Glossary

colonoscopy

A procedure using a colonoscope or scope (a long thin flexible tube with a camera) inserted into the rectum and colon to view the colon wall tissue.

deoxyribonucleic acid (DNA)

Large molecules present in almost all cells. In humans, DNA is packed into structures called chromosomes. DNA carries genetic information.

dysbiosis

Disruption of the microbiome resulting in an imbalance of microbiota and diversity, which changes the function and metabolic activities of the microbiome.

endoscope

A long thin flexible tube with a camera that is passed through the mouth or into the anus, to view the gut wall.

enteric nervous system (ENS)

Responsible for communicating information about and within the digestive system.

enteroendocrine cells (EECs)

Specialised epithelial cells found scattered along the epithelium of the gastrointestinal tract. Secretes a wide range of hormones into the blood in response to the presence (or absence) of dietary nutrients and mechanical stimuli.

enterotype

The community of bacterial groups or species in an individual, that is often classified based on their predominant bacterial species.

enzyme

A biological molecule that speeds up the rate of chemical reactions (i.e. a catalyst), but is not itself destroyed in the process. Most (but not all) enzymes are proteins.

epigenetics

Modifications of DNA that do not change the DNA code but alter the pattern of gene expression.

gastroscopy

A long thin flexible tube with a camera that is passed through the mouth to view the throat, oesophagus, stomach and first part of the duodenum i.e. the upper part of the digestive system.

genes

A gene is a sequence of nucleotides in DNA, that is transcribed to produce RNA; it can be considered as the basic unit of heredity.

gut-associated lymphatic tissue (GALT)

Collections of lymphatic cells and tissue in or around the digestive system, that support the immune response of the gut.

gut-brain axis

The cross talk between the digestive system and the brain.

individual variability in drug response (IVDR)

The difference in how one individual compared to another may respond to a drug, including serious adverse reactions.

inflammatory bowel disease (IBD)

A collection of two conditions, Crohn's disease and ulcerative colitis, associated with a chronic immune response resulting in severe inflammation, ulceration and damage to the GI tract, abdominal cavity and other body systems.

irritable bowel syndrome (IBS)

A collection of disorders associated with altered gut motility, inflammation and permeability for which the cause and pathology is not fully understood.

lymphatic system

The lymphatic organs (lymph nodes, spleen, tonsils, thymus and bone marrow) and the network of fine tubules that connect them and extend throughout the body. Leukocytes, antibodies and other specialised chemicals involved in the immune response to infection circulate between the lymphatic system, the tissues and the blood, and the lymphatic capillaries collect fluid draining from the tissues and return it to the blood stream.

microbiome

A population of viruses, bacteria and eukaryotic microbes, e.g. in the digestive tract, where it is termed the ‘gut microbiome’.

microbiota

A community of microorganisms on or in the body.

microbiota-gut-brain axis

A communication network between the microorganisms of the gut microbiome, vagus nerve, bloodstream, and brain.

nephron

The functional unit of the kidney, composed of tubules and blood vessels which produce the urine.

pathogens

Infectious agents (e.g. parasites, protists, bacteria, fungi, viruses, prions) that cause infectious diseases.

prebiotics

Substances that are eaten or drunk to promote the growth of beneficial gut microbes.

probiotics

One or more live microbial species eaten or drunk to promote gut health.

short-chain fatty acids (SCFAs)

Fatty acid molecules each consisting of 6 or less carbon atoms. It is produced by bacteria within a microbiome by digesting fibre and releasing the fat as SCFAs. Examples are butyrate, propionate and acetate. SCFAs can be used by the host’s body or by other bacteria as an important energy source.

small intestinal bacterial overgrowth (SIBO)

Excessive and abnormal growth of either healthy bacteria from the gut microbiome or pathogenic bacteria in the small intestine.

symbionts

An organism that lives with another for mutual benefit.

vagus nerve

The tenth cranial nerve that is a key mediator of the parasympathetic nervous system that extends from the brain down to the majority of organs within the thorax, abdomen and pelvis.

villi

Small, finger-like projections of tissue. Typically these are thin, consisting of only a few layers of cells. Villi are important for increasing the surface area of the tissue which is in contact with surrounding material, such as in the placenta or in the gut. This serves to increase the area of surface over which transport of substances can take place.