The pituitary gland is a pea-shaped structure that measures 1–1.5 cm (0.5 in.) in diameter

1. PITUTARY GLANDMADE BY SHITIJ GUPTA

2. ANATOMY AND POSITION
 The pituitary gland is a pea-shaped structure that measures 1–1.5 cm (0.5 in.) in diameter
 It is suspended near to the 3rd ventricle
 lies in the hypophyseal fossa of the sella turcica of the sphenoid bone.
 It attaches to the hypothalamus by a stalk, the infundibulum
 has two anatomically and functionally separate portions: the anterior pituitary and the posterior pituitary.
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3. ADENOHYPOPHYSIS
 The anterior pituitary (anterior lobe), also called the adenohypophysis, accounts for about 75% of the total
weight of the gland and is composed of epithelial tissue. The anterior pituitary consists of two parts in an adult:
1. The pars distalis is the larger portion
2. the pars tuberalis forms a sheath around the infundibulum.
 secretes hormones that regulate a wide range of bodily activities, from growth to reproduction.
 Release of anterior pituitary hormones is stimulated by releasing hormones and suppressed by inhibiting
hormones from the hypothalamus.
 Thus, the hypothalamic hormones are an important link between the nervous and endocrine systems
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5.  Somatotrophs secrete human growth
hormone (hGH), also known as somatotropin
 Thyrotrophs secrete thyroid-stimulating
hormone (TSH), also known as thyrotropin.
TSH controls the secretions and other
activities of the thyroid gland.
 Gonadotrophs secrete two gonadotropins:
follicle-stimulating hormone (FSH) and
luteinizing hormone (LH).
 Lactotrophs secrete prolactin (PRL)
 Corticotrophs secrete adrenocorticotropic
hormone (ACTH), also known as
corticotropin , which stimulates the adrenal
cortex to secrete glucocorticoids such as
cortisol. Some corticotrophs, remnants of the
pars intermedia, also secrete melanocyte-
stimulating hormone (MSH).
Types of cells in adenohypophysis
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6. HYPOTHALAMIC RELATION WITH ADENOHYPOPHYSIS
 The function of adenohypophysis is not regulated by direct innervation but instead by vascular connection with
hypothalamus.
 The arterial blood reaching the hypothalamus enters the specilaised region known as MEDIAN EMINENCE . Where
vessel into network of primary arteries And enters the hypophyseal portal system
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7. HYPOPHSEAL PORTAL SYSTEM
 Hypothalamic hormones that release or inhibit anterior
pituitary hormones reach the anterior pituitary through
a portal system.
 In the hypophyseal portal system ,blood flows from
capillaries in the hypothalamus into portal veins that
carry blood to capillaries of the anterior pituitary
 The superior hypophyseal arteries, branches of the
internal carotid arteries, bring blood into the
hypothalamus . At the junction of the median
eminence of the hypothalamus and the infundibulum,
these arteries divide into a capillary network called the
primary plexus of the hypophyseal portal system.
From the primary plexus, blood drains into the
hypophyseal portal veins that pass down the outside
of the infundibulum. In the anterior pituitary, the
hypophyseal portal veins divide again and form another
capillary network called the secondary plexus of the
hypophyseal portal system.
 Its major function is the transport and exchange of
hormones to allow a fast communication between
both glands
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9. HYPOTHALAMIC RELATION WITH NEUROHYPOPHYSIS
 NEURAL CONNECTIONS BETWEEN THE HYPOTHALAMUS AND THE POSTERIOR LOBE OF PITUATARY ARE MAINTAINED
DURING DEVELOPMENT.
 THE POSTERIOR PITUATARY CONTAINS AXONS FROM END TERMINALS OF NEURON THAT HAVE THEIR CELL BODIES
WITHIN THE HYPOTHALAMUS.
 THESE NEURONS TERMINATE CLOSE TO NUMEROUS CAPILLARIES LOCATED THROUGHOUT THE POSTERIOR
PITUATARY, THE CELL BODIES OF THESE NEURONS ARE FOUND WITHIN TWO DISTINCT AREAS OF THE
HYPOTHALAMUS, THE SUPRAOPTIC NUCLEUS AND THE PARAVENTRICULAR NUCLEUS
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10. NEUROHYPOPHYSIS
 The posterior pituitary (posterior lobe), also called the neurohypophysis,
is composed of neural tissue. It also consists of two parts:
1. the pars nervosa
2. the larger bulbar portion
3. the infundibulum.
