open day chapter 3 digestion, absorption and metabolism
TRANSCRIPT
OPEN DAY
www.lrjj.cn
Chapter 3 Digestion, Absorption and
Metabolism
OPEN DAY
www.lrjj.cn Copyright 2011, John Wiley & Sons, Inc.
Learning Objectives
• Atoms to organisms
• Digestive system
• Digestion and absorption
• Metabolism of Nutrients
OPEN DAY
www.lrjj.cn
You are what you eat!!!
OPEN DAY
www.lrjj.cn 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
www.lrjj.cn
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
www.lrjj.cn
Our Complex Bodies Are Built from Simpler Units
• Organic molecules?
• Carbohydrates, lipids, proteins, and vitamins
• Inorganic molecules?
• Water and minerals
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Digestion and Absorption
OPEN DAY
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Organ Systems of the Body(p.79)
OPEN DAY
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Organ Systems of the Body(p.79)
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
An Overview of the Digestive System
• Carbohydrate---glucose
• Protein---amino acids
• fat ---fatty acids
OPEN DAY
www.lrjj.cn
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.
OPEN DAY
www.lrjj.cn
OPEN DAY
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Overview of the Digestive System(p.81)
OPEN DAY
www.lrjj.cn
Question that make you think
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn 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
www.lrjj.cn
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
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Digestion and Absorption
• Pharynx and Epiglottis
OPEN DAY
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Digestion and Absorption
• Esophagus
OPEN DAY
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Digestion and
Absorption• The brain is
involved in digestion and absorption.
OPEN DAY
www.lrjj.cn
Question that make you think
OPEN DAY
www.lrjj.cn
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
Questions that make you think….
• What is the capacity of the stomach?• Empty:50ml, male:1400-
2400ml ， female:1200-2000ml • 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
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
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? 12-24hours
OPEN DAY
www.lrjj.cn
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn 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
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn Copyright 2010, John Wiley & Sons, Inc.
Elimination of
Metabolic Wastes:
Body Organ System
OPEN DAY
www.lrjj.cn
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
www.lrjj.cn
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
www.lrjj.cn
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