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Glossary/Dictionary

Definitions of Digestive Terms

A

Abdomen
Area between the chest and the hips that contains the stomach, small intestine, large intestine, liver, gall bladder, pancreas, and spleen.
Absorption

The process by which nutrients move from the intestines, mostly into the bloodstream, to nourish the body.

Achalasia
Failure of the lower esophageal sphincter to relax.
Acute
Sudden onset of symptoms.
Acquired
Developed after birth.
Adaptation (intestinal)
The process, after surgical resection, in which the remaining intestine compensates by increasing its ability to absorb water and nutrients.
Adaptive response
A helpful, protective response.
Aerophagia
Ingestion of air.
Afferent nerves
Nerve fibers (usually sensory) that carry impulses from an organ or tissue toward the brain and spinal cord (central nervous system), or the information processing centers of the enteric nervous system, which is located within the walls of the digestive tract.
Afferent pathways
Nerve structures through which impulses are conducted from a peripheral part (e.g., the gut or intestines) toward a nerve center (e.g., the central nervous system).
Aganglionosis
Absence of nerve cells.
Allodynia
Pain due to stimuli that do not normally provoke pain.
Allostasis
The ability of the organism to achieve stability through adaptation or change. This process, which is critical to our survival, involves the autonomic nervous system, the HPA axis, and the cardiovascular, metabolic, and immune systems which act to protect the body by responding to internal and external stimuli. Paradoxically, these same systems, when activated by stress, can protect and restore as well as damage the body.
Ambulatory care
Health services provided in a doctor's office, or on an outpatient basis.
Amino Acids
A group of 20 different kinds of small molecules that link together in long chains to form proteins. Often referred to as the "building blocks" of proteins.
Anal canal
The lowermost portion of the large intestine.
Anal fissure
Crack in the skin in or adjacent to the anal canal.
Anal incontinence
Any leakage of liquid or solid stool or excessive leakage of gas.
Analgesic
Pain relieving.
Anastomosis, intestinal
Reattachment of two portions of bowel.
Anismus
A condition marked by the failure of pelvic floor muscles to relax, or a paradoxical contraction of the pelvic floor muscles, with defecation. Also referred to as pelvic floor dyssynergia.
Anorexia
Loss of appetite.
Antigen
A substance or molecule recognized by the immune system, such as bacteria or a virus.
Antinociception
Increased tolerance to pain.
Antispasmodics
Drugs that inhibit smooth muscle contraction in the gastrointestinal tract.
Anorectal manometry
A test that can be used to measure resting and squeezing anal sphincter pressures, rectal sensation and compliance, and sphincter response.
Anus
The opening of the rectum.
Autonomic
Involuntary.
Autonomic nervous system
The part of the nervous system that controls involuntary actions of internal organs such as the bowel.

B

Bacteria
Very small organisms (microbes) that are normally in the gut (intestines). There are over 500 different kinds known to live in the gut; most (up to several billion) bacteria are in the large intestine (colon). "Normal" bacteria have important functions in life and health. Bacteria that can cause infection are called "pathogens." Normal bacteria protect against pathogens.
Barium
A metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray.
Basic science
The fundamental approach to understanding how systems work. Basic research takes place in the laboratory and often involves the study of molecules and cells.
Bile
Secretions of the liver that aid in digestion and absorption of nutrients in the intestinal tract.
Bifidobacterium infantis 35624
A type of bacteria that, in the right amount, may have a beneficial effect (probiotic), and help lessen some bowel symptoms.
Biliary tract
Gall bladder and the bile ducts.
Biofeedback therapy
A painless neuromuscular reeducation tool in which a therapist, using special sensors to monitor functions that we are usually not aware of, helps to change abnormal functions to more normal and effective functions.
Biomedical model
The model of illness and disease in Western medical education and research. It has two assumptions: (1) reductionism - that all conditions can be linearly reduced to a single cause, and (2) dualism - where illness and disease are divided either to an "organic" disorder having an objectively defined cause, or a "functional" disorder, with no specific cause or pathophysiology. The biomedical model is not sufficient to explain the functional GI disorders.[Rome II]
Biopsy
Tissue sample.
Biopsychosocial model
A model that proposes that illness and disease result from simultaneously interacting systems at the cellular, tissue, organismal, interpersonal, and environmental level. It incorporates the biologic aspects of the disorder with the unique psychosocial features of the individual, and helps explain the variability in symptom expression among individuals having the same biologic condition.
Blinding
A process in a clinical study that conceals a treatment from the patient.
Borborygmi
Audible rumbling abdominal sounds due to gas gurgling with liquid as it passes through the intestines.
Bowel
The intestines.
Bowel control
Ability to delay defecation or passing of intestinal gas in a controlled manner.
Bowel incontinence
Inability to delay defecation in a controlled manner.
Bowel management or retraining
A program to help develop a more predictable schedule for elimination and decrease unpredictable episodes of incontinence. It may involve normalizing stool consistency, usually through dietary changes; establishing a regular time for elimination; and stimulating emptying on a regular basis.
Brain-gut axis
The continuous bi-directional flow of information and feedback that takes place between the gastrointestinal tract, and the brain and spinal cord (which together comprise the central nervous system).

