digestive (PowerPoint) by liamei12345

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									Digestive System
     Function:
             to obtain nutrients




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 Digestive System
         Function: obtaining nutrients

Activities of Digestion system:
    • Ingestion – taking food or liquid into the mouth (eating or
    drinking).
    • Movements
         •Peristaltic and Segmentation
    • Digestion
         •Mechanical
             • mastication
             • churning
         • Chemical
             •Enzymes and acids
    •Absorption – movement of substances into the body (across
    epithelium).
    • Elimination – involves compaction to eliminate waste from body
The Digestive System
  Layers of Gastrointestinal Tract

• Four layers:
   – Know layers and their
     composition
• Tunic mucosa                                 QuickTime™ and a
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   – Epithelial
   – Propria
   – Muscularis mucosae
• Tunic submucosa
• Tunica muscularis externa
• Tunica serosa-visceral peritoneum
                Tunic Mucosa
•Lines digestive tract
•Moistened by glandular secretions
•Simple or stratified depending on area of tract
•Pleated for expansion (Surface Area)




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1. Tunic Mucosa

        A Mucous membrane                               QuickTime™ and a
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               1) Epithelium
               2) Lamina propria
               3) Muscularis mucosae




2. Tunic Submucosa
      •Areolar Connective Tissue                QuickTime™ and a
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      •May have glands
             Muscularis Mucosa


Smooth muscle layer capable of plasticity
   Ability to tolerate stretching
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Visceral smooth muscle
 3. Tunica Muscularis Externa
           Smooth muscle layers

               1) Inner Circular Layer                  QuickTime™ and a
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               2) Outer Longitudinal Layer




4. Tunica Serosa (or Adventitia*)
   Serous membrane – visceral peritoneum

   * Name depends on location:                                QuickTime™ and a
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   a) Inside peritoneal cavity = serosa
   b) Outside peritoneal cavity = adventitia
Histology of the G.I. Tract
                   Serous Membranes


The Peritoneum: Two layers
    Visceral peritoneum (a.k.a serosa)
    Parietal peritoneum
        Lines inner surfaces of body wall



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Mesenteries: Fused double sheets of
peritoneal membrane – to suspend portions of
digestive tract:
     Greater omentum
     Lesser omentum
     Mesentery proper
     Transverse mesocolon
     Sigmoid mesocolon
Retroperitoneal Structures – these are attached to posterior abdominal wall

    Ascending colon
    Descending colon
    Duodenum
    Pancreas
             Salivary glands

• Parotid
• Sublingual
• Submandibular


  – Slightly different secretions
  – Release enzymes - amylase
  – Lubrication oral cavity
Fig
25.6
                             Fig
                             25.7

Only example of
gomphosis joint
Incisors -clipping/cutting
Canines -tearing/slashing
Premolars - mashing/grinding
Molars mashing/grinding
                                                       Teeth

Regions:
Crown
Neck                      QuickTime™ and a
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Layers:
Enamel
Dentin
Pulp Cavity with Pulp
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Apical foramen
Root canal
Periodontal membrane
              Voluntary
              control

Pharynx and
Esophagus


Deglutition
Swallowing


Epiglottis
closes over
larynx
Tunica       Fig
muscularis   25.11
has three      Tunica
layers of      mucosa
muscle         has folds,
               rugae
               when
               empty
        Histology of Gastric glands
             Chief - Pepsinogen; Parietal - HCl; Neck/Mucous Cells




Secretin and cholecystokinin
    Inhibit gastric secretion
  Small Intestine
     Duodenum
            Jejunum
                     Ileum

Increase Surface Area for Absorption
  Plicae Circulares
  Intestinal villi
  Microvilli

     Lacteal (terminal lymphatic)
     for lipid absorption

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      Goblet cells
      Stem cells
Diagrammatic view highlighting the distinguishing
features of each region of the small intestine.
Duodenum:
       Duodenal (Brunner’s) glands produce:
          •secretin
          •CCK
          •Alkaline mucus
Ilieum: lymphatic aggregations (Peyer’s patches)
   Secretin


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          CCK


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Large intestine

Functions of large intestine
   Reabsorb water and compact feces
   Absorb vitamins
   Store fecal matter
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Cecum
   Ileocecal valve
   Collects material from small intestine
   Vermiform appendix
Colon - ascending, transverse, descending and sigmoid
Rectum
                         Histology of Large Intestine




Large Intestine:
Lack of villi
Abundance of goblet cells
Mucous-secreting intestinal glands
Muscularis reduced to Taenia coli
Fatty appendices
Rectum and Anal canal
           Other digestive organs

Horizontal section through the upper abdomen showing the position of the liver relative to other
visceral organs.
Liver
                          Bile Ducts




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Diagrammatic view of lobular organization.
Pancreas
EtOH on Liver


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Pancreas
                               Pancreas
Exocrine: acini
Endocrine:
         Pancreatic islets
         Isles of Langerhans

								
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