Types of hormones and their functions in the human body

Hormones are molecules of various types that are produced in the secretory or endocrine glands.. Together with the nervous system, they are responsible for acting, feeling and thinking like we do.

The different types of hormones are released in the blood vessels or in the interstitial space where they circulate on their own (bioavailable), or are associated with certain proteins to reach the target organs or tissues (or targets) where they act. Hormones are part of the group of chemical messengers, which also includes neurotransmitters such as dopamine, serotonin, or GABA.

    The most important functions of hormones

    The functions of hormones are varied, but whether a hormone comes from a plant, invertebrate or vertebrate animal, it is responsible for regulating several important functions. However … Why are hormones so important?

    One of the functions they perform is to ensure adequate growth. In humans, the pituitary gland is responsible for the secretion of growth hormones during childhood and adolescence. In invertebrate animals, such as insects, growth hormone is involved in the moulting or renewal of integuments (body coatings), that is, the detachment of the outer layer. In the case of plants, several hormones are responsible for the proper growth of roots, leaves and flowers.

    In addition to this very important function, hormone functions include:

    • Dynamic action on various organs
    • They activate or inhibit enzymes
    • Appropriate development
    • the reproduction
    • Sexual characteristics
    • Energy consumption and storage
    • Blood levels of fluids, salt and sugar

    Coordination with the brain

    Another fact to keep in mind is that some biological processes are less expensive if, instead of creating a constant torrent of electric fire by neurons to activate certain areas of the body, it is enough to we release types of hormones and let them get carried away by the blood until you reach your destination. This way we get an effect that lasts for several minutes while our nervous system can take care of other things.

    In this sense, hormones work in coordination with the brain to turn parts of the body on and off and thus ensure that we adapt to circumstances in real time. Of course, the effects of releasing these hormones take a little longer to be noticed than those that would provoke the neurons.

    Classification of hormones: what types of hormones are there

    however, there are different classifications of hormones.

    What are these classifications and according to what criteria are they established? Here’s how.

    1. By the proximity of its place of synthesis with its place of action

    Depending on whether they have an effect on the cells that synthesized them or on adjacent cells, hormones can be:

    • autocrine hormones: Autocrine hormones act on the same cells that synthesized them.
    • paracrine hormones: It is these hormones that act near the place where they were synthesized, that is, the effect of the hormone is produced by a neighboring cell in the sending cell.

    2. According to its chemical composition

    Depending on its chemical composition, there are four types of hormones

    • Peptide hormones: These hormones are made up of chains of amino acids, polypeptides or oligopeptides. The vast majority of this type of hormone fails to cross the plasma membrane of target cells, resulting in receptors for this class of hormones located on the cell surface. Among the peptide hormones are: insulin, growth hormone or vasopressin.
    • Amino acid derivatives: These hormones come from different amino acids, such as tryptophan or tyrosine. For example, adrenaline.
    • Lipid hormones: These types of hormones are eicosanoids or steroids. Unlike the previous ones if they manage to cross the plasma membranes. Prostaglandins, cortisol, and testosterone are a few examples.

    3. According to its nature

    Depending on this class of substances produced by the body by its nature, there are the following types of hormones:

    • Steroid hormones: These hormones come from cholesterol and are produced primarily in the ovaries and testes, as well as in the placenta and adrenal cortex. Some examples are: androgens and testosterone, produced in the testes; and progesterone and estrogen, which are produced in the ovaries.
    • Protein hormones: These are hormones formed by chains of amino acids and peptides.
    • Phenolic derivatives: Although they are protein in nature, they have a low molecular weight. One example is adrenaline, which occurs in situations where a large part of the body’s energy reserves must be invested in the rapid movement of muscles.

    4. According to its solubility in the aqueous medium

    There are two types of hormones depending on their solubility in the aqueous medium:

    • Hydrophilic hormones (water soluble): These hormones are soluble in the aqueous medium. Since the target tissue has a membrane with lipid characteristics, hydrophilic hormones cannot cross the membrane. Thus, these types of hormones bind to receptors located outside the tissue. For example: insulin, adrenaline or glucagon.
    • Lipophilic hormones (lipophilic): These hormones are not soluble in water, but they are soluble in lipids. Unlike the previous ones, these can cross the membrane. Therefore, receptors for this type of hormone can bind to intracellular receptors to carry out their action. Examples: thyroid hormone or steroid hormones.

    Types of endocrine glands

    Hormones are produced in endocrine glands throughout the body. In many ways, our nervous system needs the collaboration of other parts of the body to ensure that the processes that take place in the body are coordinated and that a certain balance is maintained.

    To achieve this level of coordination, our brains regulate the release of various types of hormones responsible for performing different functions. In addition, this class of substances varies depending on the type of gland that secretes them and their location.

    The main endocrine glands are:

    • the pituitary or pituitary gland: It is considered the most important gland in the endocrine system because it produces hormones that regulate the functioning of other endocrine glands. It can be influenced by factors such as emotions and seasonal changes.
    • The hypothalamus: This endocrine gland controls the functioning of the pituitary gland, secreting chemicals that can stimulate or inhibit hormonal secretions from the pituitary gland.
    • the fear: It secretes a hormone called thymosin, which is responsible for stimulating the growth of immune cells
    • the pineal gland: Produces melatonin, a hormone that plays an important role in adjusting sleep and wake cycles.
    • the testicles: These produce hormones called estrogen, the most important of which is testosterone, which tells men that now is the time to start the bodily changes associated with puberty, such as the change in voice and beard growth and pubic hair.
    • the the ovaries: They secrete estrogen and progesterone. Estrogen tells girls when to start the body changes associated with puberty.
    • the thyroid: This endocrine gland produces thyroxine and triiodothyronine, hormones that control the rate at which cells burn food fuel for energy.
    • the glands adrenal glands: These glands have two parts. One produces hormones called corticosteroids, which are related to the balance between mineral salts and water, stress response, metabolism, immune system, and sexual development and function. The other part produces catecholamines, for example, adrenaline
    • the parathyroid: From there it is released parathyroid, a hormone related to the concentration of calcium in the blood.
    • the pancreas: It secretes insulin and glucagon, which allows it to maintain stable blood sugar levels and provide the body with enough fuel to produce the energy it needs.

    Bibliographical references:

    • Kosfeld M et al. (2005). Oxytocin increases confidence in humans. Nature 435: 673-676.
    • Marieb, Elaine. (2014). Anatomy and physiology. Glenview, IL: Pearson Education, Inc.
    • Neave N. (2008). Hormones and behavior: a psychological approach. Cambridge: Cambridge Univ. Hurry.
    • Editor., Molina, Patricia E. (2018). Endocrine physiology. McGraw-Hill Education.

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