Digestive System

Digestive System

1. Functions

   • Ingestion
   • Digestion
     • Breakdown of food
     • Secretion
       • Exocrine
         • Do not enter blood
       • Endocrine
         • enters blood
       • Motility
         • Segmentation
           • Mixing
         • Peristalsis
           • Wave movement
   • Absorption
     • Transport into circulation
   • Storage and elimination
     • Processes and digest food

2. Organization

   • Two components
     • Digestive tract
       • Stomach
       • Intestines
     • Accessory Organs
       • Liver
       • Pancreas
       • Gallbladder
       • Salivary glands

3. Oral Cavity

   • Tongue, teeth and salivary glands
   • Mastication
     • Mixes food with saliva
   • Saliva
     • Chemical digestion (amylase) lubrication ,antibacterial
   • Deglutition
     • Swallowing
       • Medulla Oblongata
         • Coordinates process
     • Buccal Phase
       • Bolus formation and movement
     • Pharyngeal Phase
       • Movement of uvula to close off nasopharynx
       • Elevation of epiglottis
       • Reflection of glottis
       • Closure of glottis
     • Esophageal phase
       • Opening of upper esophageal sphincter
         • Peristalsis
       • Opening of lower esophageal sphincter

4. Esophagus

   • Connects pharynx to stomach
     • Muscular Externa
       • Upper 3rd
         • Skeletal muscle
         • Middle 3rd
           • Muscles of skeletal & smooth
           • Terminal portion
             • Smooth
     • Passes through diaphragm via esophageal hiatus
     • Sphincter: UES and LES
   • Peristalsis
     • Propels food thru GI tract
     • GERD

5. Stomach

   • Most distensible part of the GI tract
     • Empties into intestines
   • Function
     • Food storage
     • Absorption of NSAIDS and alcohol
     • Protein digestion
     • Bacteriostatic
     • Moves food (chyme) into intestines
   • Regions
     • Cardia
     • Fundus
     • Body
     • Pylorus
   • Organization of stomach Mucosa
     • Gastric pits
     • Gastric glands 4 types
       • Exocrine Function
         • Mucus cells
         • Chief cells
           • Manufacture inactive pepsinogen
         • Parietal cells
           • produce HCL and Inssintrcit factor
           • Activate Pepsinogen
           • Denature protein ,exposing peptide bonds
       • Endocrine Function
         • Somatostatin
           • Inhibits gastric function
         • Gastrin
           • Stimulates production of HCL acid production
         • Ghrelin
           • Hormone that stimulates appetite
         • Histamine
           • Stimulates acid production