Gastrointestinal Physiology Flashcards
Myenteric Plexus
Mainly excitatory EXCEPT Pyloric Sphincter and Ileocecal Valve
10 inches
Esophagus
Duodenum
Urethra
Absorption
Duodenum
Vitamin C
Iron
Absorption
Jejunum
Carbohydrate
Fats
Proteins
Absorption
Ileum
Vitamin B12-Intrinsic Factor (terminal part)
Vitamins ADEK
Gastrin
- G cells - Stomach Antrum
- Simulus - Gastric distention, Vagus Nerve Via GRP/ Bombesin
- Inhibition - Inc H conc, Somatostatin
- Fxn - Increase H ion secretion Growth of Gastric Mucosa
Secretin
- S cells - duodenum
- Stim H ion, Fatty acids in duodenum
- Fxn: increase pancreatic HCO3 secretion, counteracts Gastrin
Cholecystokinin
I cells in duodenum jejunum
Stm by FATTY ACIDS
Fxn Gallbladder contraction, Sphincter of Odi relaxation, increase pancreatic enzyme and HCO secretion
INHIBITS GASTRIC EMPTYING
GIP
Glucose dependent insulinotropic peptide
- Aka Incretin GLP-1
- K cells of duodenum
- Increase insulin secretion
- Inhibits gastric emptying
Motilin
- M cells of duodenum jejunum
- Stim by fasting
- Stimulates peristalsis, clearing of GI in between meals
Parasumpathetic effects on GI
- Contraction of smooth muscles
- RELAXATION of sphincters
- INC salaivation
- INC gastric secretion
- INC Pancreatic secretion
Sympathetic effect on GI
- Relaxation of smooth muscles
- CONTRACTION of sphincters
- INC Salivation
POMC
- Secreted by anorexigenic Neurons
* Anorexigenic
Neuropeptide Y
- Orexigenic neurons
* Increase appetite
Ghrelin
- Inhibits anorexigenic neurons - stimulate hunger
* Inhibited by Peptide YU
Leptin
- Anorexigenic Neuron ACTIVATOR
* Orexigenic neuron INHIBITOR
Satiety center
Ventromedial hypthalamus
Hunger center
Lateral hypothalamic area
GLP
L cells of small intestines
INC Insulin secretion
Somatostatin
Inhibits release of ALL GI Hormones
Inhibits H+ secretion
Histamine
By mast cells of GI mucosa
Increase H+
Potentiates Gastrin and Ach
Tonic Contractions
- Constant; no relaxation
- Spincters
- Subthreshold slow waves
Phasic contractions
- Periodic contraction an relaxation
- Mixing and propulsion
- Spike potentials
GI Pacemaker
- Intestinal cells of cajal
* Slow waves - not true action potential - sodium influx
Spike potentials
True AP due to calcium Influx