C

Call to stool
Feeling the need to have a bowel movement.
Case control study
A retrospective study that compares patients who already have a disease or outcome of interest (cases) with patients who do not have the disease or outcome (controls).
Case series
A report about a small group of similar patients with a disease or outcome of interest.
Celiac disease
Inability to digest and absorb the protein gliadin (a component of gluten). Gliadin is found in wheat, rye, barley, and oats. Celiac disease is also called celiac sprue, and gluten intolerance.
Cell
The basic unit of any living organism. It is a small, watery, compartment filled with chemicals and a complete copy of the organism's genome.
Central amplification
Changes that occur in the central nervous system (brain and spinal cord) that affect cell transmitters and receptors, thereby increasing the excitability of neurons and resulting in heightened perception of signals from the gastrointestinal tract.
Cholecystectomy
Surgical removal of the gallbladder.
Chronic
Symptoms occurring over a long period of time.
Chronic intestinal pseudo-obstruction (CIP)
A rare disorder of gastrointestinal motility where coordinated contractions (peristalsis) in the intestinal tract become altered and inefficient.
Clinical science
The approach aimed at understanding the diagnosis and treatment of diseases and disorders through studies involving people, usually carried out in clinical settings.
Clinical significance
A conclusion that an intervention has an effect that is of practical meaning to patients and health care providers.
Clinical trial
An experimental research study that tests new medical interventions on people. These interventions may include drugs, devices, or other instruments.
Clostridium difficile (C. difficile)
A gram-positive anaerobic bacterium. C. difficile is recognized as the major causative agent of colitis (inflammation of the colon) and diarrhea that may occur following antibiotic intake.
Cohort
A group that shares the same characteristics among its members.
Cohort study
An observational study in which outcomes in a group of patients that received an intervention are compared with outcomes in a similar group (the cohort) either contemporary or historical, of patients that did not receive the intervention.
Colectomy
Removal of part or all of the colon.
Colitis
Inflammation of the colon.
Colon
The large intestine.
Colonic inertia
Delayed colonic action. Symptoms include long delays in the passage of stool accompanied by lack of urgency to move the bowels
Colonoscopy
Colonoscopy is a fiberoptic (endoscopic) procedure in which a thin, flexible, lighted viewing tube (a colonoscope) is threaded up through the rectum for the purpose of inspecting the entire colon and rectum and, if there is an abnormality, taking a tissue sample of it (biopsy) for examination under a microscope, or removing it.
Colostomy
A surgically created opening of the colon to the abdominal wall, allowing the diversion of fecal waste.
Commensals
Non-pathogenic microorganisms that become part of the host's normal flora.
Comorbidity
Coexistence with another disease or condition.
Congenital
Conditions existing at birth, but not through heredity.
Continence
Ability to delay defecation or passing of intestinal gas in a controlled manner.
Contrast radiology
A test in which a contrast material (i.e., Barium) is used to coat the rectum, colon, and lower part of the small intestine so they show up on an x-ray.
Control
(See Randomized controlled trial) A standard of comparison which can be a conventional practice, a placebo, or no intervention.
Control group
A group of patients that serves as the basis of comparison when assessing the effects of the intervention of interest that is given to the patients in the treatment group.
Constipation
Reduced stool frequency, or hard stools, difficulty passing stools, or painful bowel movements.
Cope
How a person responds to a difficult or unwanted situation.
Corticotropin-releasing factor (CRF)
CRF is a family of peptides. They act as messengers and interact with CRF receptors on cells (CRF1 and CRF2) that receive a stimulus or message, which induce a physiological response in the body. These CRF peptides and receptors are located, among other sites, both in the brain and the gut in regions linked with digestive function, emotional behavior, and autonomic nervous system activity.
Cortisol
A hormone associated with the physical effects of the stress response within the body.
Crohn's disease
A chronic form of inflammatory bowel disease.
Cross-sectional study
A study that measures the prevalence of health outcomes and/or determinants of health in a population at a point in time or over a short period of time.
Cyclic vomiting syndrome (CVS)
A disorder with recurrent episodes of severe nausea and vomiting interspersed with symptom free periods.
Cytokines
A type of protein released by cells of the immune system, which act through specific cell receptors to regulate immune responses.

