agent (redirected from chemical agent)

agent (a´jent) something capable of producing an effect.

---

adrenergic blocking agent  one that inhibits response to sympathetic impulses by blocking the alpha (alpha-adrenergic blocking a.) or beta (beta-adrenergic blocking a.) receptor sites of effector organs.

adrenergic neuron blocking agent  one that inhibits the release of norepinephrine from postganglionic adrenergic nerve endings.

alkylating agent  a cytotoxic agent, e.g., a nitrogen mustard, which is highly reactive and can donate an alkyl group to another compound. Alkylating agents inhibit cell division by reacting with DNA and are used as antineoplastic agents.

blocking agent  an agent that inhibits a biological action, such as movement of an ion across the cell membrane, passage of a neural impulse, or interaction with a specific receptor.

calcium channel blocking agent  any of a class of drugs that inhibit the influx of calcium ions across the cell membrane or inhibit the mobilization of calcium from intracellular stores; used in the treatment of angina, cardiac arrhythmias, and hypertension.

chelating agent 

1. a compound that combines with metal ions to form stable ring structures.

2. a substance used to reduce the concentration of free metal ion in solution by complexing it.

cholinergic blocking agent  one that blocks or inactivates acetylcholine.

emulsifying agent  emulsifier.

ganglionic blocking agent  one that blocks nerve impulses at autonomic ganglionic synapses.

inotropic agent  any of a class of agents affecting the force of muscle contraction, particularly a drug affecting the force of cardiac contraction; positive inotropic agents increase, and negative inotropic agents decrease the force of cardiac muscle contraction.

luting agent  lute (1).

neuromuscular blocking agent  a compound that causes paralysis of skeletal muscle by blocking neural transmission at the neuromuscular junction.

nonsteroidal antiinflammatory agent  see under drug.

Agent Orange  a herbicide containing 2,4,5-T and 2,4-D and the contaminant dioxin; it is suspected of being carcinogenic and teratogenic.

oxidizing agent  a substance capable of accepting electrons from another substance, thereby oxidizing the second substance and itself becoming reduced.

potassium channel blocking agent  any of a class of antiarrhythmic agents that inhibit the movement of potassium ions through the potassium channels, thus prolonging repolarization of the cell membrane.

progestational agent  progestin: any of a group of hormones secreted by the corpus luteum and placenta and, in small amounts, by the adrenal cortex, including progesterone; they induce the formation of a secretory endometrium. Agents having progestational activity are also produced synthetically.

psychoactive agent , psychotropic agent psychoactive substance.

reducing agent  a substance that acts as an electron donor in a chemical redox reaction.

sclerosing agent  sclerosant; a chemical irritant injected into a vein in sclerotherapy.

sodium channel blocking agent  any of a class of antiarrhythmic agents that prevent ectopic beats by acting on partially inactivated sodium channels to inhibit abnormal depolarizations.

surface-active agent  a substance that exerts a change on the surface properties of a liquid, especially one that reduces its surface tension, as a detergent.

wetting agent  a substance that lowers the surface tension of water to promote wetting.

---

a·gent (jnt)

n.

A force or substance, such as a chemical, that causes a change.

---

Contrast (agent, medium)

A substance injected into the body that illuminates certain structures that would otherwise be hard to see on the radiograph (film).

Mentioned in: Arthrography, Computed Tomography Scans

---

agent(s),

n 1. a person or product that causes action.
n 2. a person authorized to act for, or in place of, another.

agent, adrenergic blocking,

n a drug that blocks the action of the neurohormones norepinephrine and/or epinephrine or of adrenergic drugs at sympathetic neuroeffectors.

agent, adrenolytic blocking

n an uncertain term sometimes used in reference to adrenergic blocking agents.

agent, anesthetic,

n a drug that produces local or general loss of sensation.

agent, antianxiety,

n any medication prescribed to relieve anxiety disorder symptoms, primarily stress and insomnia. The most common forms are benzodiazepine derivatives.

agent, antiarrhythmic

n.pl a substance used to prevent or relieve an irregular rhythm of heartbeat. Also mistakenly called
antidysrhythmic.

agent, antigingivitis,

n compound that inhibits, controls, or kills organisms associated with the formation of gingivitis.

agent, antihypertensive,

n a medication used to lower elevated blood pressure (e.g., diuretics, beta-blockers, and vasodilators).

agent, antiinflammatory,

n a drug that reduces inflammation.

agent, antimanic,

n a substance used to treat various nervous system and psychiatric disorders; possible effects on fetal development include sluggishness, oxygen deficiency, and physical malformations.

agent, antiparasitic,

n an antimicrobe that specifically targets pathogenic microorganisms.

agent, blocking,

n an agent that occupies or usurps the receptor site normally occupied by a drug or a biochemical intermediary (e.g., acetylcholine or epinephrine).

agent, bonding,

n a substance used to bond fillings and tooth restorations to the tooth surface.

agent, chemotherapeutic

n a chemical of natural or synthetic origin used for its specific action against disease, usually against infection.

