Harmless and beneficial bacteria far outnumber harmful varieties. Thousands of bacterial species live commensally in humans, and many provide health benefits to humans, aiding in digestion, for example, or helping to prevent the establishment of colonies of pathogenic bacteria.armless and beneficial bacteria far outnumber harmful varieties. Thousands of bacterial species live commensally in humans, and many provide health benefits to humans, aiding in digestion, for example, or helping to prevent the establishment of colonies of pathogenic bacteria.
ADH (Antidiuretic Hormone) The brain and kidneys regulate the amount of water excreted by the body. When the blood volume is low, the concentration of solutes in the blood is high. When the hypothalamus senses this low blood volume and increased serum osmolality it synthesizes ADH, a small peptide molecule.
Direct control of water excretion in the kidneys is exercised by vasopressin, or anti-diuretic hormone (ADH), a peptide hormone secreted by the hypothalamus. ADH causes the insertion of water channels into the membranes of cells lining the collecting ducts, allowing water reabsorption to occur.irect control of water excretion in the kidneys is exercised by vasopressin, or anti-diuretic hormone (ADH), a peptide hormone secreted by the hypothalamus. ADH causes the insertion of water channels into the membranes of cells lining the collecting ducts, allowing water reabsorption to occur.