Exercise Immunology

Flashcards

A

B - C

D - F

G - H

I - L

M - N

O - P

R - S

T - W

Glossary

a-amylase or amylase

A digestive enzyme found in saliva that begins the digestion of starches in the mouth (also called ptyalin). It also has an antibacterial action.

acclimatisation

Adaptation of the body to an environmental extreme (e.g., heat, cold, and altitude).

acidosis

A disturbance of the normal acid-base balance in which excess acids accumulate causing a fall in pH (e.g., when lactic acid accumulates in muscle and blood during high-intensity exercise). 

acquired immune response

Immunity mediated by lymphocytes and characterised by antigen specificity and memory.

ACSM

American College of Sports Medicine

ACTH (adrenocorticotrophic hormone)

Hormone secreted from anterior pituitary gland, which stimulates release of cortisol from adrenal glands.

active transport

The movement or transport across cell membranes by membrane carriers. An expenditure of energy (ATP) is required.

acute phase proteins

Several proteins released from liver (e.g., C-reactive protein) and leukocytes that aid body’s response to injury or infection. Rapid change in circulating concentration of acute phase proteins occurs following the initiation of an inflammatory response.

adaptogen

A name used for substances that help the body to adapt to stress situations.

Adequate Intake 

Recommended dietary intake comparable to the RNI or RDA but based on less scientific evidence. 

adipocyte

An adipose tissue cell whose main function is to store triacylglycerol (fat).

adipose tissue

White fatty tissue that stores triacylglycerol. 

adrenaline

A hormone secreted by the adrenal gland. It is a stimulant that prepares the body for 'fight or flight' and an important activator of fat and carbohydrate breakdown during exercise. Also known as epinephrine.

aerobic

Occurring in the presence of free oxygen.

AIDS

acquired immune deficiency syndrome

allergen

An antigen that causes an allergy.

allergy

An abnormally high sensitivity to certain substances, such as pollens, foods or microorganisms.

alpha-tocopherol

The most biologically active alcohol in vitamin E. 

amino acid (AA)

The chief structural molecule of protein, consisting of an amino group (NH₂) and a carboxylic acid group (CO₂H) plus another so-called R-group that determines the amino acid’s properties; 20 different amino acids can be used to make proteins.

ammonia (NH₃)

A metabolic by-product of the oxidation of amino acids. It may be transformed into urea for excretion from the body. 

AMS

acute mountain sickness

anaerobic

Occurring in the absence of free oxygen.

anaemia

A condition defined by an abnormally low blood haemoglobin content resulting in a lowered oxygen carrying capacity.

anaphylaxis

An acute, potentially life-threatening hypersensitivity reaction, involving the release of mediators from mast cells, basophils and recruited inflammatory cells.

anorexia athletica

A form of anorexia nervosa observed in athletes who show significant symptoms of eating disorders but who do not meet the criteria of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association 1987) for anorexia or bulimia nervosa. 

anorexia nervosa

An eating disorder characterised by an abnormally small food intake and a refusal to maintain a normal body weight (according to what is expected for gender, age, and height), a distorted view of body image, an intense fear of being fat or overweight and gaining weight or “feeling fat” when clearly the individual is below normal weight, and the absence of at least three successive menstrual cycles in females (amenorrhea).

ANOVA

analysis of variance

anthropometry

Use of body girths and diameters to evaluate body composition. 

antibody

Soluble protein produced by B lymphocytes with antimicrobial effects. Also known as immunoglobulin.

antigen

Usually a molecule foreign to the body but can be any molecule capable of being recognised by an antibody or T-cell receptor.

antioxidant

Molecules that can prevent or limit the actions of free radicals usually by removing their unpaired electron and thus converting them into something far less reactive. 

APC

antigen presenting cell

apoptosis

An internal programme that allows damaged or obsolete cells to commit suicide.

arteriosclerosis

Hardening of the arteries (see also atherosclerosis). 

arteriovenous (AV)

Refers to comparison of arterial and venous blood composition.

ascorbic acid

Vitamin C; its major role is as a water-soluble antioxidant.

atherosclerosis

A specific form of arteriosclerosis characterised by the formation of fatty plaques on the luminal walls of arteries

atopy

A genetic predisposition toward the development of immediate hypersensitivity reactions against common environmental antigens.

ATP (adenosine triphosphate)

A high-energy compound that is the immediate source for muscular contraction and other energy requiring processes in the cell.

atrophy

A wasting away, a diminution in the size of a cell, tissue, organ or part.

AV-differences

A difference between arterial and venous concentration of a substance, indicating net uptake or release of that substance.

average daily metabolic rate (ADMR)

The average energy expenditure over 24 hours.

bacterium

A single single-celled microscopic organism that is larger than a virus and lacking a nucleus and other organised cell structures.

base

A substance that tends to donate an electron pair or coordinate an electron.

basophil

Type of granulocyte found in the blood.

BCAA (branched-chain amino acid)

Three essential amino acids that can be oxidised by muscle. Includes leucine, isoleucine and valine.

β-carotene

A precursor for vitamin A found in plants. Also called provitamin A.

bioavailability

In relation to nutrients in food, the amount that may be absorbed into the body. 

biopsy

A small sample of tissue taken for analysis.

b.m.

Body mass in kilograms (kg).

BMI (body mass index)

Body mass in kilograms divided by height in metres squared (kg/m^{2). An index used as a measure of obesity.}

BMR (basal metabolic rate)

Energy expenditure under basal, post-absorptive conditions representing the energy needed to maintain life under these basal conditions.

bronchoconstriction

A narrowing of air passages of the lungs from smooth muscle contraction, as in asthma.

caffeine

A stimulant drug found in many food products such as coffee, tea, and cola drinks. Stimulates the central nervous system and used as an ergogenic aid.

calorie (cal)

Traditional unit of energy. One calorie expresses the quantity of energy (heat) needed to raise the temperature of 1 g (1 ml) of water 1° C (from 14.5° C to 15.5° C).

