Chapter 10: The Digestive System

1. Unit 1: Animals : Structure and Function Chapter 10: The Digestive System

2. Nutrition

3. Obtaining and Processing Food All organisms, regardless of their size or complexity, must have a way of obtaining essential nutrients Essential nutrients: the basic raw materials they need to make their own structures, perform their life functions, and obtain energy for survival

4. Macromolecules • Organic molecules contain carbon bonded to hydrogen, as well as to other atoms, such as oxygen, sulfur, and nitrogen. • Macromolecules are larger, more complex assemblies of organic molecules, also known as nutrients. • These are the raw materials that our bodies need to provide energy, to regulate cellular activities, and to build and repair tissues.

5. Often grouped into four major categories: • Carbohydrates • Lipids • Proteins • Nucleic acids

6. Macromolecules • Energy released from these macromolecules, and matter supplied by them, is used to maintain the body’s metabolism(all of the chemical processes carried out by cells to maintain life) • Together, the four major categories of macromolecules are known as essential nutrients.

7. Carbohydrates • Are macromolecules that always contain carbon, hydrogen, and oxygen • Almost always in the same proportion: • C1 : H2 : 01. • Provide short-term or long-term energy storage for organisms. • There are two main types of carbohydrates: simple sugars and polysaccharides.

8. Monosaccharides (Simple Sugars) • Carbohydrate molecules with three to seven carbon atoms. • Examples: glucose (the sugar found in blood) and fructose (the sugar found in fruit). Disaccharides • Made up of two simple sugars (di- = two). • Examples: sucrose (table sugar), lactose(the sugar found in dairy products) and maltose (the sugar found in germinating grain) Polysaccharides • Complex carbohydrates that consist of many linked simple sugars (poly- = many). • Examples: Starch stores energy in plants, and glycogen stores energy in animals.

9. Carbohydrates

10. Lipids • Are insoluble in water. • The basic structure of lipids is a molecule of glycerol • 3 carbon atoms, each attached to a fatty acid chain • Store 2.25 times more energy per gram than other biological molecules; function as energy-storage molecules.

12. Lipids Phospholipids, form cell membranes. Other Examples of lipids are fats, such as butter and lard, and oils, such as olive oil and safflower oil.

13. Proteins Assembled from small sub-units known as amino acids Polypeptides are chains for hundreds of amino acids joined together by peptide bonds Most enzymes are proteins, and so are antibodies, which combat disease. Proteins help build and repair muscles and cell membranes

14. Nucleic Acids Nucleic acids direct growth and development of all organisms using a chemical code. The two types of nucleic acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)

15. Hydrolysis • From Greek: “Hydro” – water; “lysis” –loosen • A water molecule (H2O) is added to the macromolecule. • This breaks the chemical bonds that hold together the smaller molecules from which the macromolecule is made. • Digestive enzymes help to speed up the process of hydrolysis.

16. Minerals and Vitamins • Inorganic and organic substances that enable chemical reactions to occur and aid in tissue development, growth, and immunity. • Needed by a healthy, functional human body.

17. Minerals

18. Vitamins

19. Water • Needed for the proper functioning of all cells and organs. Makes up 2/3 of body mass. • Functions include: • Transporting dissolved nutrients into the cells that line the small intestine • Flushing toxins from cells • Lubricating tissues and joints • Forming essential body fluids, such as blood and mucus • Regulating body temperature (by sweating) • Eliminating waste materials (in urine and sweat)

20. Pg 406, Q 1-6: • 1) What is the the primary function of carbohydrates in the human body? • 2) What is the difference between a monosaccharide and a disaccharide? Given an example of each. • 3) Explain how macromolecules are broken down in the body Learning Check

21. Pg 406, Q 1-6: • 4) If an athlete runs for 15 minutes, which macromolecules are likely to break down first? • 5) Which macromolecules would provide the greatest benefit as a long-term energy storage molecule to a bird that migrates long distances? • 6) Name the three functions of proteins in the human body. Learning Check

22. Types of Digestion • Intracellular digestion: • Digestion inside the cell • Phagocytosis - cell engulfs the food • Ex: single-celled organisms (paramecium, amoeba)‏ • Extracellular digestion: • Digestion outside the cells • Food enters a tube and exits from the other end • Ex: most animals, human digestive tract

23. Mechanical Digestion • The physical breakdown of large food particles into smaller ones. • Achieved through chewing, mashing, chopping, breaking food into smaller pieces. • This increases the surface area of the food, allowing more enzymes to come into contact with the food.

