Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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A

  • Acetylcholine – neurotransmitter released at the synapses of parasympathetic nerves and neuromuscular junctions
  • Achalasia – failure of the LOS to relax making swallowing difficult
  • Adventitia – the outer covering of various organs
  • Alginate – polysaccharide extracted from brown seaweed
  • Alkalosis – a condition in which the alkalinity of body fluids and tissues is abnormally high
  • Ambulatory pH monitoring – a procedure by which pH in the oesophagus and stomach can be measured continuously while the subject carries on with normal activities
  • Anticholinergic – drug that opposes the action of the neurotransmitter acetylcholine
  • Antihistamine – drug that opposes the action of histamine
  • Antrum – the bottom part of the stomach near the pyloric sphincter
  • Appendicitis – inflammation of the appendix, usually due to infection, which is associated with abdominal pain
  • Atrophic gastritis – inflammation of the stomach lining due to reduced epithelial cell turnover, especially in elderly people
  • Autodigestion – digestion of the gastric mucosa by its own secretions
  • Autonomic – non-conscious muscle control
  • Auerbach's plexus – nerve complex that controls gut motility
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B

  • Barrett's oesophagus – condition in which the stratified squamous epithelium at the lower end of the oesophagus becomes replaced with columnar (gastric) epithelium
  • Benign – description of a tumour that is non-cancerous
  • Bile – alkaline secretion produced by the liver
  • Bile salt – alkaline salts in bile necessary for the emulsification and digestion of fats
  • Body of stomach – large central portion of the stomach
  • Bolus – ball of masticated food ready to be swallowed
  • Buccal cavity – alternative name for the mouth
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C

  • Cardiac – small upper region of the stomach adjacent to the LOS
  • Carminative – substance that helps to relieve flatulence
  • Cholecystokinin (CCK) – a hormone secreted by the cells of the duodenum in response the presence of partly digested food
  • Chyme – semi-solid acidic food mass that enters the duodenum from the stomach
  • Coeliac disease – a condition in which the small intestine fails to digest and absorb food, due to a permanent sensitivity of the intestinal lining to gliadin, a substance found in gluten
  • Congenital – describing a condition that is recognized at birth or that is believed to have been present since birth
  • Constitutive expression – describes something that is always present in normal tissue
  • Cricopharyngeal sphincter – upper oesophageal sphincter, which contracts to prevent food in the oesophagus returning to the throat
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D

  • Deglutition – the process of swallowing
  • Diaphragm – the thin, membranous dome-shaped muscle that separates the thoracic and abdominal cavities
  • Digestion – process of breaking down foods into small molecules for absorption
  • Duodenum – initial 'C'-shaped section of the small intestine
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E

  • Endoscopy – viewing of the interior of the body using an endoscope
  • Enteroendocrine cells – cells of the gastric pit in the stomach
  • Enterogastrone – a hormone from the duodenum that inhibits the secretion of gastric juice by the stomach. It is released when the stomach contents pass into the small intestine
  • Enzyme – a protein that speeds up the rate of a biological reaction without being used up in the reaction itself
  • Epigastric – pertaining to the upper central region of the abdomen
  • Epiglottis – flap of cartilage that covers the entrance to the larynx during swallowing
  • Epithelium – lining tissue
  • Eructation – belching; the sudden raising of gas from the stomach
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F

  • Fundoplication – a surgical operation for gastro-oesophageal reflux disease in which the upper part of the stomach is wrapped around the lower oesophagus
  • Fundus – upper part of the stomach, which lies between the cardia and the body of the stomach
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G

