juxtaglomerular apparatus (JGA) A region of tissue found in each nephron in the kidney that is important is regulating blood pressure and body fluid and electrolytes. It is located where the distal convoluted tubule passes close to the afferent arteriole supplying the Bowman's capsule, near to the glomerulus, and contains two types of specialized cells. Large smooth muscle cells in the wall of the afferent arteriole form the juxtaglomerular cells, or granular cells; these contain granules of the proteolytic enzyme renin, which are released when the juxtaglomerular cells detect decreased blood pressure in the arteriole. The JGA also includes chemoreceptor cells of the adjacent region of the distal tubule, which form a tightly packed array called the macula densa. This detects low concentrations of sodium ions in the filtrate inside the kidney tubule (indicative of reduced plasma sodium levels) and triggers release of renin from the juxtaglomerular cells. Release of renin into the bloodstream leads to increased levels of angiotensins, which raise blood pressure and also stimulate the secretion of aldosterone from the adrenal cortex and antidiuretic hormone from the posterior pituitary. Aldosterone promotes reabsorption of sodium ions from the distal tubule, and antidiuretic hormone promotes water reabsorption.
More From encyclopedia.com
Tumor Necrosis Factor , Definition Tumor necrosis factor is a protein produced by several of the body's cell types, such as white blood cells, red blood cells, and other cel… T Cell , T cell T cell (T lymphocyte) Any of a population of lymphocytes that are the principal agents of cell-mediated immunity. T cells are derived from the… Exocytosis , Exocytosis is the cellular process in which intracellular vesicles in the cytoplasm fuse with the plasma membrane and release or "secrete" their cont… Cells , Cells Plants are multicellular organisms composed of millions of plant cells. Although individual cells may differ greatly from each other in mature… Immune System , Definition The immune system is composed of cells, organs, tissues, and molecules that protect the body from disease. The term "immunity" comes from… Cell , Cell The cell is the basic unit of a living organism. In multicellular organisms (organisms with more than one cell), a collection of cells that work…
About this article
Updated About encyclopedia.com content Print Article
You Might Also Like