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A neuron, neurone, [1] or nerve cell is an excitable cell that fires electric signals called action potentials across a neural network in the nervous system.Neurons communicate with other cells via synapses, which are specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric signal from the presynaptic neuron to the target cell through the ...
They do, however, have homologs of many genes that play key roles in synaptic function. Recent studies have shown that sponge cells express a group of proteins that cluster together to form a structure resembling a postsynaptic density (the signal-receiving part of a synapse). [13] However, the function of this structure is currently unclear.
Complete neuron cell diagram Nervous systems of sponges (porifera) and placozoans. When we think of intercellular communication we often use our nervous system as a point of reference. Nerves made up of many cells in vertebrates are typically highly specialized in form and function usually being the most complex in the brain. They ensure rapid ...
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to ...
The communication between nerve cells make use of two different methods; some of the neurons are found to have synaptic connections, but the neurons in the nerve net are highly distinctive by being fused into a syncytium, rather than being connected by synapses. Some animals outside ctenophores also have fused nerve cells, but never to such a ...
The enteric nervous system functions to control the gastrointestinal system. Nerves that exit from the brain are called cranial nerves while those exiting from the spinal cord are called spinal nerves. The nervous system consists of nervous tissue which, at a cellular level, is defined by the presence of a special type of cell, called the ...
The dopaminergic cell groups and pathways make up the dopamine system which is neuromodulatory. Dopaminergic neurons (dopamine-producing nerve cells) are comparatively few in number—a total of around 400,000 in the human brain [40] —and their cell bodies are confined in groups to a few relatively small brain areas. [41]
The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike central nervous systems, where neurons are typically grouped together, neurons found in nerve nets are spread apart. This nervous system allows cnidarians to respond to physical contact. They can detect food and other chemicals in a rudimentary way.