Digestive System Organs Alimentary canal continuous muscular tube starts in mouth and is continuous mouth pharynx stomach esophagus small intestine large intestine and exits through anus usually unidirectional except when sick and vomit our body is basically wrapped around this tube and so the only thing from the food that goes inside our body is the nutrients we absorb and the rest stays in the tube Accessory organs teeth tongue liver pancreas gallbladder salivary glands Actions Ingestion Actions Ingestion Propulsion Deglutition Peristalsis Actions Ingestion Propulsion Deglutition Peristalsis Mechanical digestion Mastication Mixing Segmentation Actions Ingestion Propulsion Deglutition Peristalsis Mechanical digestion Mastication Mixing Segmentation Chemical digestion Actions Ingestion Propulsion Deglutition Peristalsis Mechanical digestion Mastication Mixing Segmentation Chemical digestion Absorption Actions Ingestion Propulsion Deglutition Peristalsis Mechanical digestion Mastication Mixing Segmentation Chemical digestion Absorption Defecation Control Sensors mechanical and chemical are detectors that can evoke nervous activity Nerve plexuses short nerve plexuses located solely in digestive tract also long ones can detect stretch osmolarity pH presence of certain molecules response is to initiate certain reflexes stimulation of smooth muscle can cause contraction can activate glandular secretions sensors can stimulate hormonal secretion Hormones Mesentary Tunics Mucosa layer closest to the lumin predom epithelial tissue usually simple columnar secretes mucous and has glands assoc with it that can secrete many things like mucous enzymes and hormones function absorption and protection Submucosa dense conn tissue where blood vessels and lymphatic vessels are located nerves run through Muscularis externa smooth muscle 2 layers circular and longitudinal one will change diameter of lumin and the other will shorten the canal Serosa outer layer visceral layer of the peritoneal inflammation peritonitis one reason could be damage to appendix Enteric Neurons completely within the digestive tract Submucosal nerve plexus involved in stimulating glands to release glandular secretions Myenteric nerve plexus located between 2 muscle layers cause muscle contraction and motility Oral Buccal Cavity Palate Oral Buccal Cavity Palate Tongue Oral Buccal Cavity Palate Tongue Papillae has filiform give it texture and fungiform major taste buds and circumvallet taste buds or contain taste buds line back of toingue Oral Buccal Cavity Palate Tongue Papillae Salivary glands secrete saliva Saliva Water 97 99 Electrolytes Amylase enzyme Mucin mucous Lysosome immune function IgA immune function Metabolic wastes Anatomy Joke of the Day Oral Buccal Cavity Palate Tongue Papillae Salivary glands Teeth tremendously imp for the mastication process human beings have 2 types of teeth primary baby teeth 20 primary teeth replaced by permament teeth 32 of these Tooth Structure Pharynx Esophagus Upper esophageal Gastroesophageal sphincter sphincter Deglutition Food compacted into bolus Buccal phase vol swallowing Tip of tongue is placed against hard Tongue contracts to force bolus into palate oropharynx Bolus stimulates tactile pressure receptors stimulates invol portion Pharyngeal esophageal phase Tactile receptors stimulate medulla and Motor impulses sent to muscles Peristalsis moves bolus toward pons stomach Stomach Stomach Cells Goblet cells Stomach Cells Goblet cells Mucous neck cells Stomach Cells Goblet cells Mucous neck cells Parietal cells Stomach Cells Goblet cells Mucous neck cells Parietal cells Chief cells Stomach Cells Goblet cells Mucous neck cells Parietal cells Chief cells Enteroendocrine cells Gastric Secretion Cephalic reflex phase happens before food even gets there condition reflex Gastric Secretion Cephalic reflex phase Gastric phase once food makes way into stomach stomach stretches and sends signal to brain and brain sends signal back to stomach and causes production of Ach Gastric Secretion Cephalic reflex phase Gastric phase Intestinal phase as things start to leave stomach and move into the inestines there is an excitatory component stomach activity stimulated eventually stops and continued release finally causes signal to brain shut off PNS and SNS Mucosal Barrier Bicarbonate rich mucus Tight junctions in mucosal epithelium prevent leakage HCl impermeable plasma membranes in gastric gland cells Undifferentiated stem cells at junction of gastric pits and gastric glands so constantly replacing cells so they aren t exposed to the acids for a long period of time Gastric Filling Receptive relaxation before food arrives in stomach the stomach relaxes Adaptive relaxation stomach continues to relax once food arrives Gastric Contraction Basic electrical rhythm Interstitial cells of Cajal Gastric Emptying Chyme enters duodenum first portion of small intestine Stretch and chemoreceptors activated Enterogastric or enterogastone produce hormones that inhibit gastric activity reflexes initiated Gastric activity reduced Pyloric contractions reduced Duodenal filling stopped Small Intestine Subdivisions Duodenum Subdivisions Duodenum Jejunum Subdivisions Duodenum Jejunum Ileum Structural Modifications Length Structural Modifications Length Plicae circulares Structural Modifications Length Plicae circulares Villi Structural Modifications Length Plicae circulares Villi Microvilli Liver Produces bile Bile Water Bile salts Bile pigments Bilirubin Urobilinogen Cholesterol Neutral fats Phospholipids Electrolytes Lobes Right Left Caudate Quadrate Falciform ligament Ducts Common hepatic duct Bile duct Gallbladder Stores bile Concentrates bile Anatomy Joke of the Day Bile Storage Hepatopancreatic sphincter closed when not digesting Liver continually produces bile Bile backs up cystic duct Bile Release Fatty chyme entering duodenum stimulates production of cholecystokinin CCK causes parasympathetic impulses to promote gallbladder contraction CCK also relaxes hepatopancreatic sphincter Pancreas Produces pancreatic juice Pancreatic Juice Water Enzymes Bicarbonate Protease Enzymes Trypsin Trypsinogen Enterokinase Carboxypeptidase Procarboxypeptidase Trypsin Chymotrypsin Chymotrypsinogen Trypsin Other Enzymes Amylase Lipase Nucleases Control of Pancreatic Secretion Secretin CCK Parasympathetic impulses Emptying Gastroileal reflex Gastrin Pressure Anatomy Haustra Anatomy Haustra Taenia coli Anatomy Haustra Taenia coli