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How Do Neurons Work?

How Do Neurons Work?. Neurons and Synapses. Types of Neurons. Sensory. Motor. Interneurons. Sensory Neurons. INPUT From sensory organs to the brain and spinal cord. Brain. Drawing shows a somatosensory neuron Vision, hearing, taste and smell nerves are cranial, not spinal. Sensory

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How Do Neurons Work?

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  1. How Do Neurons Work?

  2. Neurons and Synapses Types of Neurons Sensory Motor Interneurons

  3. Sensory Neurons INPUT Fromsensory organs to the brain and spinal cord. Brain Drawing shows a somatosensory neuron Vision, hearing, taste and smell nerves are cranial, not spinal Sensory Neuron Spinal Cord

  4. Brain Sensory Neuron Spinal Cord Motor Neuron Motor Neurons OUTPUTFrom the brain and spinal cord To the muscles and glands.

  5. Brain Sensory Neuron Spinal Cord Motor Neuron Interneurons • Interneurons carry information between other neurons only found in the brain and spinal cord.

  6. Structures of a neuron

  7. The cell body • Round, centrally located structure • Contains DNA • Contains the cell’s Nucleus

  8. Dendrites • Information collectors • Receive inputs from neighboring neurons • Inputs may number in thousands • If enough inputs the cell’s AXON may generate an output

  9. Axon • The cell’s output structure • One axon per cell, 2 distinct parts • tubelike structure branches at end that connect to dendrites of other cells

  10. Myelin Sheath Myelin sheath • White fatty casing on axon • Acts as an electrical insulator • When present increases the speed of neural signals down the axon.

  11. How neurons communicate • Neurons communicate by means of an electrical signal called the Action Potential • Action Potentials are based on movements of ions between the outside and inside of the cell • When an Action Potential occurs a molecular message is sent to neighboring neurons

  12. Dendrite Axon Cell Body Neuron to Neuron • Axons branch out and end near dendrites of neighboring cells • Axon terminals are the tips of the axon’s branches • A gap separates the axon terminals from dendrites • Gap is the Synapse

  13. Sending Neuron Axon Synapse Terminal Synapse • axon terminals contain small storage sacs called synaptic vesicles • vesicles contain neurotransmitter molecules

  14. Neurotransmitter Release • Action Potential causes vesicle to open • Neurotransmitter released into synapse • Locks onto receptor molecule in postsynaptic membrane

  15. Locks and Keys • Neurotransmitter molecules have specific shapes • Receptor molecules have binding sites • When NT binds to receptor, ions enter positive ions (NA+ ) depolarize the neuron negative ions (CL-) hyperpolarize

  16. Some Drugs work on receptors • Some drugs are shaped like neurotransmitters • Antagonists : fit the receptor but poorly and block the NT • e.g. beta blockers • Agonists : fit receptor well and act like the NT • e.g. nicotine.

  17. Summary of TermsDo you know them? • 3 types of neurons • Ion movements • Action potentials • Synapse • Neurotransmitters • Receptors and ions • Agonists and antagonists

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