This MedLibrary.org supplementary page on Adrenal medulla is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
| Adrenal medulla | |
|---|---|
 |
|
| Medulla labeled at bottom right. | |
| Gray's | subject #277 1280 |
| Artery | superior suprarenal artery, middle suprarenal artery, Inferior suprarenal artery |
| Vein | suprarenal veins |
| Nerve | celiac plexus, renal plexus |
| Lymph | lumbar glands |
| Precursor | Neural crest |
.JPG)
The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.
Contents |
Function
Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine.
In response to stressors such as exercise or imminent danger, medullary cells release catecholamines into the blood in an 17:3 ratio of adrenaline to noradrenaline.[1]
Notable effects of adrenaline and noradrenaline include increased heart rate and blood pressure, blood vessel constriction, bronchiole dilation, and increased metabolism, all of which are characteristic of the fight-or-flight response. Release of catecholamines is stimulated by nerve impulses, and receptors for catecholamines are widely distributed throughout the body.
Origin
Medullary cells are derived from the embryonic neural crest and, as such, are simply modified neurons.
In particular, they are modified postganglionic cells of the sympathetic nervous system that have lost their axons and dendrites, receiving innervation from corresponding preganglionic fibers.
Moreover, as the synapses between pre- and postganglionic fibers are called ganglia, the adrenal medulla is actually a ganglion of the sympathetic nervous system.
Pathology
Neoplasms including:
- Pheochromocytoma (most common) a catecholamine-secreting tumor of the adrenal medulla
- Neuroblastoma a neuroendocrine tumor of any neural crest tissue of the sympathetic nervous system
- Ganglioneuroma a tumor in the nerve cells of the peripheral nervous system
See also
References
External links
- SUNY Labs 40:04-0202 - "Posterior Abdominal Wall: Blood Supply to the Suprarenal Glands"
- Anatomy Atlases - Microscopic Anatomy, plate 15.292 - "Adrenal Gland"
- Location of Adrenal medulla
|
||||||||
Wikipedia content modification information:
- This page was last modified on 31 May 2008, at 12:43.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Adrenal medulla".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.