Digestive system

Subdecks (1)

Cards (528)

  • Digestive canal
    A continuous tube that extends through the thoracic and abdominal cavities from the esophagus to the anus
  • Organs of the digestive canal
    • Esophagus
    • Stomach
    • Small intestine
    • Large intestine
    • Anal canal
  • Accessory digestive organs
    • Mouth
    • Teeth
    • Tongue
    • Salivary glands
    • Pharynx
    • Liver
    • Gallbladder
    • Pancreas
  • Digestive canal
    • Length is about 5-7 meters in a living person
    • Length is about 7-9 meters in a cadaver
  • Functions of the digestive system
    1. Ingestion
    2. Secretion
    3. Mixing and propulsion
    4. Digestion
    5. Absorption
    6. Defecation
  • Ingestion
    Taking food and liquids into the mouth (eating)
  • Secretion
    Cells within the walls of the digestive canal and accessory digestive organs secrete water, acid, buffers, and enzymes into the lumen of the digestive canal
  • Motility
    The capability of the digestive canal to mix and move material along its length
  • Mechanical digestion
    The teeth cut and grind food before it is swallowed, and smooth muscles of the stomach and small intestine churn the food
  • Chemical digestion
    Large carbohydrate, lipid, protein, and nucleic acid molecules in food are split into smaller molecules by hydrolysis catalyzed by digestive enzymes
  • Absorption
    The movement of the products of digestion from the lumen of the digestive canal into blood plasma or lymph plasma
  • Defecation
    Wastes, indigestible substances, bacteria, cells, and unabsorbed digested materials leave the body through the anus
  • The wall of the digestive canal has four layers: mucosa, submucosa, muscular layer, and serosa/adventitia
  • Mucosa
    The inner lining of the digestive canal, composed of epithelium, lamina propria, and muscularis mucosae
  • Submucosa
    Areolar connective tissue that binds the mucosa to the muscularis, containing blood/lymphatic vessels and the submucosal neural plexus
  • Muscular layer

    Contains an inner circular muscle layer and an outer longitudinal muscle layer, responsible for involuntary contractions that break down food and propel it along the canal
  • Serosa
    The superficial layer of the digestive canal suspended in the abdominal cavity, composed of areolar connective tissue and simple squamous epithelium
  • Enteric nervous system (ENS)

    The intrinsic set of nerves that regulate the digestive canal, consisting of the myenteric and submucosal neural plexuses
  • Myenteric neural plexus
    • Located between the longitudinal and circular smooth muscle layers, controls digestive canal motility
    • Contains motor, sensory, and interneurons
  • Submucosal neural plexus
    • Located within the submucosa, controls secretions of the digestive canal organs
    • Contains motor, sensory, and interneurons
  • Muscular layer of the mouth, pharynx, and superior and middle parts of the esophagus

    • Contains skeletal muscle that produces voluntary swallowing
    • Skeletal muscle also forms the external anal sphincter, which permits voluntary control of defecation
  • Muscular layer of the rest of the digestive canal

    • Consists of smooth muscle that is generally found in two sheets: an inner sheet of circular fibers and an outer sheet of longitudinal fibers
    • Involuntary contractions of the smooth muscle help break down food, mix it with digestive secretions, and propel it along the digestive canal
  • Serosa
    • A superficial layer on portions of the digestive canal that are suspended in the abdominal cavity
    • Serous membrane composed of areolar connective tissue and simple squamous epithelium (mesothelium)
    • Also called the visceral peritoneum
  • The esophagus lacks a serosa; instead, only a single layer of areolar connective tissue called the adventitia forms the superficial layer of this organ
  • Enteric nervous system
    Consists of neurons arranged into the myenteric and submucosal neural plexuses
  • Myenteric neural plexus
    One of the neural plexuses of the enteric nervous system
  • Submucosal neural plexus
    One of the neural plexuses of the enteric nervous system
  • The enteric nervous system is regulated by the autonomic nervous system
  • Digestive canal reflex pathway
    Involves sensory receptors, sensory neurons, and neurons in the enteric, autonomic, and central nervous systems that regulate digestive canal secretion and motility
  • Peritoneum
    The largest serous membrane of the body, consisting of a layer of simple squamous epithelium (mesothelium) with an underlying supporting layer of areolar connective tissue
  • Parietal peritoneum
    Lines the wall of the abdominal cavity
  • Visceral peritoneum
    Covers some of the organs in the abdominal cavity and is their serosa
  • Peritoneal cavity
    The slim space containing lubricating serous fluid that is between the parietal and visceral portions of the peritoneum
  • Ascites
    Condition where the peritoneal cavity becomes distended by the accumulation of several liters of fluid
  • Retroperitoneal
    Organs that lie on the posterior abdominal wall and are covered by peritoneum only on their anterior surfaces, not in the peritoneal cavity
  • Major peritoneal folds
    • Greater omentum
    • Falciform ligament
    • Lesser omentum
    • Mesentery
    • Mesocolon
  • Greater omentum
    • The longest peritoneal fold, drapes over the transverse colon and coils of the small intestine “fatty apron”
    • A double sheet that folds back on itself, giving it a total of four layers
    • Contains a considerable amount of adipose tissue
  • Falciform ligament
    Attaches the liver to the anterior abdominal wall and diaphragm
  • Lesser omentum
    Arises as an anterior fold in the serosa of the stomach and duodenum, and connects the stomach and duodenum to the liver
  • Mesentery
    A fan-shaped fold of the peritoneum that binds the jejunum and ileum of the small intestine to the posterior abdominal wall