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18 Cards in this Set
- Front
- Back
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What five processes supply nutrients, electrolytes, and water to the body? |
1. Motility 2. Secretion 3. Digestion 4. Absorption 5. Storage |
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What are the two primary means of regulation? |
1. Nerves 2. Endocrine secretions |
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What are the two levels of regulation within the gut? |
Extrinsic and Intrinsic |
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What is the "little brain" of the gut? |
Enteric Nervous System |
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What comprises the intrinsic control system of the GI tract? |
Nerves- enteric nervous system (ENS) Endocrine secretions- secretin, gastrin, CCK, GIP, motilin |
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What are the two main plexuses of the ENS? What are their functions? |
1. Submucosal plexus- controls secretions, blood flow, and immune function 2. Myenteric plexus- coordinates motility |
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What comprises the extrinsic control system of the GI tract? |
Nerves- vagus, pelvic (both parasympathetic) and splanchnic (sympathetic) nerves Endocrine secretions- aldosterone |
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Describe the neurocrine secretions of the ENS. |
1. Stimulatory- cholinergic neurons secrete acetylcholine; substance P, serotonin 2. Inhibitory- adrenergic neurons secrete epinephrine; nitric oxide, somatostatin |
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What does the vagus nerve innervate? Pelvic nerve? |
Vagus- entire gut, except distal colon Pelvic- distal colon only |
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Describe the two important reflexes of the gut. |
1. Gastrocolic reflex- gastric distention stimulates colonic contraction 2. Intestinal inhibitory reflex- distention or peritonitis results in ileus |
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What are the five stipulations of an endocrine hormone? |
1. Secreted by one cell and affects another 2. Transported by the blood 3. Release is stimulated by food 4. Not necessarily secreted under neuronal control 5. Synthetic agonist can be made |
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Describe gastrin. |
- Secreted in antrum of stomach and duodenum in response to gastric distention and protein - Stimulates parietal cells to secrete HCl - Also releases histamine which stimulates HCl secretion |
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Describe secretin. |
- Secreted in duodenum and proximal jejenum in response to acid, fat, protein, or bile acids - Stimulates pancreatic and biliary secretions = digestion of food - Also negative feedback mechanism for acid production and stimulates bicarbonate secretion = regulated pH in duodenum |
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Describe cholecystokinin (CCK). |
-Secreted in duodenum, jejenum, ileum in response to fat and protein - Stimulates contraction of gall bladder and secretion of bile and pancreatic enzymes - Also inhibits gastric emptying (hunger suppressant) |
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Describe gastric inhibitory peptide (GIP). |
-Secreted in duodenum and jejenum in response to glucose - Stimulates secretion of insulin |
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Describe motilin. |
-Secreted in duodenum and jejenum in response to alkaline pH - Stimulates motility via migrating myoelectric complex and causes gastric emptying - Also increases secretion of pepsinogen |
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What is a motilin agonist? |
Erythromycin |
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Describe aldosterone. |
- Only extrinsic endocrine secretion - Secreted by zona glomerulosa of adrenal cortex in response to decreased blood flow to kidneys, low Na, high K, renin- angiotensin - Stimulates increased water and Na absorption in exchange for K |
