Describe the three phases of regulation of stomach secretion.
The stomach in humans is a bag like muscular organ and functions in digestion. It receives semi digested food from the esophagus. In the stomach the gastric juices act on this to further carry out digestion.
The mucosa of the stomach contains secretory glands which secrete hydrochloric acid, mucus, gastric lipase and pepsin. The secretion of these enzymes are affected by several factors including sight, smell, thought, and taste of food, and movement of food. These factors processed by the nervous system and the endocrine system regulate the gastric secretions.
There are three phases is regulation of gastric secretion. They are the cephalic phase, gastric phase, and the intestinal phase. These phases are temporally independent, i.e., they can occur simultaneously, separately, or may overlap.
CEPHALIC PHASE
The cephalic phase, in simple terms, is to do with the head, and can be active even before food enters the human. The sight, smell, thought, or taste of food serve as sensory inputs to the hypothalamus which then sends out responses preparing the digestive system for its functions via the medullar oblongata, and then the vagus nerve. This response is a conditioned reflex and is appetite based. When the individual is full or not hungry, these stimuli do not elicit the same responses.
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