Hormones are chemical messengers that are secreted or released into our bloodstream, by specific organs known as glands. Actually there are other types of signalling molecules typically not called hormones (via wi-fi) such as paracrine (act om adjacent cells, via ethernet cable) and autocrine (act on cell of origin)
Hormones regulate or control many processes in our body, including blood glucose levels, water content in blood, general growth and blood pressure, just to name a few. As an example, Thyroxine, which is a hormone secreted by the thyroid gland, helps to regulate metabolism. Several hormones are secreted by the pituitary gland, located right below the hypothalamus in your brain. Instructions are given by the hypothalamus to the pituitary gland, according to current conditions in our body.
Hormones are chemical messengers that are secreted or released into our bloodstream, by specific organs known as glands.The secreted hormones, travel through the bloodstream to target organs, where specific responses are directly produced, or stimulates or causes the target organ to secrete its own hormones. We can think of this like a post office system. Hormones or post, must reach the correct target organs or addresses for the right response to occur. Feeling thirsty? When the hypothalamus detect low levels of water in blood, it signals or tells the pituitary gland, to release a hormone called the antidiuretic hormone or ADH into your bloodstream. ADH travels to your kidneys, in this case the target organ, and causes water to be absorbed so urine becomes more concentrated and output is decreased.
Drinking more water increases the water content in your blood, which then causes the hypothalamus to signal the pituitary gland, to secrete less ADH. Less ADH means the kidneys will absorb less water, causing urine to become less concentrated and output is increased. Ever felt suddenly frightened? When threatened, the brain activates neurons that stimulate the adrenal gland, located right above your kidneys, to rapidly secrete adrenaline. Adrenaline then acts on your heart and lungs, to increase heart rate and breathing rate. This, along with other physiological responses, is known as the Fight or Flight response and get activated very quickly. At the same time the hypothalamus signals the pituitary gland, to secrete the adrenocorticotropic hormone, which travels to the adrenal glands to secrete a hormone called Cortisol. Cortisol acts on target organs to allow the body to adapt to long-term stress. So to review, hormones are chemical messengers secreted by glands into the bloodstream and produce specific response when they reach the target organ..
As found on Youtube