D

Declaration of Helsinki
A set of guidelines adopted in Helsinki, Finland, in 1964. The Declaration addressed the ethics of clinical research and recommended specific safeguards, including informed consent.
Defecography
A test that uses x-rays to look at the behavior of the rectum and anus during attempts to defecate.
Dehydration
An excessive loss of fluids in the body.
Diabetes
A disease in which blood glucose (blood sugar) levels are above normal. Type 2 diabetes, also known as adult-onset or noninsulin-dependent diabetes mellitus (NIDDM), is the most common form of diabetes.
Diaphragm
The muscle wall between the chest and the abdomen.
Diarrhea
Passing frequent and/or loose or watery stools. Acute diarrhea goes away in a few weeks, and becomes chronic when it lasts longer than 4 weeks.
Digestion
The process by which food is converted into substances that can be absorbed and assimilated by the body.
Digestive tract 
A group of hollow organs that forms a long, twisting tube extending from the mouth to the anus through which food is ingested, digested, and expelled.
Digital examination
Physical exam in which the doctor inserts his or her finger.
Dilatation
Expansion of an organ or vessel.
Discomfort
An unpleasant, but not painful, feeling.
Disease
A condition of an organic being or of one of its parts that impairs normal living functioning.
Disorder
A disturbance in regular or normal function. An abnormal condition.
Distal esophageal spasm (DES)
A rare motility (movement) disorder of the lower (distal) two-thirds of the esophagus. Occurring equally in men and women, the most common symptoms are chest pain and difficulty swallowing. Some patients may experience unusual symptoms like an unexplained cough.
Distention
An uncomfortable swelling in the intestines.
Diverticula
Small pouches in the colon.
Diverticulitis
Occurs when diverticula become infected or irritated.
Diverticulosis
A condition of having multiple diverticulum in the walls of the colon. Also called uncomplicated diverticular disease.
Diverticulum
Singular of diverticula.
DNA
Abbreviation for deoxyribonucleic acid, the molecule that contains the genetic code for all life forms (except for a few viruses).
Domperidone
A pro-motility agent, domperidone, has been used in countries outside of the U.S. to treat gastroparesis or severe GI motility disorders.  In 2004 the FDA determined that there are some patients with severe gastrointestinal disorders that are refractory (resistant) to standard therapy, who may benefit from domperidone and in whom the drug's benefits outweigh its risks. FDA encourages physicians who would like to prescribe domperidone for their patients with severe gastrointestinal disorders that are refractory to standard therapy to open an Investigational New Drug Application (IND). Find out more at this FDA web page.
Double blinding
A process in a clinical study that conceals the treatment from both the patient and the investigator.
Dumping syndrome
A collection of symptoms that occurs when food is emptied too quickly from the stomach.
Duodenum
The first part of the small intestine.
Dysmotility (intestinal)
Abnormal contractions, of varying frequency and severity, of the muscles in the gastrointestinal tract, which may or may not be associated with symptoms. They differ from functional gastrointestinal disorders, which are defined by symptoms that may or may not have dysmotility, but which are also associated with low pain thresholds (visceral hypersensitivity). When occurring in the stomach or small intestine, dysmotility can result in disorders like gastroparesis or with or without symptoms such as bloating, pain, nausea, and vomiting due to either disorganized contractions, or weak contractions. When occurring in the large intestine, dysmotility can result in disorders like Hirschsprung's disease or colonic inertia that can produce symptoms of constipation, or other conditions that cause diarrhea. The abnormal motility involves changes in the contractions that either move or hold back stool. Abnormalities of "dysmotility" can be measured with special motility testing.
Dyspepsia
A term often used to describe pain or discomfort that occurs in the upper abdominal area.
Dysphagia
Difficulty swallowing.

E

Effectiveness
The extent to which an intervention does people more good than harm under general or routine conditions.
Efficacy
The extent to which an intervention improves the outcome for people under ideal circumstances. Testing efficacy means finding out whether something is capable of causing an effect at all.
Efferent nerves
Nerve fibers that carry impulses away from the brain and spinal cord (central nervous system), which cause a muscle or gland to contract, or which modify or inhibit its contraction.
Electrolytes
Chemicals that break down into ions (atoms) in the body's fluids and are essential to regulating many body functions. 
Encopresis
Fecal incontinence – the involuntary loss of solid liquid stool in children.
Endogenous
Internally produced, within an organism, tissue, or cell.
Endoscope
A thin, flexible tube with a light and a lens on the end used to look into the esophagus, stomach, duodenum, small intestine, colon, or rectum.
Endoscopic retrograde cholangiopancreatography (ERCP)
See ERCP
Endoscopy
A procedure that uses an endoscope to diagnose or treat a condition. There are many types of endoscopy; examples include colonoscopy, sigmoidoscopy, gastroscopy, enteroscopy, and esophogealgastroduodenoscopy (EGD).
Enteral nutrition
Food provided through a tube placed in the nose, stomach, or small intestine.
Enteric nervous system (ENS)
Autonomic nervous system within the walls of the digestive tract. The ENS regulates digestion and the muscle contractions that eliminate solid waste.
Enteritis
An irritation of the small intestine.
Enterocele
The descent of loops of small intestine into the pelvis, that bulge into the vagina during straining. An enterocele may cause pain and/or obstructed defecation.
Enterocolitis
Inflammation of the intestines.
Enteroids
Intestinal tissue models used in pre-clinical research, ex vivo.
Enteroscopy
Examination of the inside of the small intestine using an endoscope.
Eosinophilic gastroenteritis
A rare disease characterized by food-related reactions, infiltration of certain white blood cells (eosinophils) in the GI tract, and an increase in the number of eosinophils in the blood.
Epidemiology
The study of the distribution of health-related states or events in specified populations and the application of this study to the control of health problems.
Episiotomy
An incision made in the skin between the vagina and anus meant to enlarge the vaginal opening during childbirth in order to prevent tearing and to facilitate delivery of an infant.
Epithelium
The inner and outer tissue covering digestive tract organs.
ERCP (endoscopic retrograde cholangiopancreatography)
A procedure for the examination or treatment of the bile ducts (biliary tree) and pancreatic ducts that combines the use of x-rays and an endoscope. Used to diagnose and manage problems of the liver, gallbladder, bile ducts, and pancreas such as gallstones and their complications, pancreatic and biliary cancers, pancreatitis and its complications, and pancreaticobiliary pain. The procedure carries a risk of serious complications, requires conscious sedation of the patient, and is performed by gastroenterologists or other physicians with special training. 
Esophagitis
Inflammation of the esophagus.
Esophagus
The organ that connects the mouth to the stomach.
Esophogealgastroduodenoscopy (EGD)
Examination of the inside of the esophagus, stomach, and duodenum using an endoscope. (Also called Upper Endoscopy)
Etiology
Cause.
Etiologic mechanisms
The processes that cause or contribute to the cause of diseases or conditions.
Evidence-based
Findings based on the use of current best evidence from scientific and medical research.
Evidence-based medicine
The conscientious, explicit and judicious use of the current best evidence from clinical care research in making decisions about the care of individual patients
Extraintestinal
Occurring outside the intestines.
Ex vivo

The process where living cells, tissues, or organs are cultured outside of a living organism for treatment or analysis under controlled conditions.

