What are adrenal glands and what are their functions

Above the upper pole of the kidneys are small glands, known medically as adrenal glands. Despite the obvious connection with the urinary organs, adrenal function is significantly superior to the effect on the kidneys.

They are part of numerous endocrine glands along with the nervous and immune systems govern the human body mechanisms of adaptation to the conditions of the external and internal environment, provide a response to any pathogen (stress).

The adrenal glands lie in the production and supply of blood hormones, which are responsible for the protection of the internal organs by creating inflammatory reaction, isolation of the defective organ with constriction of the blood vessels, preparedness for physical and nervous stress.

The question of what are the functions of adrenal glands, were studied in experiments on animals. Modern knowledge allows to allocate certain types of hormones, to determine their biological composition and structure, and trace their role in physiological and pathological processes. Moreover, scientists have achieved the synthesis of analogs of adrenal hormones, and extensively use it in the treatment of serious diseases.

A bit of historical information

Historians of medicine disagree on the first description of the adrenal glands in the human body. Some believe that the mention of “the fat over the kidneys”, there is in the Bible, while others attributed the superiority of Claudius Galen. But this scientist has discovered only the left gland in mammals.

For the first time the structure of the adrenal glands along with their drawings explored in the XVI century, the famous anatomist and physician from Italy Bartolomeo Eustachi. He reported the presence of additional glands of the kidneys, warned “careless doctors” about the pass and error to ignore the adrenal glands, anatomy which is closely associated with blood supply to the kidneys.

The most eminent physicians, occupying a high position at the courts of European States, the Pope, the Queen of Austria Maria Theresa, the French monarch Henry IV did not understand adrenal function, generally denied any role in such education is, even counted them to malformations.

Only after 3 centuries there was a rapid study of glands, discovered how the adrenal glands, the functions associated with the endocrine system. Scottish Dr. Thomas Addison failed to prove that the cause of bronze disease, leading to death, is their failure. He was first diagnosed with metastatic cancer in the adrenal glands.

Up to the present time preserved the names of the two layers constituting the cortical substance of adrenal glands and brain. The use of microscopes with improved resolution allowed in the XIX century to separate the structure and function of the endocrine glands, to determine their relationship with the nervous system.

Psychologists-experimenters studied the adrenal function through the introduction of drawing experienced by the animal and remove them.

Methods of modern histology has allowed to identify special cells of the adrenal cortex. After the introduction into medical practice of the Adrenaline it took more than 100 years, but research is ongoing. The therapeutic effect of hormones allows you to save the lives of millions of people suffering from diseases of shock.

The external structure and appearance of the adrenal gland

The adrenal glands are located inside the adipose tissue near the top of the kidneys on both sides. On the form there are differences: right iron like a triangular pyramid on the left — curved Crescent.

When the description is divided into the outer surface, back, kidney.

Left and right glands are located asymmetrically relative to the midline of the body:

  • on the left surface of the kidney is closer to the median edge of the kidney and the formation, called “the gate”;
  • right — clearly lies above the upper pole.

The average size of glands make up the adult length of 5 cm, width — up to four cm, thickness — 1 cm Outer layer is a thick knobbly capsule yellow. It is attached to the kidney by numerous dense fibrous cords. In addition, renal adipose capsule, and the fascia is tight-fitting gland.

On the cut you can see the separation of the inner tissue (parenchyma):

  • the outer cortical layer is by weight to 90% of the gland;
  • inner — medulla.

Through the adrenal cortex into the parenchyma penetrate thick partitions (trabeculae).

The anatomical relationship with adjacent organs

Localization of the adrenal glands enables them not only through blood but also by contact contact with vital internal organs. The level is usually determined in relation to the ribs and vertebrae: this is usually XI and XII thoracic vertebrae, while the right adrenal gland lies a little below the left.

Both adrenal glands located in the retroperitoneal space

Rear surfaces of the gland adjacent to the diaphragm in its lumbar. The front part of the left adrenal gland is in contact with the tail podzheludochnoj glands, the cardiac division of the stomach closest to the center and the aorta.

Right — front is bordered with the liver and duodenum, the middle with the inferior Vena cava.

The internal structure

The adrenal cortex and the medulla were independent of the glands of internal secretion. They are structurally United in one body, but have different origins and functional purpose. Even the development stage of the embryo occur independently of each other.

