This document provides an overview of the human endocrine system and hormones. It defines glands, including exocrine glands which secrete substances through ducts and endocrine glands which secrete hormones directly into the bloodstream. It describes the major endocrine glands like the pituitary, thyroid, parathyroid, adrenal and sex glands. It explains the types of hormones, including lipophilic hormones which penetrate cell membranes and hydrophilic hormones which bind to surface receptors. In closing, it emphasizes that hormones are biochemical substances produced by endocrine glands that affect distant organs and have specific, potent effects in small amounts.

1. «Physiology of the humoral
system»

2.  Dear students, today we are holding
the last lecture of this semester! We will
start the next lecture in the second
semester after the New Year!
 Today we will repeat once again and
consider some questions on this topic in
more detail!

3. Gland
 Gland – an organ whose function is the
production of any biologically active
substances.
 Glands of external secretion (exocrine glands) have
excretory ducts and secrete their enzymes or secretions to
the surface of the body or in the body cavity.
 Endocrine glands (endocrine glands) do not have
excretory ducts and secrete hormones produced by them
directly into the blood..

4. External
secretions
(Exocrine)
Gland
Internal
Secretions
(Endocrine)
Mixed
Secretion
lacrimal, salivary,
glands of the stomach
and intestines, sweat,
sebaceous
Pituitary gland,
epiphysis, thymus
gland, thyroid gland,
adrenal glands
Pancreas, sweat
glands

5. Glands of external secretion
(exocrine)
Have special ducts to remove the secret on the surface of the
body or in hollow organs

6. Endocrine glands (endocrine)
They do not have ducts, secrete a secret into the blood.
 Pituitary gland
 Thyroid gland
 Adrenal glands

7. Glands of mixed secretion
- Pancreas
- Sex glands
- Testes
- Ovaries
They work simultaneously as exocrine and endocrine glands

8. Glands of internal and mixed secretion

9. Human Endocrine System
The endocrine system consists of the so-called
endocrine glands, which secrete physiologically active
substances into the body - hormones - and do not have
excretory ducts. Hormones are able to stimulate or weaken
the functions of cells, tissues and organs, due to which the
endocrine glands, together with the nervous system and
under its control, perform a humoral regulatory function,
ensuring the holistic work of the whole organism.

10. Major endocrine glands:
 These are the
hypothalamus, pituitary gland,
epiphysis, thyroid and
parathyroid glands, adrenal
glands, endocrine parts of the
pancreas and genital glands.
 The total weight of these
organs does not exceed 100 g,
and the amount of biologically
active substances secreted by
them is measured in ten-
thousandths of a milligram!
The ability to exert a powerful
effect on the body in negligible
concentrations is the main
feature of hormones. For
example, a gram of insulin is
enough to lower the blood
sugar levels of 125,000 rabbits.

11. The main groups of
hormones
❑ Lipophilic hormones (steroid hormones, testosterone,
calcitriol, iodthyronines, thyroxine)
❑ Hydrophilic hormones (histamine, serotonin, melatonin,
adrenaline, thyroliberin, thyrotropin, insulin, glucagon)

12. Lipophilic hormones
Mechanism of action of lipophilic hormones
 Secreted into
the blood
immediately
after synthesis
 Penetrate the
membrane
 Binds to
intracellular
receptors
 Regulate the
transcription of
individual
genes
 Transported
with protein
carriers

13. Hydrophilic hormones
• Have a peptide nature or are
derivatives of amino acids;
• Able to accumulate in the cells
of the glands;
• Do not penetrate the cell;
• Bind to a receptor located on
the membrane;
• Transported in the blood
stream without carriers
Mechanism of action of hydrophilic hormones

14. Pineal body
The epiphysis, pineal gland, or pineal body
(corpus pineale, epiphysis cerebri) is a small
organ that performs an endocrine function,
which is considered an integral part of the
photoendocrine system; it is attached by leashes
to both visual tubercles of the diencephalon.
Unpaired formation of grayish-red color, located
in the center of the brain between the
hemispheres at the site of interthalamic fusion.
Outside, the epiphysis is covered with a
connective tissue capsule, from which trabeculae
depart inside the gland, dividing it into lobules.
It produces the hormones melatonin, serotonin
and adrenoglomerulotropin.

