Hormones are message substances that affect the activity of certain target cells in the body. Hormones change the activity of certain target cells of the body. Hormones change the activity of target cells by binding to receptors of the target cells. Changing the activity of the target cells ultimately aims to maintain the homeostasis of the body. The hormone system therefore looks very much like the nervous system. Both systems maintain homeostasis. Hormones, however, have a long-term effect and usually have no direct influence on homeostasis where the nervous system does. Hormones are often transported through the blood, where the nervous system works with neurotransmitters. Hormones can consist of proteinaceous, or fatty substances. Human Growth Hormone Releaser
The similarities and differences between hormone system and nervous system
The effects of the hormone system and nervous system are very similar. Both systems maintain the homeostasis of the body through negative feedback systems. Negative feedback means that the decrease, or increase of a certain substance in the body, or process in the body, causes an increase or decrease of a certain hormone, or neurotransmitter, in order to maintain balance. A drop in blood pressure is, for example, observed by baroreceptors in the aortic wall, among others. In response to this, the nervous system secretes noradrenaline, causing the vessels to contract and blood pressure to rise.
There are also differences, however, the nervous system directly influences homeostasis and the hormone system does not. The effects of the nervous system on homeostasis are short-lived and of the long-term hormone system and the nervous system works with neurotransmitters and the hormone system with hormones.
General forms and effect of hormones
Hormones are messenger substances that bind to receptors to target cells. These receptors can be in different locations of the target cell. The receptors can be on the outside of the cell membrane, inside of the cell membrane, the mitochondria and the cell nucleus. Depending on the type of hormone, the hormone binds to a certain receptor. When the hormone binds to the receptor, a reaction is initiated that changes the activity of the target cell. Roughly hormones can be divided into two groups. These groups are the group of hormones consisting of one or more amino acids (amino acid derivatives and peptide hormones) and the group of hormones that consist more of fatty substances, such as steroids, thyroid hormones and eicosanoids.
Operation of hormones consisting of amino acids (amino acid derivatives and peptide hormones)
The hormones that consist of amino acids can not pass through the cell membrane, because the cell membrane consists of fatty substances. The hormones that consist of amino acids therefore bind to receptors on the outside of the cell membrane. The receptor on the outside of the cell membrane then activates G protein.