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G UIDED N OTES ON A CCESSORY D IGESTIVE O RGANS. 1. W HAT IS SALIVA, AND WHAT ARE THE FUNCTIONS OF ITS 2 COMPONENTS ? Saliva is a mixture of mucus and.

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Presentation on theme: "G UIDED N OTES ON A CCESSORY D IGESTIVE O RGANS. 1. W HAT IS SALIVA, AND WHAT ARE THE FUNCTIONS OF ITS 2 COMPONENTS ? Saliva is a mixture of mucus and."— Presentation transcript:

1 G UIDED N OTES ON A CCESSORY D IGESTIVE O RGANS

2 1. W HAT 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. L IST 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. W HAT 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. W HAT IS THE DIGESTIVE FUNCTION OF THE LIVER ? The liver produces bile, which enters the duodenum through the common hepatic duct.

6 5. W HAT IS BILE COMPOSED OF ? W HAT 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. W HEN 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. W HAT ARE GALLSTONES ? If bile is stored in the gallbladder too long, the cholesterol it contains may crystallize into gallstones

9 F UNCTIONS OF THE D IGESTIVE S YSTEM 1. Ingestion: an active, voluntary process of placing food in the mouth 2. Propulsion: foods are propelled from one organ to the next by peristalsis and segmentation 3. Mechanical Digestion: mixing of food in the mouth by the tongue; churning of food in the stomach, segmentation in the small intestine.

10 F UNCTIONS OF THE D IGESTIVE S YSTEM 4. Chemical Digestion: large food molecules are broken down to their building blocks by enzymes 5. Absorption: transport of digested end products from the lumen of the GI tract to the blood or lymph 6. Defecation: elimination of indigestible substances from the body

11 2. W HAT 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. W HAT 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. C ATEGORIZE THE S UGARS P ROCESSED BY THE S TOMACH : Monosaccharides: Glucose, Fructose, Galactose Disaccharides: Sucrose, Maltose, Lactose Polysaccharides: Starch

14 5. W HAT IS THE PURPOSE OF CELLULOSE IN THE DIET ? Cellulose helps to move foodstuffs along the gastrointestinal tract by providing bulk, or fiber

15 6. D ESCRIBE THE PROCESS OF PROTEIN DIGESTION Proteins are digested to their building blocks, amino acids, by enzymes in the stomach and small intestine

16 7. L IST THE STIMULI THAT ACTIVATE DIGESTIVE REFLEXES : 1. Stretch of the organ by food in the lumen 2. pH of the contents 3. Presence of certain breakdown products of digestion

17 1. H OW 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. W HAT 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. W HAT CAUSES HEARTBURN TO OCCUR ? When the cardioesophageal sphincter fails, gastric juice backs up into the esophagus, which has little protection from mucus

20 4. C OMPARE 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. H OW 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. W HAT IS VOMITING ? Vomiting is a reverse peristalsis occurring in the stomach, accompanied by contraction of the abdominal muscles and the diaphragm

23 7. W HAT FOUR FUNCTIONS DO THE PANCREATIC JUICE ENZYMES PERFORM ? 1. Complete the digestion of starch 2. Carry out protein digestion 3. Totally responsible for fat digestion 4. Digest nucleic acids

24 8. W HY 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. H OW 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. W HAT REMAINS FROM THE PROCESS OF DIGESTION ? Water Indigestible food materials (fiber) Large amounts of bacteria

27 11. W HAT FUNCTIONS DO THE BACTERIA PERFORM ? They metabolize remaining nutrients and release gas that contribute to the odor of feces

28 12. W HAT 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. W HAT 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


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