The adrenal glands ( lat. Glandulae suprarenales ) are paired endocrine glands located above the upper kidneys of vertebrates and humans .
In humans, they are located in close proximity to the upper pole of each kidney . They play an important role in the regulation of metabolism and in the adaptation of the body to adverse conditions (reaction to stressful conditions).
The adrenal glands are composed of two structures - cortical matter and medulla , which are regulated by the nervous system .
Brain substance is the main source of catecholamine hormones in the body - adrenaline and norepinephrine . Some of the cells of the cortical substance belong to the “hypothalamus – pituitary – adrenal cortex” system and serve as a source of corticosteroids .
Content
- 1 Adrenal cortex
- 1.1 Glomerular area
- 1.2 Beam zone
- 1.3 Mesh Zone
- 2 Adrenal medulla
- 3 Adrenal gland disorders
- 4 See also
- 5 notes
- 6 References
Adrenal cortex
The cortical layer of the adrenal gland has nerve tissue, which provides its main function. It forms hormones that regulate metabolic processes. Some of them contribute to the conversion of proteins into carbohydrates and increase the body's resistance to adverse effects, while others regulate salt metabolism in the body. [one]
Hormones produced in the cortex are corticosteroids . The adrenal cortex itself morpho-functionally consists of three layers:
- Glomerular zone
- Beam zone
- Mesh zone
The cortical substance of the adrenal gland has parasympathetic innervation. The bodies of the first neurons are located in the posterior nucleus of the vagus nerve. Preganglionic fibers are localized in the vagus nerve, in the anterior and posterior trunk of the vagus nerve, the hepatic branches, the celiac branches. They follow into the parasympathetic nodes and into the internal plexus. Postganglionic fibers: hepatic, splenic, pancreas, subserous, submucosal, and axillary plexuses of the stomach, small and large intestines, and other internal organs of the tubular structure.
Glomerular zone
In the glomerular zone, hormones called mineralocorticoids are formed . These include:
- Aldosterone
- Corticosterone is a low-activity glucocorticoid that also has some mineral corticoid activity.
- Deoxycorticosterone - Inactive Mineralocorticoid
Mineralcorticoids increase Na + reabsorption and K + excretion in the kidneys.
Beam Zone
Glucocorticoids are formed in the bundle zone, which include:
- Cortisol
- Cortisone
Glucocorticoids have an important effect on almost all metabolic processes. They stimulate the formation of glucose from fats and amino acids ( gluconeogenesis ), inhibit inflammatory , immune and allergic reactions, reduce the proliferation of connective tissue , and also increase the sensitivity of the senses and the excitability of the nervous system .
Mesh Zone
Sex hormones ( androgens , which are substances that are the precursors of estrogen ), are produced in the mesh zone. These sex hormones play a slightly different role than the hormones secreted by the sex glands . They are active before puberty and after puberty; including they affect the development of secondary sexual characteristics .
A lack of these sex hormones causes hair loss; excess leads to virilization - the appearance in a person of traits characteristic of the opposite sex.
Adrenal medulla
Adrenaline forms in the adrenal medulla. This hormone strengthens and speeds up heart contractions, raises blood pressure , dilates the pupils, and regulates carbohydrate metabolism (enhances the conversion of glycogen to glucose). [one]
The adrenal medulla cells produce catecholamines - adrenaline and norepinephrine . These hormones alter blood pressure, enhance and relax the heart, expand and narrow the lumens of the bronchi, and change the level of sugar in the blood. At rest, they constantly produce small amounts of catecholamines. Under the influence of a stressful situation, the secretion of adrenaline and norepinephrine by the cells of the adrenal medulla increases sharply.
The adrenal medulla receives innervation from the preganglionic fibers of the sympathetic nervous system , which makes it possible to consider it as a specialized sympathetic plexus [2] , with the difference that neurotransmitters are released directly into the vascular bed bypassing the synapse .
In addition to adrenaline and norepinephrine, cells in the brain layer produce peptides that perform regulatory functions in the central nervous system and gastrointestinal tract . Among these substances:
- Substance P
- Vasoactive intestinal peptide
- Somatostatin
- Beta Enkephalin
Adrenal gland disorders
Cortical substance:
- Addison's Disease
- Hypercorticism syndrome
- Congenital adrenal hyperplasia
- Adenocortal cancer
- Conn's syndrome
- Glomerulonephritis
Cerebral substance:
- Pheochromocytoma
See also
- Kidney
- Endocrine system
- Chromaffin cell
- Adrenal adenoma
- Adrenal cortex insufficiency (hypocorticism)
- Primary chronic adrenal insufficiency (Addison's disease)
- Primary hypercorticism
- Glucosteroma
- Primary hyperaldosteronism ( Conn syndrome )
- Secondary hyperaldosteronism
- Corticoestroma
- Androsteroma
- Congenital adrenal cortex dysfunction
- Pheochromocytoma
Notes
- ↑ 1 2 D.I. Treitak. BIOLOGY. Reference materials. - 2. - Moscow: Enlightenment, 1987.
- ↑ Sapru, Hreday N .; Siegel, Allan (2007). Essential Neuroscience. Hagerstown, MD: Lippincott Williams & Wilkins. ISBN 0-7817-9121-9 .