Question

Considerable communication along the digestive tract occurs as feedforward signals. From the examples below, select all that represent feedforward mechanisms.

	1. When stomach content enters the duodenum, the contractions in the ileum increase in strength
	2. The smell of food increases stomach motility via the vagus nerve
	3. Mass movements tend to occur ∼ 30 minutes after eating a meal.
	4. When feces enter the rectum, the internal anal sphincter relaxes.
	5. Increased movements of the large intestine prevents water absorption and leads to diarrhea.

Answer 1

The process of digestion is carried out by the digestive tract organs and involves various complex mechanisms.
Feedforward mechanism is one of them.
Feedforward mechanism results in alteration in activity of other organs and gland in response to the physiological changes in advance.

1. As the contraction of ileum increases in response to emptying of stomach content in duodenum even before the food has entered the ileum. It is a feedforward mechanism.
2. The smell of food acts as stimulus for stomach to increase its motility and prepare for arrival of food in advance. This is feedforward mechanism.
3. Mass movement occurs after the food has arrived in the stomach and intestine and not as a advanced preparation. So this is not feedforward mechanism.
4. The change is sensed by the internal anal sphincter and relaxes only after the content enters the rectum and not in advance. This is not a feed forward mechanism.
5. The increased movement of large intestine result in less absorption of water and causes dehydration. This is not Feedforward mechanism.
Answer : option 1 and 2