Search Results

This chapter surveys the properties of selected transporter families that have prominent roles in the functions of neuroglia, especially the interactions of glia with neurons, to examine how transport mechanisms may subserve glial functions. It shows that that the complement of cell surface transporters expressed in neuroglia is exquisitely adapted to glial functions and is distinctly different than that in neurons. As progress is being made in identifying a distinctive complement of transporters for each glial cell subtype, it becomes clear that the deployment of transporters in the plasma membrane is subject to a host of developmental, regional, and local cues.

This chapter provides a historical perspective that highlights the early period of glial research. Topics covered include Virchow's invention of the term neuroglia in 1856, Heinrich Müller' picture of a glial cell, stellate cells in white and gray matter, and Camillo Golgi's description of cells with characteristic features of astrocytes and oligodendrocytes.

This chapter begins by examining neuroglia and synaptic plasticity in the soma and dendrites of magnocellular neurosecretory neurons in the hypothalamus and the associated neuroglial plasticity in the neurohypophysis. It then considers plastic events in parvocellular hypothalamic neurons and the associated plastic reorganization of glia and parvocellular neurosecretory endings in the median eminence. It shows that neuroglial and synaptic remodeling may participate in the regulation of hormonal release by magnocellular and parvocellular hypothalamic neurons. Glial plastic remodeling may have different consequences for the activity of neurosecretory cells by affecting the release or availability of different factors involved in synaptic function and synaptic plasticity, by modulating neuronal membrane properties and ion channels, or by regulating in an active or permissive manner the number of excitatory and inhibitory synaptic inputs.

The complexity of fish behaviour and information processing indicates high levels of neural, anatomical and functional organization. Neural cells are conducting neurons and neuroglia with putative support and physiological roles. Neuronal conduction, synaptic transmission, reflexes and neuropils are factors in integrative activity and information processing. Fish nervous systems are organized into central (brain and spinal cord) and peripheral (including autonomic) components. Interestingly the structure and function of the fish optic tectum have been considered comparable to those of the tetrapod cerebral cortex. Also of interest are the bilaterally paired large Mauthner fibres in the teleost central nervous system, which mediate startle responses. The autonomic nervous system in fish occupies a pivotal position amongst vertebrates, including uncertainty about the existence of a posterior parasympathetic component. The trend is to regard it in terms of spinal autonomic (sympathetic) cranial autonomic (parasympathetic) and enteric systems. Accounts of the autonomic control of individual effector systems are included.

This chapter evaluates the basic unit of the human brain: the nerve cell, or neuron. These cells are also the main units of the peripheral nervous system, which sends messages from the brain to the other tissues and organs that make up our bodies. Neurons are the most well-known cells in the brain but they are not the only type of cell in this organ. The other main types are the glial cells, also known as neuroglia. Recent studies of the role of glial cells in the brain are revealing potentially important differences between humans and other species in the functions of these cells. The chapter then turns to the large-scale structure of the brain. The most dramatic changes in brain size and structure occurred in the final phase of human evolutionary change. Indeed, Neanderthals had brains similar in size to those of modern humans. An important feature of the human brain is that a larger fraction of its growth occurs outside the womb. Although humans reach adult brain size in childhood, brain development continues for decades afterwards.

Dental students and practitioners need a working knowledge of the central nervous system (CNS) for several reasons. • A general knowledge of the structure and function of the nervous system is required to understand the major roles it plays in controlling body functions. • The cranial nerves innervating the head and neck, including the oral cavity, underpin all functions in these areas; knowledge of these nerves, including their connections to the CNS is vital to understanding the anatomy and physiology of this region. • Clinically, dental students and practitioners will frequently encounter patients suffering from one or other of the many diseases affecting the central and peripheral nervous system. Satisfactory dental management of such patients requires some understanding of their illness which in turn requires knowledge of the general structure of the nervous system. The anatomy of the nervous system was described long before we understood much of its function. Like all other parts of the body, everything is named; some of the names seem to defy the logic of anatomical nomenclature used to describe structures elsewhere in the body introduced in Chapter 1. Some of the structures visible to the naked eye were named by their fanciful resemblance to everyday objects such as olives; their names, therefore, bear no resemblance to their function. However, the nerve tracts that connect different areas to form functional pathways are described using a consistent system of naming. Only the most important structures that can be observed in dissected brains or form important landmarks in functional pathways are included in these chapters on the nervous system. It is important to appreciate that much of the detailed structure of the brain can only be observed microscopically. Special microscopical methods are required to show its structure and even then, a practised eye is required to interpret them. Nevertheless, it does help to know the outline of how the connections and functions of the nervous system have been investigated to understand how we have arrived at our present level of knowledge. Initially, careful clinical observations of signs and symptoms prior to death were correlated with post-mortem changes in the brain.