Endocrine glands . Also called glands of internal secretion . They are a set of glands that produce messenger substances called hormones , pouring them without excretory duct, directly into the blood capillaries, so that they perform their function in organs distant from the body
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- 1 Features
- 2 Main Endocrine Glands
- 1 The pituitary gland
- 2 The hypothalamus
- 3 The thymus
- 4 The testicles
- 5 The ovaries
- 6 The thyroid
- 3 Sources
Endocrine glands are characterized by having lost their union with the epithelium that originated them, therefore, they are devoid of excretory ducts and the discharge discharges it directly into the blood or lymphatic flow.
They are usually made up of groups of cells that are arranged in the form of accumulations, cords and follicles, included in a support tissue made up of fine reticular 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 nerve 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 have a secondary endocrine function. for example, the kidney secretes endocrine hormones such as erythropoietin and renin.
Main Endocrine Glands
- The pituitary gland
- The hypothalamus
- the thymus
- The pineal gland
- the testicles
- The ovaries
- the thyroid
- The adrenal glands
- the parathyroid
- The pancreas
The pituitary gland
The pituitary gland is sometimes called the “master gland” because it has a great influence on the other organs of the body. Its function is complex and important for the general well-being. The pituitary gland is divided into two parts, the anterior part and the posterior part.
The anterior pituitary produces various hormones:
- Prolactin (or PRL) stimulates milk secretion in women after delivery and can affect hormone levels in the ovaries in women and in the testicles in men.
- Growth hormone. Growth hormone (GH) stimulates child 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 the activity of the nervous system.
- Follicle stimulating hormone. This hormone (also called FSH) encourages sperm production in men and stimulates the ovaries to release eggs in women. Luteinizing hormone and follicle stimulator work together to allow the ovaries or testicles to function normally.
The posterior pituitary produces two hormones:
- Oxytocin: Oxytocin causes the lactation reflex (ejection) and causes contractions during labor.
- Antidiuretic hormone. The antidiuretic hormone (ADH), also called vasopressin, is stored in the back of the pituitary gland and regulates the balance of fluid in the body. If the secretion of this hormone is not normal, problems can occur between the balance of sodium (salt) and fluid, and it can also affect the kidneys so that they function poorly.
The hypothalamus is the part of the brain located above the pituitary gland. Releases hormones that start or stop the secretion of pituitary hormones. The hypothalamus controls the production of hormones in the pituitary gland by various “releasing” hormones. Some of these are: the hormone that releases growth hormone, or GHRH (which controls the release of growth hormone); thyrotropin-releasing hormone, or TRH (which controls the release of thyroid-stimulating hormone); and corticotropin-releasing hormone, or CRH (which controls the release of adrenocorticotropin).
Gonadotropin-releasing hormone (GnRH) signals the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are important for normal puberty.
The thymus is a gland that is needed in the early years to have normal immune function. It is quite large immediately after a child is born and has a maximum weight when the child reaches puberty, when his tissue is replaced by fat. The thymus gland secretes hormones called humors. These hormones help develop the lymphoid system, or immune system, which is the system that helps the body have a mature immune reaction in cells to protect them against invasion by invading bodies, such as bacteria.
Men have twin reproductive glands, called testicles, that make the hormone testosterone. Testosterone helps a boy develop and maintain his sexual characteristics. During puberty, testosterone helps to produce the physical changes that make the boy become an adult man, such as growth of the penis and testicles, growth of facial and pubic hair, thickening of the voice, increased for muscle mass and strength, and increasing size. During adulthood, testosterone helps maintain sexual vigor, sperm production, hair growth, and muscle and bone mass.
Testicular cancer, which is the most common cancer in men ages 15 to 35, can be treated by removing one or both testicles. Decreased or low testosterone can cause decreased sex drive, impotence, an altered body image, and other symptoms.
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. Along with pituitary gonadotropins (FH and LSH), they also control the menstrual cycle. The ovaries also produce inhibin, a protein that inhibits the release of follicle-stimulating hormone produced by the anterior pituitary and helps control the development of eggs.
The most common change in ovarian hormones occurs with the onset of menopause, which is part of the natural aging process. It can also occur when the ovaries are surgically removed. Loss of ovarian function means loss of estrogen, which can lead to hot flashes, thinning of vaginal tissue, suspension of menstruation, mood changes, and bone loss or osteoporosis.
The thyroid is a small gland inside the neck, located in front of the trachea and below the larynx. Thyroid hormones control metabolism, which is the body’s ability to break down food and store it as 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. Symptoms of hypothyroidism (hormone deficiency) include loss of energy, reduced heart rate, dry skin, constipation, and feeling cold all the time. In children, hypothyroidism commonly leads to stunted growth. Babies born with hypothyroidism may have developmental delay and mental retardation if left untreated. In adults, this deficiency often causes weight gain. Thyroid growth or goiter may occur.
According to this concept, the kidneys are also endocrine glands by producing erythropoietin, the liver , the intestine itself, the lungs and other organs that produce hormones that act at a distance.