On the eighth week of pregnancy shapes the future the crust. And in a period of 12 to 16 weeks from the primary sympathetic nerve trunk separated symptomsmarine cells and grow to the Bud cortex. Of them formed the substance of the brain. Chromaffin cells are so named because of the affinity for a particular dye (potassium dichromate).

The cortical substance may intrauterine form a “plus” cancer in the form of a small calf. They are located in the uterus, the ovaries in the body of women in the epididymis in men, the inferior Vena cava, the ureter, the nerve fibers of the solar plexus or on the surface of adrenal glands in the form of nodules. Not considered true, because it does not contain brain substance.

Chromaffin cells are combined in nodes (paraganglia), except for the adrenal medulla, are present in the bifurcation of the aorta (above and below the separation), in nodes of the sympathetic ganglia, in the area of bifurcation of the common trunk of the carotid artery.

The cortical layer is divided into three zones, each of which synthesizes certain types of hormones:

  • closer to the surface is thin glomerular layer;
  • in the middle is the beam area;
  • inside, a mesh area in contact with the brain substance.
The structure of the authority is confirmed with a microscopic photo pictures

The medulla receives direct instructions from the nervous system. The work of the adrenal cortex directs the pituitary gland through its neuroendocrine hormones controlled by the hypothalamus the medulla and the renin-angiotensine system.

Peculiarities of blood supply

The kidneys and adrenal glands share a common blood supply.

They get the blood by three arteries:

  • the branch from the lower diaphragmatic artery is the main adrenal;
  • extending from the abdominal aorta — the average adrenal;
  • part of the renal artery — adrenal lower.

Venous blood goes into the right adrenal vein draining into the inferior caval, and left through the left adrenal gland, kidney in the lower phrenic vein. In abdominal surgery it takes into account the risk of damage to the right renal vein (short) during the operation to remove the adrenal gland.

About the importance of the authority decided to judge according to the degree of its blood supply on g mass. The thyroid and adrenal glands belong to the first place in each gland is made up of 60 small arterioles. This is one of the reasons for the frequent metastasis of malignant tumors in these glands.

Age features

Studies have shown features of the structure of adrenal gland in different age periods of a human.

At birth in the cortical layer there is only 2 areas:

  • germ crust;
  • very authentic thin crust.

Then begins to decrease all the gland due to the disappearance of the germinal layer. In adolescence, when there is puberty, the adrenal glands grow in size, the weight is about 10 g.

In old age there is atrophy of the parenchyma of both layers, glands decreases again.

The functionality of the adrenal glands

Adrenal function determined by the synthesis of certain hormones, biological active substances, influencing on all aspects of metabolism, development, growth, synchronizing the activity of the internal organs.

Tasks performed by the adrenal glands, are so serious that the failure of any rash or therapeutic intervention provokes increased production of some substances and reducing others. The violation of adrenal function inevitably leads to pathology. In the absence of medical intervention — with a fatal outcome.

Responsible for what cortical layer?

In the cortical layer produces different hormones, depending on the specific site of synthesis, it is ensured by the presence of specific enzymes:

  • in the glomerular layer — mineralcorticoid (aldosterone);
  • in beam — glucocorticoids (11-deoxycorticosterone, cortisol, corticosterone);
  • in the reticular (net) — sex hormones androgens and estrogens.
The cortex makes up most of mass

Mineralcorticoid produced in the body the regulation of blood pressure through renal tubules tissue retention of sodium, increased output of potassium and hydrogen ions. In cases of fluid loss because of sweating or diarrhea aldosterone retains sodium by regulating reverse suction in the colon and sweat glands.

In addition, the known activating effect of aldosterone on angiotensin II. It comes into effect in the fall of blood pressure below 90 mm Hg. article

Glucocorticoids regulate all types of metabolism in the body. Chief representative — cortisol — can enhance the production of catecholamines in the medulla, glucagon. In response to the increased release into the blood adrenocorticotropic hormone of the anterior pituitary may be sudden stimulation of the synthesis of cortisol.

The protective effect is manifested in the support of a minimal blood sugar level during fasting.

