Download NS 1150 Professor Levitsky Fall 2016 Week2: Lecture3of3

NS 1150
Professor Levitsky
Fall 2016
Week 2: Lecture 3 of 3
Keywords: esophageal sphincter, parasympathetic system, vagus nerve, tumor necrosis factor,
heartburn, gastroesophageal reflux disease, acid buffers, stomach ulcers, gastric emptying
1. The esophageal sphincter
a. Tone is modulated by the parasympathetic system, and the vagus nerve has a significant part in regulating the tone
b. The parasympathetic system can be controlled voluntarily
i. Sword swallowers are able to control their the opening of their throat, which is how
they can swallow swords
ii. Beer pourers have a similar reflex and are able to swallow up to a pitcher of beer by
controlling the opening of their throats
iii. Belches
iv. Purgers: some common symptoms of purgers include…
1. Tooth decay
2. Esophageal lesions: these are caused by the acid, which causes injury to the
cells and that leads to scarring of the lining of the throat
3. As the scarring increases, the throat becomes less flexible and the scarring
causes the esophagus to become smaller
4. Surgery may be needed if the esophagus becomes so small eating becomes difficult
5. Note: do not purge, purging does not help reduce calories
6. Cardiac irregularities
7. When purging occurs, electrolytes are lost and this can cause cardiac irregularities; in the worst situation death may occur
c. The esophageal sphincter connects to the stomach and regulates what goes into the
stomach
i. However, if there is a poison…
1. The poison stimulates the release of tumor necrosis factor (TNF)
2. TNF stimulates the stomach, opens the esophageal sphincter, closes the pyloric sphincter, inhibits the parasympathetic system (the vagus nerve)
3. The person gets rid of the toxin through throwing up
2. Heartburn
a. Heartburn is caused by stress via the sympathetic system
b. This symptom is common in older people
c. Also known as gastroesophageal reflux disease and has no relation to the heart
d. Heartburn is stimulated by various foods, including spicy fods
e. Treatments
i. There are various treatments for this symptom, all reduce acidity
1. Acid buffers
2. Bicarbonate (alka seltzer)
3. Acid blockers
4. PPI: proton pump inhibitor (Prilosec, Prevacid)
5. Problem: “rebound hypersecretion effect”
6. If taken daily, more acid is released to try and compensate for the acid inhibition and after not taking the PPI, the body releases the same high amount
of acid and this can cause a rebound effect of high acidity
7. H2 blockers: histamine blockers, histamines release acid and by inhibiting
the histamines, the acid release is also inhibited
8. Bismuth (in Pepto Bismol)
3. In the stomach…
a. Gastrin is released, primed by the PNS
i. Gastrin releases HCl
1. HCl acts as a bactericide and activates pepsinogen into pepsin
2. Pepsin breaks down proteins into smaller amino acids
3. Gastrin is stimulated by the stretching of the stomach wall
b. Gastric lipase is released, lipase digests the fats into smaller molecules
c. Ghrelin is released. Ghrelin is stimulated by an empty stomach and promotes eating.
Ghrelin is inhibited by a full stomach.
4. Stomach ulcers
a. If the mucous secretion is low, the stomach ulcers can occur aka gastric ulcers
b. Causes
i. The number one cause is by the bacteria, helicobacter pylori
1. Helicobacter pylori is acid resistant and inhibits mucous secretion cells
ii. Stress can stimulate stomach ulcers
iii. Rapid eating may cause stomach ulcers as the stomach will not have enough time
to produce mucous
5. Gastric emptying
a. Stimulated by an increase in stomach volume
b. Osmotic pressure: an increase in blood or water circulation in the stomach will decrease the osmotic pressure
i. There are osmoreceptors in the stomach, and if it senses low osmolarity, then gastric dumping is stimulated
c. Viscosity inhibits gastric dumping
i. Fiber increases viscosity (indigestible fiber - soluble and thickens bolus)
1. As the food swells, peristalsis is increased
2. This can help with dumping syndrome, which is common after gastric
surgery for weight loss
3. Those who have quick gastric emptying into the small intestine may feel
nausea
6. Dave’s dietary delusions
a. Digestive enzymes help with weight loss supposedly
b. However, enzymes are proteins that are destroyed by proteases and will not properly
aid weight loss
c. The only enzyme that helps with digestion (produced by pharmaceuticals) is lactaid,
which digests lactose by lactase