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PSY295 - Chapter 7 Notes (The Influence of Drugs and Hormones on Behaviour).docx

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Katherine Krpan

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PSY 295 CHAPTER 7: THE INFLUENCE OF DRUGS AND HORMONES ON BEHAVIOUR Agonists increases synaptic transmission by promoting release or inhibiting reuptake of a neurotransmitter Anatagonists decrease synaptic transmission by blocking or reducing a neurotransmitter Astroglia provide route for food and waste exchange between capillaries and extracellular fluid to and from other cells. Also maintain tight junctions between endothelial cells, and make capillaries dilate to increase blood flow where neuron activity is high Active Transport-Systems protein pump specialized for the transport of particular substance across a membrane Apoptosis genetically programmed cell death that occurs when a cell is under stress, or to eliminate malfunctioning or sick cells Area Postrema nucleus in the brainstem that is sensitive to blood-borne toxins and causes vomiting Barbiturates drugs used for sedative or hypnotic effects Benzodiazepine groups of minor tranquilizers that have common molecular structure and effects, such as antianxiety, muscle relaxing, or sedative effects Blood Brain Barrier rich capillary network separating circulating blood and extracellular fluid in the brain Bipolar Disorder affective disorder in which a person alternates from depression, normal, to mania Dissociative Anaesthetics anaesthetics that have restricted use due to hallucinations and altered states of consciousness date rape drugs, which are soluble in alcohol and impair memory of recent events Endothelial Cells compose capillaries that are surrounded by astroglial feet Mood Stabilizers drug used to treat bipolar disorder, like lithium and valproate Major Tranquilizers/Neuroleptics drugs that block dopamine D2 receptor, used mainly for schizophrenia MAO Inhibitors (Monoamine Oxidase Inhibitor) chemical that blocks MAO from degrading dopamine, serotonin and noradrenaline Myasthenia Gravis condition of fatigue and weakness of the muscular system without sensory disturbance or atrophy; results in reduction of acetylcholine available at synapse Major Depression mood disorder characterized by prolonged feelings of worthlessness, guilt, abnormal eating habits, sleep disturbances and slowing of behaviour Neurotoxin any substance that is poisonous or destructive to nerve tissue Organophosphates binds irreversibly to acetylcholinesterase and are extremely toxic used in insecticides and in chemical warfare Psychopharmocology how drugs affect the nervous system and behaviour Psychoactive drugs: alter mood, thought or behaviour for neuropsychological illness; also substances of abuse Pituitary Gland collection of neurons at the base of the hypothalamus. Pineal Gland symmetrical structure in the epithalamus, thought to take part in circadian rhythms Psychosis major mental disorder of organic or emotional origin in which a persons ability to think, respond, remember, communicate, behave and respond to reality is sufficiently impaired enough not to meet demands of life Physostigmine drug that inhibits acetylcholinesterase, therefore acts as agonist to increase the amount of acetylcholine in the synapse; large doses can be toxic from excessive excitation Post-Traumatic Stress Disorder (PTSD) disorder characterized by physiological arousal symptoms related to recurring memories and dreams concerning a traumatic event can happen months and years after the event Psychedelic Drugs any drug that induces behaviour characterized by visual hallucination, intensified perception and behaviour similar to psychosis Route of Administration the way in which a drug enters and passes through the body Sedative-Hypnotic Site drug that acts to depress neural activity; noradrenergic or GABAergic activity Second-Generation Antidepressants thought to be more selective than first-generation in its action on serotonin reuptake transporters Schizophrenia psychosis characterized by splitting of thought and emotive processes; hypothesized to result from excessive dopamine levels Substance Usage use of a drug for the changes that it produces other than therapeutic effects (abuse); desire for drug manifested by frequent use (dependence); display of withdrawal symptoms on cessation of use (addiction) Sensitization subsequent exposure of drug induces a stronger behavioural response than the original response Tight Junctions connection between cells when their membranes are fused Tricyclic Antidepressants antidepressant that blocks serotonin transporter Tolerance ability to endure unusually large doses of a drug without ill effects as a result of continued use