15. Until now, the functional
significance of the epiphysis for humans
has not been sufficiently studied.
Secretory cells of the epiphysis secrete
into the blood the hormone melatonin
synthesized from serotonin, which is
involved in the synchronization of
circadian rhythms (biorhythms "sleep -
wakefulness") and IR known common
functions of the epiphysis include:
inhibition of the release of growth
hormones;
inhibition of sexual development and
sexual behavior;
inhibition of tumor development.
influence on sexual development and
sexual behavior. In children, the epiphysis
is larger than in adults; upon reaching
puberty, melatonin production decreases.
Functions of the epiphysis

16. Human thyroid gland
The thyroid gland (glandula
thyroidea) is the most
Large of the endocrine glands, its
mass in an adult reaches 30-50 g. In
the gland, the right and left lobes and
the isthmus connecting them are
distinguished. From the isthmus in
some people departs to the top of the
process, called the pyramidal lobe.
The gland is located in the anterior
part of the neck and is covered with
fascia. The lobes of the gland are
adjacent to the thyroid cartilage of
the larynx and to the cartilage of the
trachea; the isthmus is located in the
front of 2-4 tracheal rings.

17. Peripheral endocrine glands
Consists of:
1. Two lateral lobes
2. Transverse isthmus
3. Pyromidal lobe
4. Adjacent to the
thyroid cartilage
Thyroid gland
the gland is abundantly
supplied with blood vessels,
the upper and lower thyroid
arteries approach it

18. Thyroid gland
With a lack of
iodine in the
body, it
develops
endemic goiter
– proliferation
of thyroid
tissue.

19. Thyroid gland
Regulates metabolism and
development of the body.
The hormone is thyroxine
With hypofunction –
myxedema
With hyperfunction –
Graves' disease

20. The thyroid gland secretes 3 hormones:
Thyroxine: Enhances the oxidation of fats,
carbohydrates and proteins in cells, thus
accelerating the metabolism in the body. Increases
the excitability of the central nervous system.
Triiodothyronine: The action is largely similar
to thyroxine.
Thyrocalcitonin: Regulates the exchange of
calcium in the body, reducing its content in the
blood, and increasing its content in bone tissue. A
decrease in the level of calcium in the blood
reduces the excitability of the central nervous
system.
Thyroid gland
From the normal function of the thyroid gland depend on such basic
biological processes as the growth, development and differentiation
of tissues.

21. Peripheral endocrine glands
Four small glands located in the neck near the
thyroid gland
Parathyroid glands
They are also abundantly supplied with blood.
Parathyroid glands secrete:
Parathyroid or parathyroid hormone
It is a polypeptide consisting of 84 amino acid
residues. The action of the hormone is aimed at
increasing the concentration of calcium and
reducing the concentration of phosphorus in the
blood, due to the effect on the excretion of calcium
(inhibits) and phosphorus (accelerates) by the
kidneys.
Parathyroid hormone, coupled with
thyrocalcitonin, provides a constant concentration of
calcium ions in the blood.

22. Peripheral endocrine glands
Lymphoepithelial organ located in the chest cavity above the
heart. Сonsists of two main lobes, which are divided into
small lobules, the basis of which is formed by the
interweaving of epithelial cells.
Thymus (thymus gland)
Thymus secretes the hormone:
Timosin, he:
• Аffects the metabolism of carbohydrates, as
well as calcium (the action is close to the
parathyroid hormone of the parathyroid glands.)
• Regulates the growth of the skeleton,
participates in the management of immune
reactions (increases the number of lymphocytes
in the blood, enhances the reaction of
immunity).

23. Peripheral endocrine glands
Digestive and endocrine gland
Pancreas gland
Structure:
1) Head
5) Tail
6) Body
Endocrine functions of the gland are
expressed in the secretion of two hormones:
Insulin:
1. Increases plasma membrane permeability to
glucose
2. Activates Key Glycolysis Enzymes
3. Stimulates glycogen formation
=> lowers the concentration of glucose in the blood
Glucagon:
1. Enhances glycogen catabolism in the liver
2. Activates gluconeogenesis, lipolysis &
ketogenesis in the liver
=> Increases the concentration of glucose in the
blood

24. Pancreas gland
Regulates the synthesis and breakdown of
sugar in the body
The main hormone is insulin
With hypofunction –
diabetes mellitus.
With hyperfunction –
vertigo
weakness
loss of consciousness.

