The adrenal medulla is located inside the adrenal cortex and produces stress hormones including epinephrine, norepinephrine, and dopamine. The main hormones secreted are epinephrine and norepinephrine, which make up 85-90% and 10-12% of secretions respectively. These catecholamines help prepare the body for emergencies by increasing heart rate, blood flow, and blood sugar levels. They are synthesized from amino acids and stored in chromaffin cells before release. Diseases like pheochromocytoma or neuroblastoma can cause high catecholamine secretion due to tumors on the adrenal glands or nerves.

1. By
Mr . Bhala Chandrudu,.
RVM Institute of Medical sciences & RC
ADRENAL MEDULLA

2. ANATOMY OF THE ADRENAL GLANDS
An adrenal gland is made of two main parts:
The adrenal cortex is the outer part and also the largest
part of an adrenal gland. It is divided into three separate
zones: zonaglomerulosa, zonafasciculata and
zonareticularis . Each zone is responsible for producing
specific hormones.
The adrenal medulla is located
inside the adrenal cortex in the
center of an adrenal gland. It
produces “stress hormones,”
including adrenaline.
(The adrenal cortex and adrenal medulla are enveloped in
an adipose capsule that forms a protective layer around
an adrenal gland).

3. ADRENAL MEDULLA:- The inner part of an adrenal
gland, The main hormones secreted by the adrenal
medulla include , epinephrine& norepinephrine &
Dopamine .
Adrenal medulla is a sympathetic ganglion in which
the post- ganglionic neurons have lost their axons and
become secretary cells
CATECHOLAMINES:- These are organic
compounds derived from Amino acid Tyrosine. These
hormones are not essential for life but they help to
prepare the individual to deal with emergencies. They
are secreted from adrenal medulla.
 Epinephrine (adrenaline)
 Norepinephrine (Noradrenaline),
 Dopamine
f which have similar
functions.

4. CATECHOLAMINES:-
85% to 90 % of cells are of the epinephrine Secreting
type.
10% -12%Norepinephrine secreting type. A small
number of cells can produce Dopamine 2%-3%.
Epinephrine is the major secretion of Adrenal
Medulla .
Nor epinephrine is the minor secretion of Adrenal
medulla.
Dopamine is the very minor secretion of Adrenal
medulla.
Normal plasma concentration ;-
Epinephrine ------> 30pg/mL
Norepinephrine ------> 300pg/mL

5. SYNTHESIS OF
CATECHOLAMINES:-
Catecholamines are synthesized from
phenylalanine & tyrosine.
Phenylalanine on hydroxylation can
converted to Tyrosine. Tyrosine on
hydroxylation gets converted to DOPA
which is on decarboxylation
converted to Dopamine. Dopamine is
converted to Nor epinephrine on
hydroxylation . This epinephrine can
converted to Epinephrine by the action
of phenylethanolamine-N -Methyltrans
-ferase. They are Stored in the
granules of Chromaffin cells & later
Secreted in to venous blood.
Catecholamine have a Half-life of 2

6. Among other things, these hormones are capable of
increasing the heart rate and force of heart
contractions, increasing blood flow to the muscles
and brain, relaxing airway smooth muscles, and
assisting in glucose (sugar) metabolism. They also
control the squeezing of the blood vessels
(vasoconstriction), helping maintain blood pressure
and increasing it in response to stress.
Like several other hormones produced by the adrenal
glands, epinephrine and norepinephrine are often
activated in physically and emotionally stressful
situations when your body needs additional
resources and energy to endure unusual strain

7. Mechanism of Action of Catecholamines :-
Catecholamine acts on the target tissue through its
corresponding receptors .
There are 2 types of Adrenergic receptors
α- Adrenergic receptor are of 2 types - α I &
α2
β-Adrenergic receptor- β are of 3 types - β I , β
2 and β 3 .
Norepinephrine excites mainly the “α” Receptors .
Epinephrine excites on the both types (α, β) of receptors
equally.
β-Receptors are coupled with adenylyl
cyclase. Therefore the action of Catecholamines
through these receptors is mediated by cAMP.
α I receptors is coupled with phosphatidylinositol.
Therefore, the action of Catecholamines through these

10. Circulating Epinephrine on CVS:-
 Increased heart rate and inotropy (β1-adrenoceptor mediated)
 Vasoconstriction in most systemic arteries and veins. (postjunctional
α 1 and α 2 adrenoceptors).
 Vasodilatation in muscle and liver vasculatures at low concentrations
(β2- adrenoceptor).
 Vasoconstriction at high concentrations (α-adrenoceptor mediated).
 The overall cardiovascular response
to low-to-moderate circulating
concentrations of epinephrine is
Increased cardiac output and a
redistribution of the cardiac out put
to muscular and hepatic circulations
with only a small change in mean
arterial pressure.
Although cardiac output is increased,
 arterial pressure does not change much because the systemic vascular
resistance falls due to activation of vascular β2-adrenoceptors. At high
plasma concentrations, epinephrine increases arterial pressure because
of binding to
α-adrenoceptors on blood vessels, which offsets the β2-adrenoceptor

11. Circulating Norepinephrine on CVS
 Increased heart rate (although only transient) and
increased inotropy ,(β1-adrenoceptor mediated) are the
direct effects norepinephrine on the heart.
 Vasoconstriction occurs in most systemic arteries and veins
(post junctional α 1 and α 2 adrenoceptors).
 The overall cardiovascular response
is increased cardiac output and
systemic vascular resistance, which
results in an elevation in arterial
blood pressure. Heart rate, although
initially stimulated by norepinephrine,
decreases due to activation of
baroreceptors and vagal -mediated slowing of the heart rate in
responses to the elevation in arterial pressure.

