Reading Essentials for Biology Glencoe (794133), страница 103
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Read the terms and their definitions in the Mini Glossary above. Circle all of the terms thatdeal with the sense of sight. Then write a paragraph using the terms.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________READING ESSENTIALSChapter 36453NameDateClassSection36.2The Senses, continued2.
Match the statements in Column 1 to the term that matches in Column 2.Column 1_____Column 21. Your eyes are squinting from thebright sunlight.a. olfactory nerves_____2. You are dizzy.c. cones_____3. You smell something burning.d.
the cochlea_____4. The lemon is sour._____5. You have hearing loss.b. taste budse. semicircular canalsCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Visit the Glencoe Science Web site at science.glencoe.comto find your biology book and learn more about the senses.454Chapter 36READING ESSENTIALSNameDateClassSection36.3 The Effects of DrugsSC.F.1.4.6 The student knows that separate parts of the body communicate with each other using electrical and/orchemical signals.◗ Before You ReadHave you ever taken an antibiotic for an infection or a pain reliever for an ache or pain? Drugs usedas medication can be helpful in treating certain health problems and relieving pain.
They should,however, be taken only when they are needed, and never without an adult’s or doctor’s permission.On the lines below, list a positive and a negative point about the medicinal use of drugs.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Drugs Act on the BodyA drug is a chemical that affects the body’s functions.
Mostdrugs interact with receptor sites on cells, probably the same onesused by neurotransmitters of the nervous system or hormones ofthe endocrine system. Some drugs increase the rate at which neurotransmitters are synthesized and released. Drugs also can slowthe rate at which neurotransmitters are broken down. Otherdrugs interfere with a neurotransmitter’s ability to interact withits receptor.LocateInformation Highlight everyheading in the reading thatasks a question. Then highlight each answer as youfind it.Medicinal Uses of DrugsA medicine is a drug that, when taken into the body, helps prevent, cure, or relieve a medical problem.
Some of the many kindsof medicines used to relieve medical conditions are discussed here.How do drugs relieve pain?Headache, muscle ache, and cramps are common pain sensations. You have just read about how pain receptors in your bodysend signals to your brain. Pain-relieving medicines manipulateeither the receptors that initiate the impulses or the central nervous system that receives them.Pain relievers that do not cause a loss of consciousness arecalled analgesics. Some analgesics, such as aspirin, work byinhibiting receptors at the site of pain from producing nerveREADING ESSENTIALSChapter 36455NameDateClassSection36.3The Effects of Drugs, continued1.
What is a pain relievercalled that does not causea loss of consciousness?________________________________________________________________________impulses. Analgesics that work on the central nervous system arecalled narcotics. Many narcotics are made from the opium poppyflower. Opiates, as they are called, can be useful in controlledmedical therapy because these drugs are able to relieve severepain from illness or injury.How are circulatory problems treated?Many drugs have been developed to treat heart and circulatoryproblems such as high blood pressure. These medicines arecalled cardiovascular drugs.
In addition to treating high bloodpressure, cardiovascular drugs may be used to normalize an irregular heartbeat, increase the heart’s pumping capacity, or enlargesmall blood vessels.Several kinds of medicines are used to help relieve symptoms ofnervous system problems. Among these medicines are stimulantsand depressants. Drugs that increase the activity of the centraland sympathetic nervous systems are called stimulants.
Amphetamines (am FE tuh meenz) are synthetic stimulants that increasethe output of CNS neurotransmitters. Amphetamines are seldomprescribed because they can lead to dependence. However,because they increase wakefulness and alertness, amphetaminesare sometimes used to treat patients with sleep disorders.Drugs that lower, or depress, the activity of the nervous systemare called depressants, or sedatives. The primary medicinal usesof depressants are to encourage calmness and produce sleep.
Forsome people, symptoms of anxiety interfere with the ability tofunction effectively. By slowing down the activities of the CNS, adepressant can temporarily relieve some of this anxiety.The Misuse and Abuse of Drugs2. Compare How does themedicinal use of drugsdiffer from drug misuse?________________________________________________________________________456Chapter 36The misuse or abuse of drugs can cause serious health problems—even death. Drug misuse occurs when a medicine is takenfor an unintended use.
Instances of drug misuse include givingyour prescription medicine to someone else, not following theprescribed dosage of medication, and mixing medicines.Drug abuse is the inappropriate use of a drug for a non-medicalpurpose. Drug abuse may involve use of an illegal drug, such ascocaine; use of an illegally obtained medicine, such as someoneelse’s prescribed drugs; or excessive use of a legal drug, such asalcohol or nicotine. Drugs abused in this way can have powerfuleffects on the nervous system and other systems of the body.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.How are nervous disorders treated?NameDateClassSection36.3The Effects of Drugs, continuedWhat is addiction to drugs?When a person believes he or she needs a drug to feel good orto function normally, that person is psychologically dependent onthe drug.