25. Peripheral endocrine glands
 Small flattened paired glands of
yellowish color. They consist of:
 external (cortical) and
• internal (cerebral) layers.
The right and left adrenal glands differ
in shape: right triangular,
and the left in the shape of a crescent
moon.
Adrenal glands
Cortical substance includes:
• glomerular
• beam and
• mesh zones.

26. Adrenal glands
Mobilize the body in extreme
situations and increase its
performance and endurance.
Essential Hormones –
adrenaline and noradrenaline.
The amount of hormones secreted
depends on the physiological
and psychological
the state of the body.

27. Sex glands
Determine the formation of the body according to the female
or male type, regulate the development of secondary sexual
characteristics.
Ovaries
Hormone –
estrogen
Testes
Hormone –
testosterone

28. Peripheral endocrine glands
Testicles
 Carry out the processes of spermatogenesis
 Produce male sex hormones – androgens
The production of androgens occurs in granulocytes (Leyding cells)
localized between the seminiferous tubules.
The main representative is
Testosterone:
Determines the development of male primary and
secondary signs, namely:
• Increased development of the genital organs
• Change of hairline
• Change the tone of voice
• Enhancing protein synthesis (building muscle mass)
Male sex glands

29. Peripheral endocrine glands
Ovaries
 They are the site of localization of the egg
 Produce female sex hormones – estrogens
Estrogen production is characterized by a certain cyclicity
associated with a change in the production of pituitary
hormones during the menstrual cycle.
The most active are:
β-Estradiol:
Determines the development of female primary
and secondary signs:
1. Increased development of the genital organs
2. Acceleration of the development of mammary glands
3. Inhibition of bone growth in length
4. Increased fat formation
Progesterone:
• Preparation of the endometrium for implantation of a
fertilized egg
• Increased activity of the mammary glands
Female sex glands

30. Controlling endocrine glands
It is the highest center of regulation of the autonomic functions
of the body. It takes part in the correlation of various somatic
functions:
regulation of the gastrointestinal tract
• sleep and wakefulness
• water-salt, fat and
• carbohydrate metabolism
• maintaining body temperature and homeostasis
• regulates activities almost all
Endocrine body systems
Hypothalamus

31. Controlling endocrine glands
Nuclei of the hypothalamus:
1 - anterior commissure
2 - final plate
3 – preoptic region
4 - ventromedial nucleus
5 - supraoptic nucleus
6 - visual crosshairs
7 - optic nerve
8 - hypothalamic sulcus
9 - paraventricular nucleus
10 - dorsomedial nucleus
11 - rear core
12 - mastoid body
13 - lateral nuclei of the grey tubercle
14 - funnel kernels
15 - funnel
16 – neurohypophysis
17 - intermediate share
18 - anterior lobe
Hypothalamus

32. Controlling endocrine glands
The hypothalamus is characterized
by:
o Abundant blood supply
o Special circulatory system with
pituitary gland
o extensive connections with
various departments of the
central nervous system:
1. With Thalamus
2. With sympathetic nodes
3. With pituitary gland
4. With frontal lobes
5. With a visual tubercle
6. With extrapyramidal system and
reticular brain stem formation
Hypothalamus

33. Controlling endocrine glands
The gland is oval in shape, located in an isolated bone bed (Turkish
saddle). In humans, the anterior (adenohypophysis) and posterior
(neurohypophysis) lobes are isolated.
Pituitary gland
Adenohypophysis produces 6 hormones,
4 trails:
• adrenocorticotropic hormone, or corticotropin
• thyroid-stimulating hormone, or thyrotropin
• follicle-stimulating gonadotropin
• luteinizing gonadotropin
and 2 effector:
• somatotropin
• Prolactin
In the neurohypophysis, oxytocin and
antidiuretic hormone (vasopressin) are
deposited

34. Pituitary gland
Controls the work of all endocrine glands, regulates
the growth and development of the body.
The main hormone –
growth hormone.
With hypofunction –
dwarfism.
With hyperfunction –
Gigantism.

