Adrenal-Anatomi Diposkan oleh dokTerCantik

Kelenjar adrenal adalah sepasang organ yang terletak dekat kutub atas ginjal, terbenam dalam jaringan lemak. Kelenjar ini ada 2 buah, berwarna kekuningan serta berada di luar (ekstra) peritoneal. Bagian yang sebelah kanan berbentuk pyramid dan membentuk topi (melekat) pada kutub atas ginjal kanan. Sedangkan yang sebelah kiri berbentuk seperti bulan sabit, menempel pada bagian tengah ginjal mulai dari kutub atas sampai daerah hilus ginjal kiri. Kelenjar adrenal pada manusia panjangnya 4-6 cm, lebar 1-2 cm, dan tebal 4-6 mm. Bersama-sama kelenjar adrenal mempunyai berat lebih kurang 8 g, tetapi berat dan ukurannya bervariasi bergantung umur dan keadaan fisiologi perorangan. Kelenjar ini dikelilingi oleh jaringan ikat padat kolagen yang mengandung jaringan lemak. Selain itu masing-masing kelenjar ini dibungkus oleh kapsul jaringan ikat yang cukup tebal dan membentuk sekat/septa ke dalam kelenjar.

Vaskularisasi

Kelenjar adrenal disuplai oleh sejumlah arteri yang masuk pada beberapa tempat di sekitar bagian tepinya. Ketiga kelompok utama arteri adalah arteri suprarenalis superior, berasal dari arteri frenika inferior; arteri suprarenalis media, berasal dari aorta ; dan arteri suprarenalis inferior, berasal dari arteri renalis. Berbagai cabang arteri membentuk pleksus subkapsularis yang mencabangkan tiga kelompok pembuluh: arteri dari simpai; arteri dari kortex, yang banyak bercabang membentuk jalinan kapiler diantara sel-sel parenkim (kapiler ini mengalir ke dalam kapiler medulla); dan arteri dari medulla, yang melintasi kortex sebelum pecah membentuk bagian dari jalinan kapiler luas dari medulla. Suplai vaskuler ganda ini memberikan medulla dengan darah arteri (melalui arteri medularis) dan darah vena (melalui arteri kortikalis). Endotel kapiler ini sangat tipis dan diselingi lubang-lubang kecil yang ditutupi diafragma tipis. Di bawah endotel terdapat lamina basal utuh. Kapiler dari medulla bersama dengan kapiler yang mensuplai kortex membentuk vena medularis, yang bergabung membentuk vena adrenal atau suprarenalis.

Functional Anatomy of the Adrenal Gland

The two adrenal glands are located immediately anterior to the kidneys, encased in a connective tissue capsule and usually partially buried in an island of fat. Like the kidneys, the adrenal glands lie beneath the peritoneum (i.e. they are retroperitoneal). The exact location relative to the kidney and the shape of the adrenal gland vary among species.

Inspection of a mammalian adrenal gland that has been sectioned reveals two distinct regions, as demonstrated to the right with a sheep adrenal (click the image to flip between surface and cut views):

An inner medulla, which is a source of the catecholamines epinephrine and norepinephrine. The chromaffin cell is the principle cell type. The medulla is richly innervated by preganglionic sympathetic fibers and is, in essence, an extension of the sympathetic nervous system.

An outer cortex, which secretes several classes of steroid hormones (glucocorticoids and mineralocorticoids, plus a few others). Histologic examination of the cortex reveals three concentric zones of cells that differ in the major steroid hormones they secrete.

Despite their organization into a single gland, the medulla and cortex are functionally different endocrine organs, and have different embryological origins. The medulla derives from ectoderm (neural crest), while the cortex develops from mesoderm. The utility, if any, of having them together in one discrete organ is not obvious. In some species, amphibians and certain fish, for example, two separate organs are found.

http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/adrenal/anatomy.html

Endocrinology

The Adrenal Glands

Anatomy of the adrenal glands:

Adrenal glands, which are also called suprarenal glands, are small, triangular glands located on top of both kidneys. An adrenal gland is made of two parts: the outer region is called the adrenal cortex and the inner region is called the adrenal medulla.

Function of the adrenal glands:The adrenal glands work interactively with the hypothalamus and pituitary gland in the following process:

The hypothalamus produces corticotropin-releasing hormones, which stimulate the pituitary gland.

The pituitary gland, in turn, produces corticotropin hormones, which stimulates the adrenal glands to produce corticosteroid hormones.

Both parts of the adrenal glands - the adrenal cortex and the adrenal medulla - perform very separate functions.

What is the adrenal cortex?The adrenal cortex, the outer portion of the adrenal gland, is essential to life by secreting hormones that have an effect on the body's metabolism, on chemicals in the blood, and on certain body characteristics. The adrenal cortex secretes corticosteroids and other hormones directly into the bloodstream. The hormones produced by the adrenal cortex include:

corticosteroid hormones

o hydrocortisone hormoneThis hormone, also known as cortisol, controls the body's use of fats, proteins, and carbohydrates.

o corticosteroneThis hormone, together with hydrocortisone hormones, suppresses inflammatory reactions in the body and also affects the immune system.

aldosterone hormoneThis hormone inhibits the level of sodium excreted into the urine, maintaining blood volume and blood pressure.

androgenic steroids (androgen hormones)These hormones have minimal effect on the development of male characteristics.

What is the adrenal medulla?

The adrenal medulla, the inner part of the adrenal gland, is not essential to life, but helps a person in coping with physical and emotional stress. The adrenal medulla secretes the following hormones:

epinephrine (Also called adrenaline.)This hormone increases the heart rate and force of heart contractions, facilitates blood flow to the muscles and brain, causes relaxation of smooth muscles, helps with conversion of glycogen to glucose in the liver, and other activities

norepinephrine (Also called noradrenaline.)This hormone has little effect on smooth muscle, metabolic processes, and cardiac output, but has strong vasoconstrictive effects, thus increasing blood pressure.

http://www.healthsystem.virginia.edu/UVAHealth/adult_endocrin/adrengl.cfm