How is the Nervous System Organized? Chapter 3-Neuroscience: The Brain and Behavior 11 Class Objectives: Identify and define the structures of the neuron Identify and discuss the role of neurotransmitters on behavior 2 The Neuron The neuron is the basic building block of the nervous system ‐ They are often grouped in bundles called nerves. 3 4 5 4 parts of the neuron 1. Dendrites are specialized to receive signals from neighboring neurons and carry them back to the cell body Thin, bushy-like structures that receive information from outside the neuron ‐ Relays the information into the cell body 6 The Neuron 2. The Cell body contains the cell nucleus The cell body relays the information down to the axon 7 The structure of a neuron 3. Axon: A thin, long structure that transmits signals from the cell body to the axon terminal. 4. Axon Terminal is the last step for the relay of information inside the neuron. 8 The cell body is covered with Axon Terminals 9 Once the information hits the terminal, it is transmitted outside the cell by neurotransmitters, which reside in the axon terminal. 10 10 How do Neurons Communicate? -Electrical Communication -Chemical Communication 11 11 12 The Electrical Part Action potential is an electrical current sent down the axon. The activity within the neurons is electrical. This current causes the neuron to “fire” ‐ This is an “all-or-none” process 13 Action potentials travel down the axon like a wave of energy 14 Synaptic transmission The Synapse is the space between neurons ‐ The synaptic gap or cleft • • Information must be transmitted across the synapse to other neurons via the neurotransmitters. This is an electrochemical process 15 Let’s Review! 16 Now, Let’s DANCE! Time to do the Neuron Dance 17 17 __________ Presynaptic Neuron ________ ________ ____________ ________________________ 18 Neurotransmitters Neurotransmitters are chemical substances that reside in the axon terminals • They communicate to other neurons by binding to receptors on neighboring neurons 19 Chemical Communication The communication between neurons is chemical Neurotransmitter are either neutralized by an enzyme or taken back up by the neuron that released it in reuptake. ‐ At least 50 different types of neurotransmitters have been identified 20 Chemical Communication 21 Synaptic Transmission The neurotransmitters are released from the vesicles and then attach to receptors located on the postsynaptic neuron. These neurotransmitters are in contact with the dendrite of the postsynaptic neuron only briefly. ‐ The chemical is almost immediately destroyed or reabsorbed 22 Neurotransmitters At least 50 different types of neurotransmitters have been identified ‐ ‐ ‐ ‐ ‐ ‐ Acetylcholine GABA Serotonin Dopamine Norepinephrine Endorphins 23 Acetylcholine Activates motor neurons controlling skeletal muscles Contributes to the regulation of attention, arousal and memory 24 Examples of Neurotransmitters Gamma-aminobutyric acid (GABA) is involved in experiences of anxiety, alcohol abuse, seizure disorders, and sleep disorders Serotonin is involved in sleep and mood regulation and appetite (appetite for carbohydrates) 25 Dopamine Involved in movement, thought processes, emotion, feelings of reward and pleasure Implicated in schizophrenia, attention deficit disorder, and drug abuse 26 Norepinephrine Involved in arousal reactions (increasing heart rate, respiration, sweating, and dilation of pupils) May also be involved in hunger, eating, and sexual activity 27 How do drugs effect behavior? 28 28 Drugs Impact on the Brain Common drugs can alter the amount of a neurotransmitter released at the synapses Some drugs can mimic/facilitate the action of the neurotransmitters while others can block the action of the neurotransmitter. 29 Agonists versus Antagonists Agonists mimic or facilitate the actions of a neurotransmitter Antagonists oppose/block the actions of a neurotransmitter Agonist Antagonist 30 Next Class… The Brain How do the neurons work together? ‐ The Central Nervous System ‐ The Peripheral Nervous System 31