How hormones work Compared with nerves, hormones tend to act more slowly and also to spin out their activity over a much longer time. In general, hormones tend to be concerned with controlling or influencing the chemistry of the target cells, for example, by determining the rate at which they use up food substances and release energy, or whether or not these cells should produce milk, hair or some other product of the body's metabolic process-es. The body makes many other hormones which act much nearer to their point of produc-tion. One example of such a local hormone is secretin, which is made in the duodenum in response to the presence of food. Other examples of local hormones, or transmitters, include the substance acetylcholine, which is made every time a nerve passes a message to a muscle cell, telling it to contract.
All hormones are active in very small amounts.
In some cases, less than a millionth of a gram is enough for a task to be car-ried out. The sex hormones and the hormones made by the outer part or cortex of the adrenal gland are all steroid hormones. Insulin is a protein and the thyroid hormones are manufactured from a protein base and are protein derivatives. All rights reserved. Powered by Please direct all your technical queries, comments, suggestions to us .