Understanding Alcohol
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National Institutes of Health
National Institute on Alcohol Abuse and Alcoholism

Understanding Alcohol

Main    Getting Started    Teacher's Guide    Student Activities    About NIH and NIAAA

Glossary    Map    Contact

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absorption phase: The time immediately after consumption when blood alcohol concentration rises sharply.

acetaldehyde: One of the first products of the body’s metabolism of alcohol. Acetaldehyde is then converted to carbon dioxide and water, which are excreted from the body.

acute: Short-term.

addiction: A state that involves a physical or psychological dependency on a drug or alcohol.

alcohol: The intoxicating chemical in drinks such as beer, wine, and distilled liquors. Alcohol is a colorless, volatile liquid with the chemical formula C2H5OH, also called ethanol or ethyl alcohol. It is a central nervous system depressant.

alcohol abuse: The continued use of alcohol despite the development of social, legal, or health problems.

alcohol addiction, alcohol dependence, or alcoholism: A chronic disease characterized by a strong craving for alcohol, a constant or periodic reliance on use of alcohol despite adverse consequences, the inability to limit drinking, physical illness when drinking is stopped, and the need for increasing amounts of alcohol to feel its effects.

alcohol dehydrogenase (ADH): An enzyme found in the liver and stomach that helps break down alcohol into substances that can be excreted from the body. Specifically, ADH converts alcohol into acetaldehyde, which is then converted to carbon dioxide and water.

alcoholic hepatitis: Liver disease caused by chronic ingestion of alcohol.

alleles: Different variations of the same gene.

arteries: Thick-walled blood vessels that carry blood away from the heart.

axon: Extensions of nerve cells that carry the nerve impulses away from the nerve cell body.

binge drinking: A pattern of heavy drinking that occurs during an extended period of time set aside for drinking. Has been described as 5/4 binge drinking: five or more drinks in a row on a single occasion for a man or four or more drinks for a woman.

blood alcohol concentration (BAC): The amount of alcohol in the blood expressed as a percent: grams of ethanol per 100 milliliters (deciliter) of blood.

brainstem: The part of the brain that connects the spinal cord with other parts of the brain.

CAGE: Refers to a questionnaire developed by Dr. John Ewing to screen for alcohol abuse and alcoholism. The name comes from the first letters of key words in the questionnaire: Cut down on drinking, Annoyed by people criticizing your drinking, Guilty about drinking, and drinking as an Eye opener.

cardiovascular system: The organ system that includes the blood, the heart, and blood vessels.

cerebellum: The region of the brain involved with coordination of muscles and maintaining balance and posture.

chromosomes: Rod-like, gene-bearing structures found in the cell nucleus. They are composed of DNA and protein. Humans have 46 chromosomes.

chronic: Long-term; refers to diseases or habits that last a long time, recur, or are difficult to cure.

cirrhosis: Hardening of connective tissue in the liver; fibrosis.

cognitive: Relating mental awareness and judgment.

coronary artery disease: A condition in which cholesterol and fat in the blood build up in clumps known as plaque on the inside walls of arteries. This build-up can restrict the flow of blood and thus of oxygen to the heart. Oxygen starvation of the heart muscle can lead to a heart attack.

cytokines: A class of molecules that help regulate the activities of the immune system.

delirium tremens (DTs): A serious alcohol-withdrawal syndrome observed in persons who stop drinking alcohol following continuous and heavy consumption. It involves profound confusion, hallucinations, and severe nervous system overactivity, typically beginning between 48 and 96 hours after the last drink.

dendrite: A cluster of small fibers that receive chemical messages from neighboring neurons and transmit them to the cell body.

depressant: A substance that causes sedation and drowsiness. Alcohol is a central nervous system depressant.

diffusion: The passive movement of a substance from a region where it is more concentrated to a region where it is less concentrated. For example, blood alcohol concentration decreases as alcohol diffuses from the blood into body tissues.

distillation: A process that uses heat to purify or separate a fraction of a complex substance. Various components of the mixture are collected as gases condense to liquids. Liquors are produced through distillation.

distribution phase: The process by which ethanol spreads from the blood to all tissues and fluids in proportion to their relative water content.

dopamine: A chemical messenger (neurotransmitter) that regulates brain processes such as those that control movements, emotions, pleasure, and pain.

