More images of melasma ... Melasma is more common in women than in men; only 1-in-4 to 1-in-20 affected individuals are male, depending on the population studied. It generally starts between the age of 20 and 40 years, but it can begin in childhood or not until middle age.
Which structure in the kidneysâ nephrons is mainly responsible for the filtration of the blood? A. collecting duct B. loop of Henle C. glomerulus D. Bowmanâs capsule.pecialized cells regulate the expression of genes because they A. do not want the genes to become worn out. B. cannot control the translation of proteins. C. do not carry the complete genetic code in their nuclei. D. do not need the proteins that are specified by certain genes.
Points to Remember. 1  Every day, the two kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid. 2  The kidneys are important because they keep the composition, or makeup, of the blood stable, which lets the body function. Each kidney is made up of about a million filtering units called nephrons. The nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process.