1. Pg. 264 - 279

2.  20-D1.1k identify the principal structures of the digestive and respiratory systems; ◦ mouth, esophagus, stomach, sphincters, small and large intestines, liver, pancreas, gall bladder  20-D1.4k describe the chemical and physical processing of matter through the digestive system into the circulatory system

3. ◦ To breakdown large molecules (polysaccharides, triglycerides, and polypeptides) into smaller components so that the cells in the body can use them to function.  There are many types of digestive systems. (diffusion (cells), gastric sac (snails), alimentary canal (humans))  Humans have an alimentary canal with accessory organs. ◦ The human digestive system consists of the mouth, pharynx, esophagus, stomach, pancreas, liver, gallbladder, small intestine, large intestine, and anus.

4.  Ingestion – taking in nutrients  Digestion – breaking down of large molecules into smaller ones using enzymes  Absorption – absorbing and transporting nutrients to all the cells in the body  Egestion/Elimination – removal of waste from the body

5.  Mechanical (Physical) Digestion – Any physical means by which the surface area of foods are increased ◦ Mouth (teeth and tongue) – chewing ◦ Stomach – churning  Once food is mechanically digested, it can be chemically digested.  Physical digestion increases the surface area available for chemical digestion to occur.

6.  Chemical Digestion – Involves using enzymes in breaking chemical bonds in carbohydrates, lipids, and protein. ◦ Mouth – salivary enzymes (hydrolysis) ◦ Small intestine – enzymes (hydrolysis)

7. http://www.dnatu be.com/video/83 62/Animation-of- the-digestive- system

8. The Digestive Tract (Organs That Contain Food) Accessory Organs (Structures That Aid Digestion) Mouth – chews and mixes food with saliva Salivary glands – secretes starch- digesting enzymes Esophagus – directs food from the mouth to the stomach Liver – manufacturers bile, a detergent- like substance that facilitates digestion of lipids and fats Stomach – adds acid, enzymes, and fluid; churns, mixes, and grinds food to a liquid mass Gallbladder – stores bile until needed Small intestine – secretes enzymes that digest macromolecules; absorbs hydrolyzed molecules into the bloodstream Pancreas – manufacturers enzymes to digest macromolecules; secretes bicarbonate to neutralize stomach acid that enters small intestine Large intestine – absorbs water and salts; passes remaining undigested material and some water out of the body Rectum – stores waste prior to elimination Anus – holds rectum closed; opens to allow elimination

9.  In the mouth, we begin with both mechanical and chemical breakdown of food  Salivary Glands ◦ Saliva  Idea, smell or taste of food stimulates salivary glands to produce saliva  Contains enzymes, such as salivary amylase (chemical breakdown of starch (amylose) into disaccharides)  Lubricates the food for swallowing  Aids teeth in tearing and grind food  Teeth ◦ Physically tears food apart  Tongue ◦ Makes the broken down food into a ball called a bolus

10.  Slowly chew a polysaccharide containing food, such as a cracker or piece of bread, until you notice the starchy food tastes sweet. This sweet taste results from the hydrolysis reaction of starch.

11.  The bolus travels from the mouth to the stomach by the esophagus  The bolus stretches the walls of the esophagus ◦ This activates muscles that produce waves of rhythmic contractions and relaxations called peristalsis.  Peristalsis helps move the bolus down the esophagus to the stomach  Peristalsis will even work if you are upside down!

12.  Site of food storage and initial protein digestion  Movement to and from the stomach is controlled by sphincters (circular muscles) ◦ Lower esophageal sphincter closes the opening between the esophagus and the stomach ◦ Pyloric sphincter regulates food movement from the stomach to the small intestine

13.  Thick layers of muscle are used to churn food (mechanical digestion) ◦ Peristalsis pushes food against the walls of the stomach, churning it, breaking it into smaller pieces, and mixing it with gastric juices (chyme) Gastrin (hormone) is produced when food in the stomach pushes against the stomach walls. ◦ Gastrin stimulates cells on the stomach’s inner wall to start to release gastric fluids (mucus, hydrochloric acid (HCl), pepsinogen, etc.) to aid in chemical digestion of proteins.  HCl kills any harmful substance ingested with the food  HCl converts pepsinogen into the active enzyme, pepsin (protease (enzyme that breaks down protein))  HCl’s acidity helps to soften and break down proteins in chyme.

14.  Stomach also must protect itself from HCl ◦ Stomach doesn’t secrete gastric juices until food is present. ◦ Stomach secretes mucus which protects the cells of the stomach lining from hydrochloric acid and enzymes. ◦ Pepsin is stored in its inactive form (pepsinogen) until hydrochloric acid is present.

15.  The stomach does not absorb nutrients, because they have not been broken down enough. ◦ The stomach does absorb some water and salts, certain anti inflammatory medications (Aspirin), and alcohol.

16.  Small intestine ◦ Main function is to complete digestion of macromolecules and absorb nutrients  Most chemical digestion done in duodenum  Secretes enzymes to break down food  Use peristalsis to move food  In the lining of the small intestine is long- finger-like projections called villi. ◦ The villi also have microvilli (fine, thread-like extensions).  Villi and microvilli increase the surface area available for digestion and absorption of nutrients.  Each villus absorbs monosaccharides and amino acids into its capillary network.  Fats are absorbed into lacteals.  Nutrients are then transported in the circulatory system.

