Lecture 12.B. - Vomiting and Defecation Flashcards
The vomit center is located in the ____ ____. Just outside the _____, there is a _____ trigger zone that detects noxious substances in the blood and informs the vomit center. This zone can also detect large concentrations of hormones in the blood, as occurs during pregnancy.
Brain stem
BBB
Chemical trigger zone
Once the vomit center signals for vomiting, reverse peristalsis begins as far along the GI tract as the ______, and moves contents backward into the stomach.
Ileum
The “Retching” process is what fills the stomach with vomit and occurs as follows:
Relaxation of stomach –> involuntary forced ______ which decreases intrathoracic and increases abdominal pressures –> abdominal muscles contract to drive gastric contents into the esophagus while the _____ relaxes.
Inspiration
LES
Contractions of the _____ mucosae minimize _____ layers, and bring different parts of mucosal surface into contact with chyme.
Muscularis mucosae
Unstirred layers
Gastro-ileal reflex –> increased stomach activity _____ (increases or decreases?) ileal contraction and movement of chyme through the ileocecal sphincter.
Ileogastric reflex –> Distention of the Ileum signals the stomach to _____ (increase or decrease?) gastric motility.
Increases
Decreases
For the concomitant contraction and relaxation of the intestine around a bolus of chyme, ______ is the signalling peptide used by the interneurons.
CGRP
The large intestine has very _____ (fast or slow?) motility.
Slow (about 4-6 contractions/min)
_____ movement is the term that describes the type of contraction in the colon that occurs 1-3 times per day. The colon remains contracted for a greater time than during normal peristalsis, and this contraction is mediated by _____ (which neurotransmitter?). Control of this process is mostly _____, but _____ stimulation increases motility (by increasing duration of slow waves), whereas _______ stimulation inhibits motility.
Mass Movement
ACh
Local
Vagal
Sympathetic
______ is a condition that occurs most often post-op, especially after abdominal surgery. It leads to buildup of contents in the intestines.
Ileus
Defecation reflex is under voluntary control, modulated by the sacral region of the spinal cord via ______ nerves (which are somatic, so voluntary).
Pelvic
Gastrocolic reflex –> food entering the stomach increases frequency of ____ ______ in colon.
Mass Movement
Like with Ileoileal reflex, _______ reflex results in concomitant contraction and relaxation of colon on either side of chyme bolus.
Colonocolonic