CAM

cell adhesion molecule

cAMP (cyclic adenosine monophosphate)

An important intracellular messenger in the action of hormones.

capillary

The smallest vessel in the cardiovascular system. Capillary walls are only cell thick. All exchanges of molecules between the blood and tissue fluid occur across the capillary walls.

carcinogen

A cancer-inducing substance.

catabolism

Destructive metabolism whereby complex chemical compounds in the body are degraded to simpler ones (e.g., glycogen to glucose; proteins to amino acids). 

catalyst

A substance that accelerates a chemical reaction, usually by temporarily combining with the substrates and lowering the activation energy, and is recovered unchanged at the end of the reaction (e.g., an enzyme). 

CBSM

cognitive behavioural stress management.

CD (clusters of differentiation or cluster designators)

Proteins expressed on cell surface of leukocytes (white blood cells) that can be used to identify different types of leukocyte or subsets of lymphocytes.

cell

The smallest discrete living unit of the body.

cell-mediated immunity

Refers to T cell-mediated immune responses; killing of infected host cells by T cytotoxic lymphocytes..

cellulose

A major component of plant cell walls and the most abundant non-starch polysaccharide. Cannot be digested by human digestive enzymes.

cerebrospinal fluid (CSF)

The fluid found in the brain and spinal cord. 

CFS

chronic fatigue syndrome

CHD (coronary heart disease)

Narrowing of the arteries supplying the heart muscle that can cause heart attacks.

chemokines

Cytokines that selectively induce chemotaxis and activation of leukocytes.

chemotaxis

Movement of cells up a concentration gradient of attractant chemical factors.

CHO (carbohydrate)

A compound composed of carbon, hydrogen and oxygen in ratio of 1:2:1 (i.e., CH₂O). Carbohydrates include sugars, starches, and dietary fibres.

CK (creatine kinase)

An enzyme that catalyses the transfer of phosphate from phosphocreatine to ADP to form ATP. Also known as creatine phosphokinase.

clone

Identical cells derived from a single progenitor.

coenzyme

Small molecules that are essential in stoichiometric amounts for the activity of some enzymes. Examples include nicotinamide adenine dinucleotide (NAD), flavin adenine dinucleotide (FAD), pyridoxal phosphate (PLP), thiamine pyrophosphate (TPP) and biotin.

colon

The large intestine. This part of the intestine is mainly responsible for forming, storing, and expelling faeces.

complement

Soluble proteins found in body fluids and produced by liver. Once activated, they exert several antimicrobial effects. 

complex carbohydrates

Foods containing starch and other polysaccharides as found in  bread, pasta, cereals, fruits, and vegetables in contrast to simple carbohydrates such as glucose, milk sugar, and table sugar.

Con A (concanavalin A)

A T-cell mitogen

concentration gradient

Difference in concentration of a substance on either side of a membrane.

condensation

A reaction involving the union of two or more molecules with the elimination of a simpler group such as H₂O.

conformation

Shape of molecules determined by rotation about single bonds, especially in polypeptide chains about carbon-carbon links.

cortisol

A steroid hormone secreted from the adrenal glands.

covalent bond

A chemical bond in which two or more atoms are held together by the interaction of their outer electrons.

C-reactive protein

An acute phase protein that is able to bind to the surface of micro-organisms and stimulates complement activation and phagocytosis by neutrophils and macrophages.

CSF (colony-stimulating factor)

A cytokine that stimulates increased production and release of leukocytes (white blood cells) from the bone marrow.

CSFE (carboxyfluorescein succinamidyl ester)

A fluorescent molecule used in flow cytometry to track the proliferation of CD4⁺ and CD8⁺ T lymphocyte subsets.

cytokine

Protein released from cells that acts as a chemical messenger by binding to receptors on other cells. Cytokines include interleukins (IL), tumour necrosis factors (TNF), colony-stimulating factors (CSF), and interferons (IFN).

cytotoxic

Ability to kill other cells (e.g., those infected with a virus).

DALDA

daily analyses of life demands in athletes questionnaire.

DC (dendritic cell)

A specialised antigen presenting cell found in the tissues.

degranulation

Release of granule contents (e.g. digestive enzymes form neutrophils).

demargination

Release into the circulation of leukocytes that were bound to endothethial cells of blood vessel walls.

diabetes mellitus

A disorder of carbohydrate metabolism caused by disturbances in production or utilisation of insulin. Causes high blood glucose levels and loss of sugar in the urine. 

diarrhoea

Frequent passage of a watery faecal discharge because of a gastrointestinal disturbance or infection. 

diffusion

The movement of molecules from a region of high concentration to one of low concentration, brought about by their kinetic energy. 

digestion

The process of breaking down food to its smallest components so it can be absorbed in the intestine.

disaccharide

Sugars that yield two monosaccharides on hydrolysis. Sucrose is the most common and is composed of glucose and fructose. 

diuretics

Drugs that act on the kidney to promote urine formation.

dm (dry matter or dry material)

Usually refers to tissue weight after removal of water.

DNA (deoxyribonucleic acid)

The compound that forms genes (i.e., the genetic material).

eccentric exercise

Types of exercise that involve lengthening of the muscle during activation, which can cause damage to some of the myofibres. Types of exercise that have a significant eccentric component include downhill running, bench stepping, and lowering of weights.

