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The Neuromuscular Junction
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The synaptic bouton becomes embedded in a small, shallow depression in the muscle, where it is closely apposed to the muscle membrane but separated from it by a synaptic cleft (Figure 5.2). The muscle membrane in the synaptic region is termed the endplate, or the motor endplate. The synaptic bouton contains an abundance of mitochondria and synaptic vesicles of 40–50 nm diameter that are filled with the neurotransmitter acetylcholine (ACh). The endplate is folded into many troughs about 500 nm deep and about 100 nm wide separated by crests of about the same width. The width of the synaptic cleft at the crests of the endplate is about 20–60 nm. Facing the opening of the troughs are thickened regions of the synaptic bouton referred to as active zones. These zones have a high concentration of vesicles, with many of these vesicles touching the inner side of the membrane of the synaptic bouton.
Bio-Inspired NoC Fault-Tolerant Algorithms
Published in Muhammad Athar Javed Sethi, Bio-Inspired Fault-Tolerant Algorithms for Network-on-Chip, 2020
Neurons are connected through synaptic junctions that are formed by connections between the dendrites of one neuron and the axon terminal of another neuron, as shown in Figure 4.2. The input to neurons comes from dendrites, and the output follows through axons to the axon terminal. The axon is covered by a myelin sheet, which protects the signals traveling inside the axon. This sheet also increases the speed of the electrical signals traveling through the axon. The neuron’s cell body is called the soma, which contains the nucleus. The neuron on one side of the junction is the presynaptic junction neuron, while the one on the other side is called a postsynaptic junction neuron. The synaptic cleft separates the axon terminal and dendrites. Neurons only receive a signal from those neurons through which they are connected. After summing all the inputs coming from various neurons, the neurons trigger the output if the signal strength is above a certain threshold. This output is in a chemical form as the electrical signal flows through the axon (Breedlove, Watson, and Rosenzweig 2007).
Mass Transfer in Binary Systems without Bulk Flow: Unsteady-State Examples
Published in İsmail Tosun, Fundamental Mass Transfer Concepts in Engineering Applications, 2019
6.28 The nerve cells in the brain that are responsible for communication are called neurons. A neuron mainly consists of three parts: dendrites, an axon, and a cell body (soma). Neurons receive input from other cells via their dendrites. Neurons talk to each other by sending an electrical message, called an action potential, throughout the entire axon. The junction between an axon and a neighboring dendrite is called a synapse, and the tiny opening between neurons is called the synaptic cleft. The axon ends in an enlargement known as the presynaptic terminal, containing tiny vesicles filled with molecules, such as acetylcholine, dopamine, glutamate, and serotonin. These substances are known as neurotransmitters. When an electrical signal arrives at the presynaptic terminal, the neurotransmitters are released from the vesicles into the synaptic cleft, where they diffuse to the postsynaptic surface and bind to their specific receptors.
Fatigue: Is it all neurochemistry?
Published in European Journal of Sport Science, 2018
Neurotransmitters are chemical compounds that act as messengers within our body and brain. They are released from nerve terminals into the synaptic cleft in order to bind receptor sites at a post-synaptic neuron in order to produce their effect that can be either inhibitory or excitatory. There is an abundance of different neurotransmitters that can be classified in different types such as amino acids, peptides and monoamines. Some examples of important neurotransmitters are serotonin, dopamine (DA), noradrenaline (NA), gamma-aminobutyric acid, glutamate, acetylcholine and adenosine. The present review will focus on the monoamines serotonin, DA and NA.
Biological function simulation in neuromorphic devices: from synapse and neuron to behavior
Published in Science and Technology of Advanced Materials, 2023
Hui Chen, Huilin Li, Ting Ma, Shuangshuang Han, Qiuping Zhao
Synapse is the specialized site where one neuron communicates with another, which consists of a presynaptic membrane, synaptic cleft, and postsynaptic membrane. The average neuron forms several thousand synaptic connections and receive a similar number with its neighboring neurons. Synaptic transmission is basic to the brain functions, such as perception, learning and memory. Two modes of synaptic transmission are found in all neurons: electrical and chemical. Based on this, the synapses are divided into electrical and chemical synapses (Figure 1(c)).