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