drug: In a medical context, any substance used in the diagnosis, prevention, treatment, or cure of a disease. In an abuse context, any substance that alters consciousness and may be habit forming.

elimination phase: The combined processes of metabolism and excretion that decrease blood alcohol concentration.

endorphins: A class of protein hormones produced in the brain that have pain-relieving properties.

endotoxin: A bacterial toxin composed of protein, lipid, and polysaccharides.

enzyme: A class of proteins that speed up chemical reactions in the body.

esophageal cancer: Cancer of the esophagus (throat).

esophagus: The part of the digestive system that receives food. This is the tube leading from the mouth to the stomach.

ethanol: See alcohol.

ethyl alcohol: See alcohol.

euphoria: A feeling of well being.

excretion: The loss of ethanol from the body through urine, sweat, breath, and other routes of exit.

fermentation: An anaerobic process (not requiring oxygen) in which organisms convert sugars into alcohol and carbon dioxide. This process does not occur in animals but is used extensively by yeast (single-celled fungi). Humans exploit this phenomenon to make bread (the gas bubbles expand the dough) as well as wine and beer (for the alcohol produced).

fetal alcohol effects (FAE): A pattern of mental and physical birth abnormalities associated with children whose mothers abused alcohol during pregnancy. The symptoms are less severe than those in fetal alcohol syndrome.

fetal alcohol syndrome (FAS): A pattern of mental and physical birth abnormalities found in some children of mothers who drank excessively during pregnancy.

fibrosis: A condition within a tissue or an organ that is characterized by an increase in fibrous tissue.

free radicals: Short-lived, highly reactive molecules that have one or more unpaired electrons.

functional tolerance: A state in which a chronic alcohol abuser learns to function under the influence of alcohol. The impairment normally associated with performing a familiar task is reduced, but the ability to perform unfamiliar tasks remains impaired.

gastritis: An inflammation of the stomach lining.

gene: The functional and physical unit of heredity. Genes are segments of DNA found along a chromosome. They typically encode information used to produce a specific protein.

genetically predisposed: Having variations in genes that increase the probability of displaying a given trait.

genotype: The genetic makeup of an individual. The expression of genotype as visible traits is called the phenotype.

glucagon: A pancreatic hormone that increases the concentration of blood sugar. Its effect is opposite to that of insulin.

growth hormones: Hormones that affect growth of the body, for example, by stimulating cell division and bone growth.

hallucination: The experience of sights and sounds that are not actually present.

hippocampus: A part of the brain that is responsible for learning and spatial relations.

hormone: A chemical released into the bloodstream that stimulates or inhibits an action in another body tissue.

hypertension: A condition of abnormally high blood pressure.

hypothalamus: A small area of the brain that is responsible for regulating the release of some hormones and maintaining body temperature.

impairment: Diminished ability, such as when alcohol decreases motor function or interferes with thinking.

inflammation: The body’s response to tissue damage characterized by redness, swelling, heat, and pain.

inhibition: As related to behavior, restraint on instinctive impulses.

insulin: A hormone produced in the pancreas that lowers the blood sugar level. Its effect is opposite to that of glucagon.

intoxication: The condition of being drunk. An abnormal state that is essentially alcohol poisoning. It is characterized by slurred speech and a loss of coordination.

limbic system: The areas of the brain involved with emotions and memory.

lymphocytes: The white blood cells, the T cells, and B cells of the immune system.

metabolism: All the chemical reactions that enable the body to function. Nutrients and materials are broken down into stored energy or into usable compounds. The biological transformation of ethanol to acetaldehyde and other products.

mitochondria: The cellular organelles that function as energy factories in the cell. Mitochondria produce ATP (the energy currency of our bodies).

motor function: The ability to use and control muscles and movements. Alcohol and drugs interfere with the neuronal messages from our brain to muscles resulting in impaired motor function.

naltrexone: A drug that has been effective in the recovery from alcoholism. It blocks receptors for endorphins, thereby reducing alcohol cravings. Use of the drug in combination with psychosocial therapy improves the effectiveness of treatment.

neurons: One of two principal classes of cells in the nervous system, composed of three parts: the cell body, dendrites, and axons. Neurons receive and conduct electrical impulses.

neurotransmission: The process by which neurons transmit messages to other neurons, muscle cells, or gland cells.

