DIGESTIVE SYSTEM & ENZYME NOTES

Transcription

1 DIGESTIVE SYSTEM & ENZYME NOTES

2 DIGESTIVE SYSTEM Includes mouth, pharynx, esophagus, stomach, small intestine and large intestine; several major glands and their secretions, including the salivary glands, the pancreas and the liver Digestion is the breakdown of food into simpler molecules that can be absorbed and used by the cells of the body

3 DIGESTIVE SYSTEM THE PROCESS OF DIGESTION: 1. Mouth - teeth break up food in a process called mechanical digestion; also salivary glands secrete the first digestive enzymes (amylase and mucous) 2. Pharynx - the top part of the throat; no digestion takes place here 3. Esophagus - the muscles of the esophagus begin to contract in waves, pushing food toward the stomach; this is called peristalsis

4 DIGESTIVE SYSTEM 4. Stomach - three secretions combine to form the gastric fluid: Mucous - keeps food lubricated and protects walls of the stomach Hydrochloric acid - helps break down food Pepsin - mixes with hydrochloric acid to begin digesting proteins The food is churned for several hours becoming a pasty mixture known as chime

5 DIGESTIVE SYSTEM 5. Small Intestine - the chime is flooded with enzymes from three sources: Duodenum (1 st part of small intestine) - releases enzymes that continue digesting Pancreas - releases pancreatic fluid that digests carbohydrates, proteins and fats Liver - secretes bile, which is stored in the gallbladder, which breaks down fats further

6 DIGESTIVE SYSTEM 5. Small Intestine - the now mostly digested food passes through the rest of the small intestine where nutrients are absorbed into the bloodstream; when it leaves the s.i., the food is nutrient free 6. Large Intestine (Colon) - main job is to remove water from undigested materials passing through it 7. Rectum store feces (solid waste)

7 Salivary Glands Pharynx Esophagus Liver Mouth Tongue Liver Stomach Stomach Pancreas Large Intestine Small Intestine Gallbladder Pancreas Anus Appendix Rectum

8 Enzymes Used in Digestion Enzyme Site of Action Site of Production Nutrient Digested Amylase Mouth Salivary Glands Carbohydrate Pepsin Stomach Lining of Stomach Protein Lipase Small Intestine Pancreas Fat Amylase Small Intestine Pancreas Carbohydrate Trypsin Small Intestine Pancreas Protein Lactase Small Intestine Lining of Small Intestine Carbohydrate Maltase Small Intestine Lining of Small Intestine Carbohydrate Sucrase Small Intestine Lining of Small Intestine Carbohydrate Peptidase Small Intestine Lining of Small Intestine Protein

9 Law of Conservation of Matter Matter can be neither created nor destroyed Atoms that you consume in food must be accounted for within your biological system 1. they are used in molecules that make up your body 2. they are excreted

10 Law of Conservation of Matter Atoms in = Atoms body + Atoms out ATOMS ARE NEVER DESTROYED IN YOUR BODY! When we use food, we don t destroy the atoms in the food, they are simply rearranged into new molecules (lipids, amino acids, water, carbon dioxide, etc.) Energy is released in this process (by breaking the bonds between the elements) which is the energy your body uses or releases as heat no atoms are converted into energy

11 What about losing weight? Where do the atoms go that you lose when losing weight? They are NOT destroyed! The fat is burned through metabolism (the fat reacts with oxygen and produces water & carbon dioxide). If you count all the atoms that you lose from your body, it s the same number of atoms you excreted through your excretory & respiratory systems

12 Law of Conservation of Mass The mass doesn t disappear it is simply transferred from one place (you) to another (the environment) in a different form Example: Burning candle

13 Chemical Reactions Chemical Reaction process that changes one set of chemicals into another set of chemicals Reactants elements or compounds that enter into a chemical reaction Products elements or compounds produced by a chemical reaction Example: 2H 2 + O 2 2 H 2 O Reactants Product

14 Chemical Reactions Chemical reactions always involve: The breaking of bonds in reactants Formation of new bonds in products Energy is released or absorbed whenever chemical bonds form or are broken

15 Enzymes Catalyst substance that speeds up the rate of a chemical reaction Enzymes proteins that act as biological catalysts (speed up chemical reactions that take place in cells); do NOT change during the reaction Enzymes help lower the activation energy of a chemical reaction (the energy needed to get a reaction started)

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17 Enzymes The reactants of enzymecatalyzed reactions are known as substrates Substrates bind to a site on the enzyme called the active site

18 Substrate Products Active Site Enzyme

19 Enzymes The fit between the active site and substrates is so precise that it is often compared to a lock and key Often named by affected substrate; ending in ase Lactase Example: lactose glucose + galactose Lactase (enzyme) speeds up this reaction of lactose (substrate)

20 Enzymes The rate of enzyme activity depends not only on its shape, but it also depends on other factors. temperature ph concentration

21 Temperature The temperature where the enzyme functions most effectively is called the optimal temperature. If the temperature is raised above OR BELOW the optimal temperature, the rate of enzyme action will decrease.

22 Temperature 1. What is the optimal temperature for enzyme A? What is the optimal temperature for enzyme B? Knowing that body temperature is approximately 22 degrees Celsius, which enzyme would work best in your body? A

23 ph The ph scale is a measure of hydrogen ions in a solution. The ph will also affect the rate of enzyme activity.

24 Bases NaOH KOH Acids HCl H 2 SO 4

25 ph Gastric Protease Intestinal Protease 1.What is the optimal ph for the enzyme 3 found in your stomach? 2.What is the optimal ph for the enzyme found in your intestine?

26 Concentration The rate of enzyme action also depends on the concentration of enzyme present. The larger the concentration of enzyme, the faster the rate of reaction; however, there is still an optimal concentration of enzyme.

27 Concentration

28 Enzyme Explanation/Animation ker/animations/enzyme%20activity.html