If the peak of the slow wave reaches the threshold the smooth muscles will

If the peak of the slow wave reaches the threshold

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If the peak of the slow wave reaches the threshold, the smooth muscles will contractReaching threshold requires an additional stimulus in the form of mechanical, nervous or hormonal inputThese additional signals will cause the BERs to reach threshold and fire action potentials, which will cause muscular contractions of the smooth muscleThe contractions will then travel down the intestine in a wave like fashion Hormones of the Intestine:These hormones can also regulate gastric motility and the secretion of digestive enzymesThe hormone secretin is released in response to the presence of acid in the intestineIt inhibits emptying from the stomach, andcauses the release of pancreatic bicarbonateand bile from the liverAs a result of the bicarbonate release from thepancreas, the acid from the stomach isneutralized and the intestinal digestive enzymescan function optimally Food causes the release of hormones, whichcauses the release of particular pancreaticenzymes and decrease motility and slowsemptying of stomach into intestine Gastric Hormones:The stomach secretes gastrin, which is secreted by G cells located in the antrum of the stomach in response to presence of proteins, mechanical distension from food and stimulation from the parasympathetic nervous systemGastrin’s primary function is to cause the secretion of HCl that will convert pepsinogen to the active enzyme pepsinPepsin will then begin to digest proteins
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Phases of Gastric Acid Secretion:HCl is secreted by parietal cells in the stomach, and the amount secreted varies during the wholeeating digestion processHCl can be secreted even before you begin eatingThe secretion of gastric acid is divided into three phases – brain/stomach/intestine Cephalic Phase:Initiated in response to the sight/smell/taste and chewing of foodAn anticipatory response to the act of eating and involves the activation of the enteric nervous system through the long loop reflexThe sight/smell/taste trigger the PSYN nervous system, which activates the enteric nervous system to cause the parietal cells to release HCl and the G cells to release gastrinAdditionally, the motility of the stomach will increase Gastric Phase:Once the food is swallowed, the stimulus is the presence of it in the stomach that distends the walls and the presence of amino acids from the breakdown of proteinsThese stimuli trigger a short loop reflex involving the enteric nervous system which causes the release of HCl, gastrin and pepsinogen and will increase gastric motility Intestinal Phase:The stimulus is the presence of glucose, fat, and acidic chime in the intestineThe overall effect of it is to decrease the motility and to inhibit the secretions in the stomachThis is performed by the enteric nervous system and hormones secretin, CCk, and glucose dependent insulinotropic peptide
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