The pituitary gland, also known as the master gland, regulates many important bodily functions through the hormones it secretes. It is located at the base of the brain and consists of an anterior and posterior lobe. The anterior lobe produces hormones that control growth, metabolism, reproduction, and lactation. These hormones are regulated by hormones from the hypothalamus. The posterior lobe stores and releases oxytocin and vasopressin, which are synthesized in the hypothalamus and influence water balance, muscle contraction, and blood pressure. Disorders of the pituitary can impact growth, metabolism, and other important processes.

1. ENDOCRINE SYSTEM:
PITUITARY GLAND
Suprabha Panda
Assistant Prof. of Zoology
Government Degree College for Women
Begumpet

2. INTRODUCTION
 The endocrine system, along with the nervous system,
functions in the regulation of body activities.
 The nervous system acts through electrical impulses and
neurotransmitters to cause muscle contraction and
glandular secretion. The effect is of short duration,
measured in seconds, and localized.
 The endocrine system acts through chemical messengers
called hormones that influence growth, development,
and metabolic activities. The action of the endocrine
system is measured in minutes, hours, or weeks and is
more generalized than the action of the nervous system.
 There are two major categories of glands in the body -
exocrine and endocrine.

3. Exocrine Glands:
 Exocrine glands have ducts that carry their secretory
product to a surface. These glands include the
sweat, sebaceous, and mammary glands and, the glands
that secrete digestive enzymes.
Endocrine Glands:
 The endocrine glands do not have ducts to carry their
product to a surface.
 They are called ductless glands. The word endocrine is
derived from the Greek terms "endo," meaning within, and
"krine," meaning to separate or secrete.
 The secretory products of endocrine glands are called
hormones and are secreted directly into the blood and
then carried throughout the body where they influence
only those cells that have receptor sites for that hormone.

5. HYPOTHALAMUS
 It secretes both releasing and inhibitory hormones
controlling the secretions of some anterior pituitary
hormones

6.  Hypothalamus produce hormones like releasing and
inhibiting hormones which control the secretions of pituitary
gland.
 1. Thyrotropin Releasing Hormone – TRH
 2. Corticotropin Releasing Hormone – CRH
 3. Growth Hormone – Releaseing Hormone – (GH-RH)
 4. Growth Hormone – Release Inhibiting Hormone (GH –
RIH) or Somatostatin.
 5. Prolactin Releasing Factor (PRF)
 6. Prolactin Inhibiting Factor (PIF)
 7. Gonadotropin Releasing Hormone (GnRH)
 8. MSH-Releasing Hormone (MRH)
 9. MSH – Release Inhibiting Hormone (MRIH)

7. PITUITARY GLAND
 The human pituitary gland is a reddish-gray oval structure about 10
mm. in diameter, 0.5 gms in weight, located on the ventral side of
diencephalon of brain.
 It hangs below the hypothalamus by a stalk called infundibulum.
 The other names of pituitary are hypophysis and master gland.

8. Pituitary gland consists of two main lobes:
1. Anterior lobe or Anterior Pituitary.
2. Posterior lobe or posterior pituitary.
 These two lobes are connected by a small intermediate lobe.

9. ADENOHYPOPHYSIS:
 Adenohypophysis consists of anterior lobe {pars distalis
and pars tuberalis) and intermediate lobe (pars inter-
media).
 Pars distalis of anterior lobe produces the following six
hormones but pars tuberalis does not secrete any
hormone and is just a supporting structure.
1. Growth Hormone (GH)/ Somatotropic hormone.
2. Thyrotrophic Hormone/ Thyroid stimulating hormone
(TSH)
3. Adrenocorticotropic Hormone (ACTH)
4. Follicle -stimulating Hormone (FSH)
5. Luteinising Hormone (LH)
6. Luteotrophin Hormone /Prolactin.

10. (i) Growth Hormone (GH):
It stimulates growth of bones, cartilages, muscles,
visceral organs and the body as a whole. It also
promotes protein synthesis, intestinal calcium absorption
and glycogenolysis.
(ii) Adrenocorticotropic Hormone (ACTH):
This hormone is a tropic hormone i.e. influences the
activity of other endocrine gland. Here the target
endocrine gland is cortex of adrenal gland which is
stimulated to produce glucocorticoids. ACTH is secreted
in more amounts during emotional and physical stress.

11. (iii) Thyroid Stimulating Hormone (TSH):
Also known as Thyrotrophic hormone (TTH). It controls the
growth and activity of thyroid gland. It also stimulates thyroid
gland to synthesise thyroxine and release it into blood.
(iv) Follicle Stimulating Hormone (FSH):
It is a gonadotropic hormone. In females it stimulates the
ovaries to develop and maturation of ovarian follicles.
The same hormone in males stimulates testes for
development of seminiferous tubules and spermatogenesis.
Due to its action on both male and female gametes, FSH is
also called Gametokinetic factor.

12. (V) Luteinizing Hormone (LH).
This is another gonadotropic hormone and is also known
as Interstitial Cell Stimulating Hormone’ (ICSH).
In females this hormone promotes final maturation of
ovarian follicle, ovulation and formation of corpus luteum.
In males it stimulates the interstitial cells of testes causing
them to release male sex hormones (androgens).
(vi) Lactogenic Hormone:
This is also called as prolactin or Luteotropic hormone
(LTH). It stimulates the growth of mammary glands in
females during pregnancy and initiates secretion of milk
after child birth.

13. PITUITARY HORMONES AND ITS TARGET ORGANS

14. INTERMEDIATE LOBE:
 The intermediate lobe or pars intermidia of pituitary
produces only one hormone i.e. Melanocyte Stimulating
Hormone (MSH) or Intermedin.
 This hormone is responsible for synthesis of melanin
pigment in melanophore or melanocyte cells.
 It also brings about dispersion of melanin pigments in
melanophore cells and the darkening of the skin is
affected.
 The dramatic phenomenon of colour-change in many
fishes, amphibians and reptiles is due to influence of this
hormone.
 In higher vertebrates including man this hormone has no
significant role but in certain conditions such as in
pregnant women the darkening of the skin is due to
increased production of MSH.

15. NEUROHYPOPHYSIS:
 The neurohypophysis or posterior lobe of pituitary
releases only two peptide hormones.
 Both these hormones are synthesized in the
hypothalamus and are carried to the posterior lobe
along the nerve fibres where they are stored. They are
released into blood as and when required.

16. 1. Oxytocin:
 This hormone stimulates the contraction of smooth muscles of uterus in
pregnant women and causes easy child birth.
 It also contracts the smooth muscles of mammary glands in lactating mother
and facilitates flow of milk at the time of suckling.
 Oxytocin also stimulates the relaxation of gall bladder, urinary bladder and
intestine.
2. Vassopressin:
 It is also called as antidiuretic hormone (ADH) or Pitressin.
 The primary function of vassopressin is to increase reabsorption of water in
the distal convoluted tubules and collecting tubules of kidney. So its
deficiency in body increases the volume of urine causing diabetes insipidus.
 This type of diabetes is different from diabetes mellitus in that the urine is free
from sugar.
 Another important function of ADH is to bring about contraction of smooth
muscles of intestine, gall bladder, urinary bladder and blood vessels. Hence,
large quantities of the hormone cause the arterial blood pressure to rise due
to contraction of peripheral, arterioles. Intake of alcohol reduces ADH
secretion.

17. DISORDERS OF PITUITARY GLAND
Acromicria : deficiency of growth hormone in adults.
Simmond’s disease: complete absences of pituitary
hormones.