Transcript Document
Biological Bases of Behavior The Nervous System The Hindbrain Neurons The Midbrain 2 Categories The Forebrain 3 Kinds Right/Left Hemisphere Anatomy of a neuron Plasticity in the brain Communication The Endocrine system Neurotransmitters Heredity and behavior CNS/PNS Agonist/Antagonist The Brain The Limbic system The Nervous System • What are the two major categories of cells in the nervous system? • Glia cells and neurons • What are the functions of glia cells? • What are the three kinds of neurons? • Sensory, Motor, and Interneuron Neurons • What are neurons? • Neurons are nerve cells specialized for processing information…they are the basic units of the nervous system • What are the components of the neuron? • Soma • Axon • Myelin sheath • Dendrites • Nodes of Ranier The Neuron The electrical charge moves down the axon from node to node. When the action potential occurs in the first segment of the axon, it quickly creates a similar change in the next segment, which then stimulates the next segment, and continues as the positive electrical impulse continues all the way down to the end of the axon. Communication • What are the two methods of communication? • Electrical and chemical • How does this occur? • Resting potential • Stimulus threshold • Absolute refractory period • The synapse and synaptic gap Action Potential • When neurotransmitters are accepted by the receptors on the receiving neurons their effect may be either excitatory (making the cell more likely to fire) or inhibitory (making the cell less likely to fire). • Neurotransmitters that are not accepted by the receptor sites must be removed from the synapse in order for the next potential stimulation of the neuron to happen. This occurs through the breaking down of the neurotransmitters by enzymes, and by reuptake…the reabsorption of the neurotransmitter in the synapse into the terminal buttons. Neurotransmitters • More than 100 chemical substances produced in the body have been identified as neurotransmitters. • Some chemicals in the body can occur either as neurotransmitters or hormones. • An agonist is a drug that has chemical properties similar to a particular neurotransmitter , mimicking the effects of the neurotransmitter. • An antagonist is a drug that reduces or stops the normal effects of a neurotransmitter. When an antagonist is ingested, it binds to the receptor sites in the dendrite, thereby blocking the neurotransmitter. The Neurochemical Messengers, Neurotransmitters • In addition… • Achetylcholine stimulates muscles to contract. It is also used in the brain to regulate memory, sleeping, and dreaming…Nicotine is an agonist that acts like acetylcholine. • Endorphins are released in response to behaviors such as vigorous exercise, orgasm, and eating spicy foods….related to compounds found in drugs such as opium, morphine, and heroin. • GABA is a major inhibitory neurotransmitter in the brain. A lack of GABA can lead to involuntary motor actions, including tremors and seizures. Alcohol stimulates the release of GABA. Low levels of GABA produce anxiety, and GABA agonists (tranquilizers) are used to reduce anxiety. • Glutamate is the most common neurotransmitter, it’s released in more than 90% of the brain’s synapses. Glutamate is found in the food additive MSG…excessive glutamate can cause overstimulation, migraines and seizures.