35. Controlling endocrine glands
Hormones of adenohypophysis:
1) Adenocorticotropic hormone (corticotropin))
• stimulates the formation of glucocorticoids in the bundle zone of the cortical
substance of the adrenal glands.
• accelerates steroidogenesis and enhances plastic processes (protein
biosynthesis, nucleic acids).
• stimulates the processes of lipolysis, enhances pigmentation
 The production of corticotropin is regulated by corticoliberin of the
hypothalamus.
 2) Thyroid-stimulating hormone (thyrotropin)
 Stimulates the formation of thyroxine and triiodothyronine in the
thyroid gland
 The work of the "iodine pump" is activated
 Promotes the release of active thyroxine and triiodothyronine into
the bloodstream.
The production of thyrotropin is regulated by thyrolyberin of the
hypothalamus.
Pituitary gland

36. Controlling endocrine
glands
Hormones of adenohypophysis:
Gonadotropic hormones, or gonadotropins
3) Follicle-stimulating gonadotropin (FSG)
4) Luteinizing (LHU)
Regulation of the secretion of gonadotropins is
carried out by gonadoliberin of the
hypothalamus.
Pituitary gland

37. Controlling endocrine
glands
Hormones of the neurohypophysis:
1) Antidiuretic hormone (АDH)
(vasopressin).
• stimulates the reabsorption of water in
the distal tubules of the kidneys
• in large doses АDH causes narrowing of
arterioles
2) Oxytocin
• causes a contraction of the smooth
muscles of the uterus (ensures the
normal course of labor)
• enhances the reduction of myoepithelial
cells in the mammary glands and thereby
promotes the release of milk
Pituitary gland

38. Hormones
Hormones - (from the Greek hormáo - I
set in motion, I induce), biologically
active substances produced by the
endocrine glands, or endocrine glands,
and released by them directly into the
blood. The term "hormones" was
introduced by the English physiologists
W. Bayliss and E. Starling in 1902
Hormones are carried by the blood and
affect the activity of organs, changing
physiological and biochemical reactions
by activating or inhibiting enzymatic
processes. There are more than 30
known hormones secreted by the
endocrine glands of mammals and
humans.

39. The main properties of hormones
 action at a distance from the
place of production;
 specificity of action - the
effect of each of them is not
adequate to the effect of the
other hormone;
 high rate of formation and
inactivation, which is
associated with the short-
term nature of their action;
 high biological activity - the
desired effect is achieved at
a very low concentration of
the substance;
 the role of an intermediary
(messenger) in the transfer
of information from the
nervous system to the cell.

40. Mechanism action of hormones
Hormones act on organs selectively, this is due to the fact that the cells of certain organs
contain special formations - receptors. Organs or cells that are affected by a particular
hormone are called target organs or target cells. The extracellular fluid contains many
different compounds, but only a very few of them recognize the receptors. In addition,
receptors must select certain molecules from a variety of others present in higher
concentrations. The figure shows that each cell can carry either one type of receptor or
several.

41. Hormone transport
Hormones, once in the bloodstream,
must go to the appropriate target organs.
The transport of high-molecular (protein)
hormones has not been studied much due
to the lack of accurate data on the
molecular weight and chemical structure
of many of them. Hormones with a
relatively small molecular weight quickly
bind to plasma proteins, so that the
content of hormones in the blood in the
bound form is higher than in the free
form; these two forms are in dynamic
equilibrium. It is free hormones that
show biological activity, and in some
cases it has been clearly shown that they
are extracted from the blood by target
organs. The significance of protein
binding of hormones in the blood is not
entirely clear. It is assumed that such
binding facilitates the transport of the
hormone or protects the hormone from
loss of activity.

42. Hormones regulate the activity
of all cells of the body
They affect the acuity of thinking and
physical mobility, physique and height,
determine hair growth, tone of voice,
sexual desire and behavior. Thanks to the
endocrine system, a person can adapt to
strong temperature fluctuations, excess or
lack of food, to physical and emotional
stress. The study of the physiological
action of the endocrine glands made it
possible to reveal the secrets of sexual
function and the miracle of the birth of
children, as well as to answer the question
of why some people are tall and others are
short, some are fat, others are thin, some
are slow, others are agile, some are strong,
others are weak.

43. Dear students, we have completed this topic with you!
First of all, today is a Hippocratic Day holiday for all
students! Congratulations, be diligent students, go and
strive for your dreams and goals. I wish you to become
excellent specialists in your medical field! Good luck and
advancement in your hard work!
And I also want to wish you a Happy New Year! Let
the New Year be marked only by victories over all the
upcoming difficulties.
Good luck to you in everything, always and
everywhere!

44. Thank you!