TAILIEUCHUNG - Lecture Human anatomy and physiology - Chapter 23: The digestive system (part a)
The main contents of chapter 23 part a include all of the following: Digestive system, digestive processes, GI tract regulatory mechanisms, esophagus, esophagus, digestive processes: mouth, deglutition, stomach: gross anatomy, stomach: microscopic anatomy,. | 23 The Digestive System: Part A Digestive System Two groups of organs Alimentary canal (gastrointestinal or GI tract) Digests and absorbs food Mouth, pharynx, esophagus, stomach, small intestine, and large intestine Digestive System Accessory digestive organs Teeth, tongue, gallbladder Digestive glands Salivary glands Liver pancreas Figure Mouth (oral cavity) Tongue Esophagus Liver Gallbladder Anus Duodenum Jejunum Ileum Small intestine Parotid gland Sublingual gland Submandibular gland Salivary glands Pharynx Stomach Pancreas (Spleen) Transverse colon Descending colon Ascending colon Cecum Sigmoid colon Rectum Vermiform appendix Anal canal Large intestine Digestive Processes Six essential activities Ingestion Propulsion Mechanical digestion Chemical digestion Absorption Defecation Figure Food Ingestion Propulsion Esophagus Stomach Pharynx Mechanical digestion Chemical digestion • Chewing (mouth) • Churning (stomach) • Segmentation (small intestine) Small intestine Large intestine Defecation Anus Feces Blood vessel Lymph vessel Absorption • Swallowing (oropharynx) • Peristalsis (esophagus, stomach, small intestine, large intestine) Mainly H2O Figure From mouth (b) Segmentation: Nonadjacent segments of alimentary tract organs alternately contract and relax, moving the food forward then backward. Food mixing and slow food propulsion occurs. (a) Peristalsis: Adjacent segments of alimentary tract organs alternately contract and relax, which moves food along the tract distally. GI tract regulatory mechanisms Mechanoreceptors and chemoreceptors Respond to stretch, changes in osmolarity and pH, and presence of substrate and end products of digestion Initiate reflexes that Activate or inhibit digestive glands Stimulate smooth muscle to mix and move lumen contents GI tract regulatory mechanisms Intrinsic and extrinsic controls Enteric nerve plexuses (gut brain) initiate short reflexes in response to stimuli in the GI tract Long reflexes in response to stimuli
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