Guided Notes on Accessory Digestive Organs

1. Guided Notes on Accessory Digestive Organs

2. 1. What is saliva, and what are the functions of its 2 components? • Saliva is a mixture of mucus and serous fluids • Mucus moistens and binds food together into a bolus • The serous fluid contains an enzyme called salivary amylase that begins starch digestion

3. 2. List the four types of permanent teeth and their shapes and functions • Incisors: chisel-shaped for cutting • Canines: fang-like, for tearing or piercing • Premolars: (bicuspids) broad crowns for grinding • Molars: broader crowns with rounded tips for grinding

4. 3. What do the enzymes produced by the pancreas do? • They break down all categories of digestible foods. • They are alkaline, so they also neutralize the acidic chyme from the stomach.

5. 4. What is the digestive function of the liver? • The liver produces bile, which enters the duodenum through the common hepatic duct.

6. 5. What is bile composed of? What is the function of bile salts? • Bile is a yellow-green, watery solution containing bile salts, bile pigments, cholesterol, phospholipids, and electrolytes • Bile salts emulsify fats by breaking large fat globules into smaller ones, giving more surface area for enzymes to work

7. 6. When is bile stored in the gallbladder? • When food digestion is not occurring, bile backs up into the cystic duct and enters the gallbladder

8. 7. What are gallstones? • If bile is stored in the gallbladder too long, the cholesterol it contains may crystallize into gallstones

9. Functions of the Digestive System • Ingestion: an active, voluntary process of placing food in the mouth • Propulsion: foods are propelled from one organ to the next by peristalsis and segmentation • Mechanical Digestion:mixing of food in the mouth by the tongue; churning of food in the stomach, segmentation in the small intestine.

10. Functions of the Digestive System • Chemical Digestion: large food molecules are broken down to their building blocks by enzymes • Absorption: transport of digested end products from the lumen of the GI tract to the blood or lymph • Defecation: elimination of indigestible substances from the body

11. 2. What is peristalsis? • Peristalsis are involuntary, alternating waves of contractions of muscles in the walls of the alimentary canal. • The net effect is to squeeze food along the digestive tract

12. 3. What is the purpose of segmentation? • Segmentation moves food back and forth across the internal wall of the organ, serving to mix it with digestive juices

13. 4. Categorize the Sugars Processed by the Stomach: • Monosaccharides: Glucose, Fructose, Galactose • Disaccharides: Sucrose, Maltose, Lactose • Polysaccharides: Starch

14. 5. What is the purpose of cellulose in the diet? • Cellulose helps to move foodstuffs along the gastrointestinal tract by providing bulk, or fiber

15. 6. Describe the process of protein digestion • Proteins are digested to their building blocks, amino acids, by enzymes in the stomach and small intestine

16. 7. List the stimuli that activate digestive reflexes: • Stretch of the organ by food in the lumen • pH of the contents • Presence of certain breakdown products of digestion

17. 1. How is food broken down in the mouth? • Food is physically broken down by chewing • Salivary amylase begins the chemical digestion of starch, breaking it down into maltose

18. 2. What regulates the secretion of gastric juice? • The sight, smell, and taste of food increase the secretion of gastric juice by the stomach cells • 2 to 3 liters of gastric juice is produced every day under normal conditions

19. 3. What causes heartburn to occur? • When the cardioesophageal sphincter fails, gastric juice backs up into the esophagus, which has little protection from mucus

20. 4. Compare pepsin and rennin: • Pepsin is a protein-digesting enzyme that is activated by hydrochloric acid • Rennin is a protein-digesting enzyme that works on milk protein. It is only produced by infants and children • Both are produced by the stomach

21. 5. How long does food generally remain in the stomach? • 4 hours if the meal is well-balanced • 6 hours if it has a high fat content

22. 6. What is vomiting? • Vomiting is a reverse peristalsis occurring in the stomach, accompanied by contraction of the abdominal muscles and the diaphragm

23. 7. What four functions do the pancreatic juice enzymes perform? • Complete the digestion of starch • Carry out protein digestion • Totally responsible for fat digestion • Digest nucleic acids

24. 8. Why is it important that pancreatic juice contains bicarbonate? • Bicarbonate is basic, so that it can neutralize the acidic chyme as they enter the small intestine together

25. 9. How are water and the end products of digestion absorbed? • Most substances are absorbed through the intestinal cell plasma membranes by active transport • Lipids are absorbed by diffusion

26. 10. What remains from the process of digestion? • Water • Indigestible food materials (fiber) • Large amounts of bacteria

27. 11. What functions do the bacteria perform? • They metabolize remaining nutrients and release gas that contribute to the odor of feces

28. 12. What are mass movements? • Mass movements are long, slow-moving, powerful contractions that move over the colon 3 or 4 times daily and force the contents toward the rectum. • They occur during or just after eating • Fiber in the diet causes them to increase in strength

29. 13. What conditions cause diarrhea to occur? • When food residue is rushed through the large intestine before sufficient time for water to be absorbed • Usually this is caused by irritation from bacteria