F

Failure to thrive (Pediatric)
A condition that occurs when a baby does not grow normally.
Familial
Tending to occur in more members of a family than expected by chance alone.
Fasting
Voluntarily not eating food over periods of time.
FDA

Food and Drug Administration (FDA), a regulatory agency within the US Department of Health and Human Services.

Fecal Incontinence (FI)
Involuntary leakage of liquid or solid stool.
Fecalith:
A hard mass of dried feces.
Feces
Waste eliminated from the bowels.
Fistula
An abnormal passage between two organs or between an organ and the outside of the body.
5-hydroxytryptamine (5-HT)
See Serotonin.
Food allergy
An immune system response by which the body creates antibodies as a reaction to certain food. Studies show that true food allergies are present in only 1-2% of adults.
Forceps
An instrument shaped like tongs that may be placed around an infant’s head to help guide it out of the birth canal during delivery.
Functional abdominal pain
Continuous, nearly continuous, or frequently recurrent pain localized in the abdomen but poorly related to gut function.
Functional bowel disorder
A functional gastrointestinal disorder with symptoms attributable to the mid or lower gastrointestinal tract.
Functional constipation
A group of functional disorders which present as persistent difficult, infrequent, or seemingly incomplete defecation.
Functional diarrhea
Daily or frequently recurrent passage of loose (mushy) or watery stools without abdominal pain or intervening constipation.
Functional disorder
A functional disorder has its basis in how a bodily system works. A functional GI disorder refers to a "disorder of functioning" where the body's normal activities in terms of the movement of the intestines, the sensitivity of the nerves of the intestines, or the way in which the brain controls some of these functions is impaired. However, there are no structural abnormalities that can be seen by endoscopy, x-ray, or blood tests. Thus a functional GI disorder is identified by the characteristics of the symptoms (e.g., Rome Criteria) and infrequently, when needed, limited tests.
Functional heartbrun
Persistent burning sensation in the absence of gastroesophageal reflux disease (GERD), a motility disorder, or a structural explanation.

G

Ganglion
(Plural: ganglia) Usually, a group of nerve cell bodies lying outside of the central nervous system (CNS); also used for one group of nerve cell bodies within the CNS – the basal ganglia.
Gastric
Related to the stomach.
Gastric emptying study
A test to measure the time it takes for the stomach to empty.
Gastric Juices
Liquids produced in the stomach to help break down food and kill bacteria.
Gastritis
An inflammation of the stomach lining.
Gastroenteritis
An infection or irritation of the stomach and intestines.
Gastroenterologist
A doctor who specializes in digestive diseases or disorders.
Gastroenterology
The field of medicine concerned with the function and disorders of the digestive system.
Gastrointestinal (GI) tract
The muscular tube from the mouth to the anus, also called the alimentary canal or digestive tract.
Gastroparesis
A disorder characterized by certain long-term symptoms together with delayed stomach emptying in the absence of any observable obstruction or blockage. Also called delayed gastric emptying.
Gastroscopy
Examination of the inside of the esophagus, stomach, and duodenum using an endoscope.
Gastrostomy (G-tube)
A method of enteral feeding in which a tube is surgically introduced through the abdominal wall.
Gene
The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.
Gene expression
The process by which the instructions in genes are converted to messenger RNA, which directs protein synthesis.
Genome
The complete genetic material of an organism.
GER (gastroesophageal reflux)
Also called acid reflux, a condition where the contents of the stomach regurgitates (or backs up) into the esophagus (food pipe), causing discomfort.
GERD (Gastroesophageal reflux disease)
A condition characterized by symptoms and/or tissue damage that results from repeated or prolonged exposure of the lining of the esophagus to acidic contents from the stomach.
Glial cell
A type of cell that surrounds nerve cells and holds them in place. Glial cells also insulate nerve cells from each other.
Global
Overall or multiple (e.g., global symptoms).
Globus
A sensation of something stuck or of a lump or tightness in the throat.
Gluten intolerance
See Celiac disease.
Gut
Esophagus, stomach and intestines.

H

H2-blockers
Medicines that reduce the amount of acid the stomach produces.
Health related quality of life
The impact an illness has on quality of life, including the individual's perception of his or her illness.
Health-related quality of life (HRQL) measures
Patient outcome measures that extend beyond traditional measures of mortality and morbidity, to include such dimensions as physiology, function, social activity, cognition, emotion, sleep and rest, energy and vitality, health perception, and general life satisfaction. (Some of these are also known as health status, functional status, or quality of life measures.)
Helicobacter pylori (H. pylori)
A bacterium that can damage stomach and duodenal tissue, causing ulcers.
Hemorrhoids
Veins around the anus or lower rectum that are swollen and inflamed.
Hepatic
Related to the liver.
Heredity
The passing of a trait from parent to offspring through genetically coded information
Hereditary
Genetically transmitted or transmittable from parent to offspring.
Heritability
The extent to which a trait is influenced by our genetic makeup.
Hiatal hernia
A small opening in the diaphragm that allows the upper part of the stomach to move up into the chest.
Hirschsprung's disease
A rare congenital disorder that is caused by absence of nerve cells (ganglion) in the rectum and/or colon.
Homeostasis
Maintenance of a relatively stable or balanced internal body state despite environmental fluctuations. The tendency in an organism toward maintenance of physiological and psychological stability.
HPA (hypothalamic-pituitary-adrenal) axis
A system within the body that responds to stress by stimulating or inhibiting the release of various hormones, in particular cortisol, into the blood which then stimulates systems essential to self-preservation.
Hyperalgesia
Lowered threshold (higher sensitivity) to pain.
Hypersensitivity
An increased or exaggerated response to stimuli.
Hypervigilance
Increased vigilance. An intensified state of paying attention to or focusing on specific things. May severely limit a person's ability to focus on specific tasks or engage in reflective thinking when their focus is on scanning for threatening stimuli. A person with a functional GI disorder or incontinence may be hypervigilant when their focus is on scanning for bodily sensations or indications that signal symptom onset.

