groups 1. Because no food has every nutrient you need to eat a variety of foods 2. The food pyramid is a tool to help people select foods that supply all the nutrients they need 3. Foods that contain the same nutrients belong to a food group

12 4. Five food groups: a) Bread and Cereal b) Fruit c) Vegetable d) Dairy e) Meat, Poultry, Fish & Beans

13 Ch 18.2 – Digestive System A. Digestion – process of breaking down food into small molecules to be absorbed 1. Mechanical Digestion – when food is physically chewed, mixed and churned 2. Chemical Digestion – when food is broken down by chemical reactions

14 B. Enzymes 1. Type of protein that speeds up rate of chemical reactions in your body 2. Many enzymes are involved in the digestion of carbs, proteins and fats

15 C. Organs of the digestive system 1
C. Organs of the digestive system 1. Accessory organs – aid in digestion but food does not pass through them a) tongue, teeth & salivary glands

16 b) Liver – produces bile for the stomach which breaks up ingested fats c) Gallbladder – small sac that stores bile produced by the liver

17 d) Pancreas – produces insulin which allows the body to process carbohydrates (sugars)

18 2. Digestive Tract – organs that food does pass through during digestion a) Mouth – here accessory organs change food into a soft mass called a bolus

19 b) Esophagus – muscular tube that moves food to the stomach using waves of muscle contractions called peristalsis

20 c) Stomach – muscular bag that digests food mechanically by peristalsis and chemically with digestive solutions of HCl acid; food becomes a thin, watery fluid called chyme

21 d) Small Intestine – nutrients are absorbed from chyme into the blood; projections called villi increase surface area for absorption Ave. adult length – 7m/23ft

22 e) Large Intestine – water absorbed from undigested chyme; peristalsis slows so chyme may remain here as long as 3 days Ave. adult length – 1.5m/5ft (but wider diameter)

23 f) Rectum & Anus – end of large intestine and opening to outside of body; controls release of remaining solid wastes

24 D. Bacteria live in many organs of the digestive tract helping to break down food and make vitamins
ESCHERICHIA COLI is a type of bacteria that lives in the intestinal tract, aiding the digestive process by suppressing the growth of harmful bacteria and synthesizing vitamins.

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