Hormones
Hormones are chemical substances that help to regulate processes in the body. Hormones are secreted by glands and travel to their target organs in the bloodstream. Several hormones are involved in the female menstrual cycle. Hormones can be used to control human fertility and have advantages and disadvantages.
There are four types of hormones in most vertebrates. They are grouped by the chemicals from which they are made
- Steroid hormones – these are made from cholesterol.
- Eicosanoids:– hormones made from lipids.
- Amino acid derived. Melatonin works on the brain, and thyroxine acts on almost all cells in the body.
- Peptides, polypeptides and proteins – small peptide hormones include TRH and vasopressin.
