Chapter 24 digestion fall '08 - Chapter 24 Chapter...

Unformatted text preview: Chapter 24 Chapter Digestion a maintenance system Today we will lecture on Today How digestion How accomplished accomplished – – – – Overview Single cell Tubes Specializations How humans digest – From mouth to bowel – ?? Controlled Digestion Defined as Defined Digestion Defined as Defined Digestive Systems “do” – Ingestion – Mechanical breakdown – Chemical breakdown – Absorption – Elimination Elimination animals Cellular digestion systems Digestion in a sac Digestion in a tube Cellular Digestion Sponge Sponge Each cell is its own digestive factory – Intracellular Intracellular digestion digestion – Food vaculole – Lysosomes Lysosomes What Phylum ? Simplest Digestive System Simplest Cnidarians – One opening sac A gastrovascular cavity Permits extracellular digestion digestion Digestion occurs outside the cell This system too slow for This active animals Digestion in a tube Digestion Permits frequent dining Has specialized regions An extracellular process – Donut Donut Tube digestion supports an active animal Donut Idea Donut Specialized Digestion Systems Specialized Why specialized?????? 1) 2) Specialized Digestion Systems Specialized Why specialized?????? 1) 2) FOR EXAMPLE Cellulose & animal systems Ruminant animals ase – Cellul RUMEN OTHER SPECIALIZATIONS OTHER Tube length, Teeth, & Gizzards Intestine length – Long/short why? crop why OTHER SPECIALIZATIONS OTHER Tube length, Teeth, & Gizzards Intestine length – Long/short why? Carnivores Herbivores Omnivores Teeth – Why teeth???? Birds & crops & gizzards Birds crops – Why????? gizzzard crop Human Digestive System System Consists of 1. digestive tube aka the alimentary canal 2. digestive organs/glands e.g. gall bladder teeth tongue 1 2 11 + 5 3 4 5 6 7 8 9 10 11 1 1. 2. 3. 4. 5. 6. 7. 8. 9. Mouth Pharynx Esophagus Cardiac Sphincter Stomach Pyloric Sphincter Small Intestine Sphincter Large Intestine 1. Colon = 9a 2. Rectum = 9b 10. Anus (sphincter) 2 A 3 4 B Liver C Gall bladder D Pancreas E Appendix D 5 7 6 B A Salivary glands C 8 E 9a 9b 10 The brain and food The Mouth Salivary glands Teeth Tongue Mouth Food enters Mouth waters 3 pr salivary glands Lube food Why? Fights bacteria via enzymes Dissolves acids/sugars Amylase Mouth Teeth Chew Tongue Taste Swallow Brain told food here. Brain tells stomach to make HCl. TASTE TASTE Salty Sour Bitter Sweet Umani Pharynx Pharynx functions 1. 2. Esophagus peristalsis CARDIAC SPHINCTER PREVENTS FOOD FROM RE-ENTERING ESOPHAGUS SEPARATES ENVIRONMENTS Stomach Stomach 1. Mechanically breaks down food 2. Stores food & slowly releases it into the duodenum 3. Chemically breaks down food Stomach Stomach 1. Mechanically breaks down food 2. Stores food & slowly releases it into the duodenum 3. Chemically breaks down food via HCl Gastric mucus juice Pepsinogen “acid” Chyme = ? pepsin = a protease “never drink on an empty never stomach” stomach” “hunger pangs” Pyloric sphincter Pyloric Separates stomach from duodenum Permits @ 1 teaspoon of “acid” chyme to Permits pass @ every 20 seconds pass =Time between stomach peristalic wave =Time contractions contractions Ulcers Ulcers Who is barry marshall? 1984 Heliocobacter pylori A good year Heliocobacter pylori Where are we in digestion? Where What’s happening!!!!!! What’s First problem Acid chyme Solved by panceatic juice NaHCO3 Amylase Protease Lipase Second problem Fats Solved byEmulsifies fats liver bile Bile salts Water Cholesterol recap recap Digestion starts in mouth (amylase) Stomach breaks down some proteins Stomach (pepsin) (pepsin) Pancreas provides enzymes to break Pancreas down fats, carbohydrates, and proteins down Liver bile emulsifies fats NEW: ENZYMES EMBEDDED IN WALL NEW: OF SMALL INTESTINE COMPLETE THE DIGESTIVE The small intestine is not only the major site of digestion but it also is the biggest player in ABSORPTION 95% Ilium & jejunum Absorption Large Intestine Large 3 parts – Colon – Rectum – Appendix Does – Absorb water – Produce vitamins HOW? – Compacts and stores waste – Eliminates Eliminates Diarrhea & Constipation Diarrhea Review Have a great break!!!! Have amen amen ...
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