1 / 16

Neurons, neuroglia and organization of the nervous system

Neurons, neuroglia and organization of the nervous system. Overview of the nervous system. Functions of the nervous system. Sensory- detection of internal and external stimuli (sensory neurons) Integrative- processing of sensory information (interneurons)

deon
Download Presentation

Neurons, neuroglia and organization of the nervous system

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Neurons, neuroglia and organization of the nervous system

  2. Overview of the nervous system

  3. Functions of the nervous system • Sensory- detection of internal and external stimuli (sensory neurons) • Integrative- processing of sensory information (interneurons) • Motor- response to integrated “decision” (motor neurons)

  4. Organization of the nervous system

  5. Structure and function of neurons • Act through propagation of action potentials • Vary considerably in size • Dendrites, cell body and axons • May be myelinated • Synapse with other neuron or muscle cell; release neurotransmitters

  6. Neurotransmitter action • About 100 neurotransmitters known • Amino acids, polypeptides, gases • Released into synaptic cleft, bind to membrane of target cell

  7. Structural diversity in neurons • Multipolar- many dendrites, one axon • Most neurons in CNS • Bipolar- one dendrite, one axon • Sensory organs • Unipolar- sensory • Axon termini extend into CNS

  8. Neuroglial cells • Much smaller than neurons and more numerous • Do not propagate action potentials • Can replace themselves

  9. Four types of neuroglia in CNS • Oligodendrocytes • Myelinating cells • Astrocytes • Blood-brain barrier (BBB) • Microglia • Phagocytes (from bone marrow) • Ependymal cells • Line ventricles of brain; produce cerebrospinal fluid (CSF)

  10. Neuroglia of the CNS

  11. Neuroglia of the PNS • Schwann cells • Myelinating cells • Help direct axon regeneration • Satellite cells • Support, protection, regulation of molecular exchange

  12. Why myelin? • Increases speed of nerve impulse transmission • Myelinating cells leave gaps on axons (nodes of Ranvier) • Schwann cells can help regenerate axons • Demyelination can lead to loss of function (MS)

  13. Gray and white matter

  14. Neural circuits in CNS vary in direction and complexity • One presynaptic→one postsynaptic is simplest • One presynaptic→ many postsynaptic (divergence) amplifies a sensory signal • Many presynaptic →one postsynaptic (convergence) brings information from many sources into one pathway • May move repeatedly through circuit (reverberating)- repeated or learned activities • Parallel-discharge- pathways diverge and then converge- complex activities requiring concentration?

  15. Repair and regeneration of neurons • Neurons can grow new dendrites or axon termini • Repair is limited to certain neurons in the PNS • Growth factors promote formation of new neurons; limited to specific regions of brain (hippocampus) in human adults • Growth does occur in fetal and juvenile stages- what turns it off?

  16. Medically significant conditions • Multiple sclerosis (demyelination) • Epilepsy (uncontrolled electrical discharges) • Tumors • Neuropathies- affect specific nerves • Infectious disease

More Related