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Histology of Nervous Tissue

Histology of Nervous Tissue. Ch. 12-2. Neuroglia. Neurons vs. Neuroglia. Neurons. Provide unique functions Sensing, thinking, remembering, controlling muscle activity, regulating glandular secretions. Support, nourish, and protect the neurons

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Histology of Nervous Tissue

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  1. Histology of Nervous Tissue Ch. 12-2

  2. Neuroglia Neurons vs. Neuroglia Neurons Provide unique functions Sensing, thinking, remembering, controlling muscle activity, regulating glandular secretions Support, nourish, and protect the neurons Maintain homeostasis in the interstitial fluid that bathes them

  3. Neurons • Vocabulary: • Neuron – nerve cell • Electrical excitability • the ability to respond to a stimulus and convert it into an action potential • Stimulus • any change in the environment that is strong enough to initiate an action potential • Action potential – nerve impulse • An electrical signal that propogates (travels) along the surface of the membrane of a neuron • Can travel up to 280 mph

  4. Parts of a Neuron • Three parts • Cell body • Main part of the cell • Includes organelles, nucleus, and cytoplasm • Dendrites • Receiving parts of the neuron • Short, tapered, and highly branched • Axon • Transmitting parts of the neuron • Long, thin, cylindrical

  5. Parts of a Neuron

  6. Parts of a Neuron Synapse – site of communication between 2 neurons or a neuron and an effector cell Synaptic end bulb – swollen end of an axon where synaptic vesicles hold neurotransmitters

  7. Neural Diversity • Multipolar neurons • Several dendrites, one axon • Found in brain and spinal cord • Bipolar neurons • One main dendrite, one axon • Eye, ear, olfactory of brain • Unipolar neurons • Axon and dendrite fuse at beginning and then branch • Occurs as an embryo

  8. Neural Diversity

  9. Others Purkinje cells – cerebellum Pyramidal cells – cerebral cortex of brain

  10. Neuroglia Actively participate in nervous tissue functioning Do not generate action potentials Can multiply and divide – neurons cannot

  11. Types of Neuroglia • CNS • Astrocytes – create blood-brain barrier, strength • Oligodendrocytes – create myelin sheath around CNS axons • Microglia – remove cellular debris during neural development • Ependymal cells – assist with circulation of cerebrospinal fluid • PNS • Schwann cells – create myelin sheath around PNS axons • Satellite cells – support, regulate exchange of materials

  12. Types of Neuroglia

  13. Types of Neuroglia

  14. Myelination Myelin sheath – multilayered lipid and protein covering around some axons Provides insulation Increases speed of nerve impulse If a cell has myelin we say that it is myelinated Gaps in the myelin sheath are called nodes of Ranvier

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