A Tour of the Digestive A Tour of the Digestive SystemSystem Mouth
◦ Tongue, teeth, salivary glands, pharynx
◦ Enzymes
Esophagus◦ Epiglottis and choking
◦ Peristalsis
Stomach◦ Cardiac and pyloric sphincters
and stomach cell types
◦ Enzymes and gastric secretions
Pancreas◦ Digestion enzymes, pH
balance and maintenance of blood sugar
Liver / Gall bladder◦ Roles in digestion and
other body processes Small intestine
◦ Specialization – structure and function three sections and of the villi
◦ Enzyme action Large intestine
◦ Functions and anaerobic bacteria within
Rectum and Anus◦ Expulsion of wastes
Small intestine zonesSmall intestine zones3 Zones: Dudodenum, Jejenum, Ilium
• Approx. 6m long
• Most of digestion and absorption of nutrients occur here
Fats break down to Fats break down to molecular level!molecular level!
Glycero
l
Fatty Acid
Fatty Acid
Fatty Acid
Glycerol
Fatty Acid
Fatty Acid
Fatty Acid
Lipase
Fat Fatty Acids and Glycerol
Digestive Enzymes from the Digestive Enzymes from the Interstitial glandsInterstitial glands
Maltase
Maltose (from carbohydrates)Glucose
Peptidase
Peptide (from proteins)Amino Acids
Inside the small intestineInside the small intestineLarge folds
line the intestine called villi and microvilli
= LOTS of surface area
How much? ~600m2 (size of a baseball diamond)
The VilliThe Villi
Outer wall
Inner wall
Pathway for Food
VilliVilliEach villus has a very
thin layer of cells around it (epithelium).
Beneath the cells are a lymphatic vessel and a blood capillary.
Fatty acids and glycerol enter the lymphatic system
Glucose and amino acids enter to the blood system and are taken to the liver where they are processed
A close up look at villiA close up look at villi
Large IntestineLarge IntestineConsists of the colon, the rectum
and the opening at the end, the anus.
Colon has 3 parts◦ascending◦transverse◦descending
How long is it?◦About 1.5m long (about 5 feet)◦Last 20 cm is the rectum
The appendix is a vestigial organ (not needed).
What does the large What does the large intestine do?intestine do?Reapsorption of waterAbsorption of certain vitaminsAlso contains: bile pigments,
heavy metals, and billions of E. coli (providing colour and odour)
What do E. coli do for you?◦break down some indigestible food◦produce some vitamins, amino acids,
and other growth factors
Physical digestion: Teeth and stomach churning broke it into
pieces Bile broke the fats into smaller globs
Chemical digestion: Salivary amylase: starch maltose Pepsin in stomach: protein peptides Pancreatic amylase: starch maltose Trypsin from the pancrea: protein
peptides Lipase from the pancreas: fats glycerol
+ fatty acids
Digestion Summary
Indigestion?Indigestion?Disorders in the large Disorders in the large
intestine and symptomsintestine and symptoms
http://www.youtube.com/watch?v=1ZIK6Ua20JA&feature=channel_page
http://www.youtube.com/watch?v=0yLPtYH6xfE
Overall review of digestion:http://www.youtube.com/watch?v=QtDgQjOGPJM
