THE NERVOUS SYSTEM IS A NETWORK OF NEURONS

Recall from Section 1.6 that molecules slow down with deaeasing 

Food coloring, three drinking glasses, ice-cold water, warm water, hot water 

Fill one glass with the ice-cold water, one with the warm water, and one with the hot water. Allow the glasses of water to stand for a couple of minutes so that the water is perfectly still. 

Add a drop of food coloring to each glass.The drop will sink to the bottom and then begin to diffuse. Observe how long it takes until the water is uniformly colored. 

Was this your answer A neurotransmitter Is a small organic molecule released by a neuron into a synaptic cleft. It influences neighboring tissue, such as the postsynaptic membrane of a neuron on the opposite side of the cleft,by binding to receptor sites. 

III any drugs function by affecting the nervous system. To understand how ill these drugs work, it is important to know the basic structure and functions of the nervous system. 

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The morphology of a neuron is characterized by a prominent round nucleus cell body, an axon (a long cell process), and dendrites (numerous short cell processes). The nervous system contains a network of neurons that communicate with each other by means of the synapse. The cell bodies of peripheral neurons originate in the spinal cord, specifically the dorsal root ganglion and autonomic ganghon, while the axons extend from the centrally located cell bodies and terminate in neuromuscular endings (motor neurons), end organs, or receptors (sensory or sympathetic fibers). 

The cholinergic nervous system is a network of neurones spread through both the central and peripheral nervous systems which are characterised by synapses. Transmission of signals within the network is electrical except at the synapses where acetylcholine (ACh) is released to carry the impulses across a small gap to the next neurone or to an effector organ. It is ACh which gives the cholinergic nervous system its name. ACh is only one of the many chemical transmitters in the nervous system, whose function is to act as amplifying relay stations for the nerve impulses from the brain. 

By now, you know that the nervous system is a communications network that serves to control your body. You also know that nerve impulses are the vehicle that carries information around this network. In addition, you know that chemical neurotransmission is the means by which these signals are passed from one neuron to another. Finally, you know that neurotransmitters, receptors, and enzymes are the key components that make all of these things happen. 

The nervous system, a network of neurons in active communication, reaches its ultimate development in the 1.5 kg human brain.149 393 396 Many invertebrates, such as leeches,3963 crayfish, insects, and snails, have brains containing no more than 104 to 105 neurons,396b/397 398 but the human brain contains 10n. Each of these neurons interconnects through synapses with hundreds or thousands of other neurons. The number of connections is estimated to be as many as 60,000 with each Purkinje cell of the human cerebellum. There may be many more than 1014 synapses in the human brain.399 400... 

The nervous system can be divided into three parts the central nervous system (CNS), the peripheral nervous system (PNS), and the autonomic nervous system (ANS) (Dawson et al. 2003). The CNS consists of the brain and spinal cord. The PNS resides outside the CNS and forms a network to collect information from sensory responses. The ANS is identified by primary ganglia of the head and neck, sympathetic chain and adrenal gland (Gabella and Larry 2009). The primary function of the nervous system is to receive input from the environment and innervate muscle tissues in response. To accomplish this task, neurons, which are the basic unit of the functional nervous system (Dawson et al. 2003), form a highly specific interconnecting network from the brain to the spinal cord. There are 12 paired cranial nerve and 31 paired spinal nerve connections between the CNS and the PNS, which result in motor/ efferent, sensory/afferent, or mixed function. Furthermore, internal environments such as cardiorespiratory activities, glandular secretions, vasodilatation and genital erectile tissue responses are monitored by an array of visceral receptors, chemoreceptors, and stretch receptors via autonomic nerves from the CNS (Keller et al. 2009). 

A description of the nervous system probabiy best starts with its basic functionai unit, the neuron (figure 2.1). Neurons have many features in common with other ceiis of the body, but there are two that make them unique. They are abie to conduct eiectrochemicai impuises and they are connected in networks suited for information processing. Their iink to the senses and motor effectors aiiows us to monitor and operate in the environment. The aduit human brain is estimated to contain 1011 neurons, and each may synapse with 10,000 other neurons. Despite some common core features, neurons are very heterogeneous in their morphoiogy, with thousands of variants. The foiiowing are components of the neuron. 

The control of gut function involves interplay between neurones and peptide hormones. Information from a variety of receptors along the digestive tract is processed by a network of nerves, the enteric nervous system, which also receives input from the brain. 

An ANN is a systematic procedure for data processing inspired by the nervous system function in animals. It tries to reproduce the brain logical operation using a collection of neuron-like entities to perform processing of input data. Furthermore, it is an example of a connectionist model, in which many small logical units are connected in a network [52]. Let us consider the proposed case, a multidetermination application employing an array of ISEs as input data. In a rather complex system,... 

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