 Pituicytes are similar to astrocytes, another type of glial cell. Their main
role is to assist in the storage and release of hormones of the posterior
pituitary. Pituicytes surround axonal endings and regulate hormone
secretion by releasing their processes from these endings
 Herring bodies or neurosecretory bodies are structures found in
the posterior pituitary. They represent the terminal end of the axons from
the hypothalamus, and hormones are temporarily stored in these locations.
They are neurosecretory terminals.
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12. INTERMEDIATE LOBE
 A third region of the pituitary gland called the pars intermedia atrophies during human foetal development and
ceases to exist as a separate lobe in adults However, some of its cells migrate into adjacent parts of the anterior
pituitary, where they persist.
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13. DEVELOPMENT OF HYPOPHYSIS
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14. 0verview of functioning of pituitary gland
 HYPOPHYSEAL CEREBRI
 CONSIDERED AS MASTER OF ENDOCRINE ORCHESTRA
 BUT UNDER THE CONTROL OF HYPOTHALAMUS
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15. HYPOTHALAMIC CONTROL OF PITUATRY GLAND
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16. HORMONES OF ADENOHYPOPHYSIS
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17. Growth hormone or Somatotropin
 It is a peptide hormone.
 The overall effect of growth hormone is to promote tissue growth .In this regard it is considered as ANABOLIC
HORMONE.
 While many effects of GH is similar to insulin ,some are exactly opposite to insulin. GH is therefore said to have both
insulin like effects and anti-insulin or “diabetogenic” effects.
1. ANTI INSULIN EFFECT- Growth hormone is often said to have anti-insulin activity, because it supresses the abilities
of insulin to stimulate uptake of glucose in peripheral tissues and enhance glucose synthesis in the liver. Stimulates
the breakdown of fat stores.
2. INSULIN –LIKE EFFECTS- It directly stimulates the uptake of amino acids from blood to muscle cells and also
stimulates protein synthesis in muscle , GH stimulates liver protein synthesis.
 actions of the growth hormone it is necessary to divide its effects into two groups:
1. Direct effect: the growth hormone binds to receptors on target cells. Fat cells (adipocytes), for example, have growth
hormone receptors. So, the growth hormone causes fat cells to break down into triglycerides and suppresses their
ability to take up and accumulate circulating lipids.
2. Indirect effect: the growth hormone causes secretion of IGF-1, an insulin-like growth factor hormone. The liver and
other tissues secrete IGF-1 in response to growth hormone. Growth effects of the growth hormone are mostly related
to the action of IGF-I.
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18. Growth hormone
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20. Chondrocytes of
bone
Other organ and
tissues
MUSCLE LIVER ADIPOSE
Amino acid uptake Protein synthesis Glucose uptake
Glucose uptake
Gluconeogenesis
Increased
muscle mass
Decreased
adiposity
Somatomedin
production
SOMATOMEDINS
LipolysisProtein synthesis
Collagen synthesis
Protein synthesis
Cell proliferation
IGF-IIIGF-I
Protein synthesis
RNA synthesis
DNA synthesis
Cell size & number
INCREASED LINEAR
GROWTH
INCREASED TISSUE
GROWTH AND ORGAN
SIZE
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21. EFFECTS OF SOMATOMEDINS
 In response to somatotropin liver tissues secretes somatomedins(IGF-I AND IGF-II)
EFFECTS OF IGF-1 EFFECTS OF IGF-II
INVOLVES IN INCREASED LINAER
GROWTH.
INVOLVES IN INCREASED TISSUE
GROWTH AND ORGAN SIZE.
IT STIMULATES SKELETAL GROWTH BY
INCREASING THE FORMATION OF
CARTILAGE IN EPIPHYSEAL PLATES. THE
CARTILAGE EVENTUALLY BE REPLACED
BY BONE MINERAL AND HENCE BONE
GROWS. IGF-I PROMOTES BONE
GROWTH BY STIMULATING
CHONDROCYTES (AS IT INCRESAES
COLLAGEN SYNTHESIS).
IT STIMULATES PROTEIN ,RNA AND DNA
SYNTHESIS THEREFORE IT IS ABLE TO
ELICIT A GENERAL ANABOLIC RESPONSE
IN A VARIETY OF DIFFERENT ORGANS
.THIS RESULTS IN GENERALISED TISSUE
GROWTH.
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22. FACTORS AFFECTING SECRETION OF GH
 STIMULATORS
1. GH-RH
2. DEEP SLEEP
3. HYPOGLYCEMIA
4. STRESS – PHYSICAL TRAUMA , INFECTION , PSYCOLOGICAL STRESS
5. AMINO ACIDS SUCH AS ARGININE
 INHIBITORS
1. R.E.M. SLEEP(RAPID EYE MOVEMENT SLEEP)
2. HYPERGLYCEMIA
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23. TSH OR THYROTROPIN
 This hormone is synthesised by the anterior pituitary and
its release is stimulated by TRH from the hypothalamus.
