Questions

How is gastric secretion controlled before food enters the stomach and during a meal?

How is gastric secretion controlled before food enters the stomach and during a meal?

The secretion of gastrin is stimulated by food arriving in the stomach. The secretion is inhibited by low pH. Secretin is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the secretion of bile in the liver. This hormone responds to the acidity of the chyme.

What triggers the gastric phase of gastric secretion?

Gastric secretion is stimulated by the act of eating (cephalic phase) and the arrival of food in the stomach (gastric phase). Arrival of the food in the intestine also controls gastric secretion (intestinal phase).

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What type of gastric secretion occurs in response to the sight of food?

The cephalic phase of gastric secretion occurs in response to stimuli received by the senses—that is, taste, smell, sight, and sound. This phase of gastric secretion is entirely reflex in origin and is mediated by the vagus (10th cranial) nerve.

How do gastric glands secrete?

Gastric juice is secreted by gastric mucosal glands, and contains hydrochloric acid, mucus, and proteolytic enzymes pepsin (which breaks down proteins), and lipase (which breaks down fats). When the stomach is empty, and not distended, the lining is thrown up into folds called rugae.

How does gastric inhibitory peptide control digestive process?

function in human digestive system Secreted by the K cells, gastric inhibitory peptide enhances insulin production in response to a high concentration of blood sugar, and it inhibits the absorption of water and electrolytes in the small intestine.

How is gastric acid secretion regulated in the cephalic and gastric phases of digestion?

The Cephalic Phase Is Mediated by the Vagus Nerve Through Acetylcholine and Gastrin. The cephalic phase of gastric secretion is mediated entirely through the vagus nerve. A variety of sensory stimuli including the sight, smell, and taste of food elicits acid secretion in the stomach.

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Which best explains why carbohydrate digestion?

Which statement BEST explains why carbohydrate digestion ceases when food reaches the stomach? Carbohydrate is completely digested in the mouth. Salivary enzymes cannot function in the acid environment of the stomach. Carbohydrate is completely absorbed in the esophagus.

What do gastric glands secrete and how do these help in digestion?

The gastric gland is an essential body component because it secretes gastric juice. The gastric juice contains hydrochloric acid, pepsin and mucus. Pepsin helps in digestion of proteins, hydrochloric acid helps in the functionality of pepsin and kills bacteria and mucus protects the inner lining of the stomach.

What are gastrointestinal secretions?

Every day, seven liters of fluid are secreted by the digestive system. This fluid is composed of four primary components: ions, digestive enzymes, mucus, and bile. About half of these fluids are secreted by the salivary glands, pancreas, and liver, which compose the accessory organs and glands of the digestive system.

What stimulates the secretion of gastric inhibitory peptide?

The intake of glucose stimulates secretion of gastric inhibitory peptide (GIP), which passes to the pancreas causing the B cells to secrete insulin (Fig. 24.5). The presence of glucose (and fatty acids also) in the ileum stimulates the release of enteroglucagon: this too increases insulin release.

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What are the three phases of secretion of the stomach?

Three Phases of gastric secretion. Regulation of secretion of the stomach is of three phases they are: Cephalic phase, Gastric phase and Intestinal phase.

How long does the gastric phase of digestion take?

Gastric Phase. This phase takes about three to four hours. In gastric phase, food has entered and distended the stomach. This distention stimulates a parasympathetic reflex through medulla oblongata, and it directly stimulates the gastric glands and releases more gastric juices.

How do endocrine glands affect gastric secretion?

Hormones secreted by different endocrine glands influence gastric secretion. i. Glucocorticoids secreted by adrenal cortex stimulated by ACTH increases acid and pepsin secretion by the stomach but decrease the mucous secretion, and thus make it more susceptable to ulceration.

How do gastric secretions facilitate the digestion of protein?

Gastric secretions facilitate the digestion of protein which commences in the stomach by acid denaturation and hydrolysis by gastric proteases or pepsins. M. Camilleri, M.I. Vazquez Roque, in Encyclopedia of the Neurological Sciences (Second Edition), 2014