Definition of Endocrine System

The endocrine systems in animals comprise a set of organs responsible for chemical intercellular communication, from what that produce and release chemical messengers: hormones, which regulate and coordinate various physiological and metabolic functions in the body. organism.

Unlike the nervous system, which uses electrical signals to transmit messages quickly, the endocrine system uses hormones to send information through the bloodstream. Hormone-mediated signals are more slow, but more durable than those of nervous impulses.

In multicellular organisms, in which there are groups of cells specialized in each of the vital functions, they must There are cellular communication mechanisms that allow all these activities to be coordinated and keep all the cells “synchronized.” cells.

Structure

The endocrine glands constitute the fundamental structure of the endocrine system in all animals. These are organs responsible for producing and releasing hormones directly into the blood.

The glands lack ducts and are therefore called "endocrine glands«, which means that they pour their products into the body, unlike the glands exocrine cells, such as those that produce sweat, which release their contents outside the body through a conduit.

Vertebrate endocrine system

The hormone-mediated chemical intracellular communication system is common to many groups of animals, and the vertebrate endocrine system is very similar in all In them, what varies is the shape and arrangement of the glands, but the hormones and their roles are similar, although certain hormones may have slightly different functions between groups of vertebrates.

The endocrine system of mammals, and, consequently, ours, is made up of the following glands.

Thyroid

Located in the neck, the thyroid gland is a butterfly-shaped structure. Produces the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

These hormones are crucial for regulate metabolism, growth and development. Thyroxine influences the rate at which cells burn energy, while triiodothyronine affects cell growth and maturation.

A thyroid gland malfunction can lead to conditions such as hypothyroidism (low levels of thyroid hormone) or hyperthyroidism (high levels of thyroid hormone), which are manifested by metabolic problems such as obesity, sudden weight loss and alterations in growth.

In amphibians, thyroid hormones are key in controlling metamorphosis.

Parathyroid

Located at the back of the thyroid gland, the parathyroid glands are small and there are usually four of them.

They produce the parathyroid hormone (PTH) which regulates calcium and phosphorus levels in the blood, which is essential for the health of the bone system and nervous system.

When blood calcium levels are low, PTH causes increased calcium reabsorption in the kidneys and in turn, the bone tissue cells mobilize the calcium stored in the bones into the blood.

Hypophysis

The pituitary gland is a small gland found at the base of the brain.

It has a very important function, since it is the responsible for communicating the nervous system with the endocrine system. The pituitary gland can respond and send both chemical messages from the endocrine system and electrical messages from the nervous system.

It is known as "the master gland" because regulates the functioning of other endocrine glands.

The pituitary gland produces hormones such as growth hormone (GH), which influences body growth and development, thyroid stimulating hormone (TSH), which regulates the functioning of the thyroid gland, oxytocin, which is involved in uterine contraction during childbirth, the release of milk during breastfeeding and the establishment of emotional bonds between individuals (mother-child, couple).

The pituitary gland also produces hormones follicle stimulating (FSH) and the hormone luteinizing (LH), so called because they play a fundamental role during the female menstrual cycle. These hormones also modulate the rate of sperm and testosterone production in males; hence They are key in the regulation of reproduction in mammals.

Adrenals

Located above the kidneys, the adrenal glands are made up of two parts: the medulla and the adrenal cortex.

The adrenal medulla produces adrenalin and the norepinephrine, which trigger the response of adaptive stress or "fight or flight" in mammals.

These hormones increase the heart rate, dilate the airways, and mobilize energy stored in the body. In other words, the stress response puts all of the body's resources at the disposal of the muscles and prepares the body to flee or confront. At the same time, it “turns off” or reduces functions that are not strictly necessary to confront the danger.

This response is known as the “stress response” and is beneficial, since it is responsible for preparing the body to defend itself against danger.

The adrenal cortex produces cortisol, which regulates metabolism and helps manage stress.

The natural stress response is temporary, and ceases once the body is out of danger. When the stress response is continuous, it is called chronic stress. It is as if our body is always “on guard”, which causes anxiety, nervousness, sleep problems and physical symptoms such as hypertension and gastrointestinal problems. Chronic stress can interfere with the normal functioning of the immune system; since immune function is one of the functions that is turned off during stress.

Pancreas

The pancreas has an exocrine function in the digestive system, producing digestive enzymes and an endocrine function.

Produces insulin, that lowers blood glucose level by allowing cells to use it as a source of energy. Insulin is the signal for cells to quickly absorb glucose from the blood.

Another hormone of the pancreas is glucagon, and its function is opposite to that of insulin. When the blood glucose concentration is too low, glucagon causes increase the release of glucose stored in the liver and muscles into the blood.

The pancreas also produces somatostatin, which regulates the release of insulin and glucagon. An imbalance in insulin production can lead to type 1 or type 2 diabetes.

Gonads

The gonads are the sexual glands: testicles in men and ovaries in women.

The testicles produce testosterone, which is responsible for the development of male sexual characteristics, sperm production, and maintenance of sexual function. Testosterone production in the testes is regulated by the pituitary hormone LH.

In women, the ovaries produce estrogen and progesterone. Estrogen is essential for the development of female secondary sexual characteristics and progesterone prepares the plays an important role during pregnancy. Both female hormones interact with the pituitary hormones LH and FSH to control blood pressure. progression of the female menstrual cycle, and are responsible for preparing the body for a possible pregnancy.

The proper balance of hormones is essential for the proper functioning of the human body. Imbalances in the endocrine system can have negative effects on the health and well-being of people and animals.