When a person’s body develops a chemical need for thedrug in order to function normally, that person is physiologicallydependent. Both are forms of addiction.When a drug user experiences tolerance to or withdrawal froma frequently used drug, that person is addicted to the drug.Tolerance occurs when a person needs a larger or more frequentdose of a drug to achieve the same effect. The need for more isrelated to the body’s becoming less responsive to the effects of thedrug. When a person stops taking a drug and actually becomes ill,it is called withdrawal.3.
Compare How doesdrug misuse differ fromdrug abuse?________________________________________________________________________Classes of Commonly Abused DrugsEach class of drug produces its own effect on the body, and itsown particular symptoms of withdrawal.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What are stimulants?You already know that stimulants increase the activity of thecentral and sympathetic nervous systems.
Increased CNS stimulation can result in mild elevation of alertness, increased nervousness, anxiety, and even convulsions.Cocaine stimulates the CNS by working the part of the innerbrain that governs emotions and basic drives, such as hunger andthirst. When these needs are met under normal circumstances,neurotransmitters—such as dopamine—are released to rewardcenters and the person experiences pleasure. Cocaine artificiallyincreases levels of these neurotransmitters in the brain. As a result,false messages are sent to reward centers signaling that a basicdrive has been satisfied.
The user quickly feels a pleasurable highcalled a rush. This feeling does not last. Soon the effects of thedrug change. Physical hyperactivity follows. Often anxiety anddepression set in.Cocaine also disrupts the body’s circulatory system by interfering with the sympathetic nervous system. At first cocaine slowsthe heart rate. However, it soon produces a rapid increase in heartrate and a narrowing of blood vessels, known as vasoconstriction.The result is high blood pressure. Heavy use of this drug weakensthe immune system and often leads to heart abnormalities.Cocaine may affect the unborn babies of addicted mothers.Sometimes the babies are born already dependent on the drug.READING ESSENTIALS4. What are some of theside effects caused bystimulants?________________________________________________________________________Chapter 36457NameDateClassSection36.3The Effects of Drugs, continued5.
What are some ofthe harmful effectsof nicotine?________________________________________________________________________6. How does alcohol affectthe body’s organs?________________________________________________________________________458Chapter 36What are depressants?Depressants slow down the activities of the CNS. All CNSdepressants relieve anxiety, but most produce drowsiness. One ofthe most widely abused drugs in the world today is alcohol. It iseasily produced from various grains and fruits.
Alcohol is distributed throughout a person’s body via the bloodstream. Like otherdrugs, alcohol affects cellular communication by influencing therelease of or interacting with receptors for several important neurotransmitters in the brain. Alcohol also appears to block themovement of sodium and calcium ions across the cell membrane.That process is important in the transmission of impulses and therelease of neurotransmitters.Tolerance to the effects of alcohol develops as a result of heavyalcohol consumption.
Addiction to alcohol—alcoholism—candestroy nerve cells and cause brain damage. Chronic alcoholuse contributes to a number of organ diseases. For example,cirrhosis, a hardening of the tissues of the liver, commonlyafflicts alcoholics.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Amphetamines are stimulants that increase levels of CNS neurotransmitters. Like cocaine, amphetamines also cause vasoconstriction, a racing heart, and increased blood pressure. Otheradverse side effects of amphetamine abuse include irregular heartbeat, chest pain, paranoia, hallucinations, and convulsions.Not all stimulants are illegal. Caffeine—asubstance found in coffee, some carbonatedsoft drinks, cocoa, and tea—is a CNS stimulant.
Its effects include increased alertness andsome mood elevation. Caffeine also causes anincrease in heart rate and urine production,which can lead to dehydration.Nicotine, a substance found in tobacco, alsois a stimulant. By increasing the release of thehormone epinephrine, nicotine increases heartrate, blood pressure, breathing rate, and stomach acid secretion. Nicotine is the addictiveingredient in tobacco. There are many otherharmful chemicals also found in tobacco products. Smoking cigarettes leads to an increasedrisk of lung cancer and cardiovascular disease.Use of chewing tobacco is associated with oraland throat cancers.NameDateClassSection36.3The Effects of Drugs, continuedBarbiturates (bar BIH chuh ruts) are sedatives and anti-anxietydrugs.
When barbiturates are used in excess, the user’s respiratoryand circulatory systems become depressed. Chronic use resultsin addiction.What are narcotics?Most narcotics are opiates, derived from the opium poppy.They act directly on the brain. Heroin is the most abused narcotic in the United States. It depresses the CNS, slows breathing,and lowers heart rate. Addiction develops quickly, and withdrawalfrom heroin is painful.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What are hallucinogens?Natural hallucinogens have been known and used for thousandsof years, but the abuse of hallucinogenic drugs did not becomewidespread in the United States until the 1960s, when new synthetic versions became widely available.Hallucinogens (huh LEW sun uh junz) stimulate the CNS—altering moods, thoughts, and sensory perceptions.
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