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Nervous System

Nervous System. Division of the nervous system. Central Nervous System Peripheral Nervous System. Brain. Spinal Cord. Cranial Nerves. Spinal Nerves. Peripheral Ganglia. Division of the nervous system. Central Nervous System Peripheral Nervous System. Brain. Spinal Cord.

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Nervous System

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  1. Nervous System

  2. Division of the nervous system • Central Nervous System • Peripheral Nervous System Brain Spinal Cord Cranial Nerves Spinal Nerves Peripheral Ganglia

  3. Division of the nervous system • Central Nervous System • Peripheral Nervous System Brain Spinal Cord Cranial Nerves Spinal Nerves Peripheral Ganglia

  4. Central Nervous System (CNS) • 7 Main Parts of the CNS • Spinal Cord • Medulla oblongata • Pons • Cerebellum • Midbrain • Diencephalon • Cerebrum

  5. Directions in the nervous system - Axes Orientation Axes in the brain Rostral-Caudal (front-back)  anterior-posterior Dorsal-Ventral (up – down) Lateral-Medial (sideways – mid)

  6. Directions in the nervous system - Planes

  7. Maturation of the CNS Brain weight at birth: 400 g At 2 years ~ 1000 g Adult ~1500 g Maturation is mostly based on differentiation of nerve-cell connectivty

  8. Nerve cells (neurons)

  9. Sketch of a neuron Nucleus Axons Dendrites Dendrites Myelin • Dendrites -- Input • Cell body (soma) -- Integration • Axon -- Output

  10. Structure of neurons - Dendrites At dendrites, the neurons recieve input via axons of other neurons at synapses dendritic spine

  11. Structure of neurons - Soma In the soma of the cells, the cell nucleus is located (containing the DNA, i.e. genetic code); the synthesis of the proteins (within ribosomes and endoplasmatic reticulum) as well as energy production (mitochondria) are performed.

  12. Structure of neurons - Axon The axon transmits the information electrically from the soma to the synapses – it is surrounded by myelin that insulate the axon, provided by oligodendrocytes (glial cells)

  13. Sketch of a neuron Nucleus Axons Dendrites Dendrites Myelin • Dendrites -- Input • Cell body (soma) – Integration; protein production, genes, energy production • Axon -- Output

  14. Electrical properties of neurons extracellular intracellular The cell membrane isolates the intracellular from extracellular space

  15. Electrical properties of neurons The membrane potential extracellular difference of -70 mV intracellular In the resting state, the intracellular space contains more negative ions than the extracellular space

  16. Ion channels connect the intra- and extracellular space Opening of ion channels lead to a flux of ions through the membrane and to a change of the membrane potential

  17. Different types of ion channels

  18. The action potential The action potential is generated by ion flux through voltage gated channels All or nothing principle!!

  19. Propagation of the action potential

  20. Synapse – Communication between neurons

  21. Synapse – Communication between neurons

  22. Synapse – Communication between neurons Presynaptic vesicles with neurotransmitter Released transmitter Transmitter binds to receptor Transmitter-Resorption from synaptic cleft Na+

  23. Animasi

  24. Excitatory and Inhibitory Synapses Inhibitory postsynaptic potential (EPSP) Excitatory postsynaptic potential (EPSP) Depending on the neurotransmitter and the receptor, the postsynaptic potential can be excitatory or inhibitory

  25. Important Neurotransmitters • Dopamine • Epinephrine • Norepinephrine • Acetylcholine • Serotonine • Glycine • GABA • Glutamate

  26. Two forms of integration of information

  27. EPSC at dendrite can lead to action potential

  28. Effect of inhibition on excitation

  29. Glial cells oligodendrocytes astrocytes

  30. Astrocytes Astrocytes connect the extraneuronal space with the blood vessels

  31. Oligodendrocytes Oligodendrocytes sheat the axons of the neurons to increase conductance of action potential

  32. Summary neuronal communication • intracellular electrical transmission of information (action potential) • neurons communicate via biochemical transmission (neurotransmitters and receptors) • integration of information in neurons by means of spatial and temporal summation

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