Brain autonomous organ

Autonomic nervous system. The portion of the nervous system outside of the brain and spinal cord that is responsible for monitoring and controlling the digestive system, cardiovascular system, and other organs that are not under direct conscious control. 

HT may be involved in a wide variety of behaviors by setting the tone of brain activity in relationship to the state of behavioral arousal/activity. Serotonin has been implicated in practically every type of behavior, e.g. appetitive, emotional, motoric, cognitive, autonomic. However, from a physiologic perspective, it is not clear whether 5-HT affects such behaviors specifically, or more generally by coordinating the activity of the nervous system, particularly to set the tone of activity in conjunction with the organism s level of arousal. 

The nervous system is divided into two parts the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists of all afferent (sensory) neurons, which carry nerve impulses into the CNS from sensory end organs in peripheral tissues, and all efferent (motor) neurons, which carry nerve impulses from the CNS to effector cells in peripheral tissues. The peripheral efferent system is further divided into the somatic nervous system and the autonomic nervous system. The effector cells innervated by the somatic nervous system are skeletal muscle cells. The autonomic nervous system innervates three types of effector cells (1) smooth muscle, (2) cardiac muscle, and (3) exocrine glands. While the somatic nervous system can function on a reflex basis, voluntary control of skeletal muscle is of primary importance. In contrast, in the autonomic nervous system voluntary control can be exerted, but reflex control is paramount. 

The nervous system is conventionally divided into the central nervous system (CNS the brain and spinal cord) and the peripheral nervous system (PNS neuronal tissues outside the CNS). The motor (efferent) portion of the nervous system can be divided into two major subdivisions autonomic and somatic. The autonomic nervous system (ANS) is largely independent (autonomous) in that its activities are not under direct conscious control. It is concerned primarily with visceral functions such as cardiac output, blood flow to various organs, and digestion, which are necessary for life. The somatic subdivision is largely concerned with consciously controlled functions such as movement, respiration, and posture. Both systems have important afferent (sensory) inputs that provide information regarding the internal and external environments and modify motor output through reflex arcs of varying size and complexity. 

Nature is economical in her means. She uses many of the same chemicals to accomplish her nervous purposes within the brain that she has already used to the same ends throughout the body. The good news is that once you have worked out the biochemistry and pharmacology of a neuromodulator in the body, you can apply a lot of what you know to its action in the brain. The bad news is that every time you target, for example, the acetylcholine system of the brain, you also hit the body. That means that the heart, the bowel, the salivary glands, and all the rest of the organs innervated by the autonomic nervous system are influenced. What is worse, the target sites within the brain may not only be as spatially dispersed as in the periphery, but may also be as functionally differentiated ... 

The brain and the immune system are accepted as the two major body s adaptive systems (Elenkov et al., 2000). The brain can modulate immune functions and the immune system also sends messages to the brain. The communication between these two systems is done mainly by the hypothalamic-pituitary-adrenal axis and the autonomic nervous system (ANS). The sympathetic nervous system (SNS), which is part of the ANS, innervates the lymphoid organs (Elenkov et al., 2000) (Flierl et al., 2007). Catecholamines, like dopamine, serotonin, epinephrine and norepinephrine, are the end products of the SNS. 

CNS—brain and spinal cord—and two separate pathways within the peripheral nervous system (PNS) for two-way communication with the peripheral organs. The PNS subdivisions are the somatic and autonomic nervous systems (Figure 11.2). The latter is further divided into sympathetic and parasympathetic divisions (Figure 11.3). 

The somatic nervous system is composed of sensory afferents and motor efferents and serves to perceive external states and to modulate appropriate body responses. The autonomic nervous system (ANS), together with the endocrine system, controls the milieu interieur. It adjusts internal organ functions to the changing needs of the organism. The ANS operates largely autonomously, beyond voluntary control, at the subconscious level. Its central components reside in the hypothalamus, brain stem, and spinal cord. The ANS has sympathetic and parasympathetic branches. Both are made up of afferent, mainly in the vagus nerve, and efferent fibers. 

The main acute pharmacologic actions of anti-ChE agents that are of concern here are those on the eye, the Intestine and ocher organs Innervated by the autonomic division of the FMS, the skeletal neuromuscular Junction, and the brain. Effects of cholinergic and adrenergic stimulation on effector organs are summarized in Table 1. 

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