The adrenal medulla is located within the adrenal glands and produces catecholamines such as adrenaline and noradrenaline which are released into the bloodstream. It is innervated by the sympathetic nervous system which causes the release of hormones during the fight or flight response, increasing functions such as heart rate, blood pressure and blood flow. Conditions affecting the adrenal medulla can cause tumors and abnormal hormone secretion leading to symptoms like blood pressure changes and nervous system issues.

1. ADRENAL GLAND

2. • ADRENAL MEDULLA: The adrenal medulla is at the centre of each
adrenal gland, and is surrounded by the adrenal cortex.
• The chromaffin cells of the medulla are the body's main source of
the catecholamines, such as adrenaline and noradrenaline, released by
the medulla.
• Approximately 20% noradrenaline (norepinephrine) and 80%
adrenaline (epinephrine) are secreted here.
• The adrenal medulla is driven by the sympathetic nervous
system via preganglionic fibers originating in the thoracic spinal cord,
from vertebrae T5–T11.Because it is innervated by preganglionic nerve
fibers, the adrenal medulla can be considered as a
specialized sympathetic ganglion.
• Unlike other sympathetic ganglia, however, the adrenal medulla lacks
distinct synapses and releases its secretions directly into the blood.

3. • Catecholamines
• Primarily referred to in the United States
as epinephrine and norepinephrine, adrenaline and noradrenaline are catecholami
nes, water-soluble compounds that have a structure made of a catechol group and
an amine group.
• The adrenal glands are responsible for most of the adrenaline that circulates in
the body, but only for a small amount of circulating noradrenaline.
• These hormones are released by the adrenal medulla, which contains a dense
network of blood vessels.
• Adrenaline and noradrenaline act by interacting with adrenoreceptors throughout
the body, with effects that include an increase in blood pressure and heart rate.]
• Actions of adrenaline and noradrenaline are responsible for the fight or flight
response, characterised by a quickening of breathing and heart rate, an increase in
blood pressure, and constriction of blood vessels in many parts of the body.

4. • Formation Catecholamines are produced in chromaffin cells in the medulla
of the adrenal gland, from tyrosine, a non-essential amino acid derived from
food or produced from phenylalanine in the liver.
• The enzyme tyrosine hydroxylase converts tyrosine to L-DOPA in the first
step of catecholamine synthesis.
• L-DOPA is then converted to dopamine before it can be turned into
noradrenaline. In the cytosol, noradrenaline is converted to epinephrine by
the enzyme phenylethanolamine N-methyltransferase (PNMT) and stored in
granules.
• Glucocorticoids produced in the adrenal cortex stimulate the synthesis of
catecholamines by increasing the levels of tyrosine hydroxylase and PNMT.
• Catecholamine release is stimulated by the activation of the sympathetic
nervous system. Splanchnic nerves of the sympathetic nervous
system innervate the medulla of the adrenal gland.
• When activated, it evokes the release of catecholamines from the storage
granules by stimulating the opening of calcium channels in the cell
membrane.

5. • Adrenal medulla function
• The adrenal medulla secretes catecholamines, hormones that help your
body respond to stress. Catecholamines include adrenaline and
noradrenaline, also known as epinephrine and norepinephrine.
• Within moments, your body releases adrenal medulla hormones to
boost organ functioning. This is also known as the fight-or-flight
response.
• Other signs of the fight-or-flight response include:
• Delayed pain if injured.
• Increase in strength or speed.
• Heightened awareness of your surroundings.

6. • Role of adrenaline
• Your medulla secretes adrenaline in response to low blood sugar
levels or exercise. It helps your body react to stress by:
• Delivering extra oxygen to muscles.
• Increasing blood pressure and heart output.
• Widening small arteries.
• Role of noradrenaline
• This hormone helps your body respond to stress by:
• Increasing blood sugar levels.
• Narrowing blood vessels.
• Raising your blood pressure.
• Norepinephrine (noradrenaline) also:
• Contributes to your brain’s ability to store memories.
• Helps you wake up.
• Increases attention and focus.
• Supports emotional health.

7. Conditions and disorders affect the adrenal medulla
• Conditions affecting the medulla are rare but can be life-threatening. These
disorders typically include medullary or adrenal tumors, most of which are
benign (noncancerous). Some tumors run in families.
• Adrenal medullary tumors include:
• Ganglioneuroma, a tumor occurring in adults and children that develops in
autonomic nervous system cells.
• Neuroblastoma, a cancer in nerve tissue that often affects children.
Neuroblastomas can also develop in your abdomen, chest or spinal cord.

8. • Paraganglioma, a tumor made of tissue (chromaffin) that's found in
your adrenal glands.
• It forms in the peripheral nervous system and affects your limbs,
head, neck and abdomen.
• Pheochromocytoma, tumor affecting the release of epinephrine and
norepinephrine.
• This condition causes dangerous blood pressure spikes (hypertensive
crisis).
• Symptoms of adrenal medullary tumors
• Medullary tumors grow slowly, so you might not notice symptoms at
first. They're often discovered in imaging studies taken for other
reasons (adrenal incidentaloma).
• Medulla tumor symptoms can affect your:
• Blood pressure.
• Digestive system.
• Nervous system.
• Respiratory system.
• Urinary system.