the human digestive system. chemical digestion of food use the following words to label the diagram...
Post on 25-Dec-2015
216 Views
Preview:
TRANSCRIPT
The Human Digestive System
Chemical Digestion of Food• Use the following words
to label the diagram (in boxes):– Triglyceride– Monosaccharides– Amino Acids– Fatty Acids– Polypeptide– Polysaccharide– Disaccharide– Glycerol
Form when eaten Form after digestion
• What is the name of the process represented by the arrows? __________________
Polypeptide
TriglycerideHydrolysis
• Carbohydrates (2 places) ______________________
• Proteins (2 places) ________________________
• Lipids ____________________________
• Which enzyme(s) digest these molecules in each location? Add to answers above:– pepsin, amylase, lipase, trypsin, sucrase, lactase, peptidase
Where does the chemical digestion of each of the following occur? Try to follow this during lecture/discussion and your reading. Return to & answer these questions after reading or lecture… We will not answer these just yet!
The Fours Stages of Food Processing
(Eating) (Breaking down food MECHANICALLY & CHEMICALLY)
(Nutrients & water go from digestive system into BLOOD, to CELLS)
(Undigested food/solid waste leaves body as poop)
Your Digestive System is like the hole in a
doughnut…
The Digestive system is like a tube that runs through the middle of your body.Food goes in one end, and food waste comes out the other.
http://thumbs.ifood.tv/files/dood.jpg
The Human Digestive System
How it begins…Mouth to Stomach
• Mouth: Food is chewed (mechanical digestion) & moistened with saliva. Salivary amylase begins chemical digestion of starches (carbohydrates).
• A slimy food ball (the bolus) leaves mouth, slides past epiglottis (covering opening to trachea) to the esophagus.
What happens if the epiglottis does not do it’s job??
http://bio1903.nicerweb.com/Locked/media/ch41/41_16SwallowPeristalsis_1.jpghttp://bio1152.nicerweb.com/Locked/media/ch41/pharynx_swallow.html
Digestive Problem: ChokingWhen you try to talk & eat at the same time…
http://thehealthybear.com/wp-content/uploads/2012/08/choking-first-aid.jpg
How it begins…Mouth to Stomach
• Esophagus: The bolus moves down this muscular tube by peristalsis (waves of muscle contractions), to the stomach.
http://images.tutorvista.com/content/nutrition/peristalsis.jpeg
Esophagus
PERISTALSISWhat happens when you do a handstand and try to eat a Gummi Bear, while upside-down?
In the Stomach
• Stomach: Muscular sac that releases hydrochloric acid (HCl) & the enzyme Pepsin to begin digestion of proteins. Stomach lining is protected from acid by continually secreting protective mucus.
• Digesting food kept in stomach by the lower esophageal sphincter (at entrance) and the pyloric sphincter (at exit).
• Pyloric sphincter squirts partially digested mix of nutrients, water, & acid into the duodenum of the small intestine over 2-6 hours. This liquid is called chyme.
http://www.drhirani.com/wp-content/uploads/2012/07/Stomach-Plain.jpg
Digestive Problem: Acid Reflux & GERD• What happens when acid escapes the stomach into the
esophagus? This is called Acid Reflux or “heartburn”.
http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/tools/heartburn-tool/understanding_heartburn.jpg
Digestive Problem: Ulcers• Mucus can be eroded by several causes: H. pylori bacterium
infection or stomach exposure to NSAIDs, asprin, alcohol, gastric hyper-acidity, cigarettes, etc.
• Result: damage to cells lining stomach gastric ulcer
http://images.wisegeek.com/peptic-ulcer-diagram.jpg
Ulcers can also occur in the esophagus or the duodenum.
Completion of Digestion in Small Intestine
http://3.bp.blogspot.com/_hhUdKwzDmA4/TGVtINRL9kI/AAAAAAAAAnY/MD6_dNm7OH8/s1600/duodenum.jpg
Small Intestine (duodenum)• Digestion of carbs, fats & proteins is completed using bile from
liver & enzyme-filled pancreatic juice & intestinal juice.• Sodium bicarbonate from the pancreas neutralizes acidic chyme in
duodenum. (not shown in picture)
Digestion is necessary
for Absorption
http://www.skinmed.co.uk/images/skinsideout/enzyme%20function.jpg
Chemical Digestion SummaryNutrient Mouth Stomach Small Intestine
Carbohydrates (Starch)
Hydrolysis of starch into disaccharides begins (by salivary amylase).
Starch into disaccharides continues (by pancreatic amylase).Disaccharides into monosaccharides (by maltase, sucrase, lactase, etc.)Monosacchrides like glucose can now be absorbed.
Proteins Large polypeptides into smaller polypeptides (by the enzyme pepsin).
Large polypeptides into smaller polypeptides (by trypsin, chymotrypsin).Smaller polypeptides into amino acids (by peptidases).Amino acids can now be absorbed.
Fats Fat globules into fat droplets (by bile salts – emulsifiers, not enzymes…more like detergent).Fats (triglycerides) into Fatty acids and glycerol (by lipase).Fatty acids and glycerol can now be absorbed.
Note: Mechanical digestion of all nutrients occurs in all locations listed above.
Absorption of Nutrients in Small IntestineSmall Intestine (jejunum & ileum)• Absorption: Nutrient monomers are transported from lumen of small
intestine into bloodstream, and from there to body’s cells.• Absorption helped by large surface area of small intestine, due to projections
called villi, and their projections called microvilli.
http://biologytb.net23.net/text/chapter29/29images/29-07.gif
Villi of Small Intestine
http://video.ecb.org/badger/download/vlc/images/VLC181_Villi_in_small_intestine.jpg
Where next?
Large Intestine: Absorption of Water & More!Large Intestine: Colon• Remaining water is absorbed & undigested solids are compacted
into feces (poop). • Home to mutualistic bacteria, like E. coli, which produce
important vitamins (B vitamins, vitamin K)
Large Intestine: Rectum• Stores waste until
elimination.
http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/media/medical/hw/h9991263_001.jpg
Problems/Diseases of Digestive System• Heartburn / Acid Reflux: HCl escapes stomach & “burns” lining of esophagus• Ulcer: “hole” in mucus & cells lining stomach, caused by HCl and H.Pylori bacterium• Lactose Intolerance: Inability to digest milk sugar, bloating & gas when dairy is consumed• Diarrhea: too much water in feces, frequent watery elimination• Constipation: not enough fiber in diet, infrequent elimination & compacted feces• Appendicitis: infection & inflammation of appendix• Gallstones: “stones” of bile salts in gall bladder, can be eliminated through narrow bile
duct into digestive system (painful)• Celiac disease: cannot process gluten (a protein found in wheat), destroys villi &
negatively affects nutrient absorption• Inflammatory Bowl Disease (IBD): chronic inflammation of all or part of your digestive
tract. IBD primarily includes ulcerative colitis and Crohn's disease. Both usually involve severe diarrhea, pain, fatigue and weight loss. IBD can be debilitating and sometimes leads to life-threatening complications.*
• Cancers of the digestive system, esp. colon or rectum (most common)
* From http://www.mayoclinic.org/diseases-conditions/inflammatory-bowel-disease/basics/definition/con-20034908
top related