DTH (delayed type hypersensitivity)

A cell-mediated immune reaction to an antigen occurring within 24-72 hours.

EBV (Epstein-Barr virus)

The virus responsible for infectious mononcleosis.

EDTA (ethylene diamine tetra acetate)

An anticoagulant that prevents blood from clotting by binding to and removing free calcium ions.

eicosanoids

Derivatives of fatty acids in the body that act as cell-cell signalling molecules. They include prostaglandins, thromboxanes and leukotrienes. 

electrolyte

A substance that, when dissolved in water, conducts an electric current. Electrolytes, which include acids, bases and salts, usually dissociate into ions carrying either a positive charge (cation) or a negative charge (anion).

ELISA (enzyme-linked immunosorbent assay)

A type of assay used to measure the concentration of soluble cytokines, hormones, antibodies etc.

ELISPOT

A sensitive type of assay used to quantify cytokine secreting cells.

endocrine

Ductless glands that secrete hormones into the blood.

endogenous

From within the body.

energy

The ability to perform work. Energy exists in various forms, including mechanical, heat, and chemical energy.

energy balance

The balance between energy intake and energy expenditure.

energy expenditure (EE)

The energy expended per unit of time to produce power.

energy expenditure for activity (EEA)

The energy cost associated with physical activity (exercise).

enzyme

A protein with specific catalytic activity; designated by the suffix '-ase' and frequently attached to the type of reaction catalysed. Virtually all metabolic reactions in the body are dependent upon and controlled by enzymes.

eosinophil

A type of blood granulocyte. Increased numbers in the circulation are found in allergic conditions.

epinephrine

A hormone secreted by the adrenal gland. It is a stimulant and prepares the body for ‘fight or flight' and an important activator of fat and carbohydrate breakdown during exercise. Also known as adrenaline. 

epitope

The part of an antigen recognised by an antibody or T-cell receptor.

ergogenic aids

Substances that improve exercise performance and are used in attempts to increase athletic or physical performance capacity. 

ergolytic

Performance impairing.

erythrocyte

Red blood cell that contains haemoglobin and transports oxygen.

essential amino acids

Amino acids that must be obtained in the diet and cannot be synthesised in the body. Also known as indispensable amino acids.

essential fatty acids

Those unsaturated fatty acids that cannot be synthesised in the body and must be obtained in the diet (e.g., linoleic acid and linolenic acid).

euhydration

Normal state of body hydration (water content).

eumenorrhea

Occurrence of normal menstrual cycles.

excretion

The removal of metabolic wastes.

exogenous

From outside the body.

extracellular fluid (ECF)

Body fluid that is located outside the cells, including the blood plasma, interstitial fluid, cerebrospinal fluid, synovial fluid and ocular fluid. 

FACS

fluorescence-activated cell sorter

faeces

The excrement discharged from the intestines, consisting of bacteria, cells from the intestines, secretions and a small amount of food residue.

fat

Fat molecules contain the same structural elements as carbohydrates but with little oxygen relative to carbon and hydrogen and are poorly soluble in water. Fats are also known as lipids (derived from the Greek word lipos) and is a general name for oils, fats, waxes and related compounds. Oils are liquid at room temperature, whereas fats are solid. 

fatty acid

A type of fat having a carboxylic acid group (COOH) at one end of the molecule and a methyl (CH3) group at the other end, separated by a hydrocarbon chain that can vary in length. A typical structure of a fatty acid is CH₃(CH₂)₁₄COOH (palmitic acid or palmitate).

Fc

Crystallisable, non-antigen binding fragment of an immunoglobulin molecule.

Fc receptor

Cell surface receptor that binds to the Fc part of immunoglobulin molecules.

female athlete triad

A syndrome that is characterised by the three conditions that are prevalent in female athletes: amenorrhea, disordered eating and osteoporosis.

ferritin

A protein that is used to store iron. Ferritin is mostly found in the liver, spleen and bone marrow. Soluble ferritin is released from cells into the blood plasma in direct proportion to cellular ferritin content. Hence, the serum ferritin concentration can be used to indicate the status of the body’s iron stores.

fibre

Indigestible carbohydrates.

fish oil

Oils high in unsaturated fats extracted from the bodies of fish or fish parts, especially the livers. The oils are used as dietary supplements. 

FITC

Fluorescein isothiocyanate; a fluorescent marker used in flow cytometry.

flux

The rate of flow through a metabolic pathway.

fMLP

formyl-methionyl-leucyl-phenylalanine. A bacterial cell wall peptide that is a chemical stimulant of phagocytes.

folic acid or folate

A water-soluble vitamin required in the synthesis of nucleic acids. It appears to be essential in preventing certain types of anaemia. 

free radical

An atom or molecule that possesses at least one unpaired electron in its outer orbit. The free radicals the superoxide (√O₂-), hydroxyl (√OH), and nitric oxide (.NO) radicals. They are highly reactive and may cause damage to lipid membranes causing membrane instability and increased permeability. Free radicals can also cause oxidative damage to proteins, including enzymes, and damage to DNA.

FSH (follicle stimulating hormone)

; a gonadotrophin secreted from the anterior pituitary gland.

