how many types of nervous systems are there
Nervous system The nervous system is the part of an animal that coordinates its actions by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events.[1] Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory or afferent. Spinal nerves serve both functions and are called mixed nerves. The PNS is divided into three separate subsystems, the somatic, autonomic, and enteric nervous systems. Somatic nerves mediate voluntary movement. The autonomic nervous system is further subdivided into the sympathetic and the parasympathetic nervous systems. The sympathetic nervous system is activated in cases of emergencies to mobilize energy, while the parasympathetic nervous system is activated when organisms are in a relaxed state. The enteric nervous system functions to control the gastrointestinal system. Both autonomic and enteric nervous systems function involuntarily. Nerves that exit from the cranium are called cranial nerves while those exiting from the spinal cord are called spinal nerves.
List of St. Elsewhere characters Portrayed by Denzel Washington
National Pledge (India) 1. Hindi भारत मेरा देश है। सब भारतवासी मेरे भाई-बहन है। मैं अपने देश से प्रेम करता/करती हूं। इसकी समृद्ध एवं विविध संस्कृति पर मुझे गर्व है। मैं सदा इसका सुयोग्य अधिकारी बनने का प्रयत्न करता/करती रहूँगा/रहूँगी। मैं अपने माता-पिता, शिक्षको एवं गुरुजनो का सम्मान करूँगा/करूँगी और प्रत्येक के साथ विनीत रहूँगा/रहूँगी। मैं अपने देश और देशवाशियों के प्रति सत्यनिष्ठा की प्रतिज्ञा करता/करती हूँ। इनके कल्याण एवं समृद्धि में ही मेरा सुख निहित है।
Autonomic nervous system The autonomic nervous system has three branches: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.[4][5][6][7] Some textbooks do not include the enteric nervous system as part of this system.[8] The sympathetic nervous system is often considered the "fight or flight" system, while the parasympathetic nervous system is often considered the "rest and digest" or "feed and breed" system. In many cases, both of these systems have "opposite" actions where one system activates a physiological response and the other inhibits it. An older simplification of the sympathetic and parasympathetic nervous systems as "excitory" and "inhibitory" was overturned due to the many exceptions found. A more modern characterization is that the sympathetic nervous system is a "quick response mobilizing system" and the parasympathetic is a "more slowly activated dampening system", but even this has exceptions, such as in sexual arousal and orgasm, wherein both play a role.[3]