LEC 24: intestines

Cards (20)

  • Deep circular folds
    • Force chyme to spiral
    • Increase mixing for nutrient absorption
  • Villi & microvilli
    • Finger-like projection
    • Increase surface area
  • Intestinal crypts
    • Tubular glands
    • Produce mucus, hormones, antimicrobial compounds that can destroy invasive bacteria (paneth cells)
  • Villus epithelium
    • Contains rapidly dividing cells
  • Goblet cells
    • Secrete mucous
    • Protect intestinal lining
  • Enterocytes
    • Absorb nutrients from chyme into bloodstream
    • Primary absorptive cells
  • Paneth cells
    • Produce antimicrobial compounds
    • Maintain gut health
  • Roles of cell types in the intestinal mucosa
    • Enterocytes - absorb nutrients from chyme into bloodstream
    • Goblet cells - secrete mucous, protect intestinal lining
    • Enteroendocrine cells - produce hormones involved in digestion & gut function
    • Paneth cells - produce antimicrobial compounds, maintain gut health
    • Stem cells - replace other cell types, regenerate intestinal epithelium
  • Major functions of large intestine
    • Absorbs water from ingestible food residues
    • Forms and stores feces
    • Houses bacteria that ferment indigestible carbohydrates
    • Synthesizes B complex vitamines and vitamin K
    • Influences the behaviour of the immune system
    • Protects against ingested pathogens
  • Diarrhoea
    Watery stool - large intestine does not have enough time to absorb remaining water in chyme
  • Causes of diarrhoea
    Irritation of the colon by bacteria or jostling of digestive viscera
  • Constipation
    • Difficulty passing stool
    • Hard and dry stool
    • Infrequent bowel movements
  • Causes of constipation
    • Food remaining in the colon for extended periods of time
    • Excessive water reabsorption
  • Components of bowel transit time
    • Stomach transit time - influenced by food volume, composition, gastric emptying rate
    • Small intestine transit time - affected by motility, presence of food particles, absorption rate
    • Colon transit time - determined by peristaltic contractions, water absorption, stool consistency
  • Intestinal juice
    Secreted in response to acidic chyme
  • Between meals, migrating motor complexes move remnants toward the large intestine in waves
  • The large intestine (also known as the colon) absorbs water from indigestible food residues and eliminates the latter as faeces
  • what transit time is influenced by food volume, composition, and emptying rate?
    stomach
  • what transit time is affected by motility, presence of food particles, and absorption rate?
    small intestine
  • what transit time is determined by peristaltic contractions, water reabsorption, and stool consistency?
    colon