agent, cholinergic blocking

n 1. a drug that inhibits the action of acetylcholine or cholinergic drugs at the postganglionic cholinergic neuroeffectors.
n 2. an anticholinergic agent.

agent, cleaning,

n.pl an abrasive substance contained in toothpastes, gels, and powders that polishes teeth and aids in the removal of stains and plaque biofilm. See also abrasion, dentifrice.

agent, coloring,

n.pl any substance contained in toothpastes, gels, and powders purely to make the product more appealing.

agent, coupling,

n a substance or material that binds to both resin and reinforcement material and helps join them to make a composite.

agent, ganglionic blocking

n a drug that prevents passage of nerve impulses at the synapses between preganglionic and postganglionic neurons.

agent, myoneural blocking,

n a drug that prevents transmission of nerve impulses at the junction of the nerve and the muscle.

agent, oxidizing,

n an agent that provides oxygen in reaction with another substance or, in the broader and more definitive chemical sense, a chemical capable of accepting electrons and thereby decreasing the negative charge on an atom of the substance being oxidized.

agent, polishing,

n an abrasive that produces a smooth, lustrous finish.

agent, postganglionic sympathetic blocking,

n.pl a medication used to treat hypertension by blocking the release of the naturally occurring hormone norepinephrine.

agent, reducing,

n a category of chemicals used in film processing that brings out the gray tones of an image by creating black metallic silver from silver halide crystals.

agent, wetting,

n any agent that will reduce the surface tension of water. Generally used in investing wax patterns.

Whitening agent, before and after.

agent, whitening,

n a bleaching substance applied to teeth to lighten their appearance.

agents, antiadrenergic, centrally acting

n.pl antihypertensive drugs used to lower blood pressure, specifically those that operate by stimulating α-receptors in the central nervous system and arterioles.

agents, antianginal,

n one of several types of medication used to treat heart disease; alleviates pain associated with angina by lowering blood pressure during systole. See also vasodilator.

agents, oxygenating,

n.pl the substances, such as hydrogen peroxide, that, when used as mouthrinses, release oxygen into gingival tissues and reduce inflammation. The process has not proved to reduce the bacteria causing the inflammation. Long-term use may cause tissue damage.

agents, sympathetic,

n.pl the medications that stimulate the sympathetic nervous system by imitating the actions of naturally occurring norepinephrine and epinephrine. They may be used to treat cardiac arrest, nasal congestion, asthma, glaucoma, and attention deficit hyperactivity disorder and may cause anxiety, loss of appetite, and arrythmias. Also called
adrenergic agents.

---

agent

1. any power, principle or substance by which something is accomplished, or which is capable of producing a chemical, physical or biological effect such as a disease.

2. of disease; any factor whose excessive presence or relative absence is essential for the occurrence of a disease.

---

adrenergic neuron blocking agent

one that inhibits the release of norepinephrine from postganglionic adrenergic nerve endings.

alkylating agent

a cytotoxic agent, e.g. a nitrogen mustard, which is highly reactive and can donate an alkyl group to another compound. Alkylating agents inhibit cell division by reacting with DNA and are used as antineoplastic agents.

anesthetic agent

substance capable of producing reversible general or local anesthesia.

anticholinergic agent

cholinergic blocking agent.

agent change

change in an animal's chemical or antigenic configuration can alter its pathogenicity. For example, a case of nitrate-nitrite poisoning in a cow can become a case of nitrite poisoning after conversion of the nitrate in the rumen. Mutation and antigenic drift are other types of change that vary agent pathogenicity.

chelating agent

a compound that combines with metals to form weakly dissociated complexes in which the metal is part of a ring, and is used to extract certain elements from a system.

chemical agent

substance that produces change by virtue of its chemical composition and its effects on living tissues and organisms.

cholinergic blocking agent

one that blocks the action of acetylcholine at nicotinic or muscarinic receptors of nerves or effector organs.

determinant agent

only some agents are determinants of diseases in that they always cause disease, and the same disease, and the disease does not occur without the agent. Many agents require the intervention of other factors, such as anaerobicity of tissue, hepatic insufficiency or physiological stress before they can establish their pathogenicity.

ganglionic blocking agent

one that blocks cholinergic transmission at autonomic ganglionic synapses.

immobilizing agent

see neuromuscular blockade.

infectious agent

an organism able to live in or on the tissue of a living animal; may not necessarily cause disease.

agent interaction

is the interaction between precipitating and predisposing causes of disease.

oxidizing agent

a substance that acts as an electron acceptor in a chemical oxidation-reduction reaction.

agent properties

are the properties which determine the pathogenicity of the agent, the solubility and acidity or biodegradability of a chemical, the virulence, adhesiveness, resistance to antibacterial agents of bacteria and viruses and so on.

reducing agent

a substance that acts as an electron donor in a chemical oxidation-reduction reaction.

surface-active agent

a substance that exerts a change on the surface properties of a liquid, especially one, such as a detergent, that reduces its surface tension. Called also surfactant.

therapeutic agent

a substance capable of producing a curative effect in a disease state.

agent without disease

exemplified by the orphan viruses. The agent is of a type that causes disease, but none is associated with the presence of the particular agent.