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Digestive System Anatomy & Physiology

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Terms in this set (24)

  • What are the major organs of the digestive system?

    Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine.

  • What are the accessory organs of the digestive system?

    Teeth, tongue, salivary glands, liver, gallbladder, pancreas.

  • What are the six basic steps of food disassembly in digestion?

    Ingestion, propulsion, mechanical breakdown, chemical digestion, absorption, defecation.

  • Define peristalsis in the digestive system.

    Coordinated contractions of muscularis externa that move bolus along the digestive tract by contracting circular muscles behind and relaxing in front of the bolus.

  • What is segmentation in the digestive tract?

    Cycles of contraction that churn and fragment the bolus, mixing contents with intestinal secretions, mainly in the small intestine.

  • Name the four layers (tunics) of the digestive tract wall.

    Mucosa, submucosa, muscularis externa, serosa (visceral peritoneum).

  • What is the function of the mucosa layer in the digestive tract?

    Secretion of mucus, digestive enzymes, hormones; absorption; protection.

  • Describe the muscularis externa layer and its role.

    Smooth muscle with inner circular and outer longitudinal layers; responsible for mechanical processing and movement of materials via peristalsis and segmentation.

  • What is the role of the serosa in the digestive tract?

    Protective outer covering of muscularis externa within the peritoneal cavity; absent in oral cavity, pharynx, esophagus, and rectum where adventitia attaches tract to adjacent structures.

  • What is the function of the salivary glands?

    Produce saliva containing water, electrolytes, buffers, mucins, enzymes (like salivary amylase), and antibodies to lubricate, digest carbohydrates, and protect oral cavity.

  • What are the three phases of swallowing (deglutition)?

    Buccal phase (voluntary), pharyngeal phase, esophageal phase (both involuntary).

  • What is the function of the lower esophageal sphincter?

    Prevents reflux of stomach contents back into the esophagus by maintaining resting muscle tone.

  • What are the main functions of the stomach?

    Storage of ingested food, mechanical breakdown, chemical digestion by acid and enzymes, production of intrinsic factor for vitamin B12 absorption.

  • Name the three types of cells in gastric glands and their secretions.

    Parietal cells secrete HCl and intrinsic factor; chief cells secrete pepsinogen; mucous cells secrete mucus to protect stomach lining.

  • How does the stomach protect itself from self-digestion?

    Mucosal barrier with bicarbonate-rich mucus, tight junctions between epithelial cells, and rapid epithelial cell replacement every 3-6 days.

  • What is the role of gastrin in gastric regulation?

    Hormone produced by G-cells that stimulates secretion of HCl and gastric enzymes and promotes gastric motility.

  • Describe the cephalic phase of gastric secretion control.

    Triggered by sight, smell, taste of food; brain stimulates vagus nerve to increase gastric secretions before food enters stomach.

  • What triggers the gastric phase of gastric secretion?

    Stomach distension, presence of peptides, and low acidity stimulate local neural and hormonal mechanisms to increase gastric juice production.

  • What happens during the intestinal phase of gastric regulation?

    Chyme entering small intestine inhibits gastric secretion and motility to control gastric emptying and protect intestinal lining.

  • What is the function of the mesenteries in the peritoneal cavity?

    Stabilize digestive organs, connect visceral and parietal peritoneum, and provide routes for blood vessels, nerves, and lymphatics.

  • Name the two main mesenteries that persist after embryonic development.

    Lesser omentum (between stomach and liver) and falciform ligament (between liver and abdominal wall).

  • What is the greater omentum and its functions?

    Large dorsal mesentery hanging from stomach; contains adipose tissue for padding, insulation, and energy storage.

  • What type of epithelium lines the oral cavity and esophagus?

    Stratified squamous epithelium, keratinized in areas exposed to abrasion, non-keratinized elsewhere.

  • What type of epithelium lines the stomach and intestines?

    Simple columnar epithelium rich in mucus-secreting cells and enteroendocrine cells.