These really are two different systems, but the endocrine system has a particular impact on the reproductive system — especially in terms of where disruptions often show up — so I’m going to try to address them together.
We all know what the reproductive system is meant to do. It facilitates reproduction. This is a complex process that can easily fill entire books, but let’s see if we can put it in a nutshell without veering too far away from “family friendly.” (I like to keep “mature” topics separate, just in case little eyes are peeking over your shoulder!)
Male Reproductive System
The male reproductive system is comprised primarily of the seminal vesicles, the testicles, the vas deferens, and the urethra (which does double-duty, serving both reproductive and urinary systems). In short, the seminal vesicles produce semen, the testicles produce sperm, which travel through the vas deferens, and at the appropriate time, the two combine and are pushed through the urethra.
Female Reproductive System
The female reproduction is somewhat more complex. The primary parts of the female reproductive system are the ovaries, fallopian tubes, and uterus. Over the course of roughly a lunar month, a series of activities occur. An egg matures in an ovary, then bursts free and passes through the adjacent fallopian tube into the uterus. In the meantime, the lining of the uterus has been building up in preparation.
If the egg is fertilized, it implants in the uterus. If it is not, the lining of the uterus is shed in a process called menstruation, and the cycle begins again.
In most instances, if a man’s reproductive system is not functioning optimally, he will only become aware of this when he and his partner attempt to conceive and do not. While infertility might be a woman’s first clue that her reproductive system is under-functioning, the tangible nature of her cycle means it might not be.
A normal menstrual cycle should be roughly four weeks long, with ovulation occurring roughly two weeks prior to the onset of menstruation. The menstrual period should be around 3-7 days, not excessively light or excessively heavy, and without severe unpleasant symptoms such as significant pain. There are normal variations, but a cycle that is very much longer or shorter than four weeks, very heavy or very light, or of an unusual duration, probably indicates that things are not as balanced as they could be.
As nice as it might be to experience no period at all, this is not normal among women who have already had an established cycle, are not breastfeeding, and are not approaching (or past) menopause. (A single period may be skipped on rare occasions due to unusual stress or illness.)
The endocrine system consists of all the various glands of the body that produce hormones. These include the hypothalamus, pituitary gland, pineal gland, pancreas, ovaries, testes (testicles), thyroid gland, parathyroid gland, and adrenal glands.
The hypothalamus is part of the brain. It controls the pituitary gland. The pituitary gland, in turn, directs most of the other glands. It’s a little like a composer (the hypothalamus) giving a set of music to a conductor (the pituitary gland). That conductor then tells all the others when to play their parts, how loudly, etc. If one instrument is too loud, too soft, out of tune, or plays at the wrong time, the music won’t sound right; it will be a dissonant mess.
That’s not unlike what happens in the body when a gland produces too much or too little of a given hormone, or produces it at the wrong times. It’s important for all of the glands to function accurately and in the proper balance with each other, or things go awry.
Because hormones contribute to so many different bodily functions, a disruption in the endocrine system, like a disruption in the nervous system, can take many forms. You should be sleeping well (as a general rule), on an even keel emotionally, with appropriately-balanced responses to stress, good digestion, good energy levels, a healthy libido, and a well-functioning reproductive system. If any of those things are not happening, hormone imbalances could be the culprit.