24. Chemical Digestion • The chemical breakdown of large molecules into smaller ones: • Carbohydrates: polysaccharides (starch) are broken into monosaccharides (simple sugars)‏ • Proteins: are broken down into amino acids • Lipids: (mainly triglycerides) are broken down into fatty acids and glycerol Note: Food particles are broken down by enzymes. Each enzyme has a pH at which it performs best.

25. Types of Feeders • Autotrophs: • Can feed themselves from inorganic molecules • Ex: plants use sun + H2O + CO2 to form organic compounds • Self-sufficient • Heterotrophs: • Depend on organic compounds made by other living things • Ex: animals, fungi, bacteria, etc. • Not self-sufficient

26. Filter Feeders • Aquatic animals that use a body structure similar to a filter basket to gather small organisms suspended in the water. • Siphons water into its mouth and then filters it to obtain small organisms to digest. • Examples include flamingoes, tube worms, clams, barnacles, and baleen whales.

27. Fluid Feeders • Obtain food by sucking or licking nutrient-rich fluids from live plants or animals. • Mouth parts are adapted to pierce or rip skin or leaf tissue and are used to suck or lick the blood or sap that is their food. • Examples: mosquitoes, ticks, aphids, spiders, bees, butterflies, vampire bats, and hummingbirds.

28. Substrate Feeders • Live in or on their food source and eat their way through it. • Examples: caterpillars and earthworms. • Caterpillars eat their way through the green tissues of leaves.

29. Bulk Feeders • Include many animals and most vertebrates (including humans). • Bulk feeders ingest fairly large pieces of food and some, like the great blue heron, swallow their food whole. • Use tentacles, pincers, claws, fangs, or jaws and teeth to kill prey, to tear off pieces of meat or vegetation, or to take in mouthfuls of animal or plant food.

30. The Digestive System

31. Introduction • There are four stages to food processing: • Ingestion: taking in food • Digestion: breaking down food into nutrients • Absorption: taking in nutrients by cells • Egestion: removing any leftover wastes

32. Digestion and the Alimentary Canal

33. Length of the Digestive Tract • Cellulose walls in plant tissue are more difficult to digest than animal tissues • As a result, whose digestive tracts would be longer? • Herbivores/omnivores OR carnivores?

34. Section 10.1 Review • Pg 410 # 1-3, 6-9, 11

35. 10.2 Introduction • The digestive system is used for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.

37. Human Digestive System • Begins when food enters the mouth (oral cavity). • It is physically broken down by the teeth (mechanical). • It is chemically broken down by enzymes released from the salivary glands.

38. Human Digestive System • The tongue moves the food around until it forms a ball called a bolus. • The bolus is passed to the pharynx (throat) and the epiglottis makes sure the bolus passes into the esophagus and not down the trachea!

39. Human Digestive System What structure prevents food from entering the nasal passageway? How?

40. Human Digestive System • The bolus passes down the esophagus by peristalsis. • Peristalsis is a wave of muscular contractions that push the bolus down towards the stomach.

41. Human Digestive System • To enter the stomach, the bolus must pass through the lower esophageal sphincter, a tight muscle that keeps stomach acid out of the esophagus.

42. Human Digestive System • The stomach has folds called rugae and is a big muscular pouch which churns the bolus (physical digestion). • The bolus is mixed with gastric juice, a mixture of stomach acid and enzymes (chemical digestion).

43. Human Digestive System • The stomach does do some absorption too. • Some medicines (i.e. aspirin), water and alcohol are all absorbed through the stomach. • The digested bolus is now called chyme and it leaves the stomach by passing through the pyloric sphincter.

45. Pg 414, Q 7, 9, 11,12 • 7) Describe where the digestion of carbohydrates begins in the body, the major glands involved, and the digestive secretions produced. • 9) Would the epiglottis be closed or open in each situation? Explain: • A) while talking B) swallowing • C) coughing D) chewing Learning Check

46. 11) A doctor orders a pH test of the esophagus for patient who is complaining about having heartburn and a burning sensation in the chest. Identify the source of the problem and explain why. • 12) How do over-the-counter antacids (eg. Calcium carbonate) help an individual with stomach pain/gastroesophageal discomfort? Learning Check

48. Stages of Digestion http://video.about.com/ibdcrohns/Digestion.htm

49. Human Digestive System • Chymeis now in the small intestine. • The majority of absorption occurs here. • The liver and pancreas help the small intestine to maximize absorption. • The small intestine is broken down into three parts: