Digestive System ProjectPart B

Learning Guide 8/9

Meal: Dinner

Foot-Long Chicken and Bacon Ranch Sub:• Chicken breast strips• Monterey Cheddar cheese• Bacon• Lettuce• Tomato• Onions• Green bell peppers• Bread• Ranch dressing

Cookie Dough Blizzard:• Chocolate Chip Cookie

Dough• Soft-serve Ice Cream• Fudge

Carbohydrates

Proteins Lipids

• Lettuce• Tomato• Onion• Peppers• Bread

• Chicken breast• Monterey Cheddar cheese

• Bacon• Ranch• Chocolate Chip Cookie

Dough• Ice Cream• Fudge

Carbohydrates• Carbohydrates (including lettuce, tomato, onions,

peppers, and bread) begin the digestive process in the mouth.

• Physical digestion begins with chewing of teeth.• The chemical digestion with enzyme, salivary amylase,

from the salivary glands, breaks down starch and glycogen into disaccharides.

• Salivary glands also secrete a mucus which coats the food and makes swallowing easier.

• The food (bolus) is forced into the pharynx by the tongue.

• As the bolus is swallowed, it moves into the esophagus, which offers passage from the pharynx to the stomach.

Proteins• Proteins, including chicken and cheese, begins the

digestive process in the mouth. • Physical digestion occurs with the chewing of the

teeth.• Salivary glands also secrete a mucus which coats the

food and makes swallowing easier.• The food (bolus) is forced into the pharynx by the

tongue.• As the bolus is swallowed, it moves into the

esophagus, which offers passage from the pharynx to the stomach.

Lipids• Lipids, including bacon, ranch dressing,

chocolate chip cookie dough, ice cream and fudge, begin the digestive process in the mouth.

• Physical digestion occurs with the chewing of the teeth.

• Salivary glands also secrete a mucus which coats the food and makes swallowing easier.

• The food (bolus) is forced into the pharynx by the tongue.

• As the bolus is swallowed, it moves into the esophagus, which offers passage from the pharynx to the stomach.

Stomach

Carbohydrates• Carbohydrates continue the digestive process in the

stomach (entering through the cardiac sphincter, which must relax in order to allow food entrance).

• Physical digestion occurs once mores as the stomach mixes and churns the food.

• The bolus becomes chyme, a mix of a paste-like bolus and gastric juices.

• Then the chyme travels through the pyloric sphincter into the first section of the small intestine, called the duodenum.

Proteins• Proteins continue the digestive process in the

stomach (entering through the cardiac sphincter, which must relax in order to allow food entrance).

• The stomach’s gastric glands begin releasing mucus, water, hydrochloric acid, and pepsinogen.

• As pepsinogen comes into contact with HCl it becomes the enzyme pepsin, which helps break the protein away from its amino acid molecule.

• After about 4 hours, the muscles in the stomach wall pushes the chyme through the pyloric sphincter and into the small intestine.

Lipids• Lipids continue the digestive process in the stomach

(entering through the cardiac sphincter, which must relax in order to allow food entrance).

• Physical digestion occurs once more as the stomach mixes and churns the food, crushing the lipids into even smaller pieces, turning the bolus into chyme.

• For the most part, lipids remain unchanged until they reach the small intestine, although a small amount of short chain triglycerides from butterfat are digested in the stomach by the enzyme tributyrase, a gastric lipase.

Small Intestine

Carbohydrates• Carbohydrates continue the digestive process in the small intestine, which

they entered through the pyloric sphincter and into the duodenum.• The enzyme pancreatic amylase is released through the pancreatic duct.

This splits molecules of starch and glycogen into disaccharides.• The interior wall of the small intestine is covered with villi, which increase

the surface area of the intestine and play a large part in the absorption of nutrients.

• The epithelial cells of the villi contain even small projections called microvilli.

• Within the microvilli are enzymes needed to further break down carbohydrates, such as sucrase, maltase, and lactase, which break down the disaccharides into monosaccharides.

• These monosaccharides are then absorbed by the villi and enter the blood capillaries to be transported to other parts of the body.

Proteins• Proteins continue the digestive process in the small intestine,

which they entered through the pyloric sphincter and into the duodenum.

• When the chyme enters the duodenum a hormone called cholecystokinin is released from the intestinal walls, which stimulates the release of pancreatic juice, which contains three enzymes, including trypsinogen.

• When the trypsinogen comes in contact with an enzyme called enterokinase the activation of trypsin occurs.

• Trypsin and two other enzymes (chymotrypsin and carboxypeptidase) work together to break down the proteins.

• The enzyme peptidase is secreted, which then begins to split peptide bonds into amino acids.

• Smaller particles of amino acids are absorbed through the villi, and are carried away by the blood.

Lipids• Lipids continue the digestive process in the small intestine, which they

entered through the pyloric sphincter and into the duodenum.• As the chyme enters the duodenum the gallbladder is stimulated to

release bile through the common bile duct.• Bile is used to emulsify fats (breaking them down into smaller droplets),

which allows lipids to be digested more effectively.• The same enzyme that stimulated the gallbladder (Cholecystokinin) also

stimulates the release of pancreatic juices, which includes pancreatic lipase; the enzyme that initiates the breaking down of lipids.

• Intestinal lipase is also released, which breaks the lipids into fatty acids and glycerol.

• The fatty acids dissolve in the epithelial cell membranes of the villi and diffuse into them.

• Some fatty acids may be absorbed directly into the blood capillary, without being converted back into fat, however others may be incorporated into large molecules of lipoprotein for transportation.

Liver

Carbohydrates• The liver plays an important part in the

digestion of carbohydrates.• It changes glycogen to glucose to increase the

blood glucose level.• It also changes glucose to glycogen to lower

the blood glucose level.• It is also capable of converting non-

carbohydrates into glucose if needed.

Proteins• The liver plays an important part in the

digestion of proteins.• It can convert amino acids to glucose by

removing the amino acids, using them to form urea nitrogen (deamination).

• Also synthesizes certain blood proteins and converts certain amino acids into other amino acids.

Lipids• The liver plays an important part in the

digestion of lipids.• It oxidizes fatty acids, synthesizes

lipoproteins, phospholipids, and cholesterol, and converts portions of carbohydrates and protein molecules into fat molecules.

Pancreas

Pancreas• Lies deep in abdominal cavity• Secretes insulin and glucagon (hormones that keep the blood

glucose level within normal limits)• Produces pancreatic juices which contains sodium bicarbonate

and digestive enzymes (sodium bicarbonate neutralizes chyme).• Endocrine gland secretes insulin and glucagon.• Endocrine tissue is called pancreatic islets• Insulin is secreted when blood glucose level is high (usually right

after eating)• Produces digestive enzymes such as pancreatic amylase, trypsin,

lipase, and nuclease.

Large Intestine

Large Intestine

• Absorbs water, salts, and some vitamins• Stores indigestible material until it is

eliminated at the anus.• The rectum is the last 20cm of the large

intestine, which opens at the anus.• The anus is where defecation (expulsion of

feces) occurs.

PicturesDigestive System Picture:http://4.bp.blogspot.com/_dOJGn2J-VHg/S__QuzNnadI/AAAAAAAAAXg/91HjB4fTcew/s1600/Human-Digestive-System-Picture.jpg

Subway Picture:http://images.businessweek.com/ss/09/10/1007_americas_fattiest_fast_foods/image/014_subway.jpg

Dairy Queen Picture:http://blog.dairyqueen.com/wp-content/uploads/2010/10/DQ10Q4081P_CookieDough_28_3x3.jpg

Carbohydrates Picture:http://www.quemark.com/images/stories/what/what-are-carbohydrates.jpg

Protein Picture:http://dietsindetails.com/userfiles/protein.jpg

Lipid Picture:http://media.sbs.com.au/news/thm/articlemain/9060_bacon-sundae-burger-king-120613-aap-b.jpg

Mouth Picture:http://upload.wikimedia.org/wikipedia/commons/f/f6/Illu_mouth.jpg

References

Information on Carbohydrates, Proteins, and Lipids:http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&sqi=2&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.mc.edu%2Ffaculty%2Findex.php%2Fdownload_file%2F1544%2F7%2F&ei=NnWpUK2SIbH4igLQtoDoDg&usg=AFQjCNHjrCH68tMjKc0G9wqQCoRx23sMcg&sig2=ANYfnOei4SbVQVpHvlAgsA

Information on Proteins:http://library.thinkquest.org/11226/main/c14txt.htm

Information on Lipids:http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2005/Castle/page3.htm