Gamma delta (γδ) T cell

A subset of T lymphocytethat recognises lipid and other non-peptide antigens. They are potent cytotoxic cells that aid the host in bacterial elimination, wound repair and delayed-type hypersensitivity reactions.

g

gram

gastrointestinal tract

Gastrointestinal system or alimentary tract. The main sites in the body used for digestion and absorption of nutrients. It consists of the mouth, oesophagus, stomach, small intestine (ileum) and large intestine (colon).

gene

A specific sequence in DNA that codes for a particular protein. Genes are located on the chromosomes. Each gene is found in a definite position (locus).

genotype

The genetic composition or assortment of genes that, together with environmental influences, determines the appearance or phenotype of an individual.

germ line

The genetic material transmitted from parents to offspring through the gametes (sperm and ova).

ginseng

A root found in Asia and the USA, although the Asian variety is more easily obtainable. Ginseng has been a popular nutritional supplement and medication in Asia for centuries. 

gluconeogenesis

The synthesis of glucose from non-carbohydrate precursors such as glycerol, ketoacids or amino acids.

glutamine

One of the 20 amino acids commonly found in proteins. It is the most abundant free amino acid in the blood plasma and is considered to be an important energy source for leukocytes.

glycaemic index (GI)

Increase in blood glucose and insulin response to a meal. The GI of a food is expressed against a reference food, usually glucose. 

glycogen

Polymer of glucose used as storage form of carbohydrate in the liver and muscles.

glycogenolysis

The breakdown of glycogen into glucose-1-phosphate by the action of phosphorylase.

glycolysis

The sequence of reactions that converts glucose (or glycogen) to pyruvate.

glycoprotein

A protein that is attached to one or more sugar molecules.

glycosidic bond

A chemical bond in which the oxygen atom is the common link between a carbon of one sugar molecule and the carbon of another. Glycogen, the glucose polymer is a branched-chain polysaccharide consisting of glucose molecules linked by glycosidic bonds.

GM-CSF

granulocyte-monocyte colony stimulating factor

GMFI (geometric mean fluorescence intensity)

A quantitative measure of the staining intensity of a fluorescent marker used in flow cytometry.

gonadotrophic hormones

Hormones released from the anterior pituitary gland that promote sex steroid hormone synthesis by the ovaries in females and the testes in males.

H⁺

Hydrogen ion or proton.

haem

Molecular ring structure that is incorporated in the haemoglobin molecule, enabling this protein to carry oxygen.

haematocrit

Proportion of the blood volume that is occupied by the cellular elements (red cells, white cells, and platelets). Also known as the packed-cell volume.

haematopoiesis

The production of erythrocytes and leukocytes in the bone marrow.

haematuria

Red blood cells or haemoglobin in the urine. 

haemodilution

A thinning of the blood caused by an expansion of the plasma volume without an equivalent rise in red blood cells.

haemoglobin

The red, iron-containing respiratory pigment found in red blood cells; important in the transport of respiratory gases and in the regulation of blood pH.

haemolysis

Destruction of red blood cells within the circulation.

haemorrhage

Damage to blood vessel walls resulting in bleeding.

half-life

Time in which half the quantity or concentration of a substance is eliminated or removed.

HCl (hydrochloric acid)

Part of gastric digestive juices.

HCO₃-

Bicarbonate ion, the principal extracellular buffer.

HDL (high-density lipoprotein)

A protein-lipid complex in the blood plasma that facilitates the transport of triacylglycerols, cholesterol and phospholipids.

hepatic glucose output

Liver glucose output. The glucose that is released from the liver as a result of glycogenolysis or gluconeogenesis.

HIV

Human immunodeficiency virus.

HLA

Human leukocyte antigen.

H₂O₂

Hydrogen peroxide.

HOCl (hydrochlorous acid)

Produced by phagocytes.

hormone

An organic chemical produced in cells of one part of the body (usually an endocrine gland) that diffuses or is transported by the blood circulation to cells in other parts of the body, where it regulates and coordinates their activities.

HPLC

High pressure liquid chromatography.

humoral

Fluid borne.

hydrogen bond

A weak intermolecular or intramolecular attraction resulting from the interaction of a hydrogen atom and an electronegative atom possessing a lone pair of electrons (e.g., oxygen or nitrogen). Hydrogen bonding is important in DNA and RNA and is responsible for much of the tertiary structure of proteins.

hydrolysis

A reaction in which an organic compound is split by interaction with water into simpler compounds.

hyperthermia

Elevated body temperature (> 37° C or 98.6°F).

hypertonic

Having a higher concentration of dissolved particles (osmolality) than that of another solution with which it is being compared (usually blood plasma, which has an osmolality of 290 mOsm/kg).

hyperventilation

A state in which an increased amount of air enters the pulmonary alveoli (increased alveolar ventilation), resulting in reduction of carbon dioxide tension and eventually leading to alkalosis. 

hyponatraemia

Below normal serum sodium concentration (< 140 mmol/L).

hypothalamus

Region at base of brain responsible for integration of sensory input and effector responses in regulation of body temperature. Also contains centres for control of hunger, appetite and thirst.

hypothermia

Lower than normal body temperature.

hypotonic

Having a lower concentration of dissolved particles (osmolality) than that of another solution with which it is being compared (usually blood plasma, which has an osmolality of 290 mOsm/kg).

hypovolaemia

Reduced blood volume.

ICAM

intercellular adhesion molecule

IFN (interferon)

A type of cytokine. Some interferons inhibit viral replication in infected cells.

Ig (immunoglobulin)

Same as antibody.

IGF

insulin-like growth factor

IL (interleukin)

Type of cytokine produced by leukocytes and some other tissues. Acts as a chemical messenger, rather like a hormone, but usually with localised effects.

IL-1ra

interleukin-1 receptor antagonist

immunodepression

Lowered functional activity of the immune system.

in vitro

Within a glass, observable in a test tube, in an artificial environment. Can also be referred to as ex vivo (outside the living body).

in vivo

Within the living body.

inflammation

Body’s response to injury, which includes redness (increased blood flow) and swelling (oedema) caused by increased capillary permeability.

innate immunity

Immunity that is not dependent on prior contact with antigen.

insulin

A hormone secreted by the pancreas involved in carbohydrate metabolism and, in particular, the control of the blood glucose concentration.

interferon

Type of cytokine; inhibits viral replication. 

interstitial

Fluid-filled spaces that lie between cells.

