Hormones may modulate the expression of behaviour, but are not causes of behaviour. Behaviour is mainly driven by internal and environmental stimuli, with different stimuli eliciting different behaviors. For example, courtship behavior occurs when a male and a female in reproductive condition meet each other.In this way, the brain adjusts its performance and control of behavior in response to a changing environment. Hormones are important agents of protection and adaptation, but stress and stress hormones, such as the glucocorticoid cortisol, can also alter brain function, including the brain's capacity to learn.

1. HARMONES AND BEHAVIOR
DR VANDANA GAUR
ASSO ASSOCIATE PROFESSOR
DEP DEPARTMENT OF PSYCHOLOGY
HORMONES AND
BEHAVIOUR

2. • “Hormones are chemicals synthesized and
produced by the specialized glands to control and
regulate the activity of certain cells and organs.
These specialized glands are known as endocrine
glands.”
• “हार्मोन क
ु छ कोशिकाओं और अंगों की गशिशिशि को
शनयंशिि और शिशनयशर्मि करने क
े शिए शििेष ग्रंशियों
द्वारा संश्लेशषि और उत्पाशिि रसायन होिे हैं। इन शिशिष्ट
ग्रंशियों को अंिःस्रािी ग्रंशियों क
े रूप र्में जाना जािा है।

3. Why are Hormones called Chemical Messengers?
• The prominent role of hormones is that of a messenger.
Hypothalamus is a part of forebrain where a numerous
amount of neurosecretory cells are present. These
neuro secretory cells are specialized in the secretion of
a hormone called neuro hormones. They stimulate the
anterior lobe of the pituitary to produce various other
hormones.
• Sometimes, hormones act more than a regulator than a
messenger. The changes in the level of hormone
production lead to certain changes in the body. Thus,
hormone as a regulator maintains the homeostasis of
the body. Once the hormones meet their target, their
production needs to be controlled and this is attained
by a mechanism called feedback control mechanism.
The feedback mechanism could either be positive or
negative.

4. Cell Signaling
The effects of hormones depend on how they are
released.
Hence, signaling effects can be classified into the
following:
• Autocrine: The hormone act on the cell that
secreted it.
• Paracrine: The hormone act on a nearby cell
without having to enter the blood circulation.
• Intracrine: The hormone is produced in the cell and
acts intracellularly means inside the cell.
• Endocrine: The hormone act on the target cells
once it is released from the respective glands into
the bloodstream.

6. TYPE OF HORMONES
• Peptide Hormones
Peptide hormones are composed of amino acids and
are soluble in water. Peptide hormones are unable to
pass through the cell membrane as it contains a
phospholipid bilayer that stops any fat-insoluble
molecules from diffusing into the cell. Insulin is an
important peptide hormone produced by the pancreas.
• Steroid Hormones
Unlike peptide hormones, steroid hormones are fat-
soluble and are able to pass through a cell membrane.
Sex hormones such as testosterone, estrogen and
progesterone are examples of steroid hormones.

7. TYPE OF ENDOCRINE GLANDS
• Hypothalamus: It controls the body temperature,
regulates emotions, hunger, thirst, sleep, moods and
allow the production of hormones.
• Pineal: Pineal is also known as the thalamus. It
produces serotonin derivatives of melatonin, which
affects sleep patterns.
• Parathyroid: This gland helps in controlling the amount
of calcium present in the body.
• Thymus: It helps in the production of T-
cells, functioning of the adaptive immune system and
maturity of the thymus.
• Thyroid: It produces hormones that affect the heart
rate and how calories are burnt.

8. • Adrenal: This gland produces the hormones that
control the sex drive, cortisol and stress hormone.
• Pituitary: It is also termed as the “master control
gland,”. This is because the pituitary gland helps in
controlling other glands. Moreover, it develops the
hormones that trigger growth and development.
• Pancreas: This gland is involved in the production of
insulin hormones, which plays a crucial role in
maintaining blood sugar levels.
• Testes: In men, the testes secrete the male sex
hormone, testosterone. It also produces sperm.
• Ovaries: In the female reproductive system, the
ovaries release estrogen, progesterone,
testosterone and other female sex hormones.

