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Table 48-1a Table 48-1b Drugs can alter your mood or your emotional state. • Excitatory drugs increase nerve impulse transmission. Examples: • Nicotine • Cocaine • Amphetamines (Dexedrine, Ritalin, Adderall) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can alter your mood or your emotional state. • Inhibitory drugs decrease nerve impulse transmission. Examples: • Benzodiazepines • Alcohol • THC (tetrahydrocannabinol) – the main psychoactive drug in marijuana Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Block a receptor for a neurotransmitter (drug has structure similar to neurotransmitter) -Therapeutic drugs called beta blockers compete with norepinephrine for receptor sites. Can treat hypertension and heart disorders by slowing heart rate and reducing force of contraction. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Block release of a neurostransmitter • -example- Tetanus and botulinum neurotoxins block neurotransmitter release • *Botox is used to cause muscle relaxation to decrease wrinkles and to help treat migraines! Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Enhance release of a neurotransmitter• example- amphetamines pass directly into neurons containing dopamine and norepinephrine; • -cause the vesicles in the synaptic terminals to fuse with the membrane and release into the cleft. -The high concentrations of dopamine cause euphoria and high concentrations of norepinephrine cause alertness and high energy effects. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Enhance neurotransmission by mimicking a neurotransmitter • (when drugs have the same chemical structure as the neurotransmitter they have the same effect but are not broken down as easily so the effect is stronger because they stay longer in the synapse) • example- nicotine mimics acetylcholine (Ach) - acts on synapses in the brain to cause a calming effect • -enzyme that breaks down acetylcholine cannot break down nicotinenicotine causes the the postsynaptic cell to release dopamine -> feeling of pleasure (reward pathway) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -another example- THC mimics the neurotransmitter anandamide, causes the postsynaptic neuron to become hyperpolarized -> interferes with short term memory and causes motor impairment • Sensations from THC vary from relaxed to a sense of panic and paranoia. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Block removal of a neurotransmitter from the synapse and prolong the effect • example- cocaine blocks the removal of dopamine from the synapse so that it builds up • this leads to overstimulation of the postsynaptic neuron -> euphoria and alertness http://science-education.nih.gov/ supplements/nih2/addiction/activities/ lesson3_cocaine.htm Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drugs can change synaptic transmission in the following ways: • -Increases the binding of the neurotransmitter to the receptor • example- Benzodiazapine increases the binding of GABA to the receptor and causes the postsynaptic neuron to become hyperpolarized. This can reduce anxiety and be used against epileptic seizures • example- Alcohol acts similar to Benzodiazapine -> sedative effect. Alcohol also helps to increase the release of dopamine. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings http://outreach.mcb.harvard.edu/animations/ synapse.swf Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Causes of Addiction: • -The body develops a tolerance and needs more and more of the drug to produce the same result. • Addiction is a chemical dependency on drugs where the drug has “rewired” the brain and has become an essential biochemical in the body. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Causes of Addiction • -Genetic predisposition (studies of twins) – Due to polygenic inheritance • - Social Factors (mental health of family or child, peer pressures, family addictions) • -Dopamine secretion- In drug addiction dopamine receptors are constantly stimulated. • Overstimulation decreases the number of receptors and the remaining receptors become less sensitive. This is called desensitization or tolerance. More and more of the drug is needed just to have a sense of well-being. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Medulla oblongata – controls automatic and homeostatic activities, such as swallowing, digestion and vomiting, breathing and heart activity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cerebellum- coordinates unconscious functions, such as movement and balance Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hypothalamus- maintains homeostasis, coordinating the nervous and endocrine systems, secreting hormones Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Pituitary gland- the posterior lobe stores and releases hormones produced by the hypothalamus and the anterior lobe produces and secretes hormones Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cerebral hemispheres- act as the integrating center for complex functions such as learning, memory and emotions Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings