TERMS action potential afferent axon dendrite depolariza tion effector cell efferent engram forebrain ganglia hindbrain limbic system DEFINITION sudden change in electrical charge of a nerve cell membrane; the electrical signal by which neurons send information neurons or groups of neurons that bring information to the central nervous system; sensory nerve long projection from a neuron that carries information from one nerve to another nerve or effector short projection on a neuron that transmits information opening of the sodium channels in a nerve membrane to allow the influx of positive sodium ions, reversing the membrane charge so it is no longer polarized cell stimulated by a nerve; may be a muscle, a gland, or another nerve cell neurons or groups of neurons that carry information from the central nervous system to an effector; motor neurons are efferent short-term memory made up of a reverberating electrical circuit of action potentials upper level of the brain; consists of the two cerebral hemispheres, where thinking and coordination of sensory and motor activity occur, contains the hypothalamus and thalamus and the area of the limbic system a group of nerve bodies most primitive area of the brain, the brainstem; consists of the pons and medulla, which control basic, vital functions, and the cerebellum, which controls motor functions that regulate balance area in the forebrain that is rich in epinephrine, norepinephrine, and serotonin and seems to control emotions mitter repolariza tion Schwann cell soma synapse anxiety anxiolytic barbiturate benzodia zepine hypnosis hypnotic sedation midbrain neuron neurotrans the middle area of the brain; it consists of many of the cranial nerves, areas related to arousal and sleep/wakefulness, sits just below the hypothalamus structural unit of the nervous system chemical produced by a nerve and sedative released when the nerve is stimulated; reacts with a specific receptor site to cause a reaction return of a membrane to a resting state, with more sodium ions outside the membrane and a relatively negative charge inside the membrane insulating cell found on nerve axons; allows “leaping” electrical conduction to speed the transmission of information and prevent tiring of the neuron cell body of a neuron; contains the nucleus, cytoplasm, and various granules junction between a nerve and an effector; consists of the presynaptic nerve ending, a space called the synaptic cleft, and the postsynaptic cell unpleasant feeling of tension, fear, or nervousness in response to an environmental stimulus, whether real or imaginary drug used to depress the central nervous system (CNS); prevents or reduces the signs and symptoms of anxiety former mainstay class of drug used for the treatment of anxiety and for sedation and sleep induction; associated with potentially severe adverse effects and many drug–drug interactions, which makes it less desirable than some of the newer agents class of drug that acts in the limbic system and the reticular activating system to make gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, more effective, causing interference with neuron firing; depresses CNS to block the signs and symptoms of anxiety; and may cause sedation and hypnosis in higher doses extreme sedation resulting in CNS depression and sleep drug used to depress the CNS; causes sleep loss of awareness of and reaction to environmental stimuli drug that depresses the CNS; produces a loss of awareness of and reaction to the environment Drugs affecting the nervous system alter its functions. A thorough review of the anatomy and physiology of the Central Nervous System and Autonomic System would help students understand the mechanisms of actions of drugs. The functional unit, neurons basic function is impulse transmission which happen by electrical and chemical process. Electrical transmission of impulses happen by action potential and chemical pocess make use of neurotransmitters to achieve its functions. Central Nervous System Brain & Spinal Cord – very important structure of the CNS is its protective mechanisms that not all chemicals can pass through it, this affects the pharmacodynamics of drugs because some of them cannot penetrate the CNS. One vital protective structure is the Blood Brain Barrier (BBB). This represents therapeutic challenge to drug treatment of brain related disorders because a large percentage of drugs are carried bound to plasma proteins and are unable to cross the brain. Peripheral Nervous System Autonomic Nervous System & Somatic Nervous System – Synapses made by the peripheral nervous system conduct impulses that is chemical in nature. These neurotransmitters have specific receptors in the neural membrane tos facilitate conduction of nerve impulses. Drugs may act in the nervous system to either stimulate or block the receptors to correct alterations in the nerovus functions. Neurons conduct impulses by Action Potential, the rapid change in the membran potential, this happens by movement of sodium into the cells causing depolarization and potassium out of the cells to cause repolarization. This movement of ions facilitated by channels in the cell membranes will be acted upon by drugs to correct changes in the nervous system causing disease process 1. Anxiolytic and Hypnotic Drugs Anxiety is a feeling of tension, nervousness, apprehension or fear that usually involves unpleasant reactions to a stimulus, whether acutal or unknown. Anxiety is classified as mild, moderate, severe and panic. Mild anxiety is normal as it helps the person to have wider perspective and focus on certain activities but increasing anxiety may cause restlessness and increase sympathetic stress reaction which may cause physical symptoms of the sympathetic stress reactions. When anxiety becomes moderate, there is a need for drug treatment. Sedation is the loss of awareness and reaction to environmental stimuli. Hypnosis is severe sedation. These conditons occur due to increase excitatory neurotansmitters causing rapid brain impulse conduction causing restlessness, irritability, loss of concentration, loss of mental focus and sympathetic responses like palpitations, tremors, diaphoresis, increase breathing and increase blood pressure.