10. • What is Hypothalamus?
• Hypothalamus is a minute region, almost the size of
an almond, present at the centre of the human
brain, near the pituitary gland.
• It consists of three main regions:
• The anterior region.
• The middle region.
• The posterior region.
• It plays a vital role in the production of hormones.
Maintaining the hypothalamus health is very
important. Its improper functioning causes several
disorders.

11. • Hormones Secreted by Hypothalamus
• The anterior region of the hypothalamus is
responsible for hormone secretion. The nuclei
present in this region lead the process. The
important hormones secreted by hypothalamus are:
• Corticotropin-Releasing Hormone: This hormone is
responsible for the regulation of metabolic and
immune response.
• Thyrotropin Releasing Hormone: It triggers the
pituitary gland to release a thyroid-stimulating
hormone which plays a major role in the
functioning of organs of the body such as heart,
muscles, etc.

12. • Gonadotropin-Releasing Hormone: It stimulates the
pituitary gland to release several reproductive
hormones.
• Oxytocin: It is involved in several processes such as
lactation, childbirth, regulating sleep cycles,
maintaining body temperature.
• Somatostatin: This hormone is also known as Growth
Hormone Inhibiting Hormone. It regulates the
endocrine system and affects the neurotransmission
and cell proliferation by interacting with G-protein
coupled receptors.
• The middle region of hypothalamus stimulates the
release of Growth Hormone Releasing Hormone. This
hormone plays a major role in the growth and
development of the body.

13. Pituitary Gland

14. Pituitary Gland
• The Pituitary gland, also known as the hypophysis,
is a pea-sized endocrine gland situated at the base
of our brain. It is often referred to as the ‘Master
Gland’ because it produces some of the important
hormones in the body. It is situated in a bony
structure called the Pituitary fossa, just below the
hypothalamus, close to the optic nerve. The
pituitary gland is divided into three parts, also
called lobes:
• Anterior pituitary
• Intermediate pituitary (Absent in adult human
beings)
• Posterior pituitary

15. Function Of Hormones Secreted By Pituitary Gland
• A healthy adult human’s pituitary gland consists of two
parts – the Anterior and the Posterior parts. The
Intermediate pituitary regresses during gestation and is
absent in adult humans. Following are the major
functions of hormones:
• Anterior Pituitary Hormones
• The anterior pituitary is responsible for the synthesis
and secretion of several key hormones in the body.
These hormones include:
• Human Growth Hormone (HGH): Responsible for the
growth and repair of all cells in the body.
• Thyroid Stimulating Hormone (TSH): Influences the
thyroid gland for the release of thyroxine, its own
hormone. TSH is also called Thyrotropin.

16. • Adrenocorticotropic Hormone (ACTH): Influences
the adrenal gland to release of Cortisol or the
“stress hormone”. ACTH is also known as
corticotropin.
• Luteinising Hormone (LH) and Follicle-Stimulating
Hormone (FSH): Collectively known as
Gonadotropins, LH and FSH control the sexual and
reproductive characteristics in males and females.
• Prolactin (PRL): Produces milk in the breast. Though
it is present at all times, the secretion is increased
during and just after pregnancy.
• Melanocyte-Stimulating Hormone (MSH): Involved
in the stimulation of the production of melanin by
skin and hair.

17. Pineal Gland

18. Pineal Gland
• It is a pinecone-shaped small gland located in the
middle of the human brain in between the two
hemispheres in an area called epithalamus. It is the
major site for melatonin secretion, which regulates
the body’s internal clock (Circadian rhythm).
• This gland is rich in calcium levels. The calcium acts
as a radiographer to locate the middle of the brain
in X-ray images. It was also one of the last glands to
be discovered.
Anatomy of Pineal Gland
• The pineal gland is about 0.3 inches long and
weighs 0.1 grams. The adrenergic nerves entering
the pineal gland regulate its functions.

