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Acetylcholine (Ach)

/əˌsētlˈkōˌlēn/  /ˌasitl-/ 1. An organic, polyatomic cation that acts as a neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans. (wikipedia.org) 2. Acetylcholine is one of many neurotransmitters in the autonomic nervous system (ANS) and is the only neurotransmitter used in the motor division of the somatic nervous system (sensory neurons use glutamate and various peptides at their synapses). Acetylcholine is also the principal neurotransmitter in all autonomic ganglia. (wikipedia.org) 3. (Biochemistry) A neurotransmitter in humans and other animals. It is an ester of acetic acid and choline with chemical formula CH3COOCH2CH2N+(CH3)3. (wiktionary.com) 4. (Chemical, Neurology, physiology) A chemical found in vertebrate neurons that carries information across the synaptic cleft, the space between two nerve cells. (biology-online.org) 5. A compound that occurs throughout the nervous system, in which it functions as a neurotransmitter. (Google...

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Actin

Noun 1. (Science: cell biology) A filamentous proteins (42 kD) involved in muscle contraction in both smooth and striated muscle and also serves as an important structural molecule for the cytoskeleton of many eukaryotic cells. (biology-online.org) 2. A globular, roughly 42-kDa multi-functional protein found in all eukaryotic cells (the only known exception being nematode sperm), where it may be present at concentrations of over 100 μM. (Wikipedia.org) 3. One of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans. Actin is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. Thus, actin participates in many important cellular processes, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape. (Wikipedia.org) 4. Filamentous Proteins that are the main constituent of the thin filaments of Muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 Amino Acids long. This is known as globular or G-actin. In conjunction with Myosins, actin is responsible for the contraction and Relaxation of Muscle. (online-medical-dictionary.org) 5. A protein found in all eukaryotic cells, forming...

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Active immunity

1. Immunity induced in the host itself by antigen and lasts much longer, sometimes lifelong. (wikipedia.org) 2. A form of acquired immunity in which the body produces its own antibodies against disease-causing antigens. (wordnetweb.princeton.edu) 3. The immunity that results from the production of antibodies by the immune system in response to the presence of an antigen. (Google Dictionary) 4. A type of immunity or resistance developed in an organism by its own production of antibodies in response to an exposure to an antigen, a pathogen or to a vaccine....

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Active Transport

Noun 1. The movement of a substance across a cell membrane against its concentration gradient (from low to high concentration). In all cells, this is usually concerned with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. (wikipedia.org) 2. The movement of a chemical substance by the expenditure of energy against a gradient in concentration or in electrical potential across a plasma membrane. (merriam-webster.com) 3. The movement of ions or molecules across a cellular membrane from a lower to a higher concentration, requiring the consumption of energy....

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Active transport

1. A kind of transport wherein ions or molecules move against a concentration gradient, which means movement in the direction opposite that of diffusion – or – movement from an area of lower concentration to an area of higher concentration. Hence, this process will require expenditure of energy, and the assistance of a type of protein called a carrier protein. (biology-online.org) 2. The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy. (online-medical-dictionary.org) 3. The movement of a substance across a cell membrane against its concentration gradient (from low to high concentration). In all cells, this is usually concerned with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids....

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