18.  Accessory organs - organs that aid in the digestive system, but food never actually moves into them. ◦ Instead, they secrete and release fluids, that contain enzymes and other chemicals, to organs where food moves through.  Three Digestive System Accessory Organs ◦ Pancreas ◦ Liver ◦ Gallbladder

19. 1. Protection from HCl  Food and stomach acids enter small intestine  Acids convert a prosecretin to secretin (hormone)  Secretin is transported to the pancreas by the circulatory system and signal the pancreas to release a solution of bicarbonate ions (HCO 3 - )  HCO 3 - neutralizes HCl and raises pH from 2 to 9. This deactivates pepsin. ◦ By releasing secretin, the small intestine protects itself from stomach acid and pepsin. 2. Secretion of Enzymes  Releases enzymes to breakdown protein, carbohydrates and lipids

20. Digestion of… Pancreas releases… Function and Activation Protein Releases trypsinogen (inactive enzyme) Trypsinogen is converted by enterokinase (enzyme in the small intestine) into its active form (trypsin). Trypsin breaks down polypeptides into small peptides. Releases erepsins (group of enzymes) Erepsins helps break down small peptides into amino acids Carbohydrat es Releases pancreatic amylase Pancreatic amylase finishes breaking down starch into maltose Releases maltase Maltase breaks down the maltose into 2 glucose molecules Lipids Releases pancreatic lipase Pancreatic lipase breaks down triglycerides Releases phospholipase Phospholipase breaks down phospholipids

21. EnzymeProduced by Reaction EnzymeProduced by Reaction LipasePancreasFat droplets + H 2 0  glycerol + fatty acids TrypsinPancreasProtein + H 2 0  peptides ErepsinPancreas, Small Intestine Peptides + H 2 0  amino acids Pancreatic amylase PancreasStarch + H 2 0  maltose (disaccharide) Maltase (disscharidase) Small Intestine Maltose + H 2 0  glucose

22.  Liver produces bile, which contains bile salts, which aid in fat digestion ◦ Bile is stored and concentrated in the gallbladder  Fats enter the small intestine and the hormone cholecystokinin (CCK) is released  CCK is carried by the blood to the gallbladder and triggers its to release the bile. ◦ Bile salts emulsify or break down large fat globules into smaller droplets (mechanical digestion)  increases surface area of fat, so that pancreatic lipase is more effective

23.  Other functions ◦ Bile contains bile pigments to be removed from the liver breaking down blood cells and stores products in gallbladder ◦ Liver stores glycogen and vitamins A, B 12, and D. ◦ Liver detoxifies body by converting harmful substances (such as alcohol) into less harmful ones, that are dissolved in the blood and eliminated through the urine.

25.  Large Intestine or Colon ◦ No chemical digestion ◦ Stores wastes ◦ Reabsorbs water and some inorganic salts, minerals and vitamins ◦ Houses E. Coli bacteria  Use waste materials to make vitamins B and K. ◦ Cellulose remain undigested and provides bulk, so that receptors can send signal to prompt a bowel movement.  Wastes are eliminated from the rectum by a sphincter called the anus.

29. SecretionSite of production Function SalivaMouthContributes to starch digestion via salivary amylase; lubricates the inside of the mouth to assist in swallowing MucusMouth, stomach, small intestine, large intestine Protects the cells lining the innermost portion of the digestive tract; lubricates food as it travels through the digestive tract EnzymesMouth, stomach, small intestine, pancreas Promote digestion of food masses into particles small amount for absorption into the bloodstream AcidStomachPromotes digestion of protein BileLiver (stored in the gallbladder) Suspense fat in water, using bile salts, cholesterol, and lecithin to aid digestion of fats in small intestine BicarbonatePancreas, small intestine Neutralizes stomach acid when it reaches the small intestine HormonesStomach, small intestine, pancreas Stimulate production and/or release of acid, enzymes, bile, and bicarbonate; help to regulate peristalsis

30.  Controlled by nervous and endocrine (hormonal) systems  Nervous System ◦ Seeing, smelling, tasting food, or swallowing stimulates production of gastric fluids  Hormonal System ◦ Secretin ◦ Gastrin  Speed of digestion can be controlled. ◦ Large meals will activate more receptors, causing more forceful stomach contractions and faster emptying. ◦ If the meal is fatty, small intestine secrets enterogastrone.  Slows peristaltic movements and allows time for fat digestion and absorption.

31.  Identify the organs that make up the human digestive tract.  Identify the accessory organs that assists the digestive system in performing its function.  Identify and describe the digestive processes that begin in the mouth.  Describe how food moves through the esophagus.  Name the structure that controls the movement of food from the esophagus into the stomach.  Describe what happens to food, chemically and physically, to transform it into chyme.  What is the function of pepsin in the stomach?  Explain why few substances are absorbed in the stomach.  Describe how the physical movements of the small intestine aid in the physical digestion of food. Include the name of this process.  Explain how surface area is maximized in the small intestine.  Outline in words, a sketch, or a flowchart the processes by which carbohydrates are digested in the small intestine and absorbed into the bloodstream.  Outline in words, a sketch, or a flowchart the processes by which proteins are digested in the small intestine and absorbed into the bloodstream.  Describe how fats are digested in the small intestine and absorbed into lymph vessels.  Describe how nucleic acids are digested and absorbed.