 It stimulates growth and activity of the thyroid gland,
which secretes the hormones thyroxine (T4) and
triiodothyronine (T3).
 Release is lowest in the early evening and highest during
the night. Secretion is regulated by a negative feedback
mechanism . When the blood level of thyroid hormones is
high, secretion of TSH is reduced, and vice versa.
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25. GONADOTROPINS
 After puberty two gonadotrophins (sex hormones) are secreted by the
anterior pituitary in response to luteinising hormone releasing
hormone (LHRH), also known as gonadotrophin releasing hormone
(GnRH). In both males and females these are:
• follicle stimulating hormone (FSH)
• luteinising hormone (LH).
 In both sexes. FSH stimulates production of gametes (ova or
spermatozoa).
 In females. LH and FSH are involved in secretion of the hormones
oestrogen and progesterone during the menstrual cycle . As the levels
of oestrogen and progesterone rise secretion of LH and FSH is
suppressed.
 In males. LH, also called interstitial cell stimulating hormone (ICSH)
stimulates the interstitial cells of the testes to secrete the hormone
testosterone
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28. PROLACTIN
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29. CORTICOTROPIN OR ACTH
 Corticotrophs secrete mainly adrenocorticotropic
hormone(ACTH). ACTH controls the production
and secretion of cortisol and other glucocorticoids
by the cortex (outer portion) of the adrenal
glands.
 Corticotrophin-releasing hormone (CRH) from the
hypothalamus stimulates secretion of ACTH by
corticotrophs.
 Stress-related stimuli, such as low blood glucose
or physical trauma, and interleukin-1, a
substance produced by macrophages, also
stimulate release of ACTH. Glucocorticoids inhibit
CRH and ACTH release via negative feedback.
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31. HORMONES OF NEUROHYPOPHYSIS
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32. OXYTOCIN
 During and after delivery of a baby, oxytocin affects two target tissues:
 the mother’s
1. uterus
2. breasts.
 During delivery, stretching of the cervix of the uterus stimulates the release of oxytocin which, in turn,
enhances contraction of smooth muscle cells in the wall of the uterus
 after delivery, it stimulates milk ejection (“let-down”) from the mammary glands in response to the mechanical
stimulus provided by a suckling infant. The function of oxytocin in males and in non-pregnant females is not
clear.
 Experiments with animals have suggested that it has actions within the brain that foster parental caretaking
behaviour toward young offspring.
 It may also be responsible, in part, for the feelings of sexual pleasure during and after intercourse.
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34. CLINICAL RELATIONSHIP BETWEEN OXYTOCIN AND
CHILDBIRTH
 Years before oxytocin was discovered, it was common practice in
midwifery to let a first-born twin nurse at the mother’s breast to speed
the birth of the second child.
 Now we know why this practice is helpful—it stimulates the release of
oxytocin. Even after a single birth, nursing promotes expulsion of the
placenta (afterbirth) and helps the uterus regain its smaller size.
 Synthetic oxytocin (Pitocin) often is given to induce labor or to increase
uterine tone and control haemorrhage just after giving birth.
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35. ANTI-DIURETIC HORMONE OR VASSOPRESSIN
 It is a hormone which decreases urine.
 ADH causes the kidneys to return more water to the blood, thus decreasing urine volume. In the absence of ADH,
urine output increases more than tenfold, from the normal 1 to 2 litres to about 20 litres a day.
 Drinking alcohol often causes frequent and copious urination because alcohol inhibits secretion of ADH.
 ADH also decreases the water lost through sweating and causes constriction of arterioles, which increases blood
pressure. This hormone’s other name, vasopressin, reflects this effect on blood pressure.
 The amount of ADH secreted varies with blood osmotic pressure and blood volume
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37. HORMONES OF PARS INTERMEDIA
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38. MELANOCYTE STIMULATING HORMONE (MSH)
 Melanocyte-stimulating hormone (MSH) increases skin pigmentation in amphibians by stimulating the dispersion
of melanin granules in melanocytes. Its exact role in humans is unknown, but the presence of MSH receptors in
the brain suggests it may influence brain activity. There is little circulating MSH in humans.
 However, continued administration of MSH for several days does produce a darkening of the skin.
 Excessive levels of corticotropin-releasinghormone (CRH) can stimulate MSH release
 dopamine inhibits MSH release.
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