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.
sex-linked disorder - any disease or abnormality that is determined by the sex hormones; hemophilia is determined by a gene defect on an X chromosome. bleeder's disease, haemophilia, hemophilia - congenital tendency to uncontrolled bleeding; usually affects males and is transmitted from mother to son.
Your Guide to Sexually Transmitted Diseases. Sexually transmitted diseases, commonly called STDs, are diseases that are spread by having sex with someone who has an STD. You can get a sexually transmitted disease from sexual activity that involves the mouth, anus, vagina, or penis.