I

Idiopathic
A disease or disorder of unknown cause or origin.
Ileostomy
A surgically created opening of the abdominal wall to the ileum, allowing the diversion of fecal waste.
Ileum
The lower third of the small intestine, adjoining the colon.
Illness
The patient's experience of feeling unwell that may include impairment of normal physiological and social function.
Imaging
Tests that produce pictures of areas inside the body.
Imperforate anus
A birth defect in which the anal canal fails to develop, treated surgically.
Incidence
Describes the occurrence of a disease or disorder in a population. It is a rate, showing how many new cases of a disease occurred in a population (typically a susceptible population called the "at-risk population" ) during a specified interval of time (usually expressed as number of new cases per unit time per fixed number of people; e.g., number of new cases per 1,000 persons in one year).
Inflammation
Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.
Inflammatory bowel disease (IBD)
Long-lasting problems that cause irritation and ulcers in the gastrointestinal tract. The most common disorders are ulcerative colitis and Crohn's disease.
Ingestion
Taking into the body by mouth.
Inherited
Transmitted through genes from parents to offspring.
Innervated
A structure supplied with intact nerves.
Institutional review board (IRB)
In the U.S. a group of scientists, doctors, clergy, and consumers at each health care facility that participates in a clinical trial. IRBs are designed to protect study participants. They review and must approve the action plan for every clinical trial. They check to see that the trial is well designed, does not involve undue risks, and includes safeguards for patients.
Interstitial cells of Cajal (ICC)
Specialized cells found throughout the gastrointestinal tract that are required for normal gastrointestinal motility.
Interstitial cystitis
A long-lasting condition also known as painful bladder syndrome or frequency-urgency-dysuria syndrome. The wall of the bladder becomes inflamed or irritated, which affects the amount of urine the bladder can hold and causes scarring, stiffening, and bleeding in the bladder.
Intervention
Anything meant to change the course of events for someone (e.g., drug, surgery, test, treatment, counseling, etc.)
Intestinal
Relating to or occuring in the intestines.
Intestinal barrier function 
The ability to control uptake across the mucosa and protect from damage of harmful substances from the lumen.
Intestinal mucosa
The surface lining of the intestines where the cells absorb nutrients.
Intestinal permeability
The barrier properties of the lining of the intestines, which prevent harmful substances from passing through into the body.
Intestinal pseudo-obstruction
A motility disorder with symptoms like those of a bowel blockage, but with no physical evidence of blockage or obstruction. Symptoms may include cramps, stomach pain, nausea, vomiting, bloating, fewer bowel movements than usual, and loose stools.
Intestines
Also known as the gut or bowels, is the long, tube-like organ in the human body that completes digestion or the breaking down of food. They consist of the small intestine and the large intestine.
Intractable
Symptoms that don't respond to usual treatments.
Investigational
In U.S. clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered investigational in other diseases or conditions. Also called experimental.
Investigational New Drug Application (IND)
A petition to the FDA to allow testing of a new drug in clinical trials.
In vitro
In the laboratory (outside the body). The opposite of in vivo (in the body).
In vivo
In the body. The opposite of in vitro (outside the body or in the laboratory).
Irritable bowel syndrome (IBS)
A functional bowel disorder in which abdominal discomfort or pain is associated with a range of symptoms. Typically, these include intermittent abdominal pain accompanied by diarrhea, constipation, or alternating episodes of both.
Ischemic colitis
Inflammation of the large intestine (colon) caused by decreased blood flow to the colon. Symptoms may include: abdominal pain, fever, vomiting, blood in the stool, diarrhea, low back pain.

J

Jejunostomy (J-tube)
A method of enteral feeding in which a tube is surgically placed in the small intestine.

L

Laboratory study
Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.
Laboratory test
A medical procedure that involves testing a sample of blood, urine, or other substance from the body. Tests can help determine a diagnosis, plan treatment, check to see if treatment is working, or monitor the disease over time.
Lactose
A sugar found commonly in milk and dairy products.
Lactose intolerance
The inability to digest or absorb lactose.
Laparoscopy
The insertion of a thin, lighted tube (called a laparoscope) through the abdominal wall to inspect the inside of the abdomen and remove tissue samples.
Large intestine
The long, tube-like organ that is connected to the small intestine at one end and the anus at the other. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anal canal and anus.
Laxative
A compound that increases fecal water content.
Limbic system
A network of brain regions involved in the regulation of the function of internal organs, emotions, and the maintenance of homeostasis.
Lumen
The cavity of a tubular organ, such as the intestines.
Lymphocyte
A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases.