12. ACTION OF CATECHOLAMINES:-
Effect on GIT :- Catecholamines cause inhibition of the GIT .
Reducing motility and secretion.
Effect on Respiration :- Catecholamines is a bronchodilator
and also stimulate respiration.
Effect on EYE:- Catecholamines cause dilation of pupils.
This results in improvement of vision.
Effect on Endocrine Glands :- Catecholamines stimulate the
various endocrine glands resulting in release of hormones .
They stimulate release of ADH, Thyroxine, Renin and insulin.
Effect on Metabolism:- catecholamines can stimulate
glycogenolysis in liver, results increasing the glucose levels.
They also stimulate gluconeogenesis.

13. ACTION OF CATECHOLAMINES:-
Effect on Metabolism:- Catecholamines are
diabetogenic & Ketogenic hormones .They activate
hormone-sensitive lipase in the fat cells & increase
plasma free fatty acid levels. They promote β
oxidation of free fatty acids in the muscle & liver to
form Ketone bodies .
Fight or Flight Response:-Catecholamines have
widespread
effects on various system of body helping an
individual to
prepare for emergency. They increase the
cardiaoutput,
rate & depth of respiration & energy supply the

14. REGULATION OF SECRETION:-
There is no standard inbuilt regulatory mechanism for
epinephrine secretion like other hormones. Increased
epinephrine secretion from adrenal medulla with
sympathetic stimulation as in the following situations:
> Severe exercise ,Anxiety, fear, pain , trauma.
> Hypovolaemia , hypoglycemia.
> Canon’s fight and flight reactions
> Diabetic Keto-acidosis, Myocardial infarction.
when there is no such stimulation ,only a small amount, called
basal
level is secreted.
Hemorrhage predominantly stimulates the epinephrine
secretion.
Emotional stress and Anger stimulate the Norepinephrine

15. DEGRADATION:- Free Catecholamines are excreted
through urine as well as their metabolites. The main
metabolites is VMA (Vanillymandelic acid). The
estimation of VMA in urine gives an idea about the
Catecholamines secreted in the body. It increases in
cause of Pheochromocytoma. There are two
enzymes are involved in the degradation of
Catecholamines in the body body
They are 1) .MAO (Mono-amino-oxidase)
2) . COMT ( Catechol-O-methyl
transferase).are present in the body, but COMT is
not found at the postganglionic sympathetic nerve
endings . A major part of NE is removed through Re-
uptake in the sympathetic nerve endings and is used
again .

16. NEUROENDOCRINE TUMORS
Neuroendocrine tumors are develops from cells in the
hormonal and nervous systems. These tumors can produce high
levels of catecholamine's.
 Pheochromocytomas are neuroendocrine tumors present in
adrenal glands. Around 80–85%Trusted Source of
pheochromocytomas grow in the inner layer of the adrenal glands,
while the remaining 15–20% grow outside of this area.
 Some possible symptoms of a pheochromocytoma include: high
blood pressure,heart palpitations ,anxiet , shaking,excessive
sweating, pale skin, tingling in the fingers and toes, blurred
vision,severe headaches,
abdominal pain,sickness , constipation ,weight loss ,high blood
sugar ,
levels & psychiatric disturbances,
 Although generally benign, some pheochromocytomas may
continue to grow without treatment. The symptoms may worsen
as the tumor grows, causing possible damage to the kidneys and
heart.
 Tumor growth also increases the risk of a stroke and heart attack.

17. NEUROBLASTOMA
 A neuroblastoma is a type of cancer that occurs in
specialized nerve cells called neuroblasts. Most of the time,
this cancer develops in an adrenal gland or in the nerve
tissues that run alongside the spinal cord. Neuroblastomas
can cause increased levels of Catecholamines.
 Neuroblastomas are the most common cancer in infants and
account for 6% of all childhood cancers Trusted Source. They
are rare in people over the age of 10.
Some possible symptoms of a neuroblastoma include:
abdominal bloating , abdominal mass,
watery diarrhea, anemia, bluish skin , blue or purple
discoloration around the eyes, bulging eyes, small pupils ,
drooping upper eyelid , Fever, an inability to sweat , high
blood pressure , bone pain ,low blood cell count , paralysis

18. DOPAMINE :-
This neurotransmitter sends signals throughout the
nervous system. It helps regulate the following:-
Movement,
emotions, memory , the brain’s reward mechanism
ADRENALINE, OR EPINEPHRINE:-
This neurotransmitter is responsible for the fight-or-
flight response. When a person experiences stress, the
body releases adrenaline to allow increased blood flow
to the muscles, heart, and lungs.
NORADRENALINE , OR NOREPINEPHRINE:-
This neurotransmitter helps the body respond to
stress. Noradrenaline release increases a person’s
heart rate and blood pressure. It is also involved in
mood regulation and the ability to concentrate.

19. THANKS