The document discusses the adrenal glands and their hormones. It describes that the adrenal glands are composed of the adrenal cortex and medulla. The cortex secretes corticosteroids like mineralocorticoids (aldosterone), glucocorticoids (cortisol) and androgens. Aldosterone regulates sodium and potassium levels while cortisol regulates carbohydrate and protein metabolism and helps in stress response. The secretion of aldosterone and cortisol is regulated by the renin-angiotensin-aldosterone system and the hypothalamic-pituitary-adrenal axis respectively.

1. Adrenal Glands
• Introduction
Adrenal glands are called the life saving glands
or the essential endocrine glands. There are two
adrenal glands. Each gland is situated on the
upper pole of each kidney.
Also known as suprarenal glands. Each gland
weight about 4gm. Each gland is composed of
two parts, the Adrenal Medulla and the
Adrenal Cortex.
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2. • The adrenal medulla is functionally related to the
sympathetic nervous system.It secretes the
hormones epinephrine and norepinephrine in
response to sympathetic stimulation.
• The adrenal cortex secretes an entirely different
group of hormones,called
corticosteroids.These hormones are all
synthesized from the steroid cholesterol,and
they all have similar chemical formulas.
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3. • Adrenal cortex is composed of three distinct
layers.
1- Zona glomerulosa
This is the outer most layer/zone of the adrenal
cortex which secretes mineralocorticoids.
2- Zona fasciculata.
This is the middle layer/zone of the adrenal cortex
which secretes glucocorticoids and adrenal
androgens. 3

4. 3- Zona reticularis
This is the inner most layer/zone of the adrenal cortex
which also secretes glucocorticoids and adrenal
androgen,but in a small quantities.
Mineralocorticoids
Mineralocorticoids are the corticosteroids that act on the
minerals (Electrolytes) particularly Sodium and
Potassium.
– Mineralocorticoids are,
1- Aldosterone (principal hormone)
2- 11-Deoxycorticosterone.
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5. Source of Secretion
• The mineralocorticoids are secreted by Zona
glomerulosa of the adrenal cortex.
Transport
• Mineralocorticoids are transported in the blood
by binding with plasma proteins, especially
Globulins. The binding is loose and 50% of
these hormones are present in free form.
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6. Chemistry and Half-Life
• Mineralocorticoids are C21 steroids having 21
carbon atoms.Half-life of mineralocorticoids is 20
minutes.
Daily output and Plasma Level
– Aldosterone, daily output,0.15 mg.
– Plasma Level, 0.006 mg/dL.
– 11-Dexoycorticosterone, daily output 0.2mg,
– Plasma Level, 0.006 mg/dL.
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7. Functions of Mineralocorticoids
• 1- Life Saving Hormones.
– Aldosterone is very essential for life and it is usually
called life saving hormone.Total loss of
corticosteroids usually causes death within 3-15
days.It is mainly b/c of loss of
mineralocorticoids.During mineralocorticoids
deficiency the potassium ion conc.of the ECF rises
markedly.
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8. • The conc.of sodium and chloride ions
decreases.The total ECF volume and blood
volume are also greatly reduced.All these
changes lead to cardiac dysfunction,shock like
state and finally death.
• The entire sequence can be prevented and life
can be saved by administration of
aldosterone.That is why, it is known as life
saving hormone.
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9. 2- Effects on Renal Tubules.
• The main action of aldosterone is to
maintain balance of the electrolyte
contents of the body fluid. The sites of
action are the ascending limb, descending
limb, loop of henle, and distal and
collecting tubules.
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10. A)- Aldosterone causes increased tubular
reabsorption of Na+ in exchange for K+ and H+
ions.The lack of aldosterone causes an excess
loss of Na+ in urine.
B)- Aldosterone increases K+ secretion into the
distal and collecting tubules of the kidneys. This
may be due to ionic exchange with Na+
reabsorption. Excess aldosterone causes
hypokalemia and muscular weakness.
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11. C)- Aldosterone causes water absorption
due to the conc. Gradient created by Na+
absorption, increasing ECF volume.
3- Effects on Sweat glands and Salivary glands.
• Aldosterone has almost the similar effect
on sweat glands and salivary glands as it
shows on renal tubules.
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12. • Sodium is reabsorbed from sweat glands
under the influence of aldosterone, thus
the loss of sodium from the body is
prevented.
• It becomes more important in hot
environment when lot of sweat is
excreted.Same effect is shown on saliva
also.Thus, aldosterone helpe conservation
of sodium in the body.
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13. 4)- Effects on Intestine.
• Aldosterone greatly enhances sodium
absorption from the intestine, especially in the
colon and prevents loss of sodium through
feces.
5)- Effects on Circulation and B.P.
• Increases blood volume and cardiac output.
• Increase in ECF volume and the blood volume
finally lead to increases in B.P.
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14. Aldosterone Escape.
• When excess aldosterone is administered, it
causes excess Na+ and water absorption
increasing ECF volume,in turn increasing blood
volume.