M

Magnetic resonance imaging (MRI)
A test that uses a magnet and radio waves to generate signals from inside the body used to construct images of internal structures.
Malabsorption
Difficulty absorbing nutrients from food.
Maldaptive response
An unhelpful or detrimental response.
Malnutrition
The condition that occurs when the body does not get enough nutrients.
Manometry
A test that measures pressure or contractions in the intestinal tract.
Mast cell
A type of immune system cell present in blood and tissue.
Mast cell degranulation
The release from within the cell of granules, or small sacs, containing chemicals that can digest microorganisms and activate other cells to fight infection.
Mediators
Substances within the body, such as hormones, that can transmit messages to nerve or muscle tissue to stimulate a response.
Meta-analyses
A method of summarizing previous research by reviewing and combining results from multiple studies.
Metabolism
The biochemical process the body uses to make energy from what we eat and drink.
Migration
The movement of cells, etc. from one position to another.
Mitochondria
Structures within cells that convert the energy from food into a form that cells can use.
Mitochondrial DNA
DNA, or genetic material, within mitochondria.
Morbidity
A disease or the incidence of disease within a population. Morbidity also refers to adverse effects caused by a treatment.
Motility
Spontaneous movement. A term used to describe the motor activity of smooth muscles in the gastrointestinal (GI) tract
MRI
Magnetic resonance imaging.
Mucosa
A mucous membrane that lines body passageways and cavities such as the esophagus, stomach, and intestines.
Myogenic
Originating in muscle tissue.

N

Natural History
A description of what happens to a medical condition over time (e.g., improves, stays the same, worsens) in the absence of treatment.
Nasograstro tube (NG-tube)
A method of enteral feeding in which a tube is placed through a nasal passageway into the stomach.
Nerve(s)
Cells in the human body that are the building blocks of the nervous system (the system that records and transmits information chemically and electrically within a person). Nerve cells, or neurons, are made up of a nerve cell body and various extensions from the cell body that receive and transmit impulses from and to other nerves and muscles.
Neural
Having to do with nerves or the nervous system, including the brain and the spinal cord.
Neurons
Nerve cells.
Neuroendocrinology
The science of how hormones and glands interact with the nervous system.
Neurological
Having to do with nerves or the nervous system.
Neuronoal intestinal dysplasia (NID)
A variety of conditions in which nerve cells (ganglion) are present in the colon but may be abnormal in their position, number, maturity, or appearance.
Neuropeptide
A member of a class of protein-like molecules made in the brain used by neurons to communicate with each other.
Neurotransmitter
A chemical in the nervous system that helps transmit messages.
NIDDK or National Institute of Diabetes and Digestive and Kidney Diseases
One of the 27 NIH Institutes and Centers, the NIDDK conducts and supports basic and applied research and provides leadership for a national program in diabetes, endocrinology, and metabolic diseases; digestive diseases and nutrition; and kidney, urologic, and hematologic diseases. Access the NIDDK web site at http://www.niddk.nih.gov.
NIH or National Institutes of Health
The focal point of biomedical research in the United States. NIH conducts research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the NIH web site at http://www.nih.gov.
Nonblinded
Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving.
Noxious stimulus
Stimulus that causes or has the potential to cause pain.
Nutrient
A chemical compound (such as protein, fat, carbohydrate, vitamins, or minerals) that make up foods.
Nutrition
The taking in and use of food and other nourishing material by the body.

O

Off-label
The practice whereby doctors may prescribe a medicine they feel is appropriate for a treatment in a manner not specifically approved by the FDA.
Ogilvie's syndrome
See Pseudo-obstruction.
Open label study
A research study in which both the health providers and the patients are aware of the drug or treatment being given.
Oral feeding
Taking in nutrition through the mouth.
Oral rehydration
Drinking a solution of water, salts, and sugars to maintain fluids.