19. • Hormones Secreted by Pineal Gland– Melatonin
• The pineal gland synthesises melatonin and
serotonin, hence they are also called as the Pineal
Gland Hormone. The pineal gland also produces
neurosteroids.
• Melatonin affects circadian rhythm.
• The secretion of gonadotropins from the
anterior Pituitary gland is blocked by melatonin
thereby affecting reproduction. These hormones aid
in the development of ovaries and testes.

20. Functions Of Pineal Gland
Secretion Of Melatonin
This gland secretes the hormone melatonin which
regulates the circadian rhythm of the body and also
certain reproductive hormones. The secretion of
this hormone depends upon the amount of light a
person is exposed to. This hormone is produced in
large amounts when it is dark. The presence of light
inhibits the secretion of melatonin which controls
our circadian rhythms.

21. • Reproduction
• Melatonin inhibits the secretion of reproductive
hormones from the anterior pituitary, which are
responsible for the development and functioning of
reproductive organs.
• Disorders Of Pineal Gland
• Listed below are few disorders caused by the
malfunctioning of the pineal gland.
• Depression.
• Mood swings.
• Peptic or stomach ulcers.
• Disruption in sleep patterns.
• An impaired pineal gland leads to hormonal imbalance.
• Sexual disorders are caused by the dysfunctioning of
the pineal gland.

22. Thyroid Gland

23. Thyroid Gland
• The thyroid gland is a ductless endocrine gland
situated in the anterior/front portion of the neck. It
roughly resembles the shape of a butterfly. It is also
one of the largest endocrine glands, weighing an
average of 25 – 30 g. This gland has two lobes on
either side of the trachea, with each lobe measuring
4 – 6 cm in length and 1.3 – 1.8 cm in width.
• The primary function of the thyroid gland is to
secrete two hormones, namely, Triiodothyronine
(T3) hormone and the Thyroxine hormone (T4).
Both T3 and T4 hormones play a very important
role and affect almost every tissue in the body.

24. • Thyroid Gland Location
• The thyroid gland is located in the anterior neck between C5
and T1 vertebrae. It consists of two lobes and parathyroid
glands are present on their posterior surfaces.
• Thyroid Hormones
• There are two thyroid hormones:
• T4: Thyroxine (Tetraiodothyronine)
• T3: Triiodothyronine
• T4
• Thyroxine is a hormone secreted by the thyroid gland in the
bloodstream. It then travels to the organs such as kidneys and
liver where it gets converted into and gets converted into its
active form triiodothyronine.
• T3
• It is a thyroid hormone that affects physiological processes
such as growth, development, metabolism, etc.

25. Thyroid Symptoms
• Sometimes, symptoms of a thyroid disorder are not
very obvious. This is because there are various other
factors that can induce similar symptoms and usually,
the treatment is given according to the symptoms. For
instance, excessive tiredness may be associated with
sleep apnea, narcolepsy etc, but the underlying
symptoms may actually be thyroid related. Some of the
common symptoms of the thyroid are:
• Nervousness
• Poor concentration and knowledge retention
• Change in the menstrual cycle
• Increased heart rate
• Muscle aches
• Weight gain
• High level of cholesterol

26. Thyroid Gland Disorders
The thyroid gland is susceptible to many disorders and diseases.
These problems might be due to the excess secretion of
hormones, unusual growth of the gland, malignant lumps etc.
• Goitre
• Thyroid cancer
• Hyperthyroidism
This condition is caused when thyroid glands excessively
produce a hormone called thyroxine. The symptoms include a
change in appetite, unexpected weight loss, insomnia,
fatigue, irritability, frequent urination, increased sweating and
heat intolerance.
• Hypothyroidism
One of the main reasons that trigger hypothyroidism is an
autoimmune disorder called Hashimoto’s disease. In this
condition, the antibodies produced by the body attack the
thyroid gland and this results in the glands producing fewer
hormones.

