[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Physiology](https://durgical.com/en/physiology/) › Gastrointestinal # Gastrointestinal Motility, secretions, gut hormones, digestion, absorption and the liver. 23 pages ## Exam priority: high - [**Bile and the enterohepatic circulation** Mechanism · The liver makes bile to emulsify fat; almost all bile salts are reabsorbed in the ileum and…](https://durgical.com/en/physiology/bile-and-the-enterohepatic-circulation/) - [**Carbohydrate digestion and absorption** Mechanism · Starch and sugars are cut down to glucose, galactose and fructose; only those monosaccharides…](https://durgical.com/en/physiology/carbohydrate-digestion-and-absorption/) - [**Fat digestion and absorption** Mechanism · Bile disperses fat, lipase cuts it, micelles carry it to the wall, and it leaves the gut packed…](https://durgical.com/en/physiology/fat-digestion-and-absorption/) - [**Gastric acid secretion** Mechanism · Parietal cells pump acid into the stomach with the H⁺/K⁺ pump; the vagus, gastrin and histamine…](https://durgical.com/en/physiology/gastric-acid-secretion/) - [**Gastrointestinal hormones** Table to know · The gut makes its own hormones: they report what food arrived and tune acid, enzymes, bile…](https://durgical.com/en/physiology/gastrointestinal-hormones/) - [**Mucus and mucosal protection in the gut** Mechanism · A slippery, alkaline gel and a fast-healing lining let the gut hold acid and enzymes without…](https://durgical.com/en/physiology/mucus-and-mucosal-protection-in-the-gut/) - [**Water and electrolyte absorption and how diarrhea happens** Mechanism · The gut handles about 9 L of fluid a day and returns nearly all of it to the blood by following…](https://durgical.com/en/physiology/water-and-electrolyte-absorption-and-how-diarrhea-happens/) ## Exam priority: medium - [**Absorption of iron, calcium and vitamin B12** Mechanism · Iron and calcium are absorbed mainly in the duodenum; vitamin B12 needs intrinsic factor from…](https://durgical.com/en/physiology/absorption-of-iron-calcium-and-vitamin-b12/) - [**Exocrine pancreatic secretion** Mechanism · The pancreas sends bicarbonate to the duodenum to neutralize acid, and enzymes that digest…](https://durgical.com/en/physiology/exocrine-pancreatic-secretion/) - [**Functions of the liver** Concept · The liver processes what is absorbed, makes blood proteins, stores energy, clears toxins and…](https://durgical.com/en/physiology/functions-of-the-liver/) - [**Gastric motility and emptying** Mechanism · The stomach stores food, grinds it and hands it to the duodenum in small portions, at the pace…](https://durgical.com/en/physiology/gastric-motility-and-emptying/) - [**Hepatic lymph, the liver as a blood reservoir, and how ascites forms** Mechanism · The liver's leaky sinusoids make lots of protein-rich lymph; when their pressure rises and the…](https://durgical.com/en/physiology/hepatic-lymph-the-liver-as-a-blood-reservoir-and-how-ascites-forms/) - [**Protein digestion and absorption** Mechanism · Proteins are cut in the stomach and duodenum down to amino acids and short peptides, which the…](https://durgical.com/en/physiology/protein-digestion-and-absorption/) - [**Small bowel and colon motility** Mechanism · The gut mixes its contents with segmenting contractions and moves them on with peristalsis; the…](https://durgical.com/en/physiology/small-bowel-and-colon-motility/) - [**Splanchnic and portal circulation** Regulation · Blood from the gut, spleen and pancreas passes through the liver first via the portal vein; it…](https://durgical.com/en/physiology/splanchnic-and-portal-circulation/) - [**Swallowing and esophageal motility** Mechanism · Swallowing starts voluntarily and continues as an automatic reflex that seals the airway and…](https://durgical.com/en/physiology/swallowing-and-esophageal-motility/) - [**The colon: salvage absorption, gut bacteria, gas and stool** Concept · The colon dries the stool, its bacteria ferment fibre into fuel and gas, and bile pigments…](https://durgical.com/en/physiology/the-colon-salvage-absorption-gut-bacteria-gas-and-stool/) - [**The enteric nervous system, slow waves and GI control** Regulation · The gut has its own network of neurons: it sets the rhythm, mixes and pushes contents; the vagus…](https://durgical.com/en/physiology/the-enteric-nervous-system-slow-waves-and-gi-control/) - [**Vomiting and its control** Regulation · Vomiting is a protective brainstem reflex that expels stomach contents; losing a lot of acid…](https://durgical.com/en/physiology/vomiting-and-its-control/) ## For completeness - [**Defecation and continence** Regulation · When stool fills the rectum, a reflex opens the internal sphincter; the voluntary external…](https://durgical.com/en/physiology/defecation-and-continence/) - [**How digestive glands secrete and what switches them on** Concept · Digestive glands package enzymes in granules and pump chloride to pull water out; touch, nerves…](https://durgical.com/en/physiology/how-digestive-glands-secrete-and-what-switches-them-on/) - [**Patterns of malabsorption** Mechanism · Malabsorption happens when luminal digestion, the absorbing mucosa or the lymphatic exit fails…](https://durgical.com/en/physiology/patterns-of-malabsorption/) - [**Salivary secretion** Mechanism · The salivary glands make 1 to 1.5 L of saliva a day to moisten food, start starch digestion and…](https://durgical.com/en/physiology/salivary-secretion/) ## A to Z - [A](https://durgical.com/en/physiology/a-z/a/) - [B](https://durgical.com/en/physiology/a-z/b/) - [C](https://durgical.com/en/physiology/a-z/c/) - [D](https://durgical.com/en/physiology/a-z/d/) - [E](https://durgical.com/en/physiology/a-z/e/) - [F](https://durgical.com/en/physiology/a-z/f/) - [G](https://durgical.com/en/physiology/a-z/g/) - [H](https://durgical.com/en/physiology/a-z/h/) - [I](https://durgical.com/en/physiology/a-z/i/) - [L](https://durgical.com/en/physiology/a-z/l/) - [M](https://durgical.com/en/physiology/a-z/m/) - [N](https://durgical.com/en/physiology/a-z/n/) - [O](https://durgical.com/en/physiology/a-z/o/) - [P](https://durgical.com/en/physiology/a-z/p/) - [R](https://durgical.com/en/physiology/a-z/r/) - [S](https://durgical.com/en/physiology/a-z/s/) - [T](https://durgical.com/en/physiology/a-z/t/) - [U](https://durgical.com/en/physiology/a-z/u/) - [V](https://durgical.com/en/physiology/a-z/v/) - [W](https://durgical.com/en/physiology/a-z/w/) [← Physiology](https://durgical.com/en/physiology/) Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given. Representative model, for educational purposes only. --- Source: https://durgical.com/en/physiology/areas/gi/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/areas/gi/