BIOL 404-Exam 4-GI 22

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What is the defecation reflex?

Stimulated by feces entering rectum (usually in response to mass movements)
What part of the NS integrates Mass movements?

Enteric nerve plexus
What stimulates Mass movements?
- Chyme in the duodenum
- Food in the stomach
What stimulates defecation?

Presence of feces in colon
How does the presence of feces in the colon stimulate defecation?

parasympathetic and local reflexes
defecation is involuntary or voluntary?

Both
Where is Populsive motility produced to push feces out?
- Descending colon
- Rectum
The involuntary portion of defecation is what?
- The propulsive motility
- Internal anal sphincter relaxation
The voluntary part of defecation consists of what?
- An increase in intra abdominal pressure
- External anal sphincter relaxation
How much flatus is expelled per day?

150 mL
What sources of flatus are there?
- Air is ingested with a meal
- Gas is produced in small intestine via production of carbon dioxide by acid neutralization
- Colon, bacterial fermentation produces gas
Where is most of Flatus derived from?
- 50% is derived from swallowed air
- Rest is produced by the digestive process