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Non-mast cell histamine is found in several tissues, including the hypothalamus region of the brain, where it functions as a neurotransmitter. Another important site of histamine storage and release is the enterochromaffin-like (ECL) cell of the stomach .
Histamine is a weak base (a compound able to react with a hydrogen ion to form an acid) that can link with acid groups within the granules of the mast cells. [8] The mechanism of the displacement theory. The crux of this theory lies in the assumption that histamine liberators release histamine by displacing it from cells.
Finally, H 4 plays roles in mast cell chemotaxis and cytokine production. [17] In humans, HDC is primarily expressed in mast cells and basophil granulocytes. Accordingly, these cells contain the body's highest concentrations of histamine granules. Non-mast cell histamine is also found in the brain, where it is used as a neurotransmitter. [21]
The histamine receptor H 2 belongs to the rhodopsin-like family of G protein-coupled receptors. It is an integral membrane protein and stimulates gastric acid secretion. It also regulates gastrointestinal motility and intestinal secretion and is thought to be involved in regulating cell growth and differentiation. [ 6 ]
The stratum granulosum (or granular layer) is a thin layer of cells in the epidermis lying above the stratum spinosum and below the stratum corneum (stratum lucidum on the soles and palms). [1] Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer.
The loosely packed cells of root cortex allow movement of water and oxygen in the intercellular spaces. [4] One of the main functions of the root cortex is to serve as a storage area for reserve foods. [4] The innermost layer of the cortex in the roots of vascular plants is the endodermis. The endodermis is responsible for storing starch as ...
The histamine receptors are a class of G protein–coupled receptors which bind histamine as their primary endogenous ligand. [1] [2] Histamine receptors are proteins that bind with histamine, a neurotransmitter involved in various physiological processes. There are four main types: H1, H2, H3, and H4.
Histamine also promotes angiogenesis. [6] Antihistamines suppress the histamine-induced wheal response (swelling) and flare response (vasodilation) by blocking the binding of histamine to its receptors or reducing histamine receptor activity on nerves, vascular smooth muscle, glandular cells, endothelium, and mast cells.