Chapter 3- Physiology of Digestion

Chapter 3- Physiology of Digestion - Chapter 3: Physiology...

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Chapter 3: Physiology of Digestion  18:50 Functional Organization of the Digestive System  4 processes that get nutrients into the body Motility  Process of moving food through the gut and breaking it up into small particles  Gut  has two types of muscles 1.  Circular bands of muscles ringing the  GI tract Digestive system and its accessory organs  Breaks down complex foods into simple components and absorbs these nutrients into  the body 2.  Longitudinal muscles running along it Muscles  have 2 kinds of contractions 1. Peristalsis Rhythmic contraction of circular muscles surrounding the gut in such a way as to move  food forward Pushes food and digestive juices  (chyme)   Bolus Mass of food in the gut  2.    Segmentation  contraction of muscles surrounding the gut in such a way as to mix it with GI secretions  Mixes food with digestive secretions and breaks up the bolus more  Factors that affect gut motility Nerves transmit signals to the gut
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Stress  can cause diarrhea Caffeine   Increase motility  Pregnancy Women experience  constipation  because the smooth muscles that cause peristalsis  are relaxed Laxatives Stimulate peristalsis  When person stops using them though, they develop rebound constipation  Sphincters Rings of muscles that act as valves, blocking or restricting flow   Keeps strong stomach acid out of the  esophagus  (connects the mouth and stomach) Gastric  Reflux  (heartburn) When sphincter fails to do its job Pyloric Sphincter Valve controlling the flow of chime from the stomach to the small intestine  Ileocecal Valve Valve separating the ileum from the colon  Anal Sphincter Retains wastes in the  rectum  (final organ of the digestive tract) until we are ready to  defecate  Secretion Synthesis and release of substances by cells in response to stimuli 
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Moisten and lubricate foods to help it pass smoothly through the gut  Hydrochloric acid Kills some of the bacteria that enter the gut with food so the immune system has less to  fight against  Denatures  protein Changes it shape and opens it up to digestion by enzymes 
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This note was uploaded on 03/14/2012 for the course NUTRI 132 taught by Professor Anderson during the Fall '11 term at Wisconsin.

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Chapter 3- Physiology of Digestion - Chapter 3: Physiology...

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