IOC

International Olympic Committee

ion

Any atom or molecule that has an electrical charge owing to loss or gain of valency (outer shell) electrons. Ions may carry a positive charge (cation) or a negative charge (anion).

ionic bond

A bond in which valence electrons are either lost or gained and atoms that are oppositely charged are held together by electrostatic forces.

ischaemia

Reduced blood supply to a tissue or organ.

isoform

Chemically distinct forms of a enzyme with identical activities usually coded by different genes. Also called isoenzyme.

isomer

One of two or more substances that have an identical molecular composition and relative molecular mass but different structure because of a different arrangement of atoms within the molecule.

isotonicity

Having the same concentration of dissolved particles (osmolality) than that of another solution with which it is being compared (usually blood plasma, which has an osmolality of 290 mOsm/kg).

isotope

One of a set of chemically identical species of atom that have the same atomic number but different mass numbers (e.g., 12-isotopes,13-isotopes, and 14-isotopes of carbon whose atomic number is 12).

IU

international units

Joule (J)

Unit of energy according to the Système Internationale. One Joule is the amount of energy needed to move a mass of 1 g at a velocity of 1 m/s.

kD

kilodalton

ketone bodies

Acidic organic compounds produced during the incomplete oxidation of fatty acids in the liver. Contain a carboxyl group (-COOH) and a ketone group (-C=O). Examples include acetoacetate and 3-hydroxybutyrate.

kinase

An enzyme that regulates a phosphorylation-dephosphorylation reaction (i.e., the addition or removal of a phosphate group). This process is one important way in which enzyme activity can be regulated.

kJ (kilojoule)

Unit of energy (1 kJ = 10³ J).

KLH (keyhole limpet haemocyanin)

A protein antigen that is unlikely to have been encountered previously and which elicits a thymus-dependent antibody response.

L

litre

lactic acid

Metabolic end product of anaerobic glycolysis.

lactoferrin

An antimicrobial protein found in plasma and saliva that chelates iron (essential for bacterial proliferation) and has antiviral properties.

LDL (low-density lipoproteins)

A protein-lipid complex in the blood plasma that facilitates the transport of triacylglycerols, cholesterol and phospholipids.

lean body mass (LBM)

All parts of the body, excluding fat.

lecithin

Common name for phosphatidyl choline, the most abundant phospholipid found in cell membranes. 

lectins

Proteins, mostly from plants, that bind specific sugars on glycoproteins and glycolipids. Several lectins are mitogenic (e.g. Con-A; PHA).

legume

The high-protein fruit or pod of vegetables, including beans, peas, and lentils.

leptin

Regulatory hormone produced by adipocytes (fat cells). When released into the circulation, it influences the hypothalamus to control appetite.

leucine

An essential amino acid that is alleged to slow the breakdown of muscle protein during strenuous exercise and to improve gains in muscle mass with strength training.

leukocyte

White blood cell. Important in inflammation and immune defence.

leukocytosis

Increased number of leukocytes in the circulation.

leukotrienes

Metabolic products of the PUFA arachidonic acid which promote inflammatory responses. Mostly produced by macrophages, mast cells and basophils.

LH (luteinising hormone)

A gonadotrophin secreted from the anterior pituitary gland.

ligand

Any molecule that is recognised by a binding structure such as a receptor.

linoleic acid

An essential fatty acid. 

linolenic acid

An essential fatty acid. 

lipid

A compound composed of carbon, hydrogen and oxygen and sometimes other elements. Lipids dissolve in organic solvents but not in water and include triacylglycerol, cholesterol and phospholipids. Lipids are commonly called fats.

lipid peroxidation

Oxidation of fatty acids in lipid structures (e.g., membranes) caused by the actions of free radicals.

lipolysis

The breakdown of triacylglycerols into fatty acids and glycerol.

LPS (lipopolysaccharide)

Endotoxin derived from Gram-positive bacterial cell walls that has inflammatory and mitogenic actions.

LTB-B4 (leukotriene-B4)

Metabolic product of the PUFA arachidonic acid, which promotes inflammatory responses. Mostly produced by macrophages.

lymph

The tissue fluid which drains into and from the lymphatic system.

lymphocyte

Type of white blood cell important in the acquired immune response. Includes both T cells and B cells. The latter produce antibodies.

lymphokines

Cytokines produced by lymphocytes.

lymphokine-activated killer cells (LAK)

Types of lymphocyte similar to natural killer cells that are activated by interleukin-2.

lysis

The process of disintegration of a cell.

lysosome

A membranous vesicle found in the cell cytoplasm. Lysosomes contain digestive enzymes capable of autodigesting the cell.

lysozyme

Enzyme that breaks down proteins and proteoglycans in bacterial cell walls. Produced by macrophages and found in tears and saliva.

