Small Intestine and Pancreas Small Intestine small Small

Small Intestine and Pancreas

Small Intestine: -“small”= Small diameter (7 m long) - Main site for digestion and absorption Duodenum:

Small Intestine: -“small”= Small diameter (7 m long) - Main site for digestion and absorption Duodenum: First 25 -30 cm of the small Intestine. Where most of the digestion occurs.

Small Intestine & the Pancreas Moving food from stomach to small intestine: Remember the food that comes from the stomach is mixed with hydrochloric acid and pepsin. = dangerous for small intestine Solution: -Release bicarbonate ions to neutralize acids

Controlling Bicarbonate Release 1) Stomach acid and food moves into the small intestine 2) Prosecretin is converted to secretin by acid

Controlling Bicarbonate Release 1) Stomach acid and food moves into the small intestine 2) Prosecretin is converted to secretin by acid 3) Secretin is absorbed into the bloodstream 4) As blood moves to pancreas the sectretin in the blood causes the pancreas to release bicarbonate into the small intestine

Controlling Bicarbonate Release 1) Stomach acid and food moves into the small intestine 2) Prosecretin is converted to secretin by acid 3) Secretin is absorbed into the bloodstream 4) As blood moves to pancreas the sectretin in the blood causes the pancreas to release bicarbonate into the small intestine 5) Bicarbonate neutralizes the acid to protect the walls of the small intestine p. H changes from 2 9 6) The new basic p. H causes pepsin to become inactive so it won’t digest the intestinal wall

Pancreas and the breakdown of food Food: 3 main groups -Protein -Carbohydrates -Lipids (fats)

Breakdown of Protein: Remember at this point protein is only broken down into short chains Enterokinase: An enzyme in the small intestine that activates trypsinogen converting it into tripsin Trypsin: Erepsins (peptidases):

Breakdown of Protein: Remember at this point protein is only broken down into short chains Enterokinase: An enzyme in the small intestine that activates trypsinogen converting it into tripsin Trypsin: Breaks down the peptone chains into shorter peptone chains Erepsins (peptidases):

Breakdown of Protein: Remember at this point protein is only broken down into short chains Enterokinase: An enzyme in the small intestine that activates trypsinogen converting it into tripsin Trypsin: Breaks down the peptone chains into shorter peptone chains Erepsins (peptidases): Break down the shorter peptone chains into individual amino acids

Breakdown of Sugar (Carbohydrates) Amylase (also released by salivary glands): Released by the pancreas. Breaks down the smaller sugar chains into disaccharides (di = 2. Saccharide = sugar) Disaccharase enzymes:

Breakdown of Sugar (Carbohydrates) Amylase (also released by salivary glands): Released by the pancreas. Breaks down the smaller sugar chains into disaccharides (di = 2. Saccharide = sugar) Disaccharase enzymes: Break down disaccharides into glucose and fructose Eg. Maltase breaks down maltose into 2 glucose molecules

Breakdown of Lipids (Fats) Lipase: Lipid digesting enzymes released by the pancreas. Two types of Lipase -Pancreatic lipase: -Cholesterol lipase:

Breakdown of Lipids (Fats) Lipase: Lipid digesting enzymes released by the pancreas. Two types of Lipase -Pancreatic lipase: breaks down triglycerides into fatty acids and glycerol -Cholesterol lipase: breaks off one fatty acid and converts it into cholesterol

Liver and Gall Bladder Liver: Has three functions related to digestion 1) Create bile salts 2) Storage of nutrients 3) Breakdown of toxins

Bile Salts Location of Bile Salts: Formed in the liver and collected in the Gall bladder where the excess water is removed (becomes more concentrated). They enter the duodenum via the bile duct.

Controlling the release of Bile Salts 1) Fats present in the small intestine 2) Fats cause the release of Cholecystokinin (CCK) a hormone.

Controlling the release of Bile Salts 1) Fats present in the small intestine 2) Fats cause the release of Cholecystokinin (CCK) a hormone. 3) CCK moves into blood 4) Blood reaches gall bladder 5) Here CCK triggers the release of bile salts from the gall bladder to the small intestine

Controlling the release of Bile Salts 1) Fats present in the small intestine 2) Fats cause the release of Cholecystokinin (CCK) a hormone. 3) CCK moves into blood 4) Blood reaches gall bladder 5) Here CCK triggers the release of bile salts from the gall bladder to the small intestine 6) Once in the small intestine the bile salts break down the large fat droplets into smaller drops (just like dish soap) = emulsification 7) This leaves a larger surface for pancreatic lipase to get at the fat

Gallstones and jaundice

Liver as a Storage organ Storage in Liver: Stores glycogen and vitamins (A, B 12, D) Breakdown of Toxins: Breaks down harmful substances into less harmful chemicals that can be dissolved into blood and excreted in urine. This process does damage liver tissue Eg. alcohol

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Problems with Detoxification Problem with detoxification: The liver cells that are damaged when they try to breakdown toxins are replaced by connective tissue and fat. = Erode the liver you lose the cells that perform functions needed by the body This leads to Cirrhosis

Diagnostic Questions • Symptom: