December 2013/January 2014 Teacher's Guide for Morphine & Urine: The Yin & Yang of Narcotics Table of Contents
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- Bu səhifədəki naviqasiya:
- Answers to Student Questions
- Background Information
- Connections to Chemistry Concepts
- Possible Student Misconceptions
- Anticipating Student Questions
- Out-of-class Activities and Projects
- Web Sites for Additional Information
December 2013/January 2014 Teacher's Guide for Morphine & Urine: The Yin & Yang of Narcotics Table of Contents About the Guide 2 Student Questions 3 Answers to Student Questions 4 Anticipation Guide 5 Reading Strategies 6 Background Information 8 Connections to Chemistry Concepts 15 Possible Student Misconceptions 15 Anticipating Student Questions 15 In-class Activities 17 Out-of-class Activities and Projects 18 References 18 Web Sites for Additional Information 19 About the GuideTeacher’s Guide editors William Bleam, Donald McKinney, Ronald Tempest, and Erica K. Jacobsen created the Teacher’s Guide article material. E-mail: bbleam@verizon.net Susan Cooper prepared the anticipation and reading guides. Patrice Pages, ChemMatters editor, coordinated production and prepared the Microsoft Word and PDF versions of the Teacher’s Guide. E-mail: chemmatters@acs.org Articles from past issues of ChemMatters can be accessed from a CD that is available from the American Chemical Society for $30. The CD contains all ChemMatters issues from February 1983 to April 2008. The ChemMatters CD includes an Index that covers all issues from February 1983 to April 2008. The ChemMatters CD can be purchased by calling 1-800-227-5558. Purchase information can be found online at www.acs.org/chemmatters Student Questions
Answers to Student Questions
Morphine is found in opium, the white sticky latex produced by poppy plants (Papver somniferum)
Opium is a mixture of different chemical compounds (sugars, proteins, fats, water and a specific class of compounds known as alkaloids) which includes morphine, an alkaloid.
The conversion of morphine to heroin involves the addition of two acetyl groups (-CH3CO) to the morphine molecule where two –OH groups are attached. Each of the two acetyl groups replaces the hydrogen (H) of an OH group, bonding to the main morphine structure.
Endorphins are natural substances produced in the brain reducing the sensation of pain as well as inducing sleepiness and feelings of pleasure in the body. Morphine has the same effect.
Morphine has the same effect on the body as do endorphins. They both bind to the opioid receptors in the brain which causes a larger than normal release of the neurotransmitter dopamine.
When heroin enters the brain, it is converted to morphine by the reverse chemical reaction by which morphine was converted to heroin. The two acetyl groups added to morphine to become heroin are removed in the reverse reaction.
Drug tolerance occurs from repeated use of a particular drug, requiring higher doses of the same drug to be effective (same intensity of effect in the case of addictive drugs).
Morphine is both blessing and a curse. It can be used very effectively to control pain. But if used for recreational purposes, it can lead to addiction which has all kinds of consequences, from medical issues to financial ones (buying more and more of the drug because of developing drug tolerance). So the drug has two sides to its usage—a two edged sword. Anticipation GuideAnticipation guides help engage students by activating prior knowledge and stimulating student interest before reading. If class time permits, discuss students’ responses to each statement before reading each article. As they read, students should look for evidence supporting or refuting their initial responses. Directions: Before reading, in the first column, write “A” or “D,” indicating your agreement or disagreement with each statement. As you read, compare your opinions with information from the article. In the space under each statement, cite information from the article that supports or refutes your original ideas.
Reading StrategiesThese graphic organizers are provided to help students locate and analyze information from the articles. Student understanding will be enhanced when they explore and evaluate the information themselves, with input from the teacher if students are struggling. Encourage students to use their own words and avoid copying entire sentences from the articles. The use of bullets helps them do this. If you use these reading strategies to evaluate student performance, you may want to develop a grading rubric such as the one below.
Teaching Strategies:
Directions: As you read the article, use your own words to complete the graphic organizer below comparing morphine and heroin. At the bottom, list properties they have in common.
