The penis plays an important role in sex, but its day job is liquid waste management – 800-2000 mL of urine leaves the body through the penis daily, while one ejaculate contains a scant 2-5 mL. More fascinating facts about semen: did you know the seminal vesicles – those rabbit ears atop the prostate – contribute the most liquid by volume to semen? Now ya know about stuff that comes out of your penis.
Relaxin is a polypeptide hormone released by the corpus luteum (ovary), uterus, placenta and mammary gland. It plays an important role in pregnancy and childbirth, but there's still much mystery around the function of this multi-tasking hormone. Some of what we do know is that relaxin prevents uterine contractions early in pregnancy to avoid premature childbirth. During childbirth, it helps the cervix dilate and the vagina to soften and widen. In blood circulation, levels of relaxin rise after ovulation and lower again if pregnancy does not occur.
Relaxin has also been discovered in men, although its function is even more unclear in men. Secreted by the prostate, it is found in semen. It is thought to assist the movement of sperm cells in the semen.
Recent findings show that relaxin also decreases tissue fibrosis in the heart, lungs, kidney and liver. It supports the growth of new blood vessels, helps heal wounds and is anti-inflammatory. Even though researchers are still figuring out what exactly it does, relaxin seems to be a pivotal hormone in various systems of the body, aside from just reproductive. Cool!