sandwich line, adding and deleting certain physical and mental characteristics. -Is this a good idea? How Your Body Communicates Internally, your body has two communication systems. One works quickly, your nervous system, and one works slowly, your endocrine system. Content Objective Neuron, Dendrite, Axon, Synapse, Myelin Sheath, Terminal Buttons, Neurotransmitter, Absolute threshold, Action potential, All-or-none principle, Plasticity, Reflex, Neural pathway, Agonist, Antagonist Language Objective First, second, then, next Initially Subsequently Simultaneously Stress and Happiness -These two systems do not just work in cooperation during stressful situations like a car accident, but also in happier situations, such as when you earn an unexpected “A,” or “fall in love.” -Why Study Them -These two systems are the biological foundations for all of our thoughts, emotions and behaviors. -When one of these two systems falters, the result can be a multitude of effects on the brain and mental functions, some mild and some life altering. Neurons: Our Building Blocks -Neurons are cells specialized to receive, process and transmit information to other cells. -Bundles of neurons are called nerves. 3 Types of Neurons While neurons can be different sizes and shapes, they all share a similar structure and function in a similar way. -Neurons are broken into three categories based on their location and function: -Sensory Neurons -Motor Neurons -Interneurons
A neuron exists to perform 3 tasks: 1.) Receive information from the neurons that feed it. 2.) Carry information down its length. 3.) Pass the information on to the next neuron. Sensory Neurons -Sensory neurons, or afferent neurons, act like one-way streets that carry traffic from the sense organs toward the brain. The sensory neurons communicate all of your sensory experience to the brain, including vision, hearing, taste, touch, smell, pain and balance. Motor Neurons -Motor neurons, or efferent neurons, form the one-way routes that transport messages away from the brain to the muscles, organs and glands. Interneurons Sensory and motor neurons do not communicate directly with each other. Instead, they rely on a middle-man. -Interneurons, which make up the majority of our neurons, relay messages from sensory neurons to other interneurons or motor neurons in complex pathways. What a Neuron Looks Like How Neurons Work -The dendrite, or “receiver” part of the neuron, which accepts most of the incoming messages. -Consists of finely branched fibers. -Selectively permeable -Dendrites complete their job by passing the incoming message on to the central part of the neuron called the soma. -The soma, or cell body, contains the cell’s nucleus and life-support machinery. -The function of the soma is to assess all messages the cell receives and pass on the appropriate information, at the appropriate time. -When the soma decides to pass-on a message, it sends the message down the axon. -The axon is a single, larger “transmitter” fiber that extends from the soma. -This is a one way street Axon The axon is the extension of the neuron through which the neural impulses are sent. -Axons speak, dendrites listen. -In some neurons, like those of the brain, the axons are very short. In others, like those in the leg, they can reach 3 feet long.