1. Extrinsic NS
    • autonomic CNS
    • P- long preganglionic fibers: vagus & pelvic nerves synapse w/i intrinsic NS
    • S- postganglionic, directly on smooth m fibers, endocrine glands, bv's
    • In GENERAL: P- inc GI motor and secretory
    • S- inhib
    • EXCEPTION: salivary secretion-both (P- long-lasting hi V, protein-poor; S- transient lo V, protein-rich)
  2. Motility:
    1. Propulsion
    2. Mixing
    3. Reservoir
    4. Sphincter
    • 1. Propulsion- aboral direction via perstalsis
    • 2. Mixing- segmentation, size reduction, mixing fooed with secretions & dig NZs
    • 3. Reservoir- Storage, relax to accomodate more
    • 4. Sphincter- separation, tonic contraction, controlled passage of food
  3. Lumen is mostly relaxed...
    • relaxed (physiological ileus) "default"- active ("on") enteric inhibitory neuron
    • But at contractions and default tonic contractions (sphincters)- inactivate ("off") enteric inhibitory neurons
    • --so sphicters become active when food needs to pass
  4. Salvia composition and tonicity
    • High rates of secretion: less hypotonic (near isotonic)
    • Low rates of secretion: more hypotonic
    • Acinus- isotonic
    • Duct- becomes hyptonic
  5. Achalasia
    "nutcracker esophagus", failure of LES to relax while swallowing
  6. Diffuse spasm
    temporaly uncoordnated contractions
  7. GERD
    "heart burn" like problems, etc. ?
  8. Stimulation of acid secretion
    1. Ach
    2. Gastrin
    3. Histamine
    • 1. Ach- neurocrine, release from intrisic motor neurons
    • 2. Gastrin- endocrine, released from G cells- stim gastrn R and releases HISTAMINE from ECL cells
    • 3. Histamine- paracrine, released from ECL cells
  9. Acid secretion
    1. Cephalic phase
    2. Gastric phase
    3. Intestinal phase
    • 1. Cephalic phase- b4 eating, vagal activation on intrinsic neurons
    • 2. Gastric phase- food in stomach, responds to distention and peptides & aa, mechonoR and vago-vagal reflex
    • 3. Intestinal phase- in intestine, Enterooxyntin released in response to aa & peptides, and distention
  10. Pepsin
    secreted in response to Ach in cephalic and gastric phases
  11. Mucus
    • Soluble- mucus neck cells, Ach from vagal stim, lubricate bolus
    • Insoluble- surface mucus cells, protective epithelial linin of stomach (irritant, alcohol, spicy food)
  12. Stomach receptive relaxation
    • vago-vagal reflex from mechanoR, activation of inhibitory intrinsic neurons, NO & VIP.
    • therefore, no inc in P
  13. Gastric emgptyin
    • Rate of gastric emptying is controlled neg fb that balances amt of chyme entering duodenum with ability od duodenum to process chyme
    • Dec emptying: DEC rate/force of gastric gontraction & INC force of contracion of pyloric sphincter
  14. Pancreas
    bicarb-rich soln for neutralization of stomach acid, hydrolytic NZ for dig
  15. Liver/GB
    • bile for dig & absorption
    • waste products (bilirubin & chol)
    • BA transport is primary driver of everything else
    • constititively: BA-dep-bile flow
    • during meal: BA-indep-bile flow (secretin)
    • Bile secreted to canalicus is isotonic.. the gets to bile duct: adds bicarb and H20 (like with pancreatic duct)
    • GB secretion- contraction by Ach via vagus & CCK relaxes SOO and contract GB
  16. Digestive NZ
    • membrane-bound: intrinsic membrane ptoteins
    • luminal NZ: secreted by pancreas act in lumen
Card Set
GI and stuff.. eeww :D