Secretions transit time 24 to 72 hours factors

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Unformatted text preview: Muscularis • Two layers of smooth muscle – Longitudinal layer and circular layer • Mixing of food mass with digestive secretions • Serosa • Secretes fluid that lubricates digestive organs How Do Gastrointestinal Motility and Secretions Facilitate Digestion? Secretions • Transit time • 24 to 72 hours • Factors affecting transit time • Sphincters • Named according to anatomical locations Sphincters Regulate the Flow of Food Food How Do Gastrointestinal Motility and Secretions Facilitate Digestion? Secretions • GI motility • Mixing and propulsion of material • Muscular contractions • Two types of movement • Segmentation – Mixes and propels food • Peristalsis – Vigorous propulsive movements Segmentation Segmentation Peristalsis Peristalsis How Do Gastrointestinal Motility and Secretions Facilitate Digestion? Secretions • GI secretions • Mucus • Protective coating • Digestive enzymes • Biological catalysts • Organs that release digestive secretions Summary of Major GI Secretions Summary How Do Gastrointestinal Motility and Secretions Facilitate Digestion? Secretions • Three regulatory control mechanisms • Neural • Enteric nervous system – Sensory receptors: chemoreceptors & mechanoreceptors • Central nervous system • Hormonal • GI hormones – Influence desire to eat The Major GI Hormones & Their Related Functions Related How Does the GI Tract Coordinate Functions to Optimize Digestion & Nutrient Absorption? Nutrient • Three phases of digestion • Cephalic phase • Before food enters mouth • Gastric phase • Arrival of food in stomach • Intestinal phase How Does the GI Tract Coordinate...
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