In females, the excitement phase can last from several minutes to several hours. The onset of vasocongestion (the swelling of bodily tissues caused by increased vascular blood flow) results in swelling of the woman’s clitoris, labia minora and vagina. The muscle that surrounds the vaginal opening grows tighter and the uterus elevates and grows in size. The vaginal walls begin to produce a lubricating organic liquid. Meanwhile, the breasts increase slightly in size and nipples become hardened and erect.