Nerve cell neurons

Designer drugs are mind-altering and can produce hallucinations. For these reasons, they are often called psychoactive or psychedelic. Designer drugs produce their effects by altering the way nerve cells (neurons) in the brain communicate with each other (Figure 1.1). 

Nerve cells (neurons) are easily excitable cells that produce electrical signals and can react to such signals as well. Their structure is markedly different from that of other types of cell. Numerous branching processes project from their cell body (soma). Neurons are able to receive signals via dendrites and to pass them on via axons. The axons, which can be up to 1 m long, are usually surrounded by Schwann cells, which cover them with a lipid-rich myelin sheath to improve their electrical insulation. 

Plants not only evolved allelochemicals with broad activities (see Section 1.3.1) but also some that can interfere vdth a particular target [3,6,17-19,25]. Targets that are present in animals but not in plants are nerve cells, neuronal signal transduction, and the endocrinal hormone system. Compounds that interfere with these targets are usually not toxic for the plants producing them. Plants have had to develop special precautions (compartmentation resin ducts, trichomes, laticifers) in order to store the allelochemicals with broad activities that could also harm the producer. 

Another example, dopamine, is a neurotransmitter, a chemical messenger released by one nerve cell (neuron), which then binds to a receptor in a neighboring target cell (Figure 25.6). Dopamine affects brain processes that control movement and emotions, so proper dopamine levels are... 

Nerve cells (neurons) are specialized so that at one end there is a flared stracture termed the dendrite. At the dendrite, the neuron is able to process chemical signals from other neurons and endocrine hormones. H the signals received at the dendrite end of the neuron are of a sufficient strength, and priperly timed, they are transformed into action potentials that sweep down the neural cell body (axon) frc n the dendrite end to the other end of the neuron, the presynaptic portion of the axon that ends at the next synapse (the extra cellular gap between neurons)in the neural pathway. The arrival of the action potential at the pre aptic terminus causes the release of ions and chemicals (neurotrananitters) that travel... 

The function of the nervous system depends on communication between nerve cells (neurons). Structurally, all neurons are composed of a cell body, dendrites, axon, and terminal boutons (see figure 3-C). Dendrites are short, terminally branched structures projecting out from the cell body. They receive and conduct information to the cell body there may be one or several dendrites on each cell. Extremely fine projections on the dendrites are called dendritic spines. The axon is a single long fiber that ends in enlarged structures called terminal boutons. The axon serves to conduct impulses away from the cell body. 

Hypotension (low blood pressure) and ischemia (restricted blood flow) associated with exposure reduces the delivery of oxygen to tissues and cells and may lead to sever damage and/or death of nerve cells (neuronal necrosis). 

The central nervous system is made up of billions of individual nerve cells (neurons). Transmission of information within a neuron is by electrical means and the transmission of such nerve impulses can be recorded with suitable equipment. However, most transmission of information between neurons or between neurons and effector systems (muscles, for example) is by chemical means. The first chemical... 

What, then, are these pathways in the central (brain) and peripheral nervous systems, which are common to all species, and on which spider toxins can exert their effects Nerve cells (neurons) are the functional units of the brain and have membranes which are "excitable" over their entire surface. Neurons communicate with each other by releasing chemical substances across the gap... 

Neurotransmitters, the chemical messengers of the nervous system, carry nerve impulses from one nerve cell (neuron) to another. A neuron consists of a bulbous body called the soma (or cell body) attached to a long stemlike projection called an axon (see I Figure 6.5). Numerous short extensions called dendrites are attached to the large bulbous end of the soma, and filaments called synaptic terminals are attached to the end of the axon. At low magnification, the synaptic terminals of one neuron s axon appear to be attached to the dendrites of an adjacent neuron. However, upon further magnification, a small gap called a synapse is visible between the synaptic terminals of the axon and the dendrites of the next neuron. 

Neurotransmitters are the chemical messengers of the nervous system. They carry nerve impulses from one nerve cell (neuron) to another. The most important neurotransmitters are acetylcholine and three other amines norepinephrine, dopamine, and serotonin. 

The human brain is a very complex organ. It contains around 10 neurons (that is, the basic processing, or nerve, cell). Neurons consist of two types (Beale and Jackson, 1990) ... 

During development of the nervous system, neurite outgrowth is necessary for the formation of connections between nerve cells. Neurons are highly polarized cells that send out distinct processes, axons, and dendrites however, the molecular regulation of the differential growth of these processes remains incompletely understood. Primary cultures of rat hippocampal neurons have been used to study many aspects of neuronal cell... 

Nervous system consists of the central nervous system (CNS) and the peripheral nervous system (PNS). CNS mainly includes the brain and the spinal cord, which receives sensory information and coordinates body activities. PNS mediates connections between the CNS and the peripheral of the body. In order to conduct information throughout the body, the nervous system possesses a large number of communication units by using electrical signals through nerve cells (neurons). While nerves are bundles of fibers made up of neurons through which sensory stimuli and motor impulses pass between the brain and other parts of CNS and other parts of the body. If nerves are severely damages, they can t... 

Biological neural networks can, on the other hand, perform these tasks apparently effortlessly using myriads of nerve cells (neurons). Current estimates place the number of neurons in the human brain at 10 . They are organized in a complex unmapped interconnection structure in which each neuron may be connected via variably weighted links (s3mapses) to several thousand other neurons. The information learnt by the network is stored in these s)mapses and processed collectively by the whole net This densely interconnected structure allows the brain to explore many competing hypotheses simultaneously. 

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