Digestion Slides 3 PDF

Lymphatic System “Second” circulatory system Open system (not a closed loop) No pump (ie heart) water can go out, nutrients but red blood cells stay Flows via muscle contraction Carries lymph pump with muscle contraction – P...

Lymphatic System “Second” circulatory system Open system (not a closed loop) No pump (ie heart) water can go out, nutrients but red blood cells stay Flows via muscle contraction Carries lymph pump with muscle contraction – Plasma (watery part of blood) – Interstitial fluid (water that surrounds cells in tissue)  Lymph created when fluid (plasma) leaves blood & enters cells Fluid then leaves cells (cytosol) to space between cells Fluid in between cells (interstitial fluid) drains into lymphatic system 85% reabsorbed by circulatory system 15% dumped back into blood at subclavian veins being soaked by lymphatic system lacteal absorbs water and oils  Lacteals Fatty acids & glycerol absorbed by lacteals (aka lymph capillaries) Merge to form lymphatic vessels Merges into larger vessel, the thoracic duct fluid with fattty Lymph = interstitial fluid circulated by muscular contraction lymphatic system in guts  Hormones Chemical signals Created by glands in the body Signal another part of the body Usually travel via the blood stream Ex: testosterone, insulin, growth hormone  Food in stomach -> stomach secretes gastrin Gastrin signals stomach to create gastric juices Chyme reaches duodenum, pancreas is signaled to secrete juices Fat reaches duodenum -> Cholecystokinin (CCK) release -> gall bladder releases bile CCK also slows down chyme release – Allows for complete digestion of food  Four Accessory Organs Organs that secrete chemicals into the digestive tract 1. The Salivary Gland 2. The Pancreas 3. The Liver 4. The Gallbladder  1. Salivary Gland Cleanse teeth Lubricates food Dissolves certain molecules so food can be tasted Amylase digests polysaccharides into disaccharides (ex. starch into maltose)  2. Pancreas Endocrine function (secrete into blood) – Insulin and glucagon – Regulate blood glucose Exocrine function (secrete into ducts & to the outside of the organ) – Sodium bicarbonate: neutralizes acid – Pancreatic amylase: starch digestion – Trypsin: protein digestion – Lipase: fat digestion  3. Liver Largest gland in the body Lobules are the structural & functional units  3. Liver Function 1. Breaks down blood pigment for excretion 2. Makes bile and stored in gallbladder 3. Converts glucose to glycogen 4. Turns fats and amino acids to glucose for energy  3. Liver Function 5. Combines CO2 with ammonia to make urea 6. Makes blood (plasma) proteins 7. Detoxifies poisonous substances in blood 8. Removes and stores iron and vit. A, D, E, K, and B12 9. Regulates cholesterol Hepatic Portal System  4. Gall Bladder Stores excess bile Secreted through common bile duct Bile salt can precipitate out of solution – Forms crystals – Can become gall stones – Obstructive jaundice  Digestive Enzymes Digestive Enzymes – Proteins with a particular shape that fits their substrate. – Have an optimum pH which maintains their shape – Break down carbohydrates, proteins, nucleic acids, and fats  Salivary Amylase – Catalyzes the reaction: Starch+ H2O à Maltose Occurs in the mouth Maltose must be broken down to glucose for absorption Pepsin – Catalyzes the reaction: Protein + H2O à Peptides Pepsinogen activated to pepsin by pH