01:119:116 Lecture Notes - Lecture 23: Pancreatic Juice, Cell Nucleus, Microvillus
30 Apr 2017
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Lecture 23 - digestion: introduction to digestion, heterotrophy. Mechanical - chewing increases surface area for enzymes. Chemical - enzymes hydrolysis: absorption - cells take up molecules, elimination - undigested passes out of system. How do you avoid digesting yourself: digestive compartments, intracellular digestion. Lysosomes: extracellular digestion - breakdown in compartments. Alimentary canal - two openings, one-way, you! Peristalsis - smooth muscle, waves of contraction. Let"s follow a meal from mouth to all the structures. Fig 41. 9: food processing prior to stomach, prior to ingestion. Tongue - forms food into a bolus: pharynx throat. Bolus to stomach & moves food in intestines. Fig 41. 9: stomach - very elastic - 2 liters! Stomach linings - puts to gastric glands. Fig 41. 11: food processing in stomach. Parietal cells - atp driven pump h+ into lumen and diffuse into cl- into lumen. Breaks internal peptide bonds at specific sites. Fig 41. 9: food processing in small intestines, small intestines (si)
