The different types of hormones in our body do more than just perform vital functions to control certain biological processes. Whether we like it or not, they condition our behavior and even our mood.
Moreover, any hormonal imbalance can sometimes lead to depression or to seeing and feeling our reality in very different ways.
We all like to think that we have total control over our behavior and thoughts. However, we are totally conditioned by this tiny universe, full of power and chaos constituted by our hormones.
These protein messengers responsible for regulating an infinite number of metabolic processes also permeate our brains, influencing our behavior and the type of thoughts we can have in our heads.
Our body secretes and circulates about 50 different hormones. These chemicals of very diverse natures are produced by endocrine cells, generally grouped in glands. They then pass through the bloodstream to reach the entire body and activate target cells.
Closely linked to the nervous system, the endocrine system controls many of the body’s functions: metabolism, homeostasis, growth, sexual activity and the contraction of smooth and cardiac muscles.
The Endocrine Glands
The endocrine system consists of about ten specialized glands (pituitary, thyroid, four parathyroid, two adrenals and thymus), plus several organs capable of producing hormones (pancreas, heart, kidneys, ovaries, testicles, intestines).
The hypothalamus, which is not a gland but a nerve center, also plays a major role in the synthesis and release of certain hormones.
The Hypothalamus And Pituitary Gland: Endocrine Control Centers
Located under the thalamus, the hypothalamus consists of several nuclei that control the autonomic nervous system, and regulate hunger, thirst, body temperature and sleep. The hypothalamus also influences sexual behavior and controls reactions of anger and fear.
Closely linked to the pituitary gland, it plays a coordinating role between the nervous system and the endocrine system.
Generally considered as the master endocrine gland, the pituitary gland secretes about ten different hormones. Some of these substances in turn act on other endocrine glands.
Unlike substances produced by the exocrine glands, which flow through channels, hormones are released directly into the space surrounding the secretory cells. The very strong vascularization of the endocrine glands allows hormones to diffuse into the bloodstream through the capillaries. Some of them circulate freely in the blood, while others must bind to transport proteins to reach the target cells.
The Action of Hormones
When a hormone diffuses out of a capillary, it can act on a target cell, i.e. a cell with receptors that correspond to it. There are two types of hormonal action. A steroid hormone is able to cross the cell membrane of the target cell.
It binds with a receptor protein inside the nucleus, which stimulates or blocks the cell’s genetic activity. A protein hormone, on the other hand, cannot enter the target cell. It binds to its membrane and activates a receptor that in turn releases a messenger inside the cell.
- Pituitary Gland: An endocrine gland located at the base of the brain and controlled by the hypothalamus, which directly secretes six hormones, several of which regulate the activity of other endocrine glands. Locate the pituitary gland in the Virtual Human Body.
- Hypothalamus: A set of small grey matter formations, located under the thalamus, that control the hormonal secretions of the pituitary gland and the activity of the autonomic nervous system. Locate the hypothalamus in the Virtual Human Body.
- Ovaries: Each of the two female genital glands on either side of the uterus, which produce eggs and sex hormones (estrogen and progesterone). Locate the ovaries in the Virtual Human Body.
- Kidneys: Each of the two organs located in the abdomen whose main function is to produce urine by filtering blood. Locate the kidneys in the Virtual Human Body.
- Testis: Each of the two male sex glands in the scrotum, which produce sperm and secrete male hormones (testosterone). Locate the testicles in the Virtual Human Body.
- Thalamus: A set of several grey matter formations located in the center of the brain.