What are the endocrine glands ?
The endocrine glands are a set of glands that produce messenger substances called hormones , pouring them without an excretory duct, directly into the blood capillaries , which take them to the cells, called white cells , to perform their function. It is also called a white organ that is regulated by hormones.
The endocrine glands are characterized by having lost their union with the epithelium that originated them, therefore, they are devoid of excretory ducts and secretion pour directly into the bloodstream or lymphatic.
They are usually made up of groups of cells that are arranged in the form of accumulations, cords and follicles, included in a supporting tissue composed of fine mesh fibers and associated with a sinusoidal or capillary network.
The endocrine glands are regulated by the nervous system, either by other endocrine glands or by a combination of nervous and endocrine factors. The endocrine or endocrine system is a system of glands that secrete a set of substances called hormones, which released into the bloodstream regulate the functions of the body.
Apart from specialized endocrine glands for this purpose, there are other organs such as the kidney , liver , heart and gonads , which has a secondary endocrine function. For example, the kidney secretes endocrine hormones such as erythropoietin and renin.
10 examples of endocrine glands
The pituitary gland
The pituitary gland is sometimes called the “master gland” because it exerts a great influence on the other organs of the body. Its function is complex and important for the general welfare. The pituitary gland is divided into two parts, the anterior and the posterior.
The anterior pituitary produces various hormones:
- Prolactin Prolactin or PRLstimulates the milk secretion in women after childbirth and can affect hormone levels of the ovaries in women and testes in men.
- Growth hormone. Growth hormone (GH) stimulates childhood growth and is important for maintaining a healthy body composition. In adults it is also important to maintain muscle and bone mass. It can affect the distribution of fat in the body.
- Thyroid stimulating hormone. Thyroid stimulating hormone (TSH) stimulates the thyroid gland to produce thyroid hormones, which, in turn, regulate the body’s metabolism, energy, growth and development, and activity of the thyroid gland. nervous system.
- Follicle stimulating hormone . This hormone (also called FSH )promotes the production of sperm in men and stimulates the ovaries to release the eggs in women. Luteinizing hormone and follicle stimulator work together to allow normal functioning of the ovaries or testes.
The posterior pituitary produces two hormones:
- Oxytocin. Oxytocin causes the breastfeeding reflex (ejection) and causes contractions during labor.
Antidiuretic hormone. Antidiuretic hormone (ADH), also called vasopressin, is stored in the back of the pituitary gland and regulates the fluid balance in the body. If the secretion of this hormone is not normal, there may be problems between the balance of sodium (salt) and fluid, and may also affect the kidneys so that they work poorly.
The hypothalamus is the part of the brain located above the pituitary gland. It releases hormones that initiate or stop the secretion of pituitary hormones. The hypothalamus controls the production of hormones in the pituitary gland by means of several “liberating” hormones. Some of these are: the hormone that releases growth hormone, or GHRH (which controls the release of growth hormone); the thyrotropin-releasing hormone or TRH (which controls the release of the thyroid-stimulating hormone); and corticotropin-releasing hormone, or CRH (which controls the release of adrenocorticotropin).
Gonadotropin-releasing hormone (GnRH) tells the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are important for normal puberty.
3. The thymus
The thymus is a gland that is needed in the first years to have a normal immune function. It is quite large immediately after a child is born and has a maximum weight when the child reaches puberty, at which time his tissue is replaced by fat. The thymus gland secretes hormones called humors. These hormones help to develop the lymphoid system or immune system, which is the system that helps the body to have a mature immune reaction in the cells to protect them against the invasion of invading bodies, such as bacteria.
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4. The testicles
Men have twin reproductive glands, called testes, that produce the hormone testosterone. Testosterone helps the boy to develop and maintain his sexual characteristics. During puberty, testosterone helps produce the physical changes that cause the child to become an adult man, such as the growth of the penis and testicles, the growth of facial and pubic hair, the thickening of the voice, the increase of muscle mass and strength, and the increase in size. During adult life, testosterone helps maintain sexual vigor, sperm production, hair growth, and muscle and bone mass.
Testicular cancer, which is the most common cancer in men aged 15 to 35 years, can be treated by the removal of one or both testicles. The reduction or lack of testosterone can cause a decrease in sex drive, impotence, an altered body image and other symptoms.
5. The ovaries
The two most important female hormones produced by the twin reproductive glands, the ovaries, are estrogen and progesterone. These hormones are responsible for developing and maintaining female sexual characteristics and maintaining pregnancy. Together with the pituitary gonadotropins (FH and LSH), they also control the menstrual cycle. The ovaries also produce inhibin, a protein that inhibits the release of the follicle-stimulating hormone produced by the anterior pituitary and helps control the development of the ovules.
The most common change in ovarian hormones occurs with the onset of menopause that is part of the natural aging process. It can also occur when the ovaries are removed surgically. The loss of ovarian function means the loss of estrogen, which can produce hot flushes, thinning of the vaginal tissue, suspension of menstruation, changes in mood and bone loss or osteoporosis.
6. The thyroid
The thyroid is a small gland in the neck, located in front of the windpipe and below the larynx. Thyroid hormones control metabolism, which is the body’s ability to break down food and store it in the form of energy, and turn food into waste products, releasing energy in the process. The thyroid produces two hormones, T3 (called triiodothyronine) and T4 (called thyroxine).
Thyroid disorders result from deficiency or excess of thyroid hormone. The symptoms of hypothyroidism (hormone deficiency) include loss of energy, reduction of heart rate, drying of the skin, constipation and cold sensation at all times. In children, hypothyroidism commonly leads to a delay in growth. Babies born with hypothyroidism may have a developmental delay and mental retardation if left untreated. In adults, this deficiency often causes weight gain. Thyroid or goiter growth may occur.
According to this concept, the kidneys are also endocrine glands when producing erythropoietin, the liver , the same intestine, the lungs and other organs that produce hormones that act at a distance.
7. The pineal gland
The pineal gland , also known as the pineal body , conarium or brain epiphysis is a small endocrine gland in the brains of vertebrates . It produces melatonin , a hormone derived from serotonin that affects the modulation of sleep patterns, both at circadian and seasonal rhythms . Its shape resembles a small cone of pine (hence its name), and is located in the epitalamo near the center of the brain, between the two hemispheres, stuck in a groove where the two halves of the thalamusjoin.
8. The parathyroid glands
The parathyroid glands are glands endocrine located in the neck, behind the thyroid lobes. These produce the parathyroid hormone or parathormone (PTH). Generally, there are four parathyroid glands, two superior and two inferior. When there is an additional gland, it is usually found in the mediastinum, in relation to the isthmus , or inside the thyroid gland .
9. The pancreas
The pancreas has two main functions, the exocrine function , for digestion and endocrine function , for the production of hormones. Endocrine or hormone production function : The most important of these is insulin , which is essential for theregulation of blood sugar levels . The cells responsible for the production of these hormones are not distributed homogeneously throughout thepancreas , but are concentrated in groups of cells that are calledislets of Langerhans . Unlike theexocrine function , the endocrine function is mainly concentrated in the body and tail of the pancreas, although islets of Langerhans can be found throughout the pancreas .