adrenal gland Endocrinology

1. ROLE OF ENDOCRINE GLANDS IN
THE REGULATION OF
HOMEOSTASIS, NONSPECIFIC
ADAPTATION OF ORGANISM

2.  Totality of physiological reactions, that take part in
the supporting of organism’s homeostasis, that were
formed during the process of evolution.
 Types of adaptation:
- specific
- nonspecific
Specific adaptation – adaptive mechanisms, that give
the ability to survive some changes of organism’s
constants (pH, blood pressure, heart rate) without
violations of its normal functions.
Adaptation

3. Nonspecific adaptation or stress - is a biological
term which refers to the consequences of the failure
of a human or animal body to respond appropriately
to emotional or physical threats to the organism,
whether actual or imagined.
Appeared after the
influence of different
abnormal irritants.
Term “Stress” brought to
medicine in 1936 by Hans
Selye

4. Stages:
1. Alarm – mobilization of all organism’s resources.
Develops within 6 hours when stressor is identified
or realized.
2. Resistance – restoration of imbalance, organism is
able to react on different irritants. Persistence of
stressor leads to further “getting used” to it (for 1-2
days).
3. Exhaustion – arises if organism not fully eliminate
the action of irritant, that become pathological.
General adaptation syndrome (stress
syndrome )

5. General adaptation syndrome
(stress syndrome )

6. General adaptation syndrome
1. Sympathetic nervous system;
2. Hormones of adrenal glands;
3. Hypothalamus-pituitary system;
4. Another factors (growth
hormone, vasopressin, thyroid
hormones).

8. Adrenal glands
 The adrenal glands are
also called suprarenal
glands. Are a pair of
organs located on the
upper poles of
kidneys. Each of the
glands are around 4 to
6 cm in length with
weight 4 grams.

10. Zones in adrenal cortex:
 Zona Glomerulosa (outer layer)
 Zona Fasciculata (middle layer)
 Zona Reticularis (inner layer)
Cross-sectional anatomy of adrenal gland
Adrenal gland consists of:
• Cortex (80 % of gland)
• Medulla (20 % of gland)

11. 3 layers of cortex have a specific function:
 Zona glomerulosa
 produce mineralocorticoids (aldosterone).
 Zona fasciculata
 produce glucocorticoids (cortisol,
hydrocortisol).
 Zona reticularis
 produce androgens and estrogens (sex
hormones).
Physiology of adrenal cortex

12. Physiology of adrenal cortex
- Adrenal cortex hormones have
collective name - corticosteroids
- All of them are lipid-soluble
- Corticosteroids act via receptors
located in nuclei in target cells

13. Transporting in blood
Mineralocorticoids (50 % bound to
transporting proteins, mainly
globulins, 50 % free active forms).
Glucocorticoids (75 % are bound to
globulin that is called transcortin,
15% are bound to albumin,near 10 %
are in free active form).
More than 90% of sex hormones
are also bound to transporting
proteins.

14. Physiology of zona glomerulosa
Major hormone produced – aldosterone
(“life saving hormone”)

15. Physiology of zona glomerulosa
Influence of aldosterone:
1. On Sodium metabolism
ultimate effect – keeping the Na+(sodium) in the body
→ increasing of water reabsorption →increasing of
blood volume (important adaptive effect) →
increasing of blood preassure.
This is done via:
 increase of reabsorption of Na+ ions in kidneys
(distal convoluted tubules and collective ducts)
 reducing the loss of Na+ with sweat/saliva
 increase the absorption of Na+ in intestines

16. Physiology of zona glomerulosa
Elevation of Na+ levels in the body due to the
action of aldosterone leads to:
1. Stimulation of secretion of atrial natriuretic
peptide (ANP) from atrial muscles of the heart.
Primary function of ANP is to stimulate excretion
(removing) of sodium in the kidneys.
2. Inducing of “pressure diuresis” – excretion of
excess salt and water with urine.
This is called aldosterone’s “escape phenomenon”.

17. Physiology of zona glomerulosa
Influence of aldosterone:
2. On Potassium metabolism
Acting on renal tubules, it increases excretion
(removing) of K+ ions (together with H+ ions) from
the body.

18. Physiology of zona glomerulosa
Factors that regulate the release of
aldosterone:
 sodium concentration in blood:
if high – aldosterone , if low - aldosterone 
 potassium concentration in blood:
if high - aldosterone , if low - aldosterone 
blood volume (level of ECF):
if low act via the action of renin - angiotensin II -
aldosterone system (aldosterone )
ACTH can also stimulate the production of
aldosterone (especially during stress).

20. Hypofunction :
Primary - Addison's disease
Secondary-Pituitary adenoma
Hyperfunction -
Primary -Conn's syndrome- tumor
of zona glomeruloza
Disorders of adrenal gland
(zona glomerulosa)

21. Physiology of zona fasciculata
Major hormone produced – cortisol -
glucocorticoids(“life protecting hormone”),
involved in protection of organism from stress.