  • Gall bladder – a pear-shaped sac lying underneath the right lobe of the liver, in which bile is stored
  • Gastric emptying – the process by which food leaves the stomach and enters the duodenum
  • Gastric inhibitory protein (GIP) – protein produced in response to acid chyme in the duodenum, which feeds back to prevent further production of hydrochloric acid and pepsinogen
  • Gastric juice – secretion containing enzymes and acid produced by the stomach to digest food
  • Gastric pits – deep channels in the stomach mucosa from which gastric juice is secreted
  • Gastric ulcer – an ulcer of the stomach caused by the action of acid and pepsin on the stomach lining
  • Gastrin – hormone secreted by the stomach that stimulates gut secretion of digestive juices
  • Gastritis – inflammation of the stomach mucosa
  • Gastrointestinal (GI) tract – the long passage running from the mouth to the anus, through which food passes to be digested and absorbed
  • Gastro-oesophageal reflux – retrograde movement of the stomach contents into the oesophagus
  • Gastro-oesophageal reflux disease (GORD) – condition caused by abnormal gastro-oesophageal reflux, including symptoms of heartburn and regurgitation. Oesophagitis and more severe complications, such as ulceration, stricture and Barrett’s oesophagus may also be present
  • Gland – organ or group of cells specialised in synthesising and secreting certain fluids
  • Glossopharyngeal nerve – The ninth cranial nerve, which supplies motor fibres to part of the pharynx and to the parotid salivary glands and sensory fibres to the tongue and soft palate
  • Gram-negative – bacteria that take up a certain dye to appear red under the microscope
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H

  • H. pylori – Helicobacter pylori, bacterium that lives in the stomach of some individuals and causes peptic ulcers
  • H2-receptor antagonists (H2-RAs) – drugs that interact with H2 receptors on the parietal cells to inhibit acid secretion
  • H2 receptors – histamine receptors found on the parietal cells of the stomach. When stimulated by histamine they cause increased acid secretion
  • Hard palate – the front part of the roof of the mouth
  • Heartburn – burning pain, usually felt in the epigastric region (of the abdomen) due to reflux of corrosive stomach contents into the oesophagus
  • Hiatus hernia – condition in which part or all of the stomach passes from the abdominal cavity through the diaphragm into the thorax
  • Histamine – hormone/chemical transmitter involved in local immune responses, regulating stomach acid production and in allergic reactions
  • Hypochondriac – pertaining to the upper left or right region of the abdomen
  • Hypogastric – pertaining to the lower central region of the abdomen
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I

  • Iliac – pertaining to the lower left or right region of the abdomen
  • Intrinsic factor – substance secreted by main gastric glands necessary for the absorption of vitamin B12.
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L

  • Lamina propria – thin layer of tissue within the gut wall
  • Laminaria hyperborean – the species of brown seaweed from which sodium alginate is extracted
  • Laparoscopy – examination of the abdominal structures by means of an illuminated tubular instrument passed through a small incision in the abdomen wall
  • Larynx – the organ responsible for the production of vocal sounds, also serving as an air passage conveying air from the pharynx to the lungs
  • Lower oesophageal sphincter (LOS) – junction of the oesophagus and the stomach that closes to prevent food returning to the oesophagus from the stomach
  • Lumbar – pertaining to the central left or right region of the abdomen
  • Lumen – the cavity 'hole' in the centre of a tubular organ such as the gut or a blood vessel
  • Lymph – fluid bathing the tissues of the body
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M

  • Mast cell – a large cell in connective tissue with many coarse cytoplasmic granules containing heparin, histamine and serotonin, which are released during inflammation and allergic responses
  • Mastication – the process of chewing food
  • Main gastric glands – principal sites of gastric juice production in the stomach
  • Medulla oblongata – the extension within the skull of the upper end of the spinal cord. Contains centres responsible for regulating the heart and blood vessels, respiration, salivation and swallowing
  • Meissner's plexus – nerve network of the alimentary canal controlling gut secretions
  • Mesentery – double layer of peritoneum attaching the abdominal organs to the posterior wall of the abdomen
  • Mucosa – tissue that secretes mucus (and often other secretions)
  • Mucous cells – cells in the gastric glands, which secrete mucus
  • Mucus – viscous fluid secreted by mucous membranes. Mucus acts as a protective barrier, a lubricant and a carrier of enzymes
  • Mucus-bicarbonate barrier – protective mechanism of the stomach mucosa
  • Muscarinic receptor – receptor on the surface of the parietal cell, which responds to acetycholine to secrete hydrochloric acid
  • Muscle layer – double layer of smooth and longitudinal muscle fibres in the gut wall
  • Muscularis externa – muscular layer of the gastrointestinal tract
  • Mylohyoid muscles – muscle in the floor of the mouth, attached at one end to the mandible and at the other to the hyoid bone
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N