P

P value
The p (probability) value is a calculation used in studies to determine if the results are caused by chance or not. The lower the p-value, the more likely it is that the difference between groups was caused by treatment. A p value less than 0.05 is statistically significant and indicates that the result is not due to chance.
Pain threshold
The point at which a person becomes aware of pain.
Palpation
Examination by pressing on the surface of the body to feel the organs or tissues underneath.
Parenteral nutrition
The slow infusion of a solution of nutrients into a vein through a catheter, which is surgically implanted. This may be partial, to supplement food and nutrient intake, or total (TPN, total parenteral nutrition), providing the sole source of energy and nutrient intake for the patient.
Pathogenesis
The origin and development of a disease or disorder.
Pathogens
Disease causing microorganisms.
Pathological
Disease related. 
Pathology
The study of the fundamental nature, causes, and development of abnormal conditions and the structural and functional changes that result.
Pathophysiologic mechanisms
Processes involved with a particular function.
Pathophysiology
Changes or alterations in function that accompany a particular syndrome or disease, generally as distinguished from structural defects.
Pelvic
Having to do with the pelvis (the lower part of the abdomen located between the hip bones).
Pelvic floor
A group of muscles that support the pelvic organs, participate in defecation, and help maintain continence.
Pelvic floor dyssynergia 
A problem with the way certain nerves and muscles function in the pelvic floor.
Peptic ulcer
A sore in the lining of the esophagus, stomach, or duodenum, usually caused by the bacterium Helicobacter pylori (H. pylori). An ulcer in the stomach is a gastric ulcer; an ulcer in the duodenum is a duodenal ulcer.
Perineum
The area of the body between the anus and the vulva in females, and between the anus and the scrotum in males.
Peristalsis
Synchronized or coordinated contraction of the muscles that propel food content through the gastrointestinal (GI) tract to facilitate normal digestion and the absorption of nutrients. Peristalsis is dependent upon the coordination between the muscles, nerves, and hormones in the digestive tract.
Pharmacokinetics
How the body handles a drug, including how it is absorbed, circulated, transformed, and eliminated.
Physiology
The study of how the body functions at the levels of organs, cells, and molecules. 
Pilot study
The initial study examining a new method or treatment.
Placebo
A placebo is an effect, not merely a thing. It is more or less a component of all healing yet is poorly understood or studied. In clinical trials a placebo pill, device, or procedure acts as a control to ensure that the effect seen with the treatment is specific, not only the result of the placebo effect or the natural evolution of an illness that accompany every therapeutic encounter. (Thompson WG. What are placebos, IFFGD 2002; Fact Sheet No. 172)
Postprandial
After meals.
Precursor
A substance, cell or component from which another is formed.
Prevalence
The proportion of people in the entire population who are found to be with a disease or disorder at a certain point in time (sometimes called a "cross section"), without regard to when they first got the disease.
Primary care
First contact medical care to patients.
Primary care physician
A doctor who manages a person's health care over time. A primary care doctor is able to give a wide range of care, including prevention and treatment, and can refer a patient to a specialist.
Primary lactase deficiency
When a person is born with the inability to digest lactose, a sugar found in milk and milk products. Lactose can't be digested because there is not enough of an enzyme, called lactase, in the body. Consuming milk and dairy products causes diarrhea, bloating, gas, and discomfort. This deficiency can also develop over time, as the amount of lactase in the body decreases with age.
Probiotics
Microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well being of the host.
Proceedings
A collection of current research reports, usually presented as brief abstracts, from a scientific meeting.
Progressive muscle relaxation
Voluntary relaxation through systematic tensing and relaxing of different muscle groups.
Prokinetic
Drugs that enhance propulsion of contents through the gut.
Prospective study
A study that utilizes carefully defined protocols to determine an outcome that is unknown beforehand.
Protease
A protein that digests other proteins.
Protein
A large complex molecule made up of one or more chains of amino acids. Proteins perform a wide variety of activities in the cell.
Protocol
An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who is eligible to participate, what study agents or other interventions they will be given, what tests they will receive and how often, and what information will be gathered.
Proton pump inhibitor (PPI)
A drug that limits acid secretion in the stomach.
Pseudo-obstruction (intestinal)
A motility disorder with symptoms like those of a bowel blockage, but with no physical evidence of blockage or obstruction. Symptoms may include cramps, stomach pain, nausea, vomiting, bloating, fewer bowel movements than usual, and loose stools. May be chronic or acute (Ogilvie's syndrome). 

Q

Quality of life
Perception of ability to meet daily needs, physical activities, well-being.

R

Radiation proctitis
Bleeding, mucous and bloody discharge, spasm of the rectal wall, urgency, and incontinence due radiation-induced damage to the rectum. Late symptoms result from scarring of the rectal and anal muscles with loss of some of the small blood vessels. The rectum becomes stiff and noncompliant (nonstretchable) and abnormal blood vessels may develop.
Random allocation
A method where all participants in a study have the same chance of being assigned to a study group, rather than allocation being assigned by the investigators,
Randomized controlled trial
A study in which people are allocated at random to receive one of several clinical interventions. One intervention is regarded as a standard of comparison or control.
Receptor
A structure in each cell that selectively receives and binds a specific substance, such as a neurotransmitter.
Rectum
The lower end of the large intestine, leading to the anus.
Refractory
Resistant to treatment.
Resection, intestinal
The surgical removal of a diseased portion of the intestines.
Retrospective study
A study in which known outcomes are examined in hindsight using existing records. A retrospective study is usually less reliable than a prospective study.
Reuptake
A process in which chemical neurotransmitters, after transmitting their message, are taken up again by nerve endings, broken down, and inactivated.
RNA
Abbreviation for ribonucleic acid, the molecule that carries out DNA's instructions for making proteins.
Rome Criteria
Lists of symptoms and criteria generally agreed upon by experts to diagnosis a functional gastrointestinal disorder.

S

Satiety
Feeling of fullness.
Scientific knowledge
The current set of peer-evaluated consensus models about how natural phenomena work, which often differ between groups of researchers at the research frontier.
Scientific progress
The cumulative growth of a system of knowledge over time, in which useful features are retained and nonuseful features are abandoned, based on the rejection or confirmation of testable knowledge.
Scintigraphy
An imaging method in which a mild dose of a radioactive substance is swallowed to show how material moves through the GI tract.
Sensitivity (diagnostic)
The ability of a test to correctly identify a disease or condition (positive test result) when it is present.
Sensitization
Enhancement of a response by an organism that is produced by delivering a strong, generally noxious, stimulus. A neuron becomes more excitable or responsive; it may respond more intensely to naturally occurring stimuli, either peripherally (in the viscera) or centrally (in the brain).
Serotonin (5-hydroxytryptamine, or 5-HT)
A chemical neurotransmitter (a chemical that acts on the nervous system to help transmit messages along the nervous system). It is found in the intestinal wall and the central nervous system. It is now widely understood that 95% of the serotonin in the body resides in the gut.
Short bowel syndrome (short gut)

A condition in which nutrients are not properly absorbed because a large part of the small intestine is missing or not functioning properly.