M (molar)

Unit of concentration (nM: nanomolar = 10-9M; μM: micromolar = 10-6M; mM: millimolar = 10-3M).

macromineral

Dietary elements essential to life processes that each constitute at least 0.01% of total body mass. The seven macrominerals are potassium, sodium, chloride, calcium, magnesium, phosphorus and sulphur.

macronutrients

Nutrients ingested in relatively large amounts (carbohydrate, fat, protein and water).

macrophage

Phagocyte and antigen-presenting cell found in the tissues; precursor is the blood monocyte. Initiates the acquired immune response.

maltodextrin

A glucose polymer (commonly containing 6−12 glucose molecules) that exerts lesser osmotic effects compared with glucose and is used in a variety of sports drinks as the main source of carbohydrate. 

maltose

A disaccharide that yields two molecules of glucose upon hydrolysis.

margination

Adherence of leukocytes to the endothelial wall of blood vessels.

mast cell

A cell found in the tissues that resembles a blood basophil. Both cell types are activated by IgE-antigen complexes resulting in degranulation and release of inflammatory mediators including histamine and leukotrienes.

megadose

An excessive amount of a substance in comparison to a normal dose (such as the RDA). Usually used to refer to vitamin supplements. 

memory cells

Clonally expanded T and B lymphocytes that are primed to respond faster on exposure to a previously encountered antigen.

metabolic acidosis

A metabolic derangement of acid-base balance where the blood pH is abnormally low.

metabolite

A product of a metabolic reaction.

metalloenzyme

An enzyme that needs a mineral component (e.g., copper, iron, magnesium and zinc) to function effectively. 

METS (metabolic equivalents)

A measurement of energy expenditure expressed as multiples of the resting metabolic rate. One MET equals approximately an oxygen uptake rate of 3.5 ml O₂/kg b.m./minute. 

MFI (mean fluorescence intensity)

Used to quantify expression of molecules.

MHC (major histocompatibility complex)

Molecules involved in antigen presentation to T cells. Class I MHC proteins are present on virtually all nucleated cells, whereas class II MHC proteins are expressed on antigen presenting cells (primarily macrophages and dendritic cells).

micromineral or trace element

Those dietary elements essential to life processes that each comprise less than 0.001% of total body mass and are needed in quantities of less than 100 mg a day. Among the 14 trace elements are iron, zinc, copper, chromium and selenium.

micronutrients

Organic vitamins and inorganic minerals that must be consumed in relatively small amounts in the diet to maintain health.

mineral

An inorganic element found in nature though the term is usually reserved for those elements that are solid. In nutrition, the term mineral is usually used to classify those dietary elements essential to life processes. Examples are calcium and iron.

minute

Unit of time; 60 seconds.

mitochondrion

Oval or spherical organelle containing the enzymes of the tricarboxylic acid cycle and electron transport chain. Site of oxidative phosphorylation (re-synthesis of ATP involving the use of oxygen).

mitogen

Chemical that can stimulate lymphocytes to proliferate (undergo rapid cell divisions).

mitosis

A type of cell division in which each of the two daughter cells receives exactly the same number of chromosomes present in the nucleus of the parent cell.

mL

millilitre

mole

The amount of a chemical compound whose mass in grams is equivalent to its molecular weight, the sum of the atomic weights of its constituent atoms.

molecule

An aggregation of at least two atoms of the same or different elements held together by special forces (covalent bonds) and having a precise chemical formula (e.g., O₂, C₆H₆O₆).

monoclonal antibody

A specific antibody derived from a single B-cell clone.

monocyte

Type of white blood cell that can ingest and destroy foreign material and initiate the acquired immune response. Precursor of tissue macrophage.

monosaccharide

A simple sugar that cannot be hydrolysed to smaller units (e.g., glucose, fructose and galactose).

mRNA

messenger ribonucleic acid

MTT

3-(4,5-dimethlythiazol-2-yl)-2,5-diphenyltetrazolium bromide. A yellow compound used in assays of lymphocyte proliferation.

mucosa

Layer of cells lining the mouth, nasal passages, airways and gut that present a barrier to pathogen entry into the body.

myoglobin

A protein that functions as an intracellular respiratory pigment that is capable of binding oxygen and only releasing it at very low partial pressures.

NETs (neutrophil extracellular traps)

A web of fibres composed of chromatin and serine proteases that trap and kill microbes extracellularly. NETs provide a high local concentration of antimicrobial components and bind, disarm and kill microbes independent of phagocytic uptake.

neurotransmitters

Endogenous signalling molecules that transfer information from one nerve ending to the next.

neutrophil

Type of white blood cell that can ingest and destroy foreign material. Very important as a first line of defence against bacteria.

NH₂

Amino group.

NH4+

Ammonium ion.

NIDDM

Non-insulin-dependent diabetes mellitus.

nitrogen balance

A dietary state in which the input and output of nitrogen is balanced so that the body neither gains nor loses tissue protein.

NK (natural killer) cell

A type of lymphocyte important in eliminating viral infections and preventing cancer.

NKCA (natural killer cytotoxic activity)

Natural killer cytotoxic activity. The ability of NK cells to destroy virally infected cells and tumour cells.

NKT (natural killer T cells)

Natural killer T cells. These cells are almost entirely CD3+ and CD8+ (so are a type of T lymphocyte) but also express the 'NK-cell markers' CD56 and CD161 and respond to glycolipids presented by CD1d.

N/L ratio

Ratio of neutrophils to lymphocytes in the blood.

NO

nitric oxide

NO-.

nitric oxide radical

NOD receptors

Nucleotide-binding oligomerisation domain receptors; a group of  intracellular surveillance proteins that can detect bacterial peptidoglycan, signalling the presence of bacteria in the host cell.

non-essential amino acids

Amino acids that can be synthesised in the body.

noradrenaline

Catecholamine hormone and the neurotransmitter of most of the sympathetic nervous system (of so-called adrenergic neurons). Also known as norepinephrine.

norepinephrine

Catecholamine hormone and the neurotransmitter of most of the sympathetic nervous system (of so-called adrenergic neurons). Also known as noradrenaline.

nutraceutical

A nutrient that may function as a pharmaceutical (drug) when taken in certain quantities. 

nutrient

Substances found in food that provide energy or promote growth and repair of tissues. 

nutrition

The total of the processes of ingestion, digestion, absorption and metabolism of food and the subsequent assimilation of nutrient materials into the tissues. 