Background Information(teacher information) More on the physiological effects of morphine Morphine and the opiates are probably some of the most valuable drugs in medicine. Their ability to alleviate pain and suffering led Thomas Sydenham, an English doctor in the nineteenth century to call them “God’s own medicine”. As noted in the ChemMatters article, there is a long history involving the use of opiates for a variety of reasons including for religious purposes. For the scientific community, it is of interest to know how these opiates work in the nervous system in order to not only make judicious and effective use of the drugs but to also develop alternatives that may not have as many side effects and/or addicting qualities. There are other drugs that relieve pain but are non-narcotic and are labeled as analgesics, the most familiar being aspirin. The specifics as to how the opiates work in the nervous system involve several chemicals endogenous to the central and peripheral nervous systems. These chemicals include naturally occurring opiate-like compounds known as endorphins, which is a word that blends two descriptive terms—endogenous (meaning developing within) and morphine. In addition, several other chemicals, through their migration and attachment to special reactor or “action” sites, control the responses of nerve cells. They include dopamine and glutamine, which are protein and amino acid molecules with specific shapes that are part of the functioning of a nerve impulse. Dopamine, endorphins and opioids, such as morphine, affect specific areas of the brain to moderate sensations of pain generated by the nervous system. Dopamine is both a hormone and a neurotransmitter. Its chemical name is 4-(2-aminoethyl)benzene-1,2-diol) and its molecular structure is shown below as: 
In the brain, it acts as a neurotransmitter and is produced in a region of the brain known as the substantia nigra. 
The diagram above [right] shows the major steps in the action of the neurotransmitter dopamine. First, dopamine is synthesized from the amino acid tyrosine. The dopamine is then stored in the synaptic vesicles of the presynaptic neuron until it receives action potentials that cause it to release the dopamine into the synaptic gap by a process called exocytosis. On the post-synaptic neuron, the dopamine then binds to specific receptors. The dopamine is subsequently reabsorbed by transporters on the terminal button of the dopaminergic presynaptic neuron. There the dopamine is either stored again in vesicles or broken down by a mitochondrial enzyme called monoamine oxidase. (source: http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_que/i_03_m_que.html) Loss of dopamine neurons in this area of the brain is the cause of Parkinson’s disease, in which people lose their ability to execute smooth, controlled movements. Dopamine has many other functions in the brain including important roles in behavior and cognition, motor activity, motivation and reward (pleasure sensations), and regulation of milk production. (For this function, dopamine is secreted by the hypothalamus portion of the brain). In the frontal lobes of the brain, dopamine assists in controlling the flow of information from other areas of the brain. Dopamine disorders in the frontal lobes can cause a decline in neurocognitive function including memory, attention, and problem solving. On the other hand, intake of various drugs including opiates, nicotine, and marijuana, increase the levels of dopamine secreted which induces a feeling of euphoria. Morphine and other opiates bind to the same neural sites as the endorphins and enkephalins, naturally occurring peptides that block pain like endorphins. In so doing, the morphine molecules keep the ion channels (primarily Cl1-) open and also block the reabsorption of the dopamine into the neurons, prolonging the sensation of euphoria. The reason that opiates such as heroin and morphine affect us so powerfully is that these exogenous substances bind to the same receptors as our endogenous opioids (endorphins and enkephalins. There are three kinds of receptors widely distributed throughout the brain—mu, delta, and kappa receptors. These receptors, through second messengers, also influence the likelihood that ion channels (primarily chloride ion) will open, which in certain cases reduces the excitability of neurons. This reduced excitability is the likely source of the euphoric effect of opiates and appears to be mediated by the mu and delta receptors. This euphoric effect also appears to involve another mechanism in which the GABA-inhibitory interneurons of the ventral tegmental area come into play. By attaching to their mu receptors, exogenous opioids reduce the amount of GABA released (see animation, referenced below). Normally, GABA reduces the amount of dopamine released in the nucleus accumbens, a section of the brain at the bottom of the frontal lobe region. (See a picture of the brain with nucleus accumbens labeled in the “More on chemically interrupting dependency” section that follows.) By inhibiting this inhibitor, the opiates ultimately increase the amount of dopamine produced and the amount of pleasure felt. Cocaine acts by blocking the reuptake of certain neurotransmitters