PHIS 206 1st Edition Lecture 26 Outline of Last Lecture I GI Tract and Homeostasis II Anatomy III Function of the Digestive System IV Wall of the GI Tube V Differences in the Gut Wall VI Hepatic Portal System VII Motility VIII Secretion IX Digestion X Absorption XI Regulation Stimuli XII Stimuli Receptors Outline of Current Lecture I Oral Cavity II Chewing Chewing Reflex III Saliva Salivary Glands IV Stimulation of salivary Secretion V Control of Salivary Secretion VI Pharynx and Esophagus VII Swallowing VIII Esophageal Phase IX Stomach Stomach Anatomy X Motility Filling XI Motility Stomach Peristalsis These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XII XIII XIV XV Gastric Emptying Vomiting Gastric Exocrine Secretions Phases of Gastric Secretion Current Lecture I II III Oral Cavity Anatomy palate roof of mouth pharynx swallowing back of mouth 4 Processes Motility chewing beginning swallowing reflex Secretion saliva Digestion small amount occurs in mouth Absorption NO absorption of nutrients o can absorb some drugs nitroglycerin tablets tablets for heart pain Chewing Chewing Reflex Reduce food size to swallow Increase surface area of food Mix food with saliva saliva helps wet food to create taste Stimulate salivary secretion Stimulate taste buds older people secrete less saliva so they may eat less b c they cannot taste the food Break down cellulose from plant foods have to chew a lot so that you can maximize the amount of nutrients your body can take from the food otherwise it will pass right through you Chewing Reflex pressure when food pushed to top of mouth jaw dropping contracts when stretch receptors are activated Saliva Salivary Glands secretion of mouth keep mouth moist for speech swallowing easier through moisture salivary amylase begins digestions of carbohydrates antibacterial effects wash away debris saliva is a solvent food is the solute stimulate of taste buds will occur saliva will aid in neutralizing acids Salivary Glands sublingual gland saliva more watery than submandibular gland glands secrete different versions of saliva IV V Stimulation of Salivary Secretion Mechanical actually chewing the food particle Chemical acidic chemicals remember saliva neutralizes the acids Neural autonomic nervous system remember Pavlov s dogs involuntary secretion of saliva when seeing the pice of meat Sympathetic and Parasympathetic Nervous Systems BOTH stimulate salivary secretion Control of Salivary Secretion completely neural VI Pharynx and Esophagus Motility swallowing Secretion Mucus Digestion NONE Absorption NONE VII Swallowing Anatomical oropharyngeal mouth pharynx v esopharyngeal esophagus Functional voluntary v involuntary VIII Esophageal Phase Skeletal muscle above bolus ONLY Food enters esophagus the upper esophageal sphincter closes to prevent reflux Peristaltic waves pushes food down esophagus Wave opens gastroesophageal sphincter to allow entrance to the stomach gastroesophageal sphincter closes again IX Stomach Stomach Anatomy Stomach Anatomy fundus and above most food storage antrum thicker muscle force greater 4 Processes Motility filling receptive relaxation peristalsis Secretion HCl enzymes mucus Digestion protein carbohydrates Absorption alcohol aspirin NO food X Motility Filling can change 20 fold in volume with little change in pressure receptive relaxation stomach relaxes when it receives food discomfort when over 1 L of food XI Motility Stomach Peristalsis stomach activity 3 min antrum thicker muscle force is greater XII Gastric Emptying Gastric Factors Volume of chyme Chyme fluidity Duodenal Factors Presence of fat Presence of acid Hypertonicity Distention XIII Vomiting Upper GI will be completely relaxed Force from diaphragm and abdominal muscles Touch back of throat irritate dizziness emotion XIV Gastric Exocrine Secretions Goblet cells Mucus protective Chief cells Pepsinogen Parietal cells Hydrochloric acid HCl Activates pepsinogen Antimicrobial action Breaks down connective tissue and muscle fibers From carbon dioxide in blood XV Phases of Gastric Secretion Cephalic seeing smelling tasting chewing and swallowing food Gastric food reaches the stomach Intestinal food reaches the duodenum
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