Lecture 12 - The Cellular Basis of Human Metabolism. Digestion Part 4 - The Liver

Lecture 12 - The Cellular Basis of Human Metabolism. Digestion Part 4 - The Liver

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1 The Cellular Basis of Human Metabolism. Digestion Part 4: The Liver Biology 1F25 for Biology Non-Majors Lecture 12 Background Reading Textbook, Chapter 8 The People Who Prepared This Lecture Harry Peery Jeff Stuart Relationship of Stomach, Pancreas and Liver Liver Gall Bladder Common bile duct Duodenum – 1 st part of small intestine Stomach Pancreas and pancreatic duct Spleen Left kidney Branch of hepatic portal vein coming from both stomach and pancreas
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2 Normal Liver 1 Anterior view Posterior view 2 Structure of the liver Arteries are red Veins are blue Bile channels are green 2 Internal Structure of the liver Arteries are red Veins are blue Bile channels are green
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3 All blood from the gastrointestinal tract goes through the liver first • The blood going from the stomach and intestines returns through the liver via the hepatic portal system. A schematic view of the hepatic portal system. Not shown is the pancreas which is also on the system and which lies under the stomach Liver and gall bladder Arteries and Veins – In brief • Arteries are blood vessels that carry blood away from the direction of the heart. • Veins are blood vessels that carry blood towards the heart or in the direction of the heart. • The hepatic portal system is a venous system because it carries blood to the liver which is in the direction of the heart. What happens next? • Blood from the hepatic portal system goes through the liver. • Liver cells act on food and drugs from the intestinal tract. • Bacteria from the intestinal tract are also removed. • The “processed blood” enters a systemic vein, the inferior vena cava, which conveys the blood to the heart for pumping to the rest of the body. What goes into your mouth gets to the liver first •P ro te ins • Any drug or food additive such as – Alcohol – Prescription drugs – Acetaminophen and other drugs you can buy
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Proteins • Proteins are composed of smaller molecules called amino acids. • The amino acids have an amine (NH2) group and an acid (COOH) group. Acid group Amine group ‘R’ means ‘the rest of the molecule’ Proteins are amino acids strung together Proteins • The amine group can be taken off and the resulting molecule can (but not always) become glucose. • The glucose is broken down to get hydrogens and CO 2 . • The hydrogens are used to generate ATP as we have already seen. NH 4 + (ammonium ion) is a problem • Once removed from the protein, NH 2 rapidly combines with H to form NH 4 + (ammonium ion). •NH 4 + is toxic to the brain. • The liver will combine two NH 4 + with CO 2 to form urea. • In its urea form, it is less harmful and can be
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This note was uploaded on 06/10/2008 for the course BIOL BIOL-1F25 taught by Professor Peery during the Spring '08 term at Brock University.

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Lecture 12 - The Cellular Basis of Human Metabolism. Digestion Part 4 - The Liver

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