Gastrointestinal Tract: Disorders of Motility 1.

The secretion of acid by the stomach is promoted by three phases. These, according to Huether and McCance (2017) are the cephalic phase, gastric phase, and the intestinal phase. As the authors further point out, while the cephalic phase is prompted by the smell, thought as well as taste of food, the gastric phase is prompted by stomach distention. The last phase, i.e. the intestinal phase, is prompted “by histamine and digested protein” (Huether and McCance, 2017, p. 888). It should be noted, from the onset, that in the words of Huether and McCance (2017), “gastric secretion is stimulated by the process of eating (gastric distention), by the actions of the hormone gastrin and paracrine pathways (e.g., histamine, ghrelin, somatostatin), and by the effects of the neurotransmitter acetylcholine and other chemicals (e.g., ethanol, coffee, protein)” (888).

A significant amount of gastric juices are secreted by the stomach. The said juices include, but they are not limited to, gastroferrin, intrinsic factor, enzymes, as well as acid and mucus (Huether and McCance, 2017). The main secretory units are the gastric glands in the stomach body and fundus. It is important to note that as Huether and McCance (2017) observe, the volume and flow rate determines the gastric juice composition. The secretion rate, on the other hand, is largely dependent on the time of day. In essence, as Huether and McCance (2017) further point out, a number of factors inhibit gastric secretion. These include pain, fear, rage, as well as tastes...

While parasympathetic impulses are inhibited by sympathetic impulses discharge, hostility as well as aggression is associated with increased secretions – and may, as a matter of fact, contribute to certain kinds of gastric pathology.
It is important to note that gastric hydrochloric acid, as Huether and McCance (2017) observe, largely concerns itself with not only the dissolution of food fibers, but also functions as “a bactericide against swallowed microorganisms” (888). Pepsinogen is also converted to pepsin by gastric hydrochloric acid. According to Huether and McCance (2017), for acid to be produced by the parietal cells, chloride and hydrogen must be transported to the stomach lumen (from the parietal cells). In the words of the authors, “at a high rate of gastric secretion, bicarbonate moves into the plasma, producing an ‘alkaline tide’ in the venous blood, which also may result into a more alkaline urine” (Huether and McCance, 2017, p. 888). The vagus nerve is responsible for prompting the secretion of acid – with acetylcholine being released and gastrin secretion being stimulated. Histamine release is then stimulated by gastrin. It is the said histamine that prompts the secretion of acid via the activation of histamine receptors (Huether and McCance, 2017). According the authors, secretin and somatostatin inhibit the secretion of acid. It should be noted that a mucus coating protects the gastric mucosa from what the authors term as “the digestive actions of acid…” (Huether and McCance, 2017, p.…