The contraction produced can be described as a twitch, summation, or tetanus, depending on the frequency of action potentials. In skeletal muscles, muscle tension is at its greatest when the muscle is stretched to an intermediate length as described by the length-tension relationship. Smooth and cardiac muscle contractions are myogenic and can be modulated by the autonomic nervous system.
Citation: Pray, L. (2008) Sex-linked diseases: the case of Duchenne muscular dystrophy (DMD). Nature Education 1(1):132. Prenatal diagnostic testing can now determine whether a fetus carries a debilitating or fatal sex-linked mutation.
Sexually transmitted diseases (STDs) are infections that are passed from one person to another through sexual contact. The causes of STDs are bacteria, parasites, yeast, and viruses. There are more than 20 types of STDs, including. Chlamydia. Genital herpes. Gonorrhea. HIV/AIDS.