The Eustachian tube is normally collapsed, i.e. closed, but opens upon positive pressure and swallowing. There are four muscles that are responsible for Eustachian tube functioning. The tensor and levator veli palatini muscles open the tube, by contracting the muscles of the soft palate.
Sickle Cell. These are the sickle-shaped blood cells of someone with sickle cell anemia, a genetic disease common among those of African descent. Sickle cell anemia is the result of a point mutation, a change in just one nucleotide in the gene for hemoglobin.This mutation causes the hemoglobin in red blood cells to distort to a sickle shape when deoxygenated. The sickle-shaped blood cells clog in the capillaries, cutting off circulation.ome well-known inherited genetic disorders include cystic fibrosis, sickle cell anemia, Tay-Sachs disease, phenylketonuria and color-blindness, among many others. All of these disorders are caused by the mutation of a single gene.
Sickle cell disease causes red blood cells to form into a crescent shape, like a sickle. The sickle-shaped red blood cells break apart easily, causing anemia. Sickle red blood cells live only 10-20 days instead of the normal 120 days.eople who inherit only one sickle hemoglobin gene are carriers (sickle cell trait) and do not have anemia or painful sickle cell crises. They may, though, have a slightly higher incidence of certain conditions such as blood in the urine or urinary tract infections. About 2 million Americans have sickle cell trait.