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Today in class

Today in class. Notes Writing assignment Vocabulary Activity Reminder – quiz tomorrow Reminder – candy neuron tomorrow – bring candy. Neurons and Neuronal Communication: The Structure of a Neuron. There are billions of neurons (nerve cells) throughout the body.

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Today in class

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  1. Today in class • Notes • Writing assignment • Vocabulary Activity • Reminder – quiz tomorrow • Reminder – candy neuron tomorrow – bring candy

  2. Neurons and Neuronal Communication:The Structure of a Neuron There are billions of neurons (nerve cells) throughout the body.

  3. Action potential:a neural impulse that travels down an axon like a wave Just as “the wave” can flow to the right in a stadium even though the people only move up and down, a wave moves down an axon although it is only made up of ion exchanges moving in and out.

  4. When does the cell send the action potential?... when it reaches a threshold How neurons communicate(with each other): The neuron receives signals from other neurons; some are telling it to fire and some are telling it not to fire. • When the threshold is reached, the action potential starts moving. • Like a gun, it either fires or it doesn’t; more stimulation does nothing. • This is known as the “all-or-none” response. The action potential travels down the axon from the cell body to the terminal branches. The signal is transmitted to another cell. However, the message must find a way to cross a gap between cells. This gap is also called the synapse. The threshold is reached when excitatory (“Fire!”) signals outweigh the inhibitory (“Don’t fire!”) signals by a certain amount.

  5. The Synapse The synapse is a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The synapse is also known as the “synaptic junction” or “synaptic gap.”

  6. Neurotransmitters Neurotransmitters are chemicals used to send a signal across the synaptic gap.

  7. Reuptake:Recycling Neurotransmitters [NTs] Reuptake: After the neurotransmitters stimulate the receptors on the receiving neuron, the chemicals are taken back up into the sending neuron to be used again.

  8. Neural Communication: Seeing all the Steps Together

  9. Roles of Different Neurotransmitters

  10. Dopamine pathways Serotonin pathways Networks of neurons that communicate with dopamine are involved in focusing attention and controlling movement. Networks of neurons that communicate with serotonin help regulate mood.

  11. Hearing the messageHow Neurotransmitters Activate Receptors When the key fits, the site is opened.

  12. Keys that almost fit:Agonist and AntagonistMolecules An antagonist molecule fills the lock so that the neurotransmitter cannot get in and activate the receptor site. An agonistmolecule fills the receptor site and activates it, acting like the neurotransmitter.

  13. RecapThe Structure of the Neuron • Basic Building block of the nervous system • Consist of cells specialized for rapidly communicating information

  14. TYPES OF NEURONS • Sensory neurons – bring information from outside world to your brain • Motor neurons – transmit responses from brain to muscles and glands • Interneurons • Connect neurons to other neurons • Join sensory and motor neurons in spinal cord

  15. Synapses • What are synapses – part of the structure of the Neuron • What is the purpose of synapses? • They are the chemical (neurotransmitter) connections between ALL neurons So can you describe the structure of the Neuron?No, not yet.

  16. Next Question… • What is the purpose of Glial cells? • Fact – most numerous cells within the nervous system • Fact – Like glue – holding neurons together • Fact – assist and support activity of neurons • Fact – forms the myelin sheath (covering of the axon) • The myelin sheath – what is the myelin sheath?

  17. Myelin Sheath • Fatty, protective covering on neuron axons • Forms over time, usually by age of 12 • Nodes of Ranvier (gaps in myelin sheath) – neural impulse may jump from node to node • Fact – Multiple sclerosis (MS) – a condition that occurs from the destruction of myelin sheath

  18. How Neurons Communicate • Ions involved: sodium, potassium, and chloride • Resting potential – neuron not activated; cell has slightly negative charge • Depolarization – stimulation leads sodium to enter cell; electrical charge now changed from negative to positive • Action Potential – neuron fires down length of axon; called a neural impulse

  19. Importance of Neurotransmitters • Synapse is tiny gap between one neuron and the next • At synapse, the impulse changes from electrical to chemical • Neurotransmitters are these chemical messengers across synapse • Chemicals from adjacent neurons may either excit or inhibit cell firing List 5 Neurotransmitters and explain what they do.

  20. Can you do the following? Do you need your outline to do it?Take out a sheet of paper and do it. • 1. Describe the structure of a neuron. • 2. Describe the process by which an action potential is triggered. • 3. Describe how nerve cells communicate, and discuss the importance of neurotransmitters for human behavior.

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