GI 9 Flashcards
What are Tonic contractions?
Relatively prolonged contractions that can isolate segments of the intestine, slow transit time and
What is the Ileocecal valve?
The valve that separates the colon and the ileum
What opens and closes the ileocecal valve?
Increases colonic pressure closes it and increased ileal pressure opens it
What is the Gastroileal reflex?
Opening of the ileocecal valve in response to food leaving the stomach
What propels and mixes contents of the colon?
Segmentation and peristalsis
Which contractions are unique to colon?
Mass action contractions
What are mass action contractions?
Simultaneous contractions of large areas of the colon 10/day
What is the function of mass action contractions?
Move material through the colon into the rectum
What is the function of tonic contractions?
To create pockets within the small intestine to slow down transit time and increase the time for absorption
What causes the defecation reflex?
An increase in rectal pressure caused by mass action contractions
What does prolonged distension of the rectum do?
Initiates reverse movement, driving rectal contents into the sigmoid colon
What can defecation be initiated by?
Voluntary straining
What happens to the muscles during defecation?
- Abdominal muscles contract
* The puborectalis relaxes to lower the pelvic floor and open the anorectal angle
What do countries with sitting have increased incidence of?
Hemorrhoids and diverticular disease
How long does it take for 50% of the stomach to be emptied?
2.5-3 hours