O₂

Oxygen molecule.

O₂-.(superoxide radical)

A highly reactive free radical.

obesity

An excessive accumulation of body fat. Usually reserved for those individuals who are 20% or more above the average weight for their size.

OH

Hydroxyl group.

OH^-. (hydroxyl radical)

A highly reactive free radical.

opsonin

A molecule that enhances phagocytosis by promoting adhesion of the antigen to the phagocyte.

osmosis

The diffusion of water molecules from the lesser to the greater concentration of solute (dissolved substance) when two solutions are separated by a membrane that selectively prevents the passage of solute molecules but is permeable to water molecules.

OTS

overtraining syndrome

oxidative (or respiratory) burst

Increased oxygen consumption and production of reactive oxygen species (ROS) by phagocytes following their activation.

PAMP (pathogen associated molecular pattern)

Molecules that are commonly expressed by micro-organisms that are not expressed by host cells.

pathogen

Micro-organism that can cause symptoms of disease.

PBMC

Peripheral blood mononuclear cells which includes all lymphocytes and monocytes but excludes granulocytes.

PBS

Phosphate buffered saline.

PE

R-phycoerythrin; a fluorescent marker used in flow cytometry.

PEM (protein energy malnutrition)

Inadequate intake of dietary protein and energy.

peptide

Small compound formed by the bonding of two or more amino acids. Larger chains of linked amino acids are called polypeptides or proteins. 

PerCP

Peridinin chlorophyll; a fluorescent marker used in flow cytometry.

perforin

Molecule produced by NK cells and cytotoxic T cells that forms a pore in the membrane of target cells leading to lysis and cell death.

PGE₂

Prostaglandin E₂.

pH

A measure of acidity/alkalinity. pH = –log₁₀[H^+].

PHA (phytohaemagglutinin)

A plant lectin that acts as a T cell mitogen.

phagocyte

Leukocyte capable of ingesting and digesting microorganisms.

phagocytosis

Process of ingestion of bacteria, virus or cell debris by cells such as neutrophils and macrophages (phago = eat; cyte = cell).

phenotype

The appearance or physiological characteristic of an individual that results from the interaction of the genotype and the environment.

phospholipids

Fats containing a phosphate group that on hydrolysis yield fatty acids, glycerol and a nitrogenous compound. Lecithin is an example. Phospholipids are important components of membranes.

PIgR (poly-Ig receptor)

A receptor molecule that specifically binds dimeric secretory IgA and transports it across the mucosal epithelial cells.

plasma

The liquid portion of the blood in which the blood cells are suspended. Typically accounts for 55−60% of the total blood volume. Differs from serum in that it contains fibrinogen, the clot-forming protein.

plasma cell

Terminally differentiated B lymphocyte that secretes large amounts of antibody.

PMA (phorbol myristate acetate)

A mitogen that directly stimulates protein kinase C.

PMN

Polymorphonuclear cells, which principally refers to neutrophils.

PMT

photomultiplier tube

pokeweed mitogen (PWM)

A plant lectin that is a T-cell-dependent B cell mitogen.

polypeptide

A peptide that, upon hydrolysis, yields more than two amino acids

polyphenols

A large class of naturally occurring compounds that include the flavonoids, flavonols, flavonones and anthocyanidins. These compounds contain a number of phenolic hydroxyl (-OH) groups attached to ring structures, which confers them with powerful antioxidant activity.

polysaccharide

Polymers of (arbitrarily) more than about ten monosaccharide residues linked glycosidically in branched or unbranched chains. Examples include starch and glycogen.

POMS

profile of mood state questionnaire

postabsorptive state

The period after a meal has been absorbed from the gastrointestinal tract. 

power

Work performed per unit of time.

precursor

A substance from which another, usually more active or mature substance, is formed.

prohormones

A protein hormone before processing to remove parts of its sequence and thus make it active.

prostaglandins

Lipids derived from the PUFA arachidonic acid that increase vascular permeability, sensitise pain receptors, initiate fever and stimulate or inhibit immune responses.

prosthetic group

A coenzyme that is tightly bound to an enzyme.

protease

An enzyme that catalyses the digestion or cleavage of proteins.

protein

Biological macromolecules composed of a chain of covalently linked amino acids. Proteins may have structural or functional roles.

PRR (pattern recognition receptors)

Receptors on APCs and phagocytes that recognise PAMPs.

PUFA (polyunsaturated fatty acid)

Fatty acid that contains more than one carbon-carbon double bond. 

pyrogen

A substance that causes body temperature to elevated, as in fever, and be regulated at a higher set point.

Ra (rate of appearance)

Usually referring to the rate at which a substance enters the blood circulation.

RBC

Red blood cell (erythrocyte).

Rd (rate of disappearance)

Usually refers to the rate at which a substance leaves the blood circulation.

RDA (recommended daily allowance)

Recommended intake of a particular nutrient that meets the needs of nearly all (97%) healthy individuals of similar age and gender. The RDAs are established by the Food and Nutrition Boards of the National Academy of Sciences.

reperfusion

Restoration of the blood supply to a tissue or organ.

rhIL-6

recombinant human interleukin-6

RIA

radioimmunoassay

ribosome

Very small organelle composed of protein and RNA that is either free in the cytoplasm or attached to the membranes of the endoplasmic reticulum of a cell. The site of protein synthesis.

