Biol 216 12 UPDATED Digestion 49-93.pdf

Biol 216 12 UPDATED Digestion 49-93.pdf - Stomach-Acidic...

Info icon This preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
5/30/17 1 Stomach-Acidic pH=2 à optimal pH for pepsin Helps unfold proteins so they can be broken down Kills unwanted bacteria Stomach’s mucus protects stomach wall from acidity and breakdown from pepsin 5/30/17 49 Stomach Can take 1-6hrs for the stomach to empty after a meal Food is not moved along faster than it can be digested Fat: is digested in small intestines and is digested more slowly than other nutrients, so further emptying of the stomach is prevented until fat is processed 5/30/17 50 Digestion in small intestine Most digestion occurs here Proteins – broken down by endopeptidases, exopeptidases Polysaccharides – hydrolyzed by amylase, then disaccharidases Triglycerides hydrolyzed by lipase Nucleic Acids hydrolyzed by nucleases (DNase, RNase) 5/30/17 51
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
5/30/17 2 The Digestive Process Absorption of nutrients begins in the small intestine Specializations to optimize absorption Intestinal villi: folds in lining of small intestine Microvilli: projections of plasma membrane of epithelial cells Villi and microvilli greatly increase the surface area of intestine 5/30/17 52 Villi in the Small Intestine 5/30/17 53 Fig. 45.11a, p. 1028 Folds of small intestine Section of small intestine Villus 5/30/17 54
Image of page 2
5/30/17 3 Brush border Capillaries Microvilli Intestinal epithelial cell Lymphatic vessel Villus 5/30/17 55 Nutrient Absorption in the Small Intestine 5/30/17 56 The Digestive Process- Small Intestine In the duodenum, digestive juices from the pancreas and liver add enzymes and digestive aids to the food mass Pancreas secrete digestive enzymes and bicarbonate ions (HCO3-: neutralize acidity) into ducts that empty into the duodenum CO2+H2O ó H2CO3 ó HCO3- + H + 5/30/17 57
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
5/30/17 4 Basic fluid: high concentration of bicarbonate ions(HCO 3 - ) Proteolytic Enzymes: trypsin chymotrypsin, carboxypeptidase Lipase Amylase Nucleases From the Pancreas Bicarbonate ions neutralizes the pH of the chyme for optimal activity of amylase, proteases, lipases, nucleases. 5/30/17 58 From the pancreas-Hormones Glucagon (alpha cells): is released when blood glucose levels start to fall too low Causes the liver to convert stored glycogen into glucose and release it into the bloodstream, raising blood glucose levels. Insulin (beta cells): causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, Storing it as glycogen in the liver and muscle, and stopping use of fat as an energy source. 5/30/17 59 Digestive Enzymes 5/30/17 60
Image of page 4
5/30/17 5 Fat digestion: small intestine Liver secretion bile (bile is a mixture of substances that act as emulsifiers) à emulsifies fats Emulsify: combine two components that usually don’t combine easily (oil-water) Eg., Salad dressing, mayonaise Bile salts: aid in fat digestion by forming a hydrophillic coat around fats.
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern