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Nervous tissue Neurons and Glial Cells

Nervous tissue Neurons and Glial Cells. Anna L. Kiss Department of Anatom , Histology and Embryology Semmelweis University 2019. Nervous tissue. Function: stimulus transmission Origin: ectoderm Structure: neurons + glial cells. Nervous tissue. Neurons: unipolar bipolar

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Nervous tissue Neurons and Glial Cells

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  1. NervoustissueNeurons and GlialCells Anna L. Kiss Department of Anatom, Histology and Embryology Semmelweis University 2019

  2. Nervoustissue • Function: stimulus transmission • Origin: ectoderm • Structure: neurons + glial cells

  3. Nervoustissue Neurons: unipolar bipolar pseudounipolar multipolar

  4. Nerve cells (neurons)

  5. Functions of neuronal compartments • Dendrites receive input from other neurons. • The axon transmits information over distance. • The termini send information to other neurons. • The soma (cell body) synthesizes proteins and membrane components.

  6. Soma: perikaryon: cell body In the soma of the cells:cell nucleus (containing the DNA, i.e. genetic code); rER:synthesis of the proteins (Nissle bodies (ribosomes and endoplasmatic reticulum) mitochondria: ATP production

  7. Processes: short: dendriteslong: axon

  8. Dendrites receive input from other neurons • Highly branched dendrites provide a large postsynaptic surface area. • The soma also receives synapses.

  9. Axons transmit excitation over distance • Axons are electrically excitable. • The axon begins with a trigger zone, the axon hillock. • Bigger axons conduct faster. • Most axons are insulated by myelin.

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

  11. Terminals transmit signals to other cells • Presynaptic terminals release neurotransmitter onto target cells. • The target may be a neuron or some other effector. • Neuroendocrine cells release transmitter into the blood.

  12. General structure of thesynapses presynapses synaptic cleft postsynapses

  13. Synapse – Communication between neurons

  14. Electricalsynapses • synaptic cleft: narrow • work faster • impulse transmission: bidirectional

  15. Chemicalsynapses • synapticcleft: wider • workslower • impulseconduction: unidirectional

  16. Synapses Axo-dendritic Axo-somatic Axo-axonic Dendro-dendritic the most ommon

  17. Resting potential anequal ion distribution: - extracellular space: Na+ - intracellular space: K+ + negatively charged proteins

  18. Action potential: depolarization

  19. Chemicalsynapses Excitatory: cholinergic: acetylcholine adrenergic: adrenalin, noradrenalin peptidergic: dopamin, serotonine Inhibitory: GABA

  20. Nervoustissue • Glial cells • The principal glia: • Schwann cells • oligodendrocytes, • astrocytes, • ependymalcells: lininglayer (centralcanal+ventricles • microglialcells: phagocytoticcells

  21. Principal glial cell types

  22. Sheath In the peripheral nervous system: Schwann cell Schwann sheath myelin sheath In the central nervous system: oligodendroglial cells myelin sheath ONLY

  23. Formation of myelin sheth in a peripheral axon.

  24. Myelinsheath Ranvier’snode axonhillock Shwanncells

  25. Axons are sheathed in myelin

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

  27. Oligodendrocytes

  28. Glial cells astrocytes

  29. Astrocytes Astrocytes connect the extraneuronal space with the blood vessels: blood/brain barrier

  30. Comparison of neurons and glia

  31. References Wikipaedia

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