Digestion In Large Intestine – Motility & Reflexes

DIGESTION IN LARGE INTESTINE – MOTILITY & REFLEXES

Q. 1

Which of the following is related with ‘gastrocolic reflex’?

 A

Mass peristalsis

 B

Segmental movement

 C

Pendular movement

 D

Colonic disorder

Q. 1

Which of the following is related with ‘gastrocolic reflex’?

 A

Mass peristalsis

 B

Segmental movement

 C

Pendular movement

 D

Colonic disorder

Ans. A

Explanation:

Gastrocolic reflex is a long reflex arc that is initiated by gastric distension. The reflex produces a generalized increase in colonic motility (peristalsis) with mass movement of feces. Mechano- and chemo sensitive components of the gastrocolic reflex are present, and 5-HT and ACh appear to be important mediators of the response. The function of this reflex is to clear the colon to ready it to receive the residues of the new meal. 

Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 27. Gastrointestinal Motility. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong’s Review of Medical Physiology, 24e.


Q. 2

Gastrocolic refelx are seen during?

 A

Adults

 B

Seen only on excessive food intake

 C

Infancy

 D

Only with GERD patients.

Q. 2

Gastrocolic refelx are seen during?

 A

Adults

 B

Seen only on excessive food intake

 C

Infancy

 D

Only with GERD patients.

Ans. C

Explanation:

Gastrocolic reflexes:

  • Facilitates mass movements after meal.
  • Resultant of stomach & duodenum distension.
    • Ex., gastrocolic reflex – Seen in early infancy
    • Where defecation following meal.

Q. 3

Defecation reflex is intiated by?

 A

Distension of rectum with feces.

 B

Post-prandial motility in duodenum

 C

Only during diseased state

 D

All of the above

Q. 3

Defecation reflex is intiated by?

 A

Distension of rectum with feces.

 B

Post-prandial motility in duodenum

 C

Only during diseased state

 D

All of the above

Ans. A

Explanation:

Defecation reflex initiated by distension of rectum with feces.

Defecation reflex:

  • Initiated by distension of rectum with feces.
  • Leads to propulsive wave extending from descending colon through sigmoid colon to rectum
  • Urge to defecate is first felt when rectal pressure increases to about 18 mm/Hg.
  • On reaching 55 mm/Hg rectal pressure – 
    • “Rectoanal inhibitory reflex” – Internal sphincter relaxes reflexly.


Leave a Reply

%d bloggers like this:
Malcare WordPress Security