Bios 2060: week 2
Bios 2060: week 2 Bios 2060
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This 4 page Class Notes was uploaded by Jessa Snyder on Tuesday September 6, 2016. The Class Notes belongs to Bios 2060 at Ohio University taught by Scott Hooper in Fall 2016. Since its upload, it has received 8 views. For similar materials see DRUGS AND THE BRAIN in Biological Sciences at Ohio University.
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Date Created: 09/06/16
Pharmacodynamics- Study of the physiological and biochemical interaction of drug molecules with cell receptors in target tissues Receptors- Proteins on cell surfaces or within cells Ligand- Molecule that binds to a receptor with some selectivity. Binding is temporary, after ligand separates the receptor is free to bind again. They have a lock and key relationship. Has to be the right shape to bind. Most hormones that act on the brain bind to receptors in the cytoplasm or nucleus. Hormone binding alters cell function by triggering changes in gene expression. Receptor Agonist- has best chemical "fit" attaches readily to the receptor and produces significant biological effect, High Affinity. Partial Agonists- have intermediate efficacy Inverse Agonists- initiate a biological action opposite to that produced by an agonist o Drugs can also act as agonists by enhancing synaptic function by increasing neurotransmitter synthesis or release. Prolonging action of the neurotransmitter within the synapse. Receptor Antagonist- also fits receptors but produce no cellular effect, Low efficacy. Up-Regulation- Number of receptors increases. Down-regulation- number of receptors is reduced in response to absence of ligands or chronic activation. Receptor subtypes- Receptors with different characteristics in different tissues. Goal of neuropharmacology- create drugs that bind with greater affinity to one receptor subtype to initiate a selective effect. Dose-response curves- describes extent of effect produced by a given drug concentration. Threshold Dose- smallest dose that produces a measurable effect. Absolute amount of drug necessary to produce a specific effect indicates the potency of a drug. Ex: Heroin is very high potency, and codeine is lower potency TD 50dose at which 50% of the population experiences a toxic effect. Comparing TD 50 (Toxic Dose) and ED 50 (Effective Dose) to see the level at which a drug is therapeutic and toxic. Competitive Antagonists- drugs that compete with agonists to bind receptors but do not initiate intracellular effects, reducing effect of the agonist. Moves the curves over. Competitive antagonists can be replaced by an excess of agonist. 4/5s of the receptors are filled with competitive antagonists. Noncompetitive Antagonists- reduce effect of agonists by.. Binding to the receptor at a site other than the agonist binding site. Disturbing the cell membrane supporting the receptor. Interfering with cell processes that were initiated by the agonist. Lowers agonist concentration. Physiological Antagonism- 2 drugs interact and reduce the effectiveness of both. Meaning taking two drugs at once this makes the drugs work less. Two drugs may also have additive effects, they could have the opposite effect. o Drug A (low) + Drug B (high) = Drug AB Adds the two together. Drug A (high) - Drug B (low) = Drug AB (lower concentration) This is for physiological antagonism Potentiation- the combination of 2 drugs produces effects greater than the sum of their individual effects. The first drug is affected to be felt 3 times as strong. Drug A (low) + Drug B (high) = Drug AB (Extremely high) Becomes 2-3 times greater than drug b. Drug tolerance- diminished response to a drug after repeated exposure. Increasing dosages must be administered to obtain the same magnitude of biological effect. Reversible when drug use stops. Homeostasis= going back to the same state. Tolerance depends on the dose and the frequency of the dose. Cross tolerance- tolerance to one drug can diminish effectiveness of a second drug. A higher alcohol tolerance = a higher tolerance in barbituates. Acute tolerance- develops during a single administration. Example: when an individual experiences greater effects of alcohol as blood level rises than several hours later, when blood level has fallen to the same point. Metabolic tolerance (drug disposition tolerance)- repeated use of a drug reduces amount of the drug available at the target tissue. Example: when drugs increase their own rate of metabolism, by inducing liver microsomal enzymes. Pharmacodynamics tolerance- changes in nerve cell function compensate for continued presence of the drug. Examples: receptor down-regulation and up-regulation. Behavioral tolerance (context-specific tolerance): tolerance is not apparent or reduced in a novel environment. Examples: some types of learning (conditioned and operant); withdrawal syndrome If you take the same drug in the same environment, the brain will trigger the symptoms you're suppose to feel o Ex: Morphine makes you hot because it raises our body temperature. Therefore if you take the drug in the same room over and over, your brain (hypothalamus) will make you sweat even before the drug is administered. Pavlovian, or classical conditioning- Many psychoactive drugs elicit reflexive effects such as cortical arousal, elevated blood pressure, or euphoria, and act as unconditioned stimuli. The drug-taking procedure or the environment may elicit a conditioned response even before the drug is taken Pavlov- Dog is given food and a bell is rung, since the dog sees food it salivates. When this is done over time soon you can ring the bell and the dog will salivate even without food being present. Operant conditioning -may also play a part in behavioral tolerance. Example: an alcoholic individual learns to maneuver efficiently while highly intoxicated to avoid detection. Positive/ Negative punishment and rewards State-dependent learning: Tasks learned in the presence of a psychoactive drug may subsequently be performed better in the drugged than nondrugged state. Conversely, learning acquired in the nondrugged state may be more available in the nondrugged state. Sensitization (reverse tolerance): enhancement of drug effects after repeated administration of the same dose. Can persist over long periods of abstinence. Some drugs induce tolerance for some effects and sensitization for others Pharmacogenetics: study of the genetic basis for variability in drug response among individuals. Goal: identify genetic factors that confer susceptibility to specific side effects, or predict therapeutic response. Chapter 2: Structure and Function of Nervous System. Stem cells- are undifferentiated cells that can become specific cell types. Embryos can be used to take stem cells and create specific stem cells Neurons- transmitting information into an electrical signal. Sensory Neurons- convert physical stimuli to electrical signals o Five senses Interneurons- Neurons that transfer the information from the sensory neurons to transmit to motor neurons. o Conscious sensations, recognition, memory, decision-making, and cognition Motor Neurons- Direct response from the interneurons. Movement o Ex: touch hot stove (sensory)- Think pain (inter)- Move hand (motor) Parts of the Neuron: Dendrite- Receives message o Dendritic Spines- increase the surface area Soma (cell body)- contains nucleus and other organelles, responsible for the metabolic care of the neuron. Proteins responsible for cell growth and maintenance. o Proteins: enzymes, receptors, and components of the cell membrane. Axon- Sends message o Axon Hillock- Action potential is generated here o Axon Collaterals- an axon splitting into branches o Terminal Buttons- are located at the dendrites, they contain synaptic vesicles so the message can be sent across the synapse Synaptic Vesicles- Small packets of neurochemicals, neurotransmitters. Synapse- the space between other cells, where the message is sent out and received by the dendrites. Convergence- the message that is received Divergence- the message that is transmitted. Myelin Sheath- a fatty insulin coating, it speeds up the process Nodes of Ranvier- breaks within the axon Glial Cells- Provide metabolic support, protection and insulation. Trying to keep bacteria, etc. out of the brain. Chromosomes- long strands of Deoxyribonucleic Acid, (DNA) Genes- portions of chromosomes that code for the manufacture of a specific protein molecule. Coding Region- a specific protein that provides the "recipe" such as a receptor or an enzyme. Transcription Factors- are nuclear proteins that direct protein production. Promoter Region- of the gene adjacent to the coding region.
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