Withdrawal Symptoms behaviour displayed by a user when drug ends PSY 295 Principles of Psychopharmacology: To be effective a drug must reach its target in the nervous system. Drugs may be injected, taken orally, by suppository, inhaled or through skin patches. Barriers of Administration: Some drugs cannot tolerate gastric secretions or penetrate digestive walls. Weak acids (alcohol) is readily absorbed into the stomach, yet weak bases must pass into the intestine to be absorbed Drugs must enter the blood stream so the drug must be hydrophilic because when the drug passes through the blood it goes through extracellular fluid where it is further diluted. As the drug passes through cell membranes the drug is at risk of being modified or destroyed by metabolic processes. Molecules of drug must be small to fit through capillaries The blood brain Routes of Drug Removal: Soon after a drug is taken, the body begins to metabolize/remove it mainly via the kidneys, liver, bile, and excretes it in the urine, feces, breast milk, sweat and exhalation. Some substances are harder to remove and can be potentially dangerous due to repeated exposure and excess build up which may become poisonous to the body. For examthe: mercury is hard to remove and caused severe neurological problems in hat makers, 19 century England coined term Mad as a Hatter. Revisiting the Blood-Brain Barrier: The blood-brain barrier is a rich capillary network where none of its neurons are farther than 50 um away from a capillary. Many drugs cannot enter the brain through the blood brain barrier, yet others can, meaning the blood brain barrier is selective. Endothelial cells compose capillaries surrounded by astroglial feet (which cover 80% of the surface). The astroglia maintain tight junctions between endothelial cells and in making capillaries dilate to increase blood flow to areas of the brain in which neurons are very active, thus substances that pass through endothelial cells junctions in the body cannot do so in the brain. Many substances such as oxygen, glucose and amino acids must travel from the blood to brain cells and other waste products must be excreted from the brain cells to the blood. Small molecules can pass through capillary walls such as oxygen and CO2 that are not ionized and fat soluble; molecules of glucose, amino acids and other nutrients can be carried across the capillary by active-transport systems. Some brain areas lack tight junctions and a blood brain barrier The pituitary gland uses pituitary chemicals that can be triggered by chemicals carried from the blood. The pineal gland remains open to chemicals that modulate day/night cycles, and the area postrema allows toxic substances detected in the blood to induce vomiting. Drug Rotes and Dosage: The most effective drugs are small, potent, weakly acidic, water/fat soluble and not easily degraded. Injecting/inhaling is more effective as it bypasses the stomach and its gastric secretions With each obstacle eliminated on the route to the brain, the drug dosage can be reduced by a factor of 10; e.g., 1000ug of amphetamine taken orally has the same effect as 100ug taken by injection or inhalation. The dosage can further be reduced to 10ug is injected directly into the CSF.PSY 295 Drug Actions in Synapses: Steps in synaptic transmission: 1.) synthesis of neurotransmitter in the body, axon, or terminal of neuron. 2.) stored in storage granules or vesicles. 3.) released from presynaptic membrane. 4.) act on receptors in postsynaptic membrane, and excess is 5.) deactivated, 6.) reuptake into presynaptic membrane, 7.) degraded. Agonists increase the effectiveness of neurotransmission by stimulating release, blocking reuptake or blocking inactivation. Antagonists decrease the effective of neurotransmission by blocking synthesis, or release from inactivation Examples of Drug Action An Acetylcholine Synapse: Toxins influence release of acetylcholine from the axon terminal Black widow venom- is an agonist because it promotes Ach release, causing excitation sufficient enough to cause paralysis and death in prey (not enough to similarly affect humans) Botulinum toxin produced by a bacterium in improperly processed canned foods. Antagonist as it blocks the release of Ach and causes paralysis of movement, breathing and can lead to death. Medical Uses: Used to treat patients with injections in the muscle to control unwanted muscle twitches (such as in cerebral palsy) and is also used as Botox, which relaxes muscles to fade wrinkles and inactivate pain fibers. Drugs that Act on Ach Receptors: Nicotine - agonist, stimulates cholinergic receptors. Cholinergic receptor at neuromuscular junction is called nicotinic receptor because of its action similar to nicotine
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