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Anatomical Sphincter
A ring of muscle that contracts to close an opening. TERM 2
Physiological Sphincter
DEFINITION 2 A sphincter that is not recognizable at autopsy because its resting arrangement cannot be distinguished from adjacent tissue. TERM 3
Upper Esophageal Sphincter
DEFINITION 3 Consists of striated muscle and is under conscious control TERM 4
Lower Esophageal Sphincter
DEFINITION 4 Opens where there is a food stimulus, and seals shut until the next food stimulus passes down the esophagus. Prevents reflux of gastric juices. TERM 5
Primary Swallow
Peristalsis
DEFINITION 5 Occurs when the bolus enters the esophagus during swallowing. The primary peristaltic wave forces the bolus down the esophagus and into the stomach in a wave lasting about 89 seconds. The wave travels down to the stomach even if the bolus of food descends at a greater rate than the wave itself, and will continue even if for some reason the bolus gets stuck further up the oesophagus.
Secondary Swallow
Peristalsis
In the event that the bolus gets stuck or moves slower than the primary peristaltic wave, stretch receptors in the esophageal lining are stimulated and a local reflex response causes a secondary peristaltic wave around the bolus, forcing it further down the oesophagus, and these secondary waves will continue indefinitely until the bolus enters the stomach. TERM 7
How long does it take half the meal to empty
out of the stomach?
DEFINITION 7 Liquids: 15 minutes Solids: 1.5-2.0 hours Liquids empty faster than solids. Solids have a "lag phase." Stomach churns until the solid particles are small enough (2mm or less) and then they flow out of the pyloric sphincter into the small intestine. TERM 8
How does the Orad Stomach serve as a
reservoir?
DEFINITION 8 The reason your stomach can act as a reservoic is because the stomach adapts to an increase in volume of food with only a small increase in gastric pressure. TERM 9
Role of the Vagus nerve in promoting the
reservoir function of the Orad Stomach.
DEFINITION 9 Intrinsic nerves (inside wall of stomach) get stimulated when food stretches the stomach. Those nerves send messages to the Vagus nerve (extrinsic nerve) which goes to the medulla. From Medulla to Vagus Nerve back to intrinsic nerves again. Neurotransmitter is released to cause relaxation (Inhibitory Reflex). Vasovagal Inhibitory Reflex TERM 10
What happens if the vagal input to the orad
stomach is interupted?
DEFINITION 10 Emptying of solids slows down, and fluids go out too quickly. Dumping syndrome.
What are the factors "sensed" by the small
intestine?
Small Intestine can sense the physical and chemical makeup of the content in the stomach (chyme) It knows distension, calories, Hydrogen ions, fat content, osmolarity, etc.) TERM 17
4 Products secreted by the stomach?
DEFINITION 17 Histamine, Somatostatin, Gastrin, and HCL Acid. TERM 18
What is the only physiologically important
substance secreted by the stomach?
DEFINITION 18 Intrinsic Factor, necessary for Vitamin B12 reabsorption. TERM 19
Role of the vagus nerve in stimulating acid
secretion during the Cephalic Phase?
DEFINITION 19 Anything emotionally attached to food will activate the vagus nerve and stimulate acid secretion. TERM 20
Role of vagus nerve in stimulating acid
secretin during the Gastric Phase?
DEFINITION 20 Food is in stomach. Protein acts as a good barrier and makes pH go from 1-2 up to 4-5. Medulla activated Achetylcholine, Gastrin is released and it stimulates acid secretion. Vago- Vagal Reflex
How does the presence of food in the
stomach promote acid secretion?
The buffer in the stomach causes the pH to rise and this stimulates acid secretion to get the pH back down. TERM 22
What happens to acid secretion if the vagus
nerve is sectioned?
DEFINITION 22 It doesn't happen like it should. It is decreased.
