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Digestive System - Anatomy & Physiology

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  • Gastrointestinal tract (GI tract)

    The muscular tube through which food passes, starting at the mouth and ending at the anus.

  • Accessory organs of the digestive system

    Salivary glands, liver, gallbladder, and pancreas that produce secretions to aid digestion.

  • Four basic layers of the GI tract

    Mucosa, submucosa, muscularis externa, and serosa or adventitia.

  • Mucosa layer components

    Epithelium, lamina propria, and muscularis mucosae.

  • Types of epithelium in the GI tract mucosa

    Stratified squamous in oral cavity, pharynx, upper esophagus, rectum; simple columnar in lower esophagus, stomach, intestines.

  • Muscularis externa function

    Two smooth muscle layers (circular and longitudinal) responsible for mechanical processing and propulsion of food.

  • Enteric nervous system plexuses

    Myenteric plexus controls motility; submucosal plexus regulates secretions and responds to food presence.

  • Functions of the digestive system

    Ingestion, mechanical processing, propulsion, chemical digestion, secretion, absorption, and compaction.

  • Main digestive hormones

    Gastrin, secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP).

  • Types of lingual papillae with taste buds

    Circumvallate, fungiform, and foliate papillae contain taste buds; filiform papillae do not.

  • Functions of saliva

    Moistens food, cleanses mouth, dissolves chemicals for taste, and begins digestion of carbohydrates and fats.

  • Types of teeth and their functions

    Incisors cut, canines tear, premolars and molars grind and crush food.

  • Pharynx regions and functions

    Nasopharynx (air only), oropharynx and laryngopharynx (food and air passage, lined with stratified squamous epithelium).

  • Esophagus muscle composition

    Upper third skeletal muscle, middle third mixed, lower two-thirds smooth muscle for peristalsis.

  • Stomach regions

    Cardiac, fundus, body, and pyloric regions.

  • Gastric gland cell types

    Chief cells secrete pepsinogen, parietal cells secrete HCl and intrinsic factor, G cells secrete gastrin and other hormones.

  • Small intestine segments

    Duodenum, jejunum, and ileum.

  • Plicae circularis and villi function

    Increase surface area for absorption in the small intestine.

  • Brush border enzymes

    Enzymes like aminopeptidase and maltase that complete digestion of peptides and carbohydrates.

  • Large intestine functions

    Reabsorbs water, absorbs vitamins from bacteria, and stores fecal material.

  • Liver digestive functions

    Filters nutrient-rich blood, regulates cholesterol, removes toxins, and produces bile for fat emulsification.

  • Pancreatic juice components

    Sodium bicarbonate, pancreatic proteases, amylase, lipases, and nucleases.

  • Gallbladder function

    Stores and concentrates bile, releasing it into the duodenum when stimulated by CCK.

  • Common bile duct

    Formed by the union of the common hepatic duct and cystic duct; drains bile into the duodenum.

  • Deglutition phases

    Buccal (voluntary), pharyngeal (involuntary), and esophageal (involuntary) phases of swallowing.

  • Dental caries cause

    Tooth enamel erosion caused by bacterial plaque leading to cavities.

  • GERD (gastroesophageal reflux disease)

    Chronic acid reflux due to failure of the cardiac sphincter to prevent stomach acid backflow.

  • Kupffer cells in the liver

    Specialized macrophages that remove debris and bacteria from blood.

  • Haustra of the large intestine

    Pocket-like sacs formed by teniae coli that allow expansion and elongation of the colon.