section 2, chapter 10: neurons and neuroglia


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neurons and neuroglia

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section 2, chapter 10: neurons and neuroglia

  1. 1. Chapter 10, Section 2 Neurons and Neuroglia
  2. 2. Structural Classification of Neurons A multipolar neuron contains many dendrites and 1 axon. • Includes most neurons in the brain and motor neurons A bipolar neuron contains 1 dendrite and 1 axon • Includes some sensory neurons such as photoreceptors and olfactory neurons A unipolar neuron contains a single process extending from the soma • Example includes the cells of the dorsal root ganglion Peripheral Process – conducts information from PNS Central Process – conducts information to CNS
  3. 3. structural classifications of neurons
  4. 4. Functional Classification of Neurons An afferent or sensory neuron conducts information from the PNS to CNS • Dendrites may act as receptors (eyes, ears, touch) • Most afferent neurons are unipolar, and some are bipolar An efferent or motor neuron conducts impulses from CNS to PNS Voluntary Control – in somatic nervous system Involuntary control – in autonomic nervous system An interneuron or association neuron is located completely within the CNS. Interneurons link neurons together in the CNS, and they also connect sensory neurons to motor neurons.
  5. 5. Functional Classification of Neurons Figure 10.7. Neurons classified by their functions. Sensory, Motor, and Interneurons.
  6. 6. Neuroglia in the CNS are different from those in the PNS Neuroglia in CNS Astrocytes “star-shaped” attach blood vessels to neurons. Astrocytes aid in metabolism, strengthen synapses, and participate in the bloodbrain-barrier Ependymal cells line the central canal of the spinal cord and the ventricles of the brain. Ependyma regulate the composition of cerebral spinal fluid (CSF)
  7. 7. Neuroglia in CNS Microglia are normally small cells, but they enlarge into macrophages during an infection. •Phagocytize bacteria and cell debris Oligodendrocytes form the myelin sheath in the CNS
  8. 8. Figure 10.8. Types of neuroglia in the CNS. Neuroglia compose half of the brain’s volume
  9. 9. Neuroglia of the PNS Schwann Cells form the myelin sheath in the PNS. Satellite Cells support clusters of cell bodies, called ganglia in PNS.
  10. 10. Disorders of Neuroglia Multiple Sclerosis (MS) The immune system attacks neurons in the CNS, destroying the myelin sheath of neurons. The damaged myelin sheath is replaced with Connective tissue, leaving behind scars (scleroses) Scars block the transmission of underlying neurons, so muscles no longer receive stimulation and begin to whither (atrophy). End Section 2, Chapter 10