such as dopamine, norepinephrine, and serotonin. By binding to the transporters that normally remove the excess of these neurotransmitters from the synaptic gap, cocaine prevents them from being reabsorbed by the neurons that released them and thus increases their concentration in the synapses (see animation). As a result, the natural effect of dopamine on the post-synaptic neurons is amplified. The group of neurons thus modified produces much more dependency (from dopamine), feelings of confidence (from serotonin), and energy (from norepinephrine) typically experienced by people who take cocaine. A description and animation of dopamine action on a neuron is found at http://www.addictionscience.net/ASNbiological.htm. Also, an animation for the effect of various drugs on the neuron activity involving GABA (gamma amino butyric acid), the chloride ion (Cl1-) channels, and dopamine secretion and reabsorption is found at this site: http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_heroine.html#drogues. Click on the “without heroin” or “with heroin” buttons at the top of the diagram. More on the sensation of pain In 1965, a theory about pain was proposed by Canadian psychologist Ronald Melzack and British neurobiologist Patrick Wall that suggested that nerve cells in the spinal cord act like gates, opening to allow pain messages to pass or closing to block pain messages from travelling to the brain. The input to the spinal cord is dependent on two different types of nerves—one type for pain and another for touch and pressure. Since the publication of the gate control theory, scientists have elucidated more clearly what it is that sends the pain message to the brain — or doesn’t. They now know, for instance, that neurotransmitters (chemical messengers found naturally in the brain and spinal cord) are important in conducting signals from one nerve cell to the next. Neurotransmitters stored in the bulbous end of a nerve cell travel across a junction (synapse) to attach to receptors on the surface of a neighboring cell and thereby either prompt or inhibit a continued electrical impulse along the nerve. Gamma-amino butyric acid (GABA), a naturally occurring amino acid, is an example of an inhibitory neurotransmitter that prevents nerve cells from firing, thus diminishing the sensation of pain. On the other hand, the neuropeptide (an organic compound composed of amino acids in a defined order) known as Substance P. is a neurotransmitter that increases the conduction of the pain stimulus to the brain. Substance P. is released in response to noxious stimuli or injury to tissues, and acts like a spark to speed the pain impulse along the nerves. … Endorphins and enkephalins bind with the nerve cell receptors required to send the electrical impulse across the synapse and thus, by closing the pain “gates,” block the release of neurotransmitters responsible for increasing pain perception. Research has shown that certain behavioral habits, like regular exercise or positive thinking, can increase levels of endorphins and enkephalins. (Harvard mag, http://harvardmagazine.com/2005/11/the-science-of-hurt.html#gates and a related second Harvard article, http://harvardmagazine.com/2005/11/relieving-pain.html ) More on controlling pain Management of pain is more than just ingesting or injecting an opioid-based medication. First there is consideration of the source of the pain. Since the 1960s, a more scientific approach has revealed a number of factors that are part of pain mitigation protocols. A fundamental principle is that the peripheral nervous system has a gate system in which two types of nerve input “compete” to breach the gate (nerve cells opening and closing) in the spinal cord. As mentioned above, one input is from pain itself, and the other is from touch and pressure. There is a balance between these two inputs that determines if the gate opens, sending signals to the brain. This balance explains why counter stimulation works. Rubbing a stubbed toe works to counter the pain. Acupuncture as well as the application of heat and cold also can counter the pain sensation (nerve impulse). The other side of pain has to do with psychological factors. An amputee sometimes still feels pain in a missing limb. And individuals with pain from such conditions as shingles, arthritis, aftereffects of abdominal surgery, have increased sensitivities to pain similar to turning up the volume on a radio. Mentally, the psyche becomes hypersensitive to pain. What that suggests is that treatment of pain may well involve treating the emotional circuitry as well as the pain transmitting circuitry. Doing surgery requires not only anesthetics but also analgesics post-operatively. You need to block the nerve pathways that transmit pain from its source as well as blocking the pain message in specific areas of the brain. There are a number of modalities that need to be considered when treating pain.
(source: http://harvardmagazine.com/2005/11/relieving-pain.html ) More on alkaloids A summary of the basics about alkaloids follows. 1. Contains nitrogen - usually derived from an amino acid. 2. Bitter tasting, generally white solids (exception - nicotine is a brown liquid). 3. They give a precipitate with heavy metal iodides.
