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DIGESTIVE SYSTEM PROCESSES and PHYSIOLOGY

DIGESTIVE SYSTEM PROCESSES and PHYSIOLOGY. Swallowing Peristalsis Absorption Key Organs Gut Feedback. Fig. 12.1. SWALLOWING. PERISTALSIS. SMALL INTESTINE. Duodenum  Jejenum  Ileum. Small Intestine. Fig. 12.6. It’s all about surface area.

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DIGESTIVE SYSTEM PROCESSES and PHYSIOLOGY

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  1. DIGESTIVE SYSTEM PROCESSES and PHYSIOLOGY Swallowing Peristalsis Absorption Key Organs Gut Feedback

  2. Fig. 12.1

  3. SWALLOWING

  4. PERISTALSIS

  5. SMALL INTESTINE Duodenum  Jejenum  Ileum

  6. Small Intestine Fig. 12.6

  7. It’s all about surface area 1.Plicae 2. Villi 3. Microvilli

  8. VILLI Microvilli

  9. Its All About Active Transport Products of Carbohydrate and Protein Digestion are actively transported from small intestine into the villus. These simple sugars and amino acids are taken into the capillary bed in the villus and transported to the Liver. Products of Fat digestion are absorbed into the central lymphatic vessel called a LACTEAL

  10. DUODENUM Functions The Duodenum is only about 45 cm (18 inches long) but it plays a couple of very important roles: 1. Receives incoming Stomach Chyme, Pancreatic Juices and Bile from Liver and Gall bladder. 2. Secretes digestive juces/enzymes from duodenal glands

  11. Large Intestine Functions 1. Receives undigested waste and helps absorb fluid (water) from those wastes back into the bloodstream, to help keep us from dehydrating. 2. Helps compact and form feces. 3. Harbours helpful bacteria which can further break down wastes to free up minerals and some bacteria will help produce and free up some vitamins, such as Vitamin K

  12. Stomach Functions 1. Storage of a meal – most expanded structure along the alimentary canal

  13. 2. Mechanical Digestion of food – Stomach is very muscular and it squeezes to churn and mix food to physically break it down

  14. 3. Chemical Digestion of food – Adds PEPSIN enzyme to start chemically breaking proteins into small peptide chains

  15. 4. Protection against Germs – HCl helps activate enzymes but it also helps kill many of the bacteria that we ingest.

  16. Fig. 12.5 The STOMACH

  17. GASTRIC GLANDS Some gastric glands are classified as being EXOCRINE. ???? They are responsible for producing gastric juice which consists of mucous, HCl, Pepsinogen and water. In the presence of HCl the Pepsinogen converts to active Pepsin. This Pepsin is a PROTEASE enzyme, breaking proteins into smaller peptide chains

  18. Stomach control When the stomach receives a meal, it gets turned on! The stomach’s exocrine glands are turned on by a Hormone called GASTRIN. Gastrin is produced and released from the stomach’s ENDOCRINE glands????

  19. PANCREAS Function The pancreas is a glandular organ that acts both as an Exocrine Gland and also as an Endocrine Gland. We mostly focus on its exocrine role. It produces a variety of hydrolytic digestive enzymes that help chemically finish off the digestion of Carbohydrates, Fats and Proteins.

  20. Pancreatic Exocrine Function When acidic chyme from the stomach enters the duodenum, the pancreas is stimulated to secrete pancreatic juice

  21. Pancreatic Juice • INGREDIENTS: • Sodium Bicarbonate – NaHCO3? • LIPASES? • PANCREATIC AMYLASE? • TRYPSIN – same function as PEPSIN • NUCLEASES (work on Nucleic Acids)?

  22. Pancreatic Endocrine Function When blood sugar is getting too high. The pancreas produces and secretes INSULIN into the bloodstream

  23. Pancreatic Endocrine Function When blood glucose levels start getting too low, the Pancreas will produce and secrete the hormone GLUCAGON. Glucagon will travel through the bloodstream to tell muscle and liver cells to break down their stored Glycogen back into glucose and send it back into the blood, to raise blood sugar levels

  24. Liver Functions

  25. You Can’t Live without your LIVER! • Produces Bile? • Converts Carbohydrates to control blood sugar levels. • Detoxifies the blood? • Makes lots of vital Plasma Proteins? • Stores Iron and Fat Soluble Vitamins – ADEK. • Helps break down nitrogenous metabolic wastes. Example : Ammonia  Urea • Produces Cholesterol and regulates blood cholesterol levels.

  26. Fig. 12.11

  27. Fig. 12.7 Controlling The Gut

  28. Fig. 12.12

  29. Tap. 237

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