• Increased blood volume causes increased
cardiac output and blood pressure. Pressure
diuresis and pressure natriuresis cause a
secondary loss of Na+ and water. This process is
called aldosterone escape.
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15. Regulation of Aldosterone Secretion.
• Aldosterone secretion is regulated by four
important factors.
1)- Increased potassium ion conc. In the
extracellular fluid greatly increases aldosterone
secretion.
2)- Increased activity of the renin-angiotensin
system (increased levels of angiotensin -II) also
greatly increases aldosterone secretion.
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16. 3)- Increased sodium ion conc. In the
extracellular fluid very slightly decreases
aldosterone secretion.
4)- ACTH from the anterior pituitary gland is
necessary for aldosterone secretion but
has little effect in controlling the rate of
secretion.
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17. Glucocorticoids
Introduction
• Glucocorticoids are the corticosteroids
which act mainly on glucose metabolism.
Glucocorticoids are
1- Cortisol. (Principal hormone)
2- Corticosterone.
3- Cortisone.
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18. Source of Secretion
• Glucocorticoids are secreted mainly by Zona
fasciculata of adrenal cortex.A small quantity of
glucocorticoids is also secreted by Zona
reticularis.
Chemistry and Half-Life
• Glucocorticoids are C21 steroids having 21
carbon atoms.
• Half-Life of Cortisol is 70-90 minutes.
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19. Daily output and Plasma Level.
Daily output, 15.0mg.
Plasma Level, 12.0ug/dL.
Functions of Glucocorticoids.
1- Life protecting hormone.
Like aldosterone, cortisol is also essential for life
but in a different way.Aldosterone is a life saving
hormone,whereas cortisol is a life protecting
hormone b/c,it helps to withstand the stress and
trauma in life.
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20. • 2- Effects of Cortisol on Carbohydrate
Metabolism.
• A)- The best known metabolic effect of cortisol
on metabolism is their ability to stimulate
gluconeogensis, (formation of carbohydrate from
proteins and some other substances) by the
liver.
• B)- Cortisol also causes a moderate decrease in
the rate of glucose utilization by the cells
everywhere in the body.
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21. • C)- Both, the increased rate of gluconeogensis
and the moderate reduction in the rate of
glucose utilization by the cells cause the blood
glucose conc.to rise.This condition is called
Adrenal diabetes.
• 3)- Effects on Protein Metabolism.
• A)- The principle effects of cortisol on the
metabolic system of the body isreduction of
protein stores in all body cells except those of
the liver.
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22. • This is caused by both decreased protein
synthesis and increased catabolism of protein in
the cells.
• B)- It inhibits amino acid entry into all cells
except the liver.
• C)- It increases amino acid conc. In blood.
• 4)- Effects on Fat metabolism.
• A)- It mobilizes fatty acids from adipose tissues.
• B)- It increases free fatty acid conc. In blood.
• C)- It increases utilization of free fatty acid for
energy.
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23. 5)-Electrolyte Metabolism.
• A)- It promotes Na+ and CI- retention from the
renal tubules.
• B)- It increases excretion of K+ by the kidneys.
6)- Water Metabolism.
• It causes diuresis by suppressing ADH secretion
or by increasing destruction of ADH by the liver
cells.
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24. General Effects
• On C.N.S.
– Low cortisol level cause restlessness, insomnia, and
inability to concentrate.
– Causes excitation of the CNS.
• On C.V.S.
• Cortisol increases B.P b/c of increased
production of angiotensionogen.
• Increased sensibility of vascular smooth muscle
to noradrenaline and adrenaline.
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25. On Blood Cells
• Increases the platelet count.
• Increases total WBCs.
• Increase neutrophils, monocytes and
RBCs count.
• Decreases lymphocytes and basophils.
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26. • On Bone
• Stimulate the bone resorption (osteoclastic
activity) and inhibit bone formation and
mineralization( osteoblastic activity).
• It decreases the deposition of calcium.
• Anti-inflammatory Effects.
• Causes stabilization of membrane of
lysosome.This inhibits the release of proteolytic
enzymes responsible for inflammation.
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27. • Release of substances like histamine and
proteolytic enzymes from affected tissues
is prevented.
• Anti-Allergic Actions.
• Prevent the various reactions in allergic
conditions as in the case of inflammation.
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28. Regulation of Cortisol
• The secretion of glucocorticoids is
regulated by hormone of anterior pituitary
gland called adrenocorticotropic hormone
(ACTH).
• The control of glucocorticoids secretion is
under a typical negative feedback
mechanism.
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29. • The two principle stimuli are stress and low
blood level of glucocorticoids.
• Both conditions stimulate the hypothalamus to
secrete a regulating hormone called
corticotropin releasing hormone (CRH).
• This secretion initiates the release of ACTH from
the anterior pituitary gland.
• ACTH is carried through blood to the adrenal
cortex where it stimulates glucocorticoid
secretion.
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