27. Parathyroid Gland

28. Parathyroid Hormone
• Parathyroid hormone is secreted by the four parathyroid glands.
These tiny glands are present in the neck behind the thyroid
glands. Parathyroid hormone controls and regulates the levels of
calcium in the blood and raises their levels when they are too low.
• There are two main types of Parathyroid hormone:
• Parathormone
• Calcitonin
• The primary purpose of parathyroid glands is to regulate calcium
in the blood in a very strict range between 9.0 and 10.1 mg/dL.
Parathyroids also manage the amount of calcium in the bones and
determine their strength.
• Bones – The parathyroid hormone (PTH) stimulates the release of
calcium from stores of calcium present in the bones into the
bloodstream.
• Intestine – PTH increases the calcium absorption in the intestine
by food through its impacts and affects the metabolism of
vitamin D.
• Kidneys – PTH minimizes the calcium loss in the urine and also
stimulates active vitamin D formation in the kidneys.

29. Parathyroid hormone Levels
• What if the parathyroid hormone is too high?
• Hyperthyroidism is an endocrine disorder which causes
oversecretion of parathyroid hormone in the body. This
oversecretion of PTH causes an abnormal rise in the
blood calcium levels.
• Oversecretion of parathyroid hormone can make a
person depressed, irritable, insomnia, memory loss,
lack of energy and worried are the most common
symptoms in patients with parathyroid disease.
• What if the parathyroid hormone is too little?
• Hypoparathyroidism is a rare condition in which there
is low production of parathyroid hormone in the body
this condition results in abnormally low levels of
calcium in the blood. It is treated medically with
vitamin D analogues and oral calcium supplements.

30. Pancreas

31. Pancreas
• Pancreas is an abdominal organ located behind the
stomach and surrounded by spleen, liver and small
intestine. It is a vital part of the digestive system
and is responsible for regulating blood sugar levels.
• The pancreas secretes digestive enzymes such as
amylase, proteases and lipase into the duodenum.
These enzymes help in digesting sugar, proteins and
fat respectively. Islets of Langerhans are embedded
in the pancreas that secretes hormones such as
insulin and glucagon into the blood.

32. Pancreas Function
• Exocrine Function
• The pancreas consists of exocrine glands that produce
enzymes trypsin and chymotrypsin that are essential
for digestion. These enzymes contain chymotrypsin and
trypsin to digest proteins, amylase for the digestion of
carbohydrates and lipase to break down fats. These
pancreatic juices are liberated into the system of ducts
and culminated in the pancreatic duct when the food
enters the stomach.
• Endocrine Function
• The endocrine part of the pancreas comprises Islets of
Langerhans that release insulin and glucagon directly
into the bloodstream. They help in regulating the blood
sugar levels of the body.

34. Adrenal Gland
• The adrenal glands are endocrine glands that perform
quite a lot of functions in the body.
• On the anterior side of the right adrenal gland sits the
Inferior vena cava and the right lobe of the liver. The
posterior side is flanked by the right crus of the
diaphragm..
Adrenal Gland Anatomy
• As stated in the introduction, the human body has two
adrenal glands, the right gland is pyramidal in shape
and the left gland is semilunar in shape.
• The left adrenal gland is also comparatively larger than
the right.

35. • Adrenal Capsule
The capsule is a protective layer of fat that surrounds
each adrenal glands.
• Adrenal Cortex
The adrenal cortex is the outermost layer of the adrenal
gland which is devoted to the production of
aldosterone, cortisol, and androgens hormones. There
are three layers of cortex called zones which can be
examined and easily differentiated under a microscope:
• Adrenal Medulla
The last and innermost part of the adrenal gland is the
medulla. It contains the Chromaffin cells, which
produce the body’s main source of catecholamines
(such as adrenaline and noradrenaline) and
endorphins. These are stored and released in response
to stress.

