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Neurons and Synapses

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 Neuron. Spinal Cord.

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Neurons and Synapses

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  1. Neurons and Synapses Types of Neurons Sensory Motor Interneurons

  2. 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

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

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

  5. Action Potential Demonstration • Psych Simulation- 4.0

  6. Structures of a neuron

  7. The cell body • Round, centrally located structure • Contains DNA • Controls protein manufacturing • Directs metabolism • No role in neural signaling • 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. Dendritic Growth • Mature neurons generally can’t divide • But new dendrites can grow • Provides room for more connections to other neurons • New connections are basis for learning

  10. 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

  11. Myelin Sheath Myelin sheath • White fatty casing on axon • Acts as an electrical insulator • Not present on all cells • When present increases the speed of neural signals down the axon.

  12. Dendrite Axon Cell Body Neuron to Neuron • Axons branch out and end near dendrites of neighboring cells • 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. Neurotransmission • http://camel2.conncoll.edu/academics/zoology/courses/zoo202/Nervous/synapse.html

  15. Locks and Keys • Neurotransmitter molecules have specific shapes • Receptor molecules have binding sites • When NT binds to receptor, ions enter

  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 • 3 types of neurons • The cell membrane • Ion movements • Action potentials • Synapse • Neurotransmitters • Receptors and ions • Agonists and antagonists

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