Sigmoid colon
The S-shaped section of the colon that connects to the rectum.
Sigmoidoscopy
Examination of the inside of the sigmoid colon and rectum using an endoscope -- a thin, lighted tube (sigmoidoscope). Samples of tissue or cells may be collected for examination under a microscope. Also called proctosigmoidoscopy.
Significant or statistically significant
A statistical term indicating that the results of a study are stronger than would be expected from chance alone.
Skin test
A test for an immune response to a compound by placing it on or under the skin.
Small intestine
The part of the digestive tract that is located between the stomach and the large intestine.
Soiling
Staining or soiling undergarments with stool.
Somatic
Pertaining to the physical body.
Somatization
The body's propensity to accentuate certain pain; physical symptoms and no recognizable physical abnormality.
Specificity (diagnostic)
The ability of a test to correctly classify an individual as not having a disease or condition (negative test result) when it is absent.
Sphincter
Ring of muscle that opens and closes.
Sphincter of Oddi
A muscle at that juncture of the bile and pancreatic ducts and the small intestine. It functions by opening and closing these ducts.
Sphincter of Oddi Dysfunction
An abnormality of the contractions of the sphincter of Oddi, which may be seen with a biliary and/or pancreatic type of pain in the upper right and middle parts of the abdomen (below the breastbone). It most commonly occurs in middle-aged women who have had their gallbladder removed. Treatment may involve surgery or medicines aimed at decreasing resistance to the flow of bile or pancreatic juice caused by the sphincter dysfunction. 
Spinal cord
A column of nerve tissue that runs from the base of the skull down the back. It is surrounded by three protective membranes, and is enclosed within the vertebrae (back bones). The spinal cord and the brain make up the central nervous system, and spinal cord nerves carry most messages between the brain and the rest of the body.
Squamous cell
A flat cell that looks like a fish scale under a microscope. Squamous cells cover internal and external surfaces of the body.
Stress
The neurophysiological and subjective response to stimuli. In contrast to the common interpretation of the term "stress" as a psychological phenomenon, it should be understood as any real or perceived perturbation of an organism's homeostasis, or state of harmony or balance. Stress may disrupt the function of nerve and even immune cells in the GI tract and in the brain. The central stress system involves the release of chemical stress mediators in the brain, which in turn orchestrate an integrated autonomic, behavioral, neuroendocrine, and pain modulatory response. This biological response in turn will alter the way the brain and the viscera (internal organs such as the gut/intestines) interact, and this altered brain-gut interaction can result in worsening of symptoms in functional GI disorders. For example, stress can increase GI symptoms by changing how the brain controls unwanted and painful sensation.
Stressor
Internal or external factors or stimuli that produce stress. They can be physical, biological, environmental, or psychological; each can activate central stress circuits in an individual. For example, worry about the untimely and unpredictable onsets of uncontrollable abdominal pain or an uncontrollable bowel movement qualify as stressors sufficient to activate the central stress system.
Stricture
Abnormal narrowing of a body opening.
Synapse
The point between two nerve cells (neurons), across which chemical neurotransmitters carry messages.
Syndrome
A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease.
Systemic
Affecting the entire body.

T

Tertiary care
Medical care in a highly specialized center.
Tortuous colon
A colon which is longer than normal or which has additional twists and turns.
Transit time (intestinal)
The time it takes for food to move through the intestines. 
Translational science
Conversion of basic science discoveries into the practical applications that benefit people.

U

Ulcerative colitis
A form of inflammatory bowel disease that causes ulcers and inflammation in the inner lining of the colon and rectum.
Ultrasound
An imaging method in which high-frequency sound waves are used to outline a part of the body.
Upper endoscopy
Examination of the inside of the esophagus, stomach, and duodenum using an endoscope.
Upper GI series
X-rays of the esophagus, stomach, and duodenum.
Urgency
Having very little time between feeling the urge to have a bowel movement
and the need to pass stool.

V

Vagus nerve

A nerve that extends from the brain to the abdomen, important in regulating functions of the viscera. Signals on the vagus nerve travel from the brain to the gut and from the gut to the brain.

Validity
The extent to which a measure accurately reflects the concept that it is intended to measure.
Valsalva maneuver
Voluntary increasing pressure in the abdominal cavity with the diaphragm and abdominal muscles to bear down on the rectum to facilitate defecation.
Villi
Tiny finger-like projections on the surface of the small intestine that help absorb nutrients.
Viscera
Internal organs such as the gut/intestines or bladder.
Visceral
Relating to the internal organs, such as the gut/intestines or bladder.
Visceral hypersensitivity (intestinal)
Enhanced perception, or enhanced responsiveness within the gut — even to normal events.

Zollinger-Ellison syndrome (ZES)
A rare disorder that causes tumors in the pancreas and duodenum. The tumors secrete a hormone called gastrin that causes the stomach to produce too much acid, which in turn causes stomach and duodenal ulcers (peptic ulcers).

Other References:

  • British Journal of Medicine, Randomized Controlled Trials
  • The Cochrane Collaboration, Research Glossary for Consumers
  • National Digestive Diseases Information Clearinghouse (NIDDK), Digestive Diseases Dictionary
  • National Institutes of Health, National Human Genome Research Institute
  • National Institutes of Health, National Womens Health Information Center
  • National Library of Medicine, National Information Center on Health Services Research & Health Care Technology (NICHSR), Glossary
  • Rome II, The Functional Gastrointestinal Disorders
Last modified on November 19, 2014 at 10:33:02 AM