22. Influence of glucocorticoids:
 On carbohydrate metabolism – increase of glucose
level in blood (stimulate gluconeogenesis).
 On protein metabolism – increase of breakdown of
proteins (catabolic effect).
 On fat metabolism – increase of breakdown of fats.
 On water and mineral metabolism – mild
mineralocorticoid effect.
 On cardiac muscle – increase of force of contraction.
 On inflammation – anti-inflammatory action.
 On immunity – suppression of immune system
(inhibition of activity of T-lymphocytes).
 On allergy – anti-allergic effect.
Overall effect – mobilizing of body metabolic processes
in order to withstand the stress!
Physiology of zona fasciculata

23. Regulation of glucocorticoids
synthesis
Is controlled by hypothalamus
(corticotropic releasing hormone) and
anterior pituitary (ACTH) and is different
during day: the highest concentrations of
them are in the early morning and to the
afternoon, the lowest – in the evening.

24. Physiology of zona fasciculata

25. 
Corticotropic-releasing hormone
(from hypothalamus) 
adrenocorticotropic hormone
(ACTH) from anterior pituitary 
corticosteroids (from adrenal
cortex).
Feedback is present (!).
Regulation of release of adrenal
hormones

26. Regulation of release of adrenal hormones

27. Hyperfunction
Cushing's syndrome (Itsenko-Cushing
syndrome or hyperadrenocorticism or
hypercorticism.)
Disorders of adrenal gland
(zona fasciculata)

28. Physiology of zona reticularis
Secretes sexual hormones, mainly of male
type (androgens); small amounts of
female type (estrogens).

29.  Both adrenal cortex (zona reticularis) and sexual
glands (male – testes; female – ovaries) produce
steroid sex hormones:
 in males  androgens (the most active –
testosterone).
 in females  estrogens (the most active – estradiol,
also there are estriol and estrone).
 Humankind is being divided into two sexes having
different sexual characteristics.
Physiology of zona reticularis

30.  Androgens (particularly testosterone)
are produced by Leydig cells in testes.
 Estrogens are produced by developing
follicles in ovaries (granulosa cells), the
corpus luteum and the placenta.
Sources of secretion of sex
hormones in sexual glands:

31.  1) development of the male (formation of primary
and secondary sexual characteristics);
2) spermatogenesis – formation of sperm;
3) inhibition of fat deposition – males have typically
less adipose tissue than females;
 4) muscle mass – having strong anabolic effect they
increase weight and power of the skeletal muscles;
5) on brain – influence on behavior (aggression and
libido).
Functions of androgens include

32.  1) development of the female (formation of
primary and secondary sexual
characteristics);
2) having anabolic effect – increase of
protein synthesis;
3) various effects – role in coagulation, salt
and water retention, decrease motility of
intestine etc
Functions of estrogens include

33. There are to kinds of sexual
characteristics:
 Primary – they are from the birth
 in males  penis, scrotum with testes, prostate gland..
 in females  ovaries, Fallopian tubes, uterus, vagina,..
 Secondary – develop during puberty
 in males  shoulders wider than hips, deep voice, hair
distribution throughout the body (facial, underarm,
chest, pubic), prominent Adam’s apple, increased
muscle and bone mass
 in females  wide hips and narrow shoulders,
enlargement of breasts, hair distribution throughout
the body (underarm, pubic), soft voice averagely, fat
distribution (mainly on hips and buttocks).

34.  This cycle occurs in females only and
happens on a monthly basis. A typical cycle
is 28 days long and begins with
menstruation (period). Changes in
hormone levels make this cycle possible.
The two hormones involved are estrogen
and progesterone.
Menstrual cycle

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40. Physiology of adrenal medulla
The adrenal medulla is the core
of the adrenal gland, and is
surrounded by the adrenal
cortex.
Has chromaffin cells of 2
types:
Adrenaline secreting cells (90 %)
Noradrenaline, dopamine (10%)
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 Autonomic nervous system that have lost
their axons and dendrites, receiving innervation from

41.  Medullary Hormones-Catecholamines
 Synthesis of catecholamines begins with the amino
acid tyrosine.
 In general, circulating adrenaline (epinephrine) and
noradrenaline (norepinephrine) released from the
adrenal medulla have the same effects on target
organs as direct stimulation by sympathetic nerves.
Release of adrenaline and noradrenaline is
triggered by nervous stimulation in response to
physical or mental stress.
Physiology of adrenal medulla

42.  1. On carbohydrate metabolism: cause
hyperglycemia;
 2. On lipid metabolism: stimulate
lypolysis and mobilization of free fatty
acids from adipose cells;
 3. Effects on visceral systems are the
same as in sympathetic nervous system
Effects of Catecholamines

43. In the adrenal medulla also
synthesized peptide hormones:
substance P, vasoactive intestinal
polypeptide ( VIP), somatostatin,
beta-enkephalin.
Physiology of adrenal medulla

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