  • NSAIDs – non-steroidal anti-inflammatory drugs; for example, aspirin and ibuprofen, that exert their effects by interfering with prostaglandin synthesis
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O

  • Oesophagitis – inflammation of the oesophagus, usually due to irritation by stomach acid and enzymes
  • Oesophagus – gullet; a muscular tube approximately 25 cm long that extends from the pharynx to the stomach. Food passes along the oesophagus aided by waves of peristalsis
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P

  • Pancreas – a compound gland that lies behind the stomach. It is composed of clusters of cells, which secrete pancreatic juice containing several digestive enzymes
  • Pancreatic lipase – enzyme secreted into the duodenum to digest fats
  • Parietal cells – acid-secreting cells in main gastric glands
  • Pathogens – micro-organisms that cause disease
  • Pepsin – protein-splitting enzyme produced by main gastric glands
  • Pepsinogen – inactive proenzyme converted to the active protein-splitting enzyme (pepsin) by the action of hydrochloric acid
  • Peptic ulcer – a lesion of the gastric or duodenal mucosa caused by the combined digestive action of pepsin and acid
  • Peristalsis – alternating muscular contractions and relaxations, which propel food through the gut
  • Peritoneal cavity – abdominal cavity in which the intestines lie
  • Peritoneum – outer lining of digestive organs in the abdominal cavity
  • Pharynx – muscular chamber that forms part of the respiratory system and alimentary canal
  • Plexus – a network of nerve fibres
  • Prokinetic – a drug that speeds up gastric emptying to alleviate symptoms of gastro-oesophageal reflux disease
  • Prostaglandins – a group of hormones with many actions; contraction of smooth muscle, mediation of inflammation, mucus production in the stomach
  • Proton pump – protein in the membrane of the parietal cell that secretes hydrochloric acid into the lumen of the gastric gland
  • Proton pump inhibitor (PPI) – pharmaceutical product that interacts with the proton pump to inhibit acid secretion by the parietal cells of the stomach
  • Pyloric sphincter – ring of muscle at the junction between the bottom of the stomach and the duodenum that contract to prevent chyme leaving the stomach prematurely
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R

  • Reflux – retrograde movement of the stomach contents back into the oesophagus
  • Reflux suppressant – compound that produces a physical barrier to reflux of the stomach contents into the oesophagus
  • Refluxate – material refluxed into the oesophagus from the stomach; contains food, acid, pepsin and bile
  • Regurgitation – the bringing up of undigested food from the stomach to the mouth
  • Retrosternal – behind the sternum (breast bone)
  • Rugae – folds in the stomach mucosa that stretch when food enters
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S

  • Saliva – alkaline liquid secreted into the mouth
  • Salivary glands – glands that produce saliva
  • Secretin – Hormone secreted by the duodenum in response to acidified food leaving the stomach
  • Serosa – tissue that secretes a serous fluid
  • Serous – thin or watery
  • Small intestine – part of the intestine comprising the duodenum, jejunum and ileum
  • Soft palate – the rear part of the roof of the mouth
  • Sphincter – a ring of muscle in the intestine which, when contracted, can close off a section of gut
  • Squamous epithelium – epithelium made up of flat cells
  • Stomach – sac-like organ that forms part of the expandable GI tract between the oesophagus and the duodenum
  • Stricture – a narrowing of any tubular structure in the body
  • Sublingual gland – one of a pair of salivary glands situated in the lower part of the mouth on either side of the tongue
  • Submaxillary gland – one of a pair of salivary glands situated below the parotid glands
  • Striated muscle – skeletal muscle that is under conscious control
  • Submucosa – layer of the gut between the mucosa and the muscle layer
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T

  • Trachea – windpipe; tube that connects the pharynx to the lungs
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U

  • Ulcer – lesion in the mucosa
  • Umbilical – pertaining to the central region of the abdomen
  • Urease – enzyme produce by H. pylori, which converts urea to ammonia and carbon dioxide
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V

  • Vagus – nerve that supplies most of the abdominal organs
  • Voluntary muscle – muscle that is under voluntary control
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Z

  • Zollinger-Ellison syndrome – condition in which there is hypersecretion of gastric juice due to excessive levels of the hormone gastrin
  • Zymogenic cells – cells in main gastric glands that secrete the enzyme pepsin
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