4. Alkaloids are basic - they form water soluble salts. Most alkaloids are well-defined crystalline substances which unite with acids to form salts. In plants, they may exist
5. Occur in a limited number of plants. Nucleic acid exists in all plants, whereas, morphine exists in only one plant species. (http://www.friedli.com/herbs/phytochem/alkaloids/alkaloid1.html ) More details about alkaloids: Alkaloid, a chemical substance of plant origin composed of carbon, hydrogen, nitrogen, and (usually) oxygen. The alkaloids are organic bases similar to the alkalis (inorganic bases); the name means alkali-like. Most alkaloids have pronounced effects on the nervous system of humans and other animals. Many are used as drugs. Some familiar alkaloids are caffeine, nicotine, quinine, cocaine, and morphine. Alkaloids occur mainly in various genera of seed plants, such as the opium poppy and tobacco plant. Alkaloids can be found in almost all parts of these plants, including the leaves, roots, seeds, and bark. Each plant part usually contains several chemically related alkaloids. The function of alkaloids in plant metabolism is not known. Of the hundreds of alkaloids found in nature, only about 30 are used commercially. Alkaloids must be extracted from plants before they can be used. After the plants have been dried and crushed, chemical reagents such as alcohol and dilute acids are used to extract the alkaloid content from the plant material. Pure alkaloid extracts are usually bitter, colorless solids. Some alkaloids, such as reserpine and morphine, are synthesized (produced artificially). Uses of Alkaloids Some alkaloids, such as nicotine, are used in pesticides, and others are used as chemical reagents. The primary use of alkaloids, however, is in medicine, because they can act quickly on specific areas of the nervous system. Alkaloids are the active components of many anesthetics, sedatives, stimulants, relaxants, and tranquilizers. They are taken by mouth and administered by injection. Except under a physician's supervision, use of alkaloids is dangerous, because most are habit-forming (for example, almost all narcotics are alkaloids) and large doses can be poisonous. Strychnine, used in small doses as a stimulant and a tonic, is highly poisonous. Quinine, used in treating malaria, can cause dizziness if taken in large doses. Morphine and cocaine are among the most effective drugs known for temporarily relieving pain without causing loss of consciousness. However, these two alkaloids are habit-forming and can be harmful if their use is continued. Curare, used as a muscle-relaxing drug and in arrow poisons used by South American Indians, is a mixture of various alkaloids. Alkaloid Substitutes In most cases, the extraction of natural alkaloids and the synthesis of alkaloids are complicated, costly processes. Furthermore, alkaloid drugs usually produce unpleasant side effects. For these reasons, several synthetic compounds have been developed for use as alkaloid substitutes. For example, Novocain (a trade name for procaine) is often used instead of cocaine, and Demerol (a trade name for meperidine) is often substituted for morphine. Alkaloid substitutes are usually less toxic than alkaloids, but are also generally less potent. (from http://science.howstuffworks.com/alkaloid-info.htm) More on the history of heroin A timeline for the recent history of heroin is as follows: 1853 Hypodermic needle-syringes with a point fine enough to pierce the skin are invented simultaneously by Charles Gabriel Pravaz (French surgeon) and Alexander Wood (Scottish physician). It is first used to inject morphine intravenously. 1874 Heroin is first synthesized from Morphine by chemist C.R. Alder Wright at St. Mary's Hospital in London. Its potential was not recognized. 1897 Heroin is synthesized by Felix Hoffman at Bayer Pharmaceutical. Bayer immediately recognized its potential and began marketing it heavily for the treatment of a variety of respiratory ailments. 1898 One year after beginning sales, Bayer exports heroin to 23 countries. Early 1900s Doctors and pharmacists begin noticing that patients are consuming large amounts of heroin containing cough remedies. 1906 Pure Food and Drug Act is passed, regulating the labelling of products containing Alcohol, Opiates, Cocaine, and Cannabis, among others. The law went into effect Jan 1, 1907 1911 British Pharmaceutical Codex notes that heroin is as addictive as morphine. 1913 Bayer ceases producing heroin. Dec 17, 1914 The Harrison Narcotics Tax Act is passed, regulating and imposing a tax upon the sale of Opium, Heroin and Cocaine for the first time. The Act took effect Mar 1, 1915. 1924 The Heroin Act passes, making manufacture and possession of heroin illegal in the U.S. 1965-1970 U.S. involvement in Vietnam is blamed for the surge in illegal heroin being smuggled into the States. 1971 10-15% of American servicemen in Vietnam are addicted to heroin. (from http://www.erowid.org/chemicals/heroin/heroin_timeline.php) More on chemically interrupting drug dependency 
Neuroscientists have known for some time that marijuana—along with many other drugs with abuse potential, including nicotine and opiates—induces a feeling of euphoria by increasing levels of dopamine in the brain. In recent times, Robert Schwarcz (Univ. of Maryland) and others have also discovered that kynurenic acid is crucially involved in the regulation of brain activity driven by dopamine. (effect is in the nucleus accumbens region of the brain) Knowing the role of kynurenic acid, which has a similar molecular structure to dopamine, Schwarcz has found that increasing the levels of the acid interferes with the euphoric effects of various opiates as well as marijuana and nicotine by decreasing the activity level of the dopamine neurotransmitter which is associated with pleasure. The question now is whether investigators can find a safe way to administer the kynurenic acid because there is a need to have the correct level (homeostasis) of dopamine through kynurenic acid control. 
