OPEN DAY Chapter 3 Digestion, Absorption and Metabolism

OPEN DAY Copyright 2011, John Wiley & Sons, Inc. Learning Objectives Atoms to organisms Digestive system Digestion and absorption Metabolism of Nutrients

OPEN DAY You are what you eat!!!

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption Biochemically, “you are what you eat” is true! Food and fluid taken into the body is broken down into smaller components so it provides all of the energy we need to stay alive and active.

OPEN DAY Our Complex Bodies Are Built from Simpler Units We are all made of atoms, which are the smallest units of an element that still retain the properties of that elements Atoms can be linked by chemical bonds to form molecules

OPEN DAY Our Complex Bodies Are Built from Simpler Units Organic molecules? Carbohydrates, lipids, proteins, and vitamins Inorganic molecules? Water and minerals

OPEN DAY Cells form tissues, tissues form organs, organs form organ systems In any living systems, molecules are organized into cells Cells that are similar in structure and function form tissues Tissues are organic in varying combination into organs.

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Organ Systems of the Body(p.79)

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Organ Systems of the Body(p.79)

OPEN DAY Digestive system Primarily responsible for the movement of nutrients into the body Endocrine, nervous,urinary, respiratory, and integumentary systems all help the nutrients digest and absorb in our body.

OPEN DAY An Overview of the Digestive System The digestive system provides two major functions: digestion and absorption –Digestion is the process of breaking food into components small enough to be absorbed into the body –Absorption is the process of taking substances into the interior of the body

OPEN DAY An Overview of the Digestive System Carbohydrate---glucose Protein---amino acids fat ---fatty acids

OPEN DAY Structure of the Gastrointestinal Tract Gastrointestinal tract/GI/gut/digestive tract/intestinal tract/alimentary canal Include the mouth, pharynx, esophagus, stomach, small and large intestine, and anus.

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OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Overview of the Digestive System(p.81)

OPEN DAY Question that make you think

OPEN DAY Food Must Be Digested for Nutrients to be Absorbed Digestive activity begins with the sights, sounds, and smells of food The nervous system signals the digestive system to ready itself for a meal. Mouth---moist Stomach—secrete digestive substances

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption The mouth is the entry point for food into the digestive tract. Saliva contains salivary amylase, which helps to break down carbohydrates and lysozymes, which help to inhibit bacterial growth in the mouth. Chewing mechanically breaks food down, increasing the surface area in contact with digestive enzymes. Breaks apart fiber that traps nutrients in some foods.

OPEN DAY Roles of Saliva It moistens the food so that it an easily be tasted and swallowed. It begins the enzymatic digestion of starch. It cleanses the mouth and protects teeth from decay. It lubricates the upper GI tract.

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption Pharynx and Epiglottis

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption Esophagus

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Digestion and Absorption The brain is involved in digestion and absorption.

OPEN DAY Question that make you think

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OPEN DAY Vegetable and Grain’s Digestion time Zucchini, broccoli, cauliflower, string beans, yellow squash, corn on cob - all 45 min. digestion time Concentrated Carbohydrates - Grains 90 min. digestion time

OPEN DAY Animal proteins ‘s Digestion time Egg yolk - 30 min. digestion time Whole egg - 45 min. Fish - cod, scrod, flounder, sole seafood - 30 min. digestion time Fish - salmon, salmon trout, herring, (more fatty fish) - 45 min. to 60 digestion time

OPEN DAY Animal proteins ‘s Digestion time Chicken – 1.5 to 2 hours digestion time (without skin) Turkey - 2 to 2 1/4 hours digestion time (without skin) Beef, lamb - 3 to 4 hours digestion time Pork – 4.5to 5 hours digestion time

OPEN DAY Questions that make you think…. What is the capacity of the stomach? Empty:50ml, male: ml ， female: ml What is chyme? Bolus mixed with highly acidic stomach secretions to from a semiliquid food mass How long will the chyme normally store in the stomach? 2-6hours

OPEN DAY Stomach Water, alcohol and a few drugs absorbed in stomach. Hydrochloric acid kills most bacteria present in food, stops the function of salivary amylase. 3 layers of muscle. A Thick mucus layer protect the wall of stomach. Pepsin: protein digesting enzyme.

OPEN DAY Small intestinal Pancreas secrets pancreatic juice, which contains bicarbonate ions and digestive enzymes to digest carbohydrate, fats and protein. Bile which produced in liver and stored in gallbladder for fat digestion and absorption.

OPEN DAY How the small intestine’s structure help absorption of nutrients? 20 feet in length Intestinal walls are arranged in large circular folds, increase the surface area in contact with nutrients Inner surface covered with villi Ville covered with tiny microvilli to increase the surface area about size of tennis court.

OPEN DAY Questions that make you think…. What is the length of the small intestinal? 7 meters Where does most digestion and absorption occur? Small intestine How long will the chyme normally stay in the small intestinal? 3-5 How long will water, nutrients, and fecal matter normally stay in large intestinal? hours

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OPEN DAY Metabolic Reactions Synthesize and Break Down Molecules Our bodies use nutrients to produce energy and to manufacture substances needed by the body to grow and maintain itself The sum of these chemical reactions is called metabolism

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Metabolism of Nutrients Metabolic pathways are a series of reactions needed to transform food into a final product that can be used by the body. Catabolic pathways release energy trapped in chemical bonds. Energy from catabolic reactions is converted into ATP. ATP is the energy currency of the cell.

OPEN DAY Metabolic Pathways Use energy from ATP to build body compounds are referred to as anabolic pathways. The anabolic and catabolic pathways of metabolism occur in the body continually and simultaneously(p.106)

OPEN DAY Elimination of Metabolic Wastes Substances that cannot be absorbed by the body, such as fiber, carbon dioxide, nitrogen and water must also be removed from the body. What are the ways to eliminate metabolic waste products?

OPEN DAY Copyright 2010, John Wiley & Sons, Inc. Elimination of Metabolic Wastes: Body Organ System

OPEN DAY Waste Products Must Be Eliminated from the Body The waste products of metabolism are eliminated by the lungs, the skin, and the kidneys At the lungs, red blood cells release the carbon dioxide, which is then exhaled into the environment

OPEN DAY Waste Products Must Be Eliminated from the Body A significant amount of water is also lost from the lungs, by evaporation Some water, minerals, and byproducts breakdown are lost through the skin perspiration or sweat. But the kidney is the primary site for the excretion of water and the nitrogen-containing byproducts of protein breakdown

OPEN DAY After completing this chapter, the student should be able to: Name organs that involved in the gastrointestinal track Where does most digestion and absorption occur? What products of digestion are transported by the lymphatic system List 4 ways that waste products are eliminated from the body