Week 6 - Digestive System

Week 6 - Digestive System

1. Function

   • Ingestion
     • E.g Oral Cavity
   • Movement
     • Eg. Muscles
   • Secretion
     • Eg. Saliva Gland
   • Digestion
     • Eg Enzymes
   • Absorption
     • Eg. Intestines
   • Excretion
     • Eg. Anus
   • Control
     • Eg. Nerves
   • Protection
     • Eg. from stomach acid
   • Defence
     • Eg. Immune System
   • Repair
     • E.g In the stomach
   • Storage
     • E.g Liver Stomach

2. Parts of the Digestion system

   • The Oral Cavity
     • Saliva Glands/Ducts
       • Sec. serous fluid = Amalase (breaks carbs) + mucus (protect + lube) + water
         • Submandibular
         • Paratoid
         • Sublingual
     • Teeth
       • For mechanical digest. Break food to bolus
     • Tounge
       • Mix saliva into bolus. Made of Skel. Musc - (vol.). 3D movement - fibers all direct.
         • Musc lined by CT, lined by St.Sq.E
     • Basic Gut tube
       • 4 Layers
         • 1. Mucosa
           • 1. E, 2. CT, 3. M
         • 2. Sub-mucosa
           • CT - Blood Sup.
         • 3. Muscularis
           • 1. Inner Circ, 2. Outer longitudinal
         • 4. Serosa
           • 1. CT 2.E
       • The Oesophagus - mouth →stomach
         • 1. Mucosa
           • st.sq.E - protect if bolus large or hot + CT
         • 2. Sub-mucosa
           • CT- loosely arranged = expansion
         • 3. Muscularis
           • Top 1/3 = Sk. Musc, Bot 1/3= Sm. Musc (circ+long)
         • 4. Adventitia
           • No epithlium
         • Stomach
           • Lower Osephageal Sph + Phylloric Sph.
           • Rugae - folding of walls - plastic bag
           • 3 layers
             • 1. Mucosa
               • 1. E, 2. CT, 2. SmM
             • 2. Submucosa
             • 3. Muscularis
               • 1. Oblique (3D mixing), 2. Inner Circ, 3. Outer long
           • Chief cell - Sec Pepsinogen
             • Parietal cell - Sec HCl
               • Combine to make Pepsin - breaks down proteins
                 • Gastric Glands - Sec Gastric juice. Mucous/Goblet cells - Sec Alkaline Mucus
           • Undifferntiated cells repair
           • Small Intestine
             • 3 Sections
               • Duodenom
                 • Chemical Digest
               • Jujunum
                 • Absorb
               • Ileum
                 • Tidy up
               • 1. Mucosa
                 • 2. Sub-mucosa
                   • 3. Muscularis
                     • 4. Serosa
             • Function - ↑SA
               • Absorption
                 • Fats - lacteal
                 • Carb/prot/water - capilliers - go to liver
               • Circ. folds mucosa
               • Villi + Microvilli
               • Secretion
                 • s.Col.E on villi surface sec. lipase - lipid digest.

3. Mechanical - Teeth chewing

4. Chemical - Enzymes breaking