DIGESTIVE SYSTEM Through stomach

Overall Digestive Process Ingestion Movement Digestion (mechanical & chemical) Absorption (into blood/lymph vessels) Elimination = Defecation

GI Organization Digestive tract = canal Gastrointestinal tract Alimentary canal Accessory Structures – outside of the tract

Microstructure - general Mucosa – Mucous membrane – May have villi and microvilli Submucosa – Very vascular Muscularis Serosa = Visceral Peritoneum

Peritoneum Parietal peritoneum Visceral peritoneum Peritoneal cavity

Folds of Peritoneum Binds organs together, anchors them, suspends vessels Mesentery proper (SI-Dorsal BW) Mesocolon & Mesorectum (LI-Dorsal BW Falciform ligament (Li-Ventral BW) Lesser omentum (Lesser curvature/duodenum-Li) Greater omentum (Greater curvature-Dorsal BS

Oral Cavity Labia Labial frenulum Hard palate Soft palate – Uvula

Tongue (accessory) Glosso- Lingu- Skeletal muscle covered by mucous membrane Lingual frenulum

Tongue Papillae Taste Zones – Sweet, Salt – Sour, Bitter Function – Bolus formation

Salivary Glands (accessory) Parotid Submandibular Sublingual

Saliva 1-1 ½ liters/day 99% water Mucins Amylase Lysozyme – anti-microbial

Saliva Secretion Controls Nervous System – Medulla oblongata & Pons ANS Smell, thought, sight, irritation Dehydration, Fear

Teeth (accessory) Gingivae Crown Root Neck

Tooth Components Periodontal ligament Dentin Pulp cavity & pulp Apical foramen Enamel Cementum

Teeth Deciduous – 20 Permanent - 32

Teeth - shape Incisor Canine Premolar Molar

Dental Terminology Labial Buccal Lingual Palatal Occlusal

Digestion in Oral Cavity Ingestion Mastication Chemical digestion Deglutition

Pharynx Already did under Respiratory

Esophagus Hiatus Sphincters Function – Peristalsis – Heartburn is actually esophageal “burn”

Stomach (gastric) Anatomy – Cardia – Fundus – Body – Pylorus and Pyloric Sphincter – Greater Curvature – Lesser Curvature

Digestion in Stomach Stores food Chyme Motility, Mixing & Emptying Peristalsis To Pyloric Sphincter, to Duodenum Pacemaker cells make smooth muscle contract about 3x/minute when food present

Controls of Stomach Motility 2-6 hours to empty Controls include volume & distention GASTRIN – Hormone released by pyloric cells in response to distention. Stimulates gastric motility. – Caffeine stimulates gastrin release

Controls of Stomach Motility ENTEROGASTRIC REFLEX – As duodenum distends, it inhibits gastric motility SECRETIN CHOLECYSTOKININ GASTRIC INIHIBITORY PEPTIDE

Gastric Secretion “Juice” Zymogenic Cells make Pepsinogen Parietal Cells make HCl – Alkaline blood following a meal Mucus Cells make protective mucus

Controls of Stomach Secretion GASTRIN Cephalic, Gastric & Intestinal phase of seeing and eating food ENTEROGASTRIC REFLEX GIP, CHOLECYSTOKININ, SECRETIN

Stomach Physiology Very little absorption