CHAPTER 4: FOOD AND DIGESTION Miss Sabia

FOOD AND ENERGY Section 1

1.Why do we need food? 2.What are the six nutrients? s

Do Now What is your favorite part of Thanksgiving dinner?

We all need food! Nutrients: substances in food that provide the raw materials and energy the body needs to carry out all the essential processes 6 kinds: –Carbohydrates –Fats –Proteins –Vitamins –Minerals –Water

Carbohydrates Body’s main source of energy! Examples: sugar, potatoes, noodles, rice, bread

Proteins Made of amino acids Make up cell membrane, make up many organelles, make up hair, etc. Examples—meat, eggs, fish, nuts, and beans

2013: “The International Year of the Quinoa” (according to the Food and Agricultural Organization of the United Nations) A complete protein source—contains all the essential amino acids!

Lipids Used for storing energy in the body Cholesterol is a lipid found in food that comes from animals…too much cholesterol can clog your blood vessels Saturated or unsaturated

Water Without water, most chemical reactions that take place in cells would not happen! Water also helps cells keep their size and shape

Vitamins Act as helper molecules in a variety of chemical reactions within the body Fat soluble or Water soluble A, D, E, KB, C

Nutrients that are not made by living things— they are present in soil and absorbed by plants through their roots Calciumchlorinesodium FluorinePotassium IronMagnesium

HEALTHY EATING Section 2

What is a calorie? Energy in food is measured in calories A calorie is the amount of energy needed to raise 1 gram of water 1 °C # of calories in each food varies # of calories each person needs varies

TIME TO PLAY

Keeping a Balance To maintain a balanced state (homeostasis), all organisms have a minimum daily intake of each type of nutrient based on species, size, age, sex, activity, etc. An imbalance in any nutrients might result in weight gain, weight loss, or a diseases state

% Daily Value indicates how the nutrition content of one serving fits into the diet of a person who consumes 2,000 calories a day

Americans Guess What 100 Calories Looks Like Is Holiday Coffee Worth the Calories?

Metabolism Metabolism is the sum of all the life processes that occur within a living organism

THE DIGESTIVE SYSTEM Sections 3 & 4

Do Now Draw what you think the path of the digestive system in your body looks like

1. What are the major organs of the digestive system? 2. What does a basic diagram of the digestive system look like?

The Digestive System The bodily system that enables us to eat and digest our food The main players: – Mouth (including teeth and tongue) ENTER – Esophagus – Stomach – Small Intestine – Large Intestine – Rectum & AnusEXIT

Other Organs & Structures Involved Pharynx Liver Pancreas Gallbladder

Functions of the Digestive System Digestion: breaking down food into smaller molecules Absorption: nutrient molecules pass through the wall of your digestive system into your blood – Materials that are not absorbed are eliminated as waste

The Mouth Mechanical digestion—chewing breaks food into smaller pieces Chemical digestion—breaking down complex molecules into simpler ones – Saliva starts the breakdown of carbohydrates Unsalted cracker challenge

The Esophagus Epiglottis: flap of tissue that seals off your windpipe and prevents food from entering Esophagus: muscular tube that connects mouth and stomach Mucus: thick, slippery substance that makes food easier to be swallowed and moved along Peristalsis: involuntary muscle contractions that move food

The Stomach Stomach: J-shaped muscular pouch located in abdomen – Expands to hold food as you eat The average adult’s stomach can hold 2 Liters of food

The Stomach (continued) Most mechanical digestion occurs here – Muscles of stomach contract to produce a churning motion that mixes food and fluids Chemical digestion occurs too! – Churning mixes food with digestive juice – Digestive juice contains pepsin (enzyme that breaks down proteins) – Digestive juice contains hydrochloric acid (kills bacteria you swallow, allows pepsin to work)

Do Now FIRST, place your hand palm-side down on a table, keeping your thumb and fingers tightly together. Lay a string along the outline of your hand, and then measure the string. SECOND, place your hand palm-side down, but this time spread your fingers. Lay a string along the outline of your hand and then measure the string.

The Small Intestine Almost all chemical digestion and absorption of nutrients occurs here 6 meters long, makes up 2/3 of the digestive system – Called “small” because of its diameter, only 2-3 cm wide

The Small Intestine (cont’d) Enzymes in small intestines are produced by other organs – Liver  bile (breaks down fats) – Gallbladder  stores bile – Pancreas  enzymes (break down starches, proteins, and fats)

The Small Intestine (cont’d) Villi cover the surface of the inner lining to increase the surface area, to allow for max absorption – Nutrient molecules pass from the villi into blood vessels – If all the villi were laid out, the total surface area of the small intestine would be about as large as a tennis court

The Large Intestine 1.5 meters long – Large diameter, about 4-6 cm wide The last section of the digestive system – As material moves through, water is absorbed into the bloodstream – Everything else is readied for elimination

Large Intestine (cont’d) Ends in the rectum, a short tube that compresses waste into a solid form Waste is eliminated through the anus, a muscular opening at the end of the rectum