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The Human Digestive System. Major stages of digestion: 1. Ingestion (eating) 2. Digestion (breaking food into molecules the body can absorb) 3. Absorption (nutrients absorbed from digestive tract) 4. Elimination (removal of undigested wastes). Digestive organs HERE.
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Major stages of digestion: 1. Ingestion (eating) 2. Digestion (breaking food into molecules the body can absorb) 3. Absorption (nutrients absorbed from digestive tract) 4. Elimination (removal of undigested wastes)
Digestive organs HERE http://www.templejc.edu/dept/biology/RHicks/biol2404Int/cavities.gif
BLUE = ACCESSORY ORGANS The cecum is a pouch connecting ileum with first part of LI. Ileocecal valve (sphincter) markes beginning of LI. Appendix is connected to cecum. http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html
http://classes.midlandstech.edu/carterp/Courses/bio211/chap23/chap23.htmhttp://classes.midlandstech.edu/carterp/Courses/bio211/chap23/chap23.htm
Nucleic acids are another essential ORGANIC nutrient! Water is another essential inorganic nutrient!
Saliva contains mainly water, mucus, buffers and salivary amylase. Salivary amylase: optimal pH is 7.
Glottis – vocal cords and space between them The epiglottis is made of elastic cartilage tissue which guards the entrance of glottis by “closing” as the larynx rises during swallowing so food cannot enter trachea. epiglottis Vocal cords (2 membranes stretched across larynx which vibrate w/ air to produce sound). Closed when holding breath. T R A C H E A glottis http://www.faemse.org/downloads/glottis1.jpg
Peristalsis (wave-like) Alternating contraction & relaxation of smooth muscles propel materials forward all through the alimentary canal.
muscles muscles http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html
Sphincters close off top & bottom of stomach. Rugae = deep folds in stomach wall (incr. SA). Layers of smooth muscle continue to churn food. http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/image_article_collections/anatomy_pages/stomach_72.jpg
“Gastric Juice” contains mainly water, mucus, HCl and pepsin. Though the stomach is not considered a nutrient-absorption organ, it does in fact absorb small amounts of water, some drugs/medications, glucose & alcohol.
1. FOOD ENTERS STOMACH 2. GASTRIN PRODUCTION IS STIMULATED 3. HCL PRODUCTION IS STIMULATED 4. PEPSIN IS ACTIVATED BY HCl (optimal pH 2-3)
http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.htmlhttp://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html
“Pancreatic Juice” contains mainly water, NaHCO3, amylase, nucleases, lipases, proteases.
The emulsification process is physical/mechanical, NOT chemical!
http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.htmlhttp://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html http://upload.wikimedia.org/wikipedia/commons/6/64/Illu_pancrease.jpg
We know that the SI is important as the major area of nutrient and water absorption. But let's not forget that it releases enzymes of its own!
Intestinal Lipases also act to break down lipids http://www.slideshare.net/sciencechris/digestion-366112
http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.htmlhttp://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html
PANCREAS -sodium bicarbonate (neutralize chyme – need pH around 8-9 now) -proteases (trypsin, chymotrypsin) -carbohydrases (amylase) -lipases -nucleases LIVER -bile (salts – not an enzyme - to emulsify fats) SMALL INTESTINE -proteaseses (peptidases) -carbohydrases (sucrase, lactase, maltase) -nucleases SI – a busy place!
“Intestinal Juice” contains mainly water, mucus, peptidases, maltase/sucrase/lactase, nucleases and lipases.
http://cikgurozaini.blogspot.com/2010/08/human-digestive-system.htmlhttp://cikgurozaini.blogspot.com/2010/08/human-digestive-system.html
Trypsin and chymotrypsinare proteases released by pancreas Carboxypeptidase, aminopeptidase, dipeptidase – all are peptidases (proteases) released by SI itself http://classes.midlandstech.edu/carterp/Courses/bio211/chap23/chap23.htm