neurotransmitter: A chemical substance that transmits a nerve impulse across a synapse.

nucleus accumbens: The part of the brain related to the limbic system that controls emotions.

pancreatitis: An acute or chronic inflammation of the pancreas associated with alcoholism and marked by severe abdominal pain, nausea, and fever.

pharmacokinetics: The study of the absorption, distribution, and elimination of alcohol and other drugs.

physical dependence: A condition in which the presence of a drug or alcohol is required to maintain normal functioning of the central nervous system. (See withdrawal symptoms.) Physical dependence is caused by changes in the relationships among nerve cell membranes, neurotransmitters and their receptors, and the reward pathway.

placenta: A membranous organ that develops during pregnancy. It lines the uterine wall, partially envelopes the fetus, and is attached to the umbilical cord. The placenta exchanges nutrients, wastes, and gases between maternal and fetal blood. Substances ingested by the mother during pregnancy pass through the placenta to the fetus.

polygenic: A trait, such as alcoholism, whose expression is influenced by more than one gene.

predispose: To make susceptible, such as to certain health problems or to alcohol dependency. For example, the presence of certain gene combinations or environmental conditions can predispose an individual to develop alcoholism.

prefrontal cortex: The part of the frontal lobe of the brain that relates to pleasure.

psychosocial: Involving both social and psychological behavior.

reinforcement: The positive effects of alcohol, such as its euphoric and anxiety-reducing effects, that help promote continued drinking. Specific neurotransmitters and regions of the brain are implicated in alcohol’s reinforcing effects.

relapse: To fall back or revert to an earlier state; to regress after partial recovery. In the context of alcohol abuse and alcoholism, relapse means to start drinking again after giving up alcohol.

reproductive hormones: Hormones that influence development of secondary sexual traits and the production of or maturation of the sperm and the egg. These include testosterone, leutinizing hormone (LH), follicle stimulating hormone (FSH), estrogen, and progesterone.

reward pathway: A specialized network of neurons in the brain that produce and regulate pleasure associated with eating, drinking, and sex. These neurons use dopamine as a neurotransmitter. Alcohol activates the reward pathway. Alcohol abusers and alcoholics use alcohol to avoid the pain (lack of pleasure) associated with withdrawal.

sobriety: The condition of refraining from drinking alcohol.

sodium-potassium pump: Proteins embedded in the cell membrane that actively move potassium ions into the cell and, at the same time, move sodium ions out.

soluble: Capable of being dissolved in a solvent such as water or another liquid.

stimulant: A substance such as caffeine, nicotine, or amphetamines that temporarily arouses or accelerates physiological activity in the brain.

stupor: A state of impaired consciousness accompanied by diminished responsiveness to external stimuli and surroundings.

synapse: The tiny space between two nerve cells or between a nerve cell and a muscle or gland cell.

synaptogenesis: The time frame from about the sixth month of pregnancy to a child’s second birthday when the brain experiences a growth spurt and brain cells form most of their interconnections.

testosterone: A sex hormone responsible for secondary sex characteristics. Present in both males and females but at lower concentrations in females.

tolerance: The body’s ability to adapt to chronic alcohol or substance use. Higher BACs are needed to produce intoxication in alcohol abusers and alcoholics. Chronic alcohol use leads to increased levels of liver enzymes that metabolize alcohol. Since they allow the liver to more efficiently break down alcohol, the individual must consume a larger dose to reach a given BAC. This increased level of alcohol can severely damage the body’s physiological systems, despite the apparent “normalcy” displayed by the individual.

tuberculosis: A communicable disease caused by a bacterium that causes lesions of the lung, bone, and other body parts. Drug and alcohol abusers are infected at a rate 15–200 times greater than that of nonabusers.

ventral tegmental area: Component of the reward pathway in the brain; located near the top of the brainstem.

withdrawal symptoms: Severe alcohol cravings as well as physical and psychological problems caused by the withdrawal from excessive, chronic alcohol consumption. The biochemical changes lead to short-term memory loss, disruption of cognitive and motor function, reduced perceptual abilities, and emotional and personality changes that include acts of aggression.

zero-tolerance laws: Laws that exist in all states and the District of Columbia making it illegal for anyone under the age of 21 to drive a car after drinking any alcohol.