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 occurs from genetic changes that cause abnormalities in hemoglobin molecules: 1  Hemoglobin A (HbA) . 2  HbA is the hemoglobin molecule found in normal red blood cells during childhood and adulthood. 3  People who do not have sickle cell disease generally have this type of hemoglobin in their blood cells.ickle cell disease (also called sickle cell anemia) is an inherited blood disorder that affects red blood cells. The sickle cell gene causes the body to produce abnormal hemoglobin. In sickle cell disease, the hemoglobin clumps together, causing red blood cells to become stiff and develop a C-shaped (âsickleâ) form.