Flashcards in this deck (63)

• What is the function of the cardia in the stomach?

  • ~5% surface area
  • Transition zone: squamous columnar epithelium
  • Mucus secretion for lubrication & acid neutralization
  anatomy stomach
• What cells are found in the fundus and body of the stomach?

  • Parietal cells (HCl, intrinsic factor)
  • Chief cells (pepsinogen)
  anatomy stomach
• What is the pacemaker zone in the stomach?

  Generates Basic Electrical Rhythm (BER) at 3-4 cycles/min
  physiology stomach
• What is the role of the antrum in the stomach?

  Functions as a 'gastric pump' for churning & mixing of chyme
  anatomy stomach
• What does the pylorus do?

  Secretes mucus and regulates gastric emptying
  anatomy stomach
• What is the function of the Lower Oesophageal Sphincter (LES)?

  Prevents reflux; relaxes during swallowing (receptive relaxation)
  physiology stomach
• What mediates the relaxation of the LES?

  NO & VIP from myenteric plexus innervated by the vagus nerve
  physiology nervous_system
• What is achalasia?

  Failure of LES + cardia to relax during deglutition
  pathology stomach
• What are the symptoms of achalasia?

  • Dysphagia
  • Regurgitation
  • Chest pain
  pathology symptoms
• How is achalasia managed physically?

  Pneumatic dilation of LES
  treatment stomach
• What pharmacological treatment is used for achalasia?

  Botulinum toxin injection to inhibit ACh release
  treatment stomach
• What is the role of peristalsis in the stomach?

  Propels chyme distally
  physiology stomach
• What is the role of churning in the stomach?

  Mixing & grinding to assist digestion
  physiology stomach
• What factors affect gastric emptying?

  • High carbs: fastest
  • High protein: slower
  • High fat: slowest
  physiology digestion
• What is the ileal brake?

  Prolonged antral contraction > duodenal contraction to prevent reflux
  physiology digestion
• What do parietal cells secrete?

  • HCl
  • Intrinsic factor
  anatomy stomach
• What do chief cells secrete?

  Pepsinogen
  anatomy stomach
• What substances does gastric juice contain?

  • HCl
  • Mucus
  • Pepsin
  • Gastric lipase
  anatomy digestion
• What is the function of HCl in gastric juice?

  • Antibacterial
  • Converts Fe to Fe2+ for absorption
  • Breaks down collagen
  physiology digestion
• What is the role of mucus in the stomach?

  • Lubrication
  • Protection against acid and pepsin injury
  physiology stomach
• What is the function of intrinsic factor?

  Essential for Vitamin B12 absorption
  physiology nutrition
• What stimulates HCl secretion?

  • ACh
  • Gastrin
  • Histamine
  physiology digestion
• What is the regulation of HCl secretion?

  • Stimulatory: ACh, Gastrin, Histamine
  • Inhibitory: PGE₂
  physiology digestion
• What are the phases of HCl secretion?

  1. Cephalic: sight, smell, taste
  2. Gastric: distension, peptides
  3. Intestinal: distension, acidity
  physiology digestion
• What can cause gastric mucosal damage?

  • Gastritis
  • Alcohol/NSAIDs
  • H. pylori infection
  • Achlorhydria
  pathology stomach
• What is the role of the parasympathetic nervous system in the GIT?

  ↑ motility, ↑ secretion
  neurophysiology git
• What does the sympathetic nervous system do to GIT functions?

  ↓ motility, secretion
  neurophysiology git
• What is the function of the myenteric plexus?

  Motility control
  neurophysiology git
• What is the role of the submucosal plexus?

  Secretion control
  neurophysiology git
• What hormone does G cells produce?

  Gastrin
  endocrinology git
• What does Gastrin do?

  ↑ motility, secretion
  endocrinology git
• What hormone is produced by K cells?

  CCK (Cholecystokinin)
  endocrinology git
• What does CCK stimulate?

  Bile/pancreatic enzyme release
  endocrinology git
• What hormone is secreted by S cells?

  Secretin
  endocrinology git
• What does Secretin promote?

  ↑ bicarbonate
  endocrinology git
• What is the function of Mo cells?

  Secrete Motilin (MMC)
  endocrinology git
• What is peristalsis?

  Propulsive movement of bolus
  git movement
• What neurotransmitters are involved in peristalsis contraction?

  ACh, Substance P
  git neurotransmitters
• What mediates relaxation during peristalsis?

  NO, ATP, VIP
  git neurotransmitters
• What is the primary function of segmentation?

  Mixing, ↑ contact with mucosa
  git movement
• What is receptive relaxation?

  Facilitates food entry into stomach
  git movement
• What happens during churning in the stomach?

  Mixing with gastric juices
  git movement
• What is the Migrating Motor Complex (MMC)?

  A pattern of motility between meals
  git movement
• What is the role of mass movements in the large intestine?

  Move fecal matter towards defecation
  git movement
• What does active transport in the GIT involve?

  ATPase pumps, Na-K ATPase
  git transport
• What is the function of Na-K ATPase?

  Pumps 3 Na⁺ out and 2 K⁺ in
  git transport
• What does SGLT do?

  Co-transport of glucose with Na⁺ in small intestines
  git transport
• What hormone increases calcium absorption in the GIT?

  Vitamin D (1,25-DHC)
  git hormones
• What is clathrin-mediated endocytosis?

  Receptor-dependent absorption via vesicles
  git transport
• What does micropinocytosis involve?

  Membrane pockets engulfing extracellular fluid
  git transport
• What is the function of the GIT in digestion?

  Physical and chemical breakdown of food
  git digestion
• What is the role of the GIT in absorption?

  Nutrients, electrolytes, water, drugs, toxins
  git absorption
• Where is glucose absorbed in the GIT?

  Small intestine
  git absorption
• What mechanism is used for amino acid absorption?

  Na-Amino acid symporter
  git absorption
• How are fat-soluble vitamins absorbed?

  Passive diffusion to enterocytes
  git absorption
• What is the absorption site for Vitamin B12?

  Terminal ileum
  git absorption
• What type of transport is used for iron absorption?

  Organic Fe via Heme carrier
  git absorption
• What process allows fat to enter enterocytes?

  Simple diffusion
  biology digestion
• What is formed in enterocytes from fats?

  Chylomicrons
  biology digestion
• What process releases chylomicrons into lacteals?

  Exocytosis
  biology digestion
• Which vitamins are absorbed in the same area as fats?

  Fat-soluble vitamins
  biology nutrition
• What type of endocytosis is used for vitamin absorption with intrinsic factor?

  Receptor-mediated endocytosis
  biology nutrition
• How is organic iron absorbed?

  Via Heme carrier protein
  biology nutrition