Lecture 01, 2

• What is the primary function of the gastrointestinal (GI) tract?

  Digestion and absorption of food
• What role do accessory organs play in the GI tract?

  They supply secretions for food breakdown
• What regulates GI function?

  Neuronal and hormonal regulation
• What are the main structures of the GI tract?

  • Mouth
  • Pharynx
  • Oesophagus
  • Stomach
  • Small intestine (duodenum, jejunum, ileum)
  • Large intestine (cecum, ascending, transverse, descending, sigmoid)
  • Rectum
  • Anus
• What are the accessory digestive organs?

  Teeth, tongue, salivary glands, gallbladder, liver, pancreas
• What is the function of the gallbladder?

  Stores bile for fat emulsification
• What does the pancreas produce for digestion?

  Digestive enzymes and bicarbonate ions
• What are the layers of the GI tract cross-section?

  1. Mucosa
  2. Submucosa
  3. Muscularis externa
  4. Serosa

  
• What is the role of the mucosa in the GI tract?

  Lubricates food masses and facilitates movement
• What is the function of the muscularis externa?

  Contracts to force food down the gut
• What does the enteric nervous system regulate?

  GI tract movements and gastric acid secretion

  
• What are the four major activities of the GI tract?

  1. Motility
  2. Secretion
  3. Digestion
  4. Absorption
• What is motility in the GI tract?

  Propels ingested food from mouth to rectum
• What is the purpose of segmentation contractions?

  Mixes food and keeps it in contact with epithelium

  
• What is the role of tonic control by sphincters?

  Regulates passage and prevents backflow
• What does the upper oesophageal sphincter prevent?

  Prevents aspiration and reduces backflow
• What is the function of the pyloric sphincter?

  Regulates food passage and prevents backflow
• What is the role of the enteric nervous system in motility?

  Coordinates peristalsis and smooth muscle contractions

  
• What triggers swallowing?

  Closure of epiglottis and opening of sphincters
• What are the three main regions of the stomach?

  1. Fundus
  2. Body/corpus
  3. Antrum

  
• What is the function of gastric pits?

  Secrete mucus and bicarbonate ions
• What are the three functions of the stomach?

  Protection, digestion, and storage
• What is the primary function of the liver?

  Metabolic regulation and bile production
• What is the role of bile in digestion?

  Emulsifies fats for digestion

  
• What does pancreatic juice contain?

  Digestive enzymes and bicarbonate
• What are the components of pancreatic juice?

  1. Lipase
  2. Amylase
  3. Chymotrypsinogen
  4. Nuclease
  5. Trypsinogen
  6. HCO3-
• What is the function of goblet cells in the small intestine?

  Secrete mucus to protect the gut wall
• What initiates salivation?

  Anticipation and presence of food
• What is the role of salivary amylase?

  Begins to digest starch
• What does intrinsic factor do?

  Helps absorb vitamin B12
• What is the pH of gastric acid?

  1-2
• What is the primary role of the G cells in the GI tract?

  Secrete gastrin in response to amino acids
• What does somatostatin do in the GI tract?

  Inhibits gastric acid secretion
• What is the function of cholecystokinin (CCK)?

  Stimulates bile release and digestion of fats

  
• What does secretin respond to?

  pH levels between 2-4.5
• What is the role of GIP in the GI tract?

  Stimulates insulin secretion in response to glucose
• What is the action of acetylcholine in the GI tract?

  Causes smooth muscle contraction and increased secretion
• What does nitric oxide do in the GI tract?

  Causes smooth muscle relaxation
• What is the role of serotonin in the GI tract?

  Acts as an excitatory neurotransmitter
• What does substance P do in the GI tract?

  Causes smooth muscle contraction