Adrenal medulla Health Dictionary

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Adrenal Medulla: From 1 Different Sources

The inner part of the adrenals, derived embryonically from spinal nerve precursors, they secrete epinephrine, norepinephrine and dopamine; used locally as neurotransmitters, sensitive receptors can be mobilized totally by the adrenal medullas.
Health Source: Herbal Medical
Author: Health Dictionary

Adrenal Glands

Also known as suprarenal glands, these are two small triangular ENDOCRINE GLANDS situated one upon the upper end of each kidney. (See diagram of ABDOMEN.)

Structure Each suprarenal gland has an enveloping layer of ?brous tissue. Within this, the gland shows two distinct parts: an outer, ?rm, deep-yellow cortical (see CORTEX) layer, and a central, soft, dark-brown medullary (see MEDULLA) portion. The cortical part consists of columns of cells running from the surface inwards, whilst in the medullary portion the cells are arranged irregularly and separated from one another by large capillary blood vessels.

Functions Removal of the suprarenal glands in animals is speedily followed by great muscular prostration and death within a few days. In human beings, disease of the suprarenal glands usually causes ADDISON’S DISEASE, in which the chief symptoms are increasing weakness and bronzing of the skin. The medulla of the glands produces a substance – ADRENALINE – the effects of which closely resemble those brought about by activity of the SYMPATHETIC NERVOUS SYSTEM: dilated pupils, hair standing on end, quickening and strengthening of the heartbeat, immobilisation of the gut, increased output of sugar from the liver into the bloodstream. Several hormones (called CORTICOSTEROIDS) are produced in the cortex of the gland and play a vital role in the metabolism of the body. Some (such as aldosterone) control the electrolyte balance of the body and help to maintain the blood pressure and blood volume. Others are concerned in carbohydrate metabolism, whilst others again are concerned with sex physiology. HYDROCORTISONE is the most important hormone of the adrenal cortex, controlling as it does the body’s use of carbohydrates, fats and proteins. It also helps to suppress in?ammatory reactions and has an in?uence on the immune system.... adrenal glands

Congenital Adrenal Hyperplasia

See ADRENOGENITAL SYNDROME and GENETIC DISORDERS.... congenital adrenal hyperplasia

Medulla

The inside part of an organ or tissue that is distinct from the outer part – for example, the marrow in the centre of a long bone, or the inner portion of the kidneys or adrenal glands.... medulla

Medulla Oblongata

The hindmost part of the BRAIN, continuing into the SPINAL CORD. In it are situated several of the nerve centres which are most essential to life, such as those governing breathing, the action of the heart and swallowing.... medulla oblongata

Adrenal Cortex

The outer covering of the two adrenal glands that lie atop each kidney. Embryonically derived from gonad tissue, they make steroid hormones that control electrolytes, the management of fuels, the rate of anabolism, the general response to stress, and maintenance of nonspecific resistance.... adrenal cortex

Adrenal-activator

An agent which stimulates the adrenal glands thereby increasing secretion of cortisol and adrenal hormones. A herb with a mild cortico-steroid effect. Liquorice. Ginseng. Sarsaparilla. ... adrenal-activator

Adrenal Failure

Insufficient production of hormones by the adrenal cortex (the outer part of the adrenal glands).

It can be acute or chronic.

Adrenal failure may be caused by a disorder of the adrenal glands, in which case it is called Addison’s disease, or by reduced stimulation of the adrenal cortex by ACTH, a hormone produced by the pituitary gland.... adrenal failure

Adrenal Gland Disorders

A range of uncommon but sometimes serious disorders due to deficient or excessive production of hormones by one or both of the adrenal glands.

A genetic defect causes congenital adrenal hyperplasia, in which the adrenal cortex is unable to make sufficient hydrocortisone and aldosterone, and androgens are produced in excess. In adrenal failure, there is also deficient production of hormones by the adrenal cortex; if due to disease of the adrenal glands, it is called Addison’s disease. Adrenal tumours are rare and generally lead to excess hormone production.

In many cases, disturbed activity of the adrenal glands is caused, not by disease of the glands themselves, but by an increase or decrease in the blood level of hormones that influence the action of the adrenal glands. For example, hydrocortisone production by the adrenal cortex is controlled by ACTH, which is secreted by the pituitary gland. Pituitary disorders can disrupt production of hydrocortisone.... adrenal gland disorders

Adrenal Tumours

Cancerous or noncancerous tumours in the adrenal glands, usually causing excess secretion of hormones. Adrenal tumours are rare. Tumours of the adrenal cortex may secrete aldosterone, causing primary aldosteronism, or hydrocortisone, causing Cushing’s syndrome. Tumours of the medulla may cause excess secretion of adrenaline and noradrenaline. Two types of tumour affect the medulla: phaeochromocytoma and neuroblastoma, which affects children. These tumours cause intermittent hypertension and sweating attacks. Surgical removal of a tumour usually cures these conditions.... adrenal tumours

Conus Medullaris

the conical end of the spinal cord, at the level of the lower end of the first lumbar vertebra.... conus medullaris

Medullary Carcinoma

a tumour whose consistency was thought to resemble that of bone marrow. Medullary carcinoma of the thyroid has associations with tumours of other organs (multiple endocrine neoplasia; see MENS) and is often familial: it arises from the *C cells of the thyroid and produces calcitonin, which can often be used as a *tumour marker.... medullary carcinoma

Medullated Nerve Fibre

(myelinated nerve fibre) see myelin.... medullated nerve fibre

Adrenal Hyperplasia, Congenital

An uncommon genetic disorder in which an enzyme defect blocks the production of corticosteroid hormones from the adrenal glands. Excessive amounts of androgens (male sex hormones) are produced, which can result in abnormal genital development in an affected fetus. Other effects include dehydration, weight loss, low blood pressure, and hypoglycaemia. Hyperplasia (enlargement) of the adrenal glands occurs and there is excessive skin pigmentation in skin creases and around the nipples.

In severe cases, the disorder is apparent soon after birth. In milder cases, symptoms appear later, sometimes producing premature puberty in boys and delayed menstruation, hirsutism, and potential infertility in girls.

Congenital adrenal hyperplasia is confirmed by measuring corticosteroid hormones in blood and urine. Treatment is by hormone replacement. If this is started early, normal sexual development and fertility usually follow.... adrenal hyperplasia, congenital


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