The value of brain matter

In the adrenal medulla accounts for 80% of the body’s adrenaline and 20% norepinephrine. They are synthesized in chromaffin cells. In the process of production enters tyrosine (one of the amino acids). It turns out methoxyphenylalanine. Then there is a reaction of decarboxylation with the formation of dopamine. From it under the influence of enzymes, it turns out the noradrenaline, then adrenaline.

These hormones provide a protective mobilization of all systems and organs in the event of a threat. Activation starts after receiving “orders” from the sympathetic nervous system fibers of the thoracic spinal cord. Also participates cortical hormone cortisol.

A chain reaction can be represented in the following diagram: agent-irritant, regarded by the brain as dangerous → the transfer of excitation in nuclei of the hypothalamus → a transition pulse to the spinal sympathetic centers in the thoracic region → distribution of the nerve fibres → getting into the medulla of the adrenal glands and the production of adrenaline, norepinephrine (out of pellets).

Read more about the role of the adrenal glands to humans can be found in this article.

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The effect of adrenal glands on sexual characters, pregnancy

Change of the adrenal glands in women for the net area and disturbed the balance between estrogen, androgens. For men, androgens determine the development in the puberty of male sexual characteristics. Women should have a certain level of testosterone and men estrogen. Both varieties sex hormones important in the ability to have offspring, to make pregnancy.

The adrenal glands are associated with almost all endocrine glands

Estrogens are called defenders of the female body. Produced in the ovaries and age-related atrophy only by the adrenal glands. They allow you to maintain cholesterol metabolism at the required level, preventing the deposition of atherosclerotic plaques in blood vessels. During menopause the adrenal glands responsible for the function of maintaining the level of estrogen without ovaries.

During pregnancy the anterior pituitary is increased in 2 times. It stimulates the adrenal glands. To the fetus the required regulation of water-salt metabolism, therefore, requires more mineralokortikoidov. The physiology of the mother is associated with the reaction to the fetus, therefore an increased synthesis of glucocorticoids provides the necessary immunosuppression to block the possible rejection.

A negative effect is observed in the form of increased pigmentation, increased hair growth on the body of the mother, education straw on the skin.

Insufficiency of adrenal hormones in women often manifested as menstrual dysfunction, problems with pregnancy, men may experience obesity, impotence.

The physiology of stress and adrenal glands

Stress first is in the nature of protection and provides training for all systems and organs to work in extreme conditions. But the frequent repetition of “panic attacks” is the depletion net cortices. Formed adrenal weakness or insufficiency.

Fascination with fashionable muscle growth and acceptance of anabolic steroids has a similar mechanism of suppression of the adrenal glands

The body’s ability to respond to irritant falls. You should pay attention to such stress factors as starvation, exhausting physical exercise.

When fasting, the body protects itself, using the possibility of production of glucocorticoids to support blood glucose. Occurs biochemical process of glucogenesis with the breakdown of carbohydrates and proteins. The load of the adrenal glands increases significantly. This could further exacerbate the effects of stress, lead to chronic failure, loss of vital energy for survival.

No wonder professional athletes see doctors. Know enough cases of the appearance of male sexual characteristics in women with extraordinary development of muscle.

After retiring from professional sports obstetricians get exhausted physically expectant mothers who require increased attention to be able to have a healthy baby.

We should not forget that the loss of libido in young people is also beginning symptom of adrenal overload.

Analysis is judged on the daily cortisol production

For some indicators is the work of adrenal glands?

If you have symptoms of insufficiency or hyperfunction of adrenal tests are performed:

  • A saliva test taken four times during the day in separate test tubes. It allows you to determine the level of fluctuations in hormones.
  • In the same way investigate the serum for cortisol and other hormones.
  • Adrenaline and cortisol determined in collected urine day.
  • If you do not carry out the test with the stimulation of adrenocorticotropic hormone. It allows you to judge the response of the adrenal glands. Take the initial blood test, then administered Corticotropin intramuscularly. After half an hour re-investigating the hormones.
  • At high levels carry out the test with Dexamethasone. It is given inside the control tests conducted in a day or two days.

Problems of adrenal insufficiency often occurs in patients with long-term current diseases. So shows the use of their analogs in the treatment. It is impossible to arrange additional overload your body. Further, the reaction is unpredictable even for very strong people.