Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)


Adrenal medulla
Gray1185.png
Medulla labeled at bottom right.
Latin '
Gray's subject #277 1280
System
MeSH [1]
[[Image:|190px|center|]]

Medullary part of the adrenal gland (on the pointer).

The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.

Function[edit | edit source]

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 a 85:15 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[edit | edit source]

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[edit | edit source]

Neoplasms including:

See also[edit | edit source]

References[edit | edit source]

  1. University of Michigan|Anatomy at UMich intro_autonomics_2_module/autonomics_05

External links[edit | edit source]

Community content is available under CC-BY-SA unless otherwise noted.