I read somewhere that daily 5 gallons of water is dumped into the intestine. So enquired further.
Daily Fluid Secretion
Volumes (ml/day) Composition Regulation
Oral secretions
1500 ml
99.8% water; low in sodium
high in calcium and phosphate to help remineralise tooth enamel
Mucin, IgA, amylase, lipase
Stimulated by eating; markedly decreased in patients who are fasted, asleep, sedated or intubated
Oesophageal secretions
Minimal
Thick bicarbonate-rich mucus
Vagal regulation
Gastric acid
2000 ml
Cl- 170mmol/L, K+ 12-20 mmol/L
pH ~ 1.5
Mucus, pepsin, gastric lipase, intrinsic factor
Stimulated by gastrin, histamine, and vagal activity (M3 receptors)
Inhibited by somatostatin, VIP, cholecystokinin and secretin
Bile
600 ml
95% water; concentrated (~ 600 mOsm/kg), alkaline (pH ~ 7.5-8.0)
Bile acids, phospholipids, cholesterol and bilirubin
Secretion is increased by catecholamines, secretin, cholecystokinin, gastrin and glucagon
Release from the gallbladder is mainly mediated by cholecystokinin
Pancreatic exocrine secretions
2500 ml
Isotonic with plasma, but markedly alkaline (pH up to 8.3)
Cl- 30mmol, HCO3- 140 mmol
Enzymes: lipase, amylase, trypsin, numerous others
Stimulated by vagus, enteropancreatic reflexes, gastrin, cholecystokinin, and secretin
Inhibited by sympathetic stimulation and somatostatin
Intestinal secretions
2000 ml
Bicarbonate-rich mucus
pH ~ 7.5-8.0
Mainly originating from the duodenum
Stimulated by gastrin, histamine, and vagal activity (M3 receptors)
Inhibited by somatostatin, VIP, cholecystokinin and secretin
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