36. • Adrenal Gland Function
• One of the most well-known responses – the Fight
or Flight Response is triggered by the release of
stress hormones from the adrenal glands.
• The adrenal glands produce a variety of hormones.
These hormones are very crucial for the normal
functioning of the body. For instance, the glands
secrete cortisol, which has anti-inflammatory
properties and aids the immune system.

37. Adrenal Gland Hormones
• Epinephrine: Also called adrenaline, this hormone
rapidly responds to stress by increasing the heart rate
and raising blood glucose levels in the blood.
• Norepinephrine: Also called noradrenaline, this
hormone works with epinephrine in reacting to stress.
Its primary function is to mobilize the body and brain
for action.
• Hydrocortisone: It is commonly known as cortisol or a
steroid hormone. It is involved in regulating body
functions like the conversion of fats, and carbohydrates
to energy and also plays a vital role in other metabolic
processes.
• Corticosterone: This hormone works with
hydrocortisone to control the immune response and
prevents inflammatory reactions.

38. Gonads
• Gonads are the female and male reproductive organs. Testes
are the male gonads and ovaries in females.
• Gonads: Sex Hormones
• Being a component of Endocrine system, both male and
female gonads generate sex hormones. Gonadal hormones
are regulated by hormones secreted by the pituitary gland in
the brain. Hormones that are responsible for stimulating the
gonads to produce sex hormones are called gonadotropins.
The gonadotropins called luteinizing hormone (LH) and
follicle-stimulating hormone (FSH) are secreted by the
pituitary.
• The pituitary hormones influence reproductive organs in
many ways.
• The tests are stimulated by the LH to secrete the sex hormone
testosterone and ovaries to secrete estrogens and
progesterone. The FSH is involved in the maturation of
ovarian follicles (sacs that contain ova) in females and
production of sperm in males.

39. • Female Gonad Hormones
• The major hormones of the ovaries are progesterone
and estrogens.
• Estrogens – It is a group of female sex hormones
essential for reproduction and the development of the
female reproductive system. Estrogens are responsible
for maturation and growth of the vagina and uterus,
widening of pelvis, breast and the uterus changes
during the menstrual cycle, and increasing growth of
hairs on the body.
• Progesterone – These are the hormones whose
function is to prepare the uterus for conception,
regulating changes in the uterus during the Menstrual
cycle, ovulation aids, and stimulating gland
development for the production of milk during
pregnancy.

40. • Male Gonad Hormones
• Androgens are hormones that majorly influence the
development of the male reproductive system.
• Testosterone is responsible and essential for
increased growth of bone and muscle, growth of
body hair, developing broader shoulder, voice
deepening and growth of the penis.
• Androstenedione – These are the hormones that
act as a precursor to estrogens and testosterone.
• Inhibin – These hormones inhibit the release of FSH
and thought to be involved in sperm cell regulation
and development.

41. List of Important Hormones
• Cortisol – It has been named as the “stress hormone” as it
helps the body in responding to stress. This is done by
increasing the heart rate, elevating blood sugar levels etc.
• Estrogen-This is the main sex hormone present in women
which bring about puberty, prepares the uterus and body for
pregnancy and even regulates the menstrual cycle. Estrogen
level changes during menopause because of which women
experience many uncomfortable symptoms.
• Melatonin – It primarily controls the circadian rhythm or
sleep cycles.
• Progesterone – It is a female sex hormone also responsible
for menstrual cycle, pregnancy and embryogenesis.
• Testosterone – This is the most important sex hormone
synthesized in men, which cause puberty, muscle mass
growth, and strengthen the bones and muscles, increase
bone density and controls facial hair growth.

42. • Functions of Hormones
• Following are some important functions of
hormones:
• Food metabolism.
• Growth and development.
• Controlling thirst and hunger.
• Maintaining body temperature.
• Regulating mood and cognitive functions.
• Initiating and maintaining sexual development and
reproduction.