The adrenal glands are located above the kidneys and are composed of an outer cortex and inner medulla. The cortex produces three types of hormones - glucocorticoids, mineralocorticoids, and sex hormones. Glucocorticoids such as cortisol help regulate metabolism and the stress response, while mineralocorticoids like aldosterone control water and electrolyte balance. The medulla secretes adrenaline and noradrenaline in response to sympathetic nervous system stimulation to initiate the fight-or-flight response. Both parts of the adrenal glands help maintain homeostasis during stress.

1. Anatomy
ADRENAL GLANDS

2. ADRENAL (SUPRARENAL) GLANDS
There are two adrenal glands,
one situated on the upper pole of each
kidney enclosed within the renal fascia.

3. They are about 4 cm long and 3 cm
thick.

4. The arterial blood supply to the glands is by
branches from the abdominal aorta and renal
arteries.
The venous return is by suprarenal veins.

5. The right gland drains into the inferior vena
cava
and the left into the left renal vein.

6. The glands are composed of two parts
which have different structures and
functions.

7. The outer part is the cortex and the inner
part the medulla.
The adrenal cortex is essential to life.

8. ADRENAL CORTEX
The adrenal cortex produces three groups
of steroid hormones from cholesterol.

9. They are collectively called adreno
corticocoids
(corticosteroids, corticoids).

10. They are:
• Glucocorticoids
• Mineralocorticoids
• Sex hormones (androgens).

11. The hormones in each group have
different characteristic actions but due to
their structural similarity their actions may
overlap.

12. GLUCOCORTICOIDS
Cortisol (hydrocortisone),
corticosterone and cortisone are
the main glucocorticoids.

13. They are essential for life,
regulating metabolism and
responses to stress.

14. Secretion is stimulated by ACTH from the
anterior pituitary and by stress.
 In non-stressful conditions secretion
hasmarked circadian variations.

15. The highest level of hormones occurs
between 4 a.m. and 8 a.m. and the lowest,
between midnight and 3 a.m.

16. When the sleeping and waking pattern is
changed it takes several days for
adjustment of the ACTH/cortisol
secretion to take place.

17. FUNCTIONS Of Glucocorticoids
• Gluconeogenesis
(formation of new sugar from, for
example, protein)

18. Lipolysis
(breakdown of triglycerides into fatty
acids.
and glycerol for energy production).

19. Stimulating breakdown of protein,
releasing amino acids,
which can be used for synthesis of other
proteins,
e.g. enzymes, or for energy (ATP)
production.

20. Promoting absorption of sodium and
water from renal tubules.

21. In pathological and pharmacological
quantities glucocorticoids:
• have an anti-inflammatory action.

22. suppress the immune response
suppress the response of tissues to
injury
Helps in wound healing.

23. MINERALOCORTICOIDS
(ALDOSTERONE)
Aldosterone is the main
mineralocorticoid.

24. FUNCTIONS OF
MINERALOCORTICOIDS
Its functions are associated with the
maintenance of water and electrolyte
balance in the body.

25. It stimulates the reabsorption of sodium
(Na+) by the renal tubules and excretion of
potassium (K+) in the urine.

26. Sodium reabsorption is also accompanied
by retention of water
and therefore aldosterone is involved in the
regulation of blood volume and blood
pressure too.

27. The blood potassium level regulates the
amount of aldosterone produced by the
adrenal cortex.

28. When the blood potassium level rises,
more aldosterone is secreted.
 Low blood potassium has the opposite
effect.

29. Angiotensin also stimulates the release of
aldosterone.

30. RENIN-ANGIOTENSIN-
ALDOSTERONE SYSTEM.
When renal blood flow is reduced or blood
sodium levels fall the enzyme renin is
secreted by kidney cells.

31. Renin converts the plasma protein
angiotensinogen,
produced by the liver, to angiotensin 1.

32. Angiotensin converting enzyme (ACE),
formed in small quantities in the lungs,
proximal kidney tubules and other tissues
converts angiotensin 1 to angiotensin 2,
which stimulates secretion of aldosterone.

33. It also causes vasoconstriction and
increases blood pressure.

34. SEX HORMONES
Sex hormones secreted by the adrenal
cortex are mainly androgens (male sex
hormones) and the amounts produced are
insignificant compared with those secreted
by the testes and ovaries in late puberty
and adulthood.

35. Their role is unclear but it is thought that
they contribute to the onset of puberty.
An elevated level in females causes
masculinisation.
Control of secretion is poorly understood.

36. ADRENAL MEDULLA
The medulla is completely surrounded by
the cortex.
It develops from nervous tissue in the
embryo and is part of the sympathetic
division of the autonomic nervous system.

37. It is stimulated by its extensive sympathetic
nerve supply to produce the hormones
adrenaline and nor adrenaline.

38. ADRENALINE AND
NORADRENALINE
Noradrenaline is the postganglionic
neurotransmitter of the sympathetic
division of the autonomic nervous
system.

39. Adrenaline and some noradrenaline are
released into the blood from the adrenal
medulla during stimulation of the
sympathetic nervous system.

40. They are structurally very similar and this
explains their similar effects.
Together they potentiate the fight or flight
response after initial.

41. sympathetic stimulation by:
• increasing heart rate
• increasing blood pressure

42.  Diverting blood to essential organs including
the heart, brain and skeletal muscles by dilating
their blood vessels and constricting those of
less essential organs, such as the skin.

43. increasing metabolic rate
• Dilating the pupils.

44. Adrenaline has a greater effect on the heart
and metabolic processes whereas
noradrenaline has more influence on blood
vessels.

45. RESPONSE TO STRESS
When the body is under stress homeostasis
is disturbed.
To restore it and, in some cases, to maintain
life there are immediate and, if necessary,
longer-term responses.

46. Stressors include exercise, fasting, fright,
temperature changes, infection, disease and
emotional disturbances/ situations.

47. The immediate response is sometimes
described as preparing for 'fight or flight'.

48. In the longer term, ACTH from the anterior
pituitary stimulates the release of
glucocorticoids and mineralocorticoids
from the adrenal cortex and a more
prolonged response to stress occurs.

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