Numerous substances produced by the body transmit messages and influence metabolism, growth, and reproduction. They are formed in many places in the body and released into the blood or tissues. They are involved in a finely tuned regulatory system. Disturbances can be the cause of a wide variety of complaints and diseases.
Hormones serve to transmit information within the body. They are usually produced by specialized cells in hormone glands and released into the blood. Since they move with the bloodstream or through tissue, they take much longer than nerves to reach their destination. Once there, they bind to specific receptors and initiate a specific chemical reaction, or they move into the cell and activate genes in the nucleus.
Classification-diversity in a complex system
Hormones can be classified based on several criteria:
- Site of formation
- Structure
- Place of action and function
Place of education
Some forms are formed by nerve tissue, for example in the brain and are called neurosecretory hormones. The most common are glandular hormones, which are formed and released in endocrine glands such as the adrenal gland, pancreas and thyroid.
The third type is tissue hormones, which are produced in tissues that perform many other functions and often act directly there. One example is gastrin, which is formed in the stomach for digestion. The place of origin is often also reflected in the name, for example thyroid hormones.
Structure
Hormones can originate from proteins (peptide hormones, for example, insulin) or be formed from steroids or fatty acids (steroid hormones, for example, estrogen).
Site of action and function
The supreme regulatory authority is the hypothalamus in the diencephalon. It checks the hormone concentration in the blood and decides whether it needs to be boosted or curbed. To do this, it sends messengers to subordinate agencies located in the same house in the pituitary gland: Releasing hormones spread the message that work must continue, inhibiting hormones ensure that overtime is worked off.
If the signs are pointing to work, field workers swarm out into the blood, each to the region for which he or she is responsible. They are easy for everyone to recognize by their name: the ending “-trop” shows that they come from the anterior pituitary lobe, the first part designates the area of responsibility, or the hormones that are produced there. Unfortunately, only experts understand this name – who else knows that thyroidea is the thyroid gland, so thyroetropin acts on it? That’s why there are nicknames – abbreviations like ACTH, which are easier to remember and pass the lips better (than, for example, adrenocorticotropic hormone).
In any case, these friendly ladies and gentlemen carry the good news to the factories that short-time work is over. So production is cranked up there and hormones roll off the assembly line again. These reach the end customer via the – sometimes clogged – arteries and unfold their direct effect there by proclaiming their glad tidings. Market researchers from the upper regulatory authority check the number of hormones in circulation as well as the reaction of consumers and have the circuit adjusted accordingly. Incidentally, market research is also carried out at the lower levels and thus production is often already adjusted through the small official channels before the center of power finds out about it. As in the market economy: overall, it’s all a matter of supply and demand.