RNA

ribonucleic acid

RNI (recommended nutrient intake)

Defined as the level of intake required to meet the known nutritional needs of more than 97.5% of healthy persons. In the UK, the RNI is very similar to the original RDA.

ROS (reactive oxygen species)

Collective name for free radicals and other highly reactive molecules derived from molecular oxygen. ROS include superoxide radical (O₂-√), hydroxyl radical (OH-√), hydrogen peroxide (H₂O₂), and perchlorous acid (HOCl).

s (second)

A unit of time.

sarcolemma

The cell membrane of a muscle fibre.

sarcomere

The smallest contractile unit or segment of a muscle fibre and is defined as the region between two Z lines.

sarcoplasm

The cytoplasm or intracellular fluid within a muscle fibre.

sarcoplasmic reticulum

An elaborate bag-like membranous structure found within a muscle cell. Its interconnecting membranous tubules lie in the narrow spaces between the myofibrils, surrounding and running parallel to them.

SD (standard deviation)

A measure of variability about the mean; 68% of the population is within 1 standard deviation above and below the mean, and about 95% of the population is within 2 standard deviations of the mean.

SE (standard error)

A measure of variability about the mean. 

serum

Fluid left after blood has clotted.

SI (stimulation index)

Lymphocyte proliferation expressed as ratio of mitogen-stimulated proliferation rate to unstimulated proliferation rate.

s-IgA

salivary immunoglobulin A

SOD

superoxide dismutase

solute

A substance dissolved in a solvent liquid such as water.

solvent

A liquid medium in which particles can dissolve.

stable isotope

An isotope is a specific form of a chemical element. It differs from atoms of other forms (isotopes) of the same element in the number of neutrons in its nucleus. 'Stable' refers to the fact that the isotope is not radioactive, in contrast to some other types of isotopes.

starch

A carbohydrate made of multiple units of glucose attached together by bonds that can be broken down by human digestion processes. Starch is also known as complex carbohydrates.

steroid

A complex molecule derived from the lipid cholesterol containing four interlocking carbon rings.

Système Internationale (SI)

(Système Internationale d’unités) the International System of Units, a worldwide agreed uniform system of units.

TBARS (thiobarituric acid-reactive substances)

Stable compounds produced as a consequence of free radical actions on lipid structures, which are commonly used as a measure of oxidative stress.

Tc

T cytotoxic lymphocyte; effector cell of cell-mediated immunity.

TCR (T cell receptor)

Antigen receptor present on surface of T lymphocytes that recognises fragments of antigenic peptides presented by MHC class II proteins on APCs.

testosterone

The male sex hormone responsible for male secondary sex characteristics at puberty. It has anabolic and androgenic effects.

TGF (transforming growth factor)

An inhibitory cytokine produced by T regulatory cells.

Th

T helper lymphocyte.

thymus

The lymphoid gland located in the chest where lymphocytes differentiate into immunocompetent T cells.

tissue

An organised association of similar cells that perform a common function (e.g., muscle tissue).

TLR (Toll-like receptor)

Family of evolutionary conserved PRRs present on APCs and phagocytes that detect PAMPs and initiate the acquired immune response to pathogens.

TNF (tumour necrosis factor)

A cytokine that promotes inflammation.

trafficking (of leukocytes)

Movements of leukocytes into or out of the circulation.

transcription

The process by which RNA polymerase produces single-stranded RNA complimentary to one strand of the DNA.

translation

The process by which ribosomes and tRNA decipher the genetic code in mRNA to synthesise a specific polypeptide or protein.

Treg

T regulatory lymphocyte, a major producer of the anti-inflammatory cytokine, interleukin-10.

UK

United Kingdom

UPS (unexplained underperformance syndrome)

 Also known as overtraining syndrome.

urea

End product of protein metabolism. Chemical formula CO(NH2)2.

URI (upper respiratory illness)

A term that is increasingly used to describe symptoms of illness affecting the upper respiratory tract where an infectious cause of symptoms cannot be confirmed and other causes (e.g. airway inflammation) may be responsible.

uric acid

A breakdown product of nucleic acids; present in small quantity in the plasma and urine of man and most mammals.

urine

Fluid produced in the kidney and excreted from the body. Contains urea, ammonia and other metabolic wastes.

URTI

Upper respiratory tract infections like colds and flu.

USA

United States of America

vegan

Vegetarian who eats no animal products. 

vegetarian

One whose food is of vegetable or plant origin.

virus

A microscopic organism that cannot replicate or express its genes without a host living cell. Viruses invade living cells and use the nucleic acid material they contain to replicate themselves.

vitamin

An organic substance necessary in small amounts for the normal metabolic functioning of the body. Must be present in the diet because the body cannot synthesise it (or cannot synthesise an adequate amount of it).

vitamin B₁

Thiamine

vitamin B₂

Riboflavin

vitamin B₆

Pyridoxine

vitamin B₁₂

Cyanocobalamin

vitamin C

Ascorbic acid.

vitamin D

Cholecalciferol, the product of irradiation of 7-dehydrocholesterol found in the skin.

vitamin E

Alpha-tocopherol.

vitamin K

Menoquinone

V_max

Maximal velocity of an enzymatic reaction when substrate concentration is not limiting.

VO₂

Rate of oxygen uptake.

VO₂max

Maximal oxygen uptake. The highest rate of oxygen consumption by the body that can be determined in an incremental exercise test to exhaustion.

W (watt)

Unit of power or work rate (J/s).

water

The universal solvent of life (H₂O). The body is composed of 60% water. 

WBC (white blood cell)

Leukocyte. Important cells of the immune system that defend the body against invading micro-organisms.

WHO

World Health Organization.

w.w.

wet weight