Sistema Nervioso Autonomo

Presentación del tema: "Sistema Nervioso Autonomo"— Transcripción de la presentación:

1 Sistema Nervioso Autonomo
Dr. Ricardo A. Fernández C. 2013

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3 Sistema Nervioso Autonomo
El sistema Nervioso Autónomo es la parte del Sistema Nervioso que es responsable de la homeostasis Excepto por el musculo esquelético, que tiene su inervación del sistema nervioso somato motor, la inervación para los otros órganos es suplida por el Sistema Nervioso Autónomo . Terminaciones nerviosas están localizadas en el musculo liso (ej., vasos sanguíneos, pared intestinal, vejiga urinaria), musculo cardiaco y glándulas (ej., glándulas sudoríparas, glándulas, salivales). The autonomic nervous system (ANS) is the part of the nervous system that is responsible for homeostasis. Except for skeletal muscle, which gets its innervation from the somatomotor nervous system, innervation to all other organs is supplied by the ANS. Nerve terminals are located in smooth muscle (eg, blood vessels, gut wall, urinary bladder), cardiac muscle, and glands (eg, sweat glands, salivary glands).

4 Aunque la supervivencia es posible sin el Sistema Nervioso Autónomo, la habilidad para adaptarse a los estresores ambientales y otras amenazas está severamente comprometida. Although survival is possible without an ANS, the ability to adapt to environmental stressors and other challenges is severely compromised (see Clinical Box 17–1). The ANS has two major divisions: the sympathetic and parasympathetic nervous systems. As will be described, some target organs are innervated by both divisions and others are controlled by only one. In addition, the ANS includes the enteric nervous system within the gastrointestinal tract. The classic definition of the ANS is the preganglionic and postganglionic neurons within the sympathetic and parasympathetic divisions. This would be equivalent to defining the somatomotor nervous system as the cranial and spinal motor neurons. A modern definition of the ANS takes into account the descending pathways from several forebrain and brain stem regions as well as visceral afferent pathways that set the level of activity in sympathetic and parasympathetic nerves. This is analogous to including the many descending and ascending pathways that influence the activity of somatic motor neurons as elements of the somatomotor nervous system.

5 EL SNA tiene dos divisiones mayores: el sistema nervioso simpático y el sistema nervioso parasimpatico. Como se describirá algunos órganos blanco son inervados por amboas dividiones del SNA y otros son controlados por uno solo. Además el SNA incluye Sistema Nervioso Entérico dentro del sistema gastrointestinal. Although survival is possible without an ANS, the ability to adapt to environmental stressors and other challenges is severely compromised (see Clinical Box 17–1). The ANS has two major divisions: the sympathetic and parasympathetic nervous systems. As will be described, some target organs are innervated by both divisions and others are controlled by only one. In addition, the ANS includes the enteric nervous system within the gastrointestinal tract. The classic definition of the ANS is the preganglionic and postganglionic neurons within the sympathetic and parasympathetic divisions. This would be equivalent to defining the somatomotor nervous system as the cranial and spinal motor neurons. A modern definition of the ANS takes into account the descending pathways from several forebrain and brain stem regions as well as visceral afferent pathways that set the level of activity in sympathetic and parasympathetic nerves. This is analogous to including the many descending and ascending pathways that influence the activity of somatic motor neurons as elements of the somatomotor nervous system.

6 La definición clásica del Sistema Nervioso Autónomo es la de las neuronas preganglionares y postganglionares dentro de las divisiones simpáticas y parasimpáticas. Esto es equivalente a definir el sistema nervioso somatomotor como las motoneuronas craneales y motoneuronas espinales. Una definición moderna del SNA toma en cuenta las vías descendentes de varias regiones del encéfalo y el tallo cerebral asi como vías aferentes viscerales que regulan el nivel de actividad en los nervios del simpático y parasimpático.

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8 Sistema Simpático En contraste con - las neuronas motoras, que están ubicadas en todos los segmentos espinales, las neuronas preganglionares simpáticas se encuentran en el IML de solamente del primer segmento torácico a la tercera o cuarta segmentos lumbares. Por esta razón el sistema nervioso simpático a veces se llama la división toracolumbar del Sistema Nervioso Autónomo. In contrast to -motor neurons, which are located at all spinal segments, sympathetic preganglionic neurons are located in the IML of only the first thoracic to the third or fourth lumbar segments. This is why the sympathetic nervous system is sometimes called the thoracolumbar division of the ANS. The axons of the sympathetic preganglionic neurons leave the spinal cord at the level at which their cell bodies are located and exit via the ventral root along with axons of - and -motor neurons (Figure 17–2). They then separate from the ventral root via the white rami communicans and project to the adjacent sympathetic paravertebral ganglion, where some of them end on the cell bodies of the postganglionic neurons. Paravertebral ganglia are located adjacent to each thoracic and upper lumbar spinal segments; in addition, there are a few ganglia adjacent to the cervical and sacral spinal segments. These ganglia form the sympathetic chain bilaterally. The ganglia are connected to each other via the axons of preganglionic neurons that travel rostrally or caudally to terminate on postganglionic neurons located at some distance. This arrangement is seen in Figures 17–2 and 17–3

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12 Parasimpatico El sistema nervioso parasimpático a veces es llamado la división craneosacra del Sistema Nervioso Autónomo debido a la localización de sus neuronas preganglionares. The parasympathetic nervous system is sometimes called the craniosacral division of the ANS because of the location of its preganglionic neurons (Figure 17–3). The parasympathetic nerves supply the visceral structures in the head via the oculomotor, facial, and glossopharyngeal nerves, and those in the thorax and upper abdomen via the vagus nerves. The sacral outflow supplies the pelvic viscera via branches of the second to fourth sacral spinal nerves. Parasympathetic preganglionic fibers synapse on ganglia cells clustered within the walls of visceral organs; thus these parasympathetic postganglionic fibers are very short.

13 Parasimpatico Los nervios parasimpaticos suplen inervación a las estructuras viscerales en la cabeza a través de los nervios ocular común, facial y glosofaríngeo, y aquellos en el tórax y el abdomen superior vía los nervios vago. La salida a nivel del sacro suplen las visceras pélvicas a través de las ramas del segundo a cuarto nervio espinal sacro. The parasympathetic nervous system is sometimes called the craniosacral division of the ANS because of the location of its preganglionic neurons (Figure 17–3). The parasympathetic nerves supply the visceral structures in the head via the oculomotor, facial, and glossopharyngeal nerves, and those in the thorax and upper abdomen via the vagus nerves. The sacral outflow supplies the pelvic viscera via branches of the second to fourth sacral spinal nerves. Parasympathetic preganglionic fibers synapse on ganglia cells clustered within the walls of visceral organs; thus these parasympathetic postganglionic fibers are very short.

14 Parasimpatico Parasympathetic preganglionic fibers synapse on ganglia cells clustered within the walls of visceral organs; thus these parasympathetic postganglionic fibers are very short. The parasympathetic nervous system is sometimes called the craniosacral division of the ANS because of the location of its preganglionic neurons (Figure 17–3). The parasympathetic nerves supply the visceral structures in the head via the oculomotor, facial, and glossopharyngeal nerves, and those in the thorax and upper abdomen via the vagus nerves. The sacral outflow supplies the pelvic viscera via branches of the second to fourth sacral spinal nerves. Parasympathetic preganglionic fibers synapse on ganglia cells clustered within the walls of visceral organs; thus these parasympathetic postganglionic fibers are very short.

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