- [Voiceover] Now looking at the gonads, we'll start with the testes, so starting on the male side of things. The functions of testosterone and several other androgens actually start before birth. Before birth, so in utero, they're responsible for development of the external male genitalia. So we're talking about the penis, the scrotum, the testes themselves. But after birth and once he's at puberty, really in the stages of puberal is helping to develop the normal functionality of sperm, It's helping to develop the male sex drive. It's helping make sure the male reproductive organs are functioning properly. But it also regulates all the secondary sexual characteristics that are typical of a male. So there's quite a few different functions for testosterone and this handful of other androgens. Now small amounts of androgens are produced by the adrenal glands, which is kind of interesting because that means the adrenal glands are actually producing some of the sex hormones. As adrenal glands in both male and female, not a lot but still just a little bit's being produced of these androgens in both genders. On the female side of things, look at the ovaries and how they produce estrogen and progesterone. The first hormone, estrogen, is really initiating development of the secondary sexual characteristics. So whatever is typical of a secondary female sexual characteristics, so they get all of the development of the mammary tissue, the breasts, the kind of settling of fat deposits around the body. It also helps to regulate the menstrual cycle. Progesterone, on the other hand, also helps to regulate the menstrual cycle. So both hormones have their specific roles in controlling and regulating the menstrual cycle. But we have to talk about a couple of other disorders. Now I've already mentioned diabetes insipidus before, now this is diabetes mellitus. In diabetes mellitus, there's actually two types, type 1 and type 2. Type 1 is going to be the insulin-dependent diabetes. That's only about 5-10% of all cases. The individual has an inadequate production of insulin, so the way it's treated is to give insulin injections. While type 2, that's the non-insulin-dependent. It's about 90-95% of all the cases of diabetes mellitus. What happens is the individual is insulin resistant; the insulin's there, it's just not quite working properly. The thyroid gland has a problem. Looking at hypothyroidism. Well "hypo" means not enough, so hypothyroidism means the thyroid gland is underactive. It's not producing enough hormones. So in children if they have hypothyroidism, that can be the disorder cretinism. In the disorder cretinism, the entire body slows in growth, brain development is altered, puberty can have a long delayed onset. So cretinism. If an adult goes into a hypothyroidism state, then that can result in edema. Edema is the swelling or collection of fluid in the body. They can look lethargic, just slowing down, relaxing more. Weight gain, low BMR. BMR is basal metabolic rate. If you have a low basal metabolic rate that means the body itself isn't doing a whole lot. On the flip side, hyperthyroidism means you have an overactive thyroid, you have too much. This will increase your BMR or basal metabolic rate. It'll cause hyperactivity and nervousness, agitation, weight loss, the person will be very fidgety, hard to sit still. One example of hyperthyroidism is Grave's disease. Now this is the autoimmune form of hyperthyroidism, so it's not a true, exact type but is autoimmune-based hyperthyroidism. Autoimmune is when your own body attacks your own body cells. So hypothyroidism, not enough; hyperthyroidism, too much.