Digestive system

Digestive system

1. Oral cavity

   • Structures
     • Tongue
     • Soft and hard palate
     • Salivary gland
     • Uvula
       • Prevent food entering early
     • Teeth
   • Functions
     • Sensory analysis
     • Mechanical processing
     • Lubrication
     • Initial digestion (carb +lipids)

2. Pharynx

   • Structure
     • 3 sections
       • Nasopharynx
       • Oropharynx
       • Laryngopharynx
     • Stratified squamous epithelium
       • Mucous glands: lubrication
     • Pharyngeal constrictor mucles
   • Functions
     • Passageway for food + air
     • Muscular propulsion into oesphagus

3. Oesophagus

   • Structures
     • Smooth muscles
     • 25cn long, 2cm wide
     • Upper and lower oesophageal sphincter
   • Functions
     • Transport foods into stomach

4. Stomach

   • Structures
     • 4 regions
       • 1. cardia
       • 2. Fundus
       • 3. Body
       • Pylorus
     • Epithelium lining
       • Parietal cell: intrinsic factor + HCL
       • Chief cell: pepsinogen
     • Pyloric sphincter: release chyme into intestine
   • Functions
     • Mechanical processing
     • Chemical breakdown (acid_enzyme)
     • Store ingested food
     • Glycoprotein synthesis (B12 ab)

5. Small intestine

   • Structures
     • 3 regions
       • 3.Ileum
       • 2.Jejunum
       • 1.Duodenum
     • Villi
   • Functions:
     • Enzymatic digestion
     • Mostly ABSORPTION

6. Large intestine

   • Structures
     • 3 parts
       • 1. Cecum
       • 2. Colon
         • Descending
         • Transverse
         • Ascending
       • 3. Rectum
         • internal anal sphincters
           • involuntary control
         • external anal sphincter
           • voluntary control
     • Intestinal wall
       • Smooth muscles
       • Microvilli (absorptive)
       • Goblet cell (mucus secretion
   • Functions
     • Water reabsorption
     • Compaction of indigested materials
     • Temporary storage for faecal matter