Morphology of Dorsal root ganglia (DRG)ĭorsal root ganglia (sensory ganglia) contain the cell bodies of primary afferent neurons that transmit the sensory information from the periphery into the central nervous system (CNS). Removing K + from the perineuronal environment would reduce neuronal excitation and therefore contribute to the lowering of pain.Ģ. It is known that astrocytes in the central nervous system perform ‘spatial buffering’ (regulation of K +) and it is presumed that SGCs also perform the same function. Satellite glial cells have been implicated in neuronal nutrition, homeostasis, and the process of apoptosis. The somatic ganglia of all the mammalian and avian species demonstrate this arrangement. The neuron and its surrounding satellite glial cells form a distinct morphological and probably a functional unit. A distinctive feature of satellite glial cells by which they are distinguished from astrocytes is that they completely surround the individual sensory neuron. The satellite cells that surround the pseudounipolar neuron are continuous with the Schwann cell sheath that surrounds the axon. Small satellite glial cells tightly wrap the cell bodies of the pseudounipolar neurons in the ganglion. Structurally and electrophysiologically, both these processes show characteristic features of the axon. The neurons in sensory ganglia are at first bipolar, but the two neurites soon unite to form a single process during development. Somatic ganglia contain small to large pseudounipolar neurons while the autonomic ganglia contain small multipolar neurons. The nerve cell bodies in each of these differ in their size and shape. Thus ganglia can be divided into two types somatic and autonomic ( Figure 1). Some of them have independent nomenclature like the “Gasserian ganglion” for the Vth nerve. Ganglia are present in the dorsal root of spinal nerves, the sensory root of the trigeminal nerve (Vth), Facial (VIIth), Glossopharyngeal (IXth), Vagus (Xth) nerves and in the autonomic nervous system. The nerve cell bodies are of varying sizes and shapes. The nervous system is subdivided, morphologically into two components, the central nervous system (CNS) consisting of the brain and spinal cord and the peripheral nervous system (PNS) comprising of cranial and spinal nerves and ganglia.ĭiscrete collections of nerve cell bodies in the CNS are known as nuclei while in PNS, these are called ganglia. The human nervous system is an extremely efficient, compact, fast and reliable computing system, yet it weighs substantially less than most of the computers and performs at an incredibly greater capacity. Clinically, these cells were implied to be related to the many neurological disorders. These cells have been identified to get activated when confronted by the noxious stimuli, injury or inflammation. Many quantitative studies have identified the different proportion of satellite glial cells for individual neurons. Besides covering the neurons, they share features very much similar to the astrocytes such as expression of glutamine synthetase. These cells ensheath the neurons from all the sides. The neurons in the DRG were surrounded by the satellite glial cells (SGC). Peripheral process collects the impulses from the peripheral receptors and the central process reaches out to the central nervous system. Dorsal root ganglion neurons constitute the first-order neurons for the pain pathways and can be categorized as small, medium and large varieties. The single process from the soma or body will divide into the central and peripheral processes. The neurons in the dorsal root ganglion are pseudounipolar in type. E.Dorsal root ganglion (DRG) or spinal ganglia are present in relation to the dorsal ramus of the spinal nerves. more than one cell body.Īnswer: _ support the axon from within. one axon and many dendrites.Īnswer: A neuron may have A. seeing, feeling, and touching.Īnswer: Masses of myelinated nerve fibers appear A. predictive, manipulative, and integrative. integrative, motor, and sensory.Īnswer: Three general functions of the nervous system are A. none of the above.Īnswer: Sensory receptors A. all of the aboveĪnswer: Neurons that convey impulses from the CNS to muscles or glands are A. integrates information from several sources and uses it to respond appropriately. detects changes in the internal or external environment. neurons and muscle cells.Īnswer: The space between neurons is a A. synapses.Īnswer: The two types of cells of the nervous system are A. Answer: The cytoplasmic extensions that, together with the cell body, provide the main receptive surfaces for neurons are A.
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