(dopamine) (kynurenic acid) Connections to Chemistry Concepts(for correlation to course curriculum)
Possible Student Misconceptions(to aid teacher in addressing misconceptions)
Anticipating Student Questions(answers to questions students might ask in class)
(from http://www.theatlantic.com/health/archive/2013/01/why-we-took-cocaine-out-of-soda/272694/)
In-class Activities(lesson ideas, including labs & demonstrations)
Out-of-class Activities and Projects(student research, class projects)
References(non-Web-based information sources) 
Gottfried, S; Sedotti, M. Horses and Heroin (“Mystery Matters”). ChemMatters 1988, 6 (3), pp.14–15. Presented as a forensic mystery, this article presents a drug bust case (based on a true event) and the chemistry used in the lab, known as the Marquis test, to detect heroin in suspected drug material. Tracey, M. Positive Emission Tomography (PET) Scan. ChemMatters 1994, 12 (1), pp 13–15. This detailed and illustrated article relates the use of PET Scans to locate where in the brain various drugs activate the nervous system. In particular, a PET scan allows researchers to elucidate the connection between dopamine neurotransmitters and cocaine, utilizing compounds with radioactive C-11, a very short lived isotope that has to be made just before it is injected into the study patient. Goldfarb, B. Seeds of Doubt. ChemMatters 1995, 13 (2), pp 5–6. This article complements one of the anticipated student misconceptions about poppy seed ingestion (from a bagel, for example) and its effect on a urine test for morphine. It includes information about fat-soluble and water-soluble drugs and their ability to cross the blood brain barrier. The solubility factor is the basis for the difference in the speed of action of heroin versus morphine. Karabin, S. New Types of Pain Killer From Sea Snails. ChemMatters 2011, 29 (4), p 4. A short brief on the polypeptide structure (with the amino acid sequence) of a toxin taken from sea snails is found in this issue of ChemMatters. (See other Web-based references on the sea snail venom as well as snake venom in the current Teacher’s Guide.) Web Sites for Additional Information(Web-based information sources) More sites on the neurological basis of pain and its management Two complementary articles (previously mentioned in the “More on …” sections of the Teacher’s Guide, above) that outline a comprehensive approach to treating pain are found at http://harvardmagazine.com/2005/11/relieving-pain.html and http://harvardmagazine.com/2005/11/the-science-of-hurt.html#gates. Some newer alternatives to morphine that are being investigated for pain management include the use of snake venom. Refer to http://www.scientificamerican.com/podcast/episode.cfm?id=snake-venom-contains-potent-painkil-12-10-04 and http://www.nature.com/nature/journal/v490/n7421/full/nature11494.html. Another potential source of a pain killer is the venom that can be extracted from a particular species of cone snail. Besides being used to reduce pain, it has potential to treat epilepsy and depression among other neurological disorders. A detailed article can be found at http://www.scientificamerican.com/article.cfm?id=healing-the-brain-with-snail-venom. Another article explains the biochemistry behind the toxins (which are polypeptides) that are extracted from sea snails. These toxins, now synthesized because the amino acid sequence is known, block important calcium channels in neurons, inhibiting the transmission of pain signals. Pictures of various sea snails that students might recognize from their days at the seashore can be found at https://www.google.com/search?q=sea+snail+vs.+cone+snail&tbm=isch&tbo=u&source=univ&sa=X&ei=kQV0UqvHMqbTsAS9uYCACA&ved=0CHYQsAQ&biw=1414&bih=914. There is also a video about cone shell venom at http://www.pbs.org/wnet/nature/episodes/the-venom-cure/cone-shell-cures/2061/. An alternate opiate called remifentanil can be used at higher doses than morphine without some of its limitations. Refer to http://www.scientificamerican.com/article.cfm?id=high-dose-opiates-could-crack. A very useful reference (which you can adjust for level of explanation—beginner, intermediate, advanced—about the neurological basis of pain and drug action can be found at three sites (from the same basic electronic source); they are http://thebrain.mcgill.ca/flash/d/d_03/d_03_cr/d_03_cr_dou/d_03_cr_dou.html, http://thebrain.mcgill.ca/flash/a/a_03/a_03_cr/a_03_cr_dou/a_03_cr_dou.html, and http://thebrain.mcgill.ca/flash/i/i_03/i_03_cr/i_03_cr_dou/i_03_cr_dou.html. More sites on endorphins and enkephalins A detailed history of the research that went into discovering the existence and role of endorphins and enkephalins is found at http://thebrain.mcgill.ca/flash/d/d_03/d_03_m/d_03_m_dou/d_03_m_dou.html. Yüklə 96,79 Kb. Dostları ilə paylaş:
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