Pituitary Gland or Hypophysis

1. By-
Dr. Dinesh C. Sharma
Head, Zoology
K.M. Govt. Girls P. G. College
Badalpur, G.B. Nagar
dr_dineshsharma@hotmail.com
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2. 2

3. Fore Brain Hind Brain
Mid
Brain
Olfactory bulb Cerebrum Diencephalon
Epithalamus
Thalamus
Hypothalamus
Pituitary
Pineal
Pineal
Pituitary
Cerebrum
Thalamus
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4. The Pituitary Gland
 Pituitary Gland is also known as Hypophysis; it is found
attached with the hypothalamus (Ventral part of
diencephalon)
 It is situated in a depression of sphenoid bone , called
sella tursica.
 It is connected to ‘brain by’ pituitary stalk.
 Physiologically it is divided :-
A) Anterior Pituitary : adeno hypophysis
B) Posterior Pituitary : neuro hypophysis.
A B
Pituitary
Sphenoid bone
Sella tursica
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5. 5

6. Origin of Pituitary-
•Pituitary has dual origin its anterior lobe is originates
from Rathkis pouch, which is an evagination of
stomodium (fore gut).
•The posterior lobe of pituitary originates as downward
growth from hypothalamus called infandibulam.
•Thus anterior lobe is made up of epithelial tissue while
posterior of nervous tissue.
•Because both stomodium and nervous system originates
from ectoderm; both lobe of pituitary or entire pituitary
is of ectodermal in origin.
Infandibulam
Rathkis pouch
Hypothalamus
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7. Structure of pituitary
Ant. Lobe
Post. Lobe
Ant. Lobe
Post. Lobe
Pars tuberalis
Pars destalis
Lumen
Pars intermediata
Herrings body
=
Terminal buttons
Pituicytes
=
Glial cells
Axons
cyton
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8. Posterior lobe of pituitary has herrings body which
are modified terminal buttons of axons whose cell
bodies are located in hypothalamus.
Packing cells (Glia or neuroglea) between herrings
bodies are called as Pituicytes.
Hormones of Ant. Lobe are produced in it self but
controlled by hypothalamic factors, whereas
hormones of posterior lobe are produced in
hypothalamus of brain.
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9. Hypothalamic-hypophyseal connections
There are two types of connection between the hypothalamus and
pituitary :
1-Vascular connection between the hypothalamus and anterior
Pituitary gland in the form of hypothalamic- hypophyseal portal
circulation.
2- nervous connection between hypothalamus and posterior
Pituitary gland in form of hypothalamic-hypophyseal tract .
The hypothalamus receives signals from almost all sources in the
nervous system, thus when a person is exposed to pain, a portion of
the signals is transmitted to the hypothalamus that acts as a
collecting center for internal body information's then Control
secretion of pituitary glands .
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12. Control of anterior pituitary secretion by hypothalamus
There are neurohormones produced by the median eminence
ofthe hypothalamus that regulate the functions of anterior
pituitary.
These neurohormones diffuse into a primary plexus of
capillaries
and are transported down in large portal vessels in the
pituitary stalk to a secondary set of capillaries in the anterior
pituitary gland : it is called the hypophyseal portal system.
These neuro hormones comprise both releasing & inhibitory
hormones.
For each type of anterior pituitary hormone, there is a
corresponding hypothalamic releasing hormone
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14. Note
The anterior pituitary receives
portal blood
The posterior pituitary receives
arterial blood.
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15. Hormones of anterior pituitary :
Seven (7) Hormones are produced by ant. pituitary
1.Thyroid stimulating Hormone (TSH)
2.Adreno-cortico trophic Hormone (ACTH)
3.Follicle Cells Stimulating Hormone (FSH)*
4.Interstecial cells stimulating Hormone (ICTH) or
Leutinizing Hormone (LT) *
5.Prolactin Hormone (PH)
6.Growth Hormone (GH)
7.Melonocyte Stimulating Hormone (MSH)- Secrated
by intermediate lobe
*FSH & ICTH Combindenly known as Gonado trophic
Hormone.
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17. Actions of Ant. Pituitary Hormones
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18. 1- Growth Hormone (GH) or Somatotrophic Hormone (STH)
 Somatotrophic H. = Somatotropin
 It is formed of multiple amino acids.
 It causes growth of all tissues.
 It promotes both size and number of cells.
 It promotes protein synthesis and
deposition.
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19. Metabolic effects of Growth Hormone
A) Growth h. increases protein synthesis :
Increase transport of amino acid through cell membrane.
Increase protein synthesis by ribosome.
Stimulates nucleus for formation of RNA.
It decreases protein catabolism (I.e.protein sparer)
B) Effect on fats is: it has a lipolytic effect:
To give energy.
C) Effect on Carbohydrate Metabolism: It has
diabetogenic effect
 Decrease glucose utilization
Increase glycogen deposition.
Decrease number of insulin receptors.
Decrease glucose uptake by the cells19

20. Other Effects of Growth Hormone :
Stimulates Erythropoiesis.
Increase Ca++
absorption at GIT &
produce phosphate balance.
 Decrease urinary excretion of Na+
,
K+: both needed for growth of tissues.
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21. Regulation Of Growth H. Secretion
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22. Regulation Of Growth H. Secretion
A) Hypothalamic control :
1- G H R H & Somatostatin H. (G H I H )
 Mainly by negative Feed - Back Control
 Somatostatin produced by : hypothalamus and delta cell of islets of langerhans
of pancreas, inhibits secretion of : Growth Hormone, insulin glucagon.
2- Insulin like growth factors -IGFs:it is produced by the liver, it decrease G H
secretion by direct inhibition of pituitary& ↑somatostatin.
3-Ghrelin H, secreted by stomach→ ↑G H + ↑appetite.
B) Stimuli that increase GH Secretion :
 Hypoglycemia
 Decrease level of cell protein.
 Increase conc. of fatty acids in blood.
 Deep sleep.
 Exercise, emotions, stress.
 Growth Hormone level has diurnal variation.22

23. Effect of sleep & exercise on GH secretion
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24. Growth hormone exerts its effects on bones through
somatomedins
Growth hormone causes the liver to form somatomedins
that stongly increase all aspects of bone growth as:
stimulation of osteoblasts, increased protein deposition
by chondrocytic & osteogenic cells .
Effects of somatomedins on growth are similar to that of
insulin so it is called Insulin like growth factors( IGFs).It
cause increase glucose &amino acids uptake by the
cells. It also decrease lipolysis.
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25. Result of Abnormal secretion of GH
Hyposecretion of GH-
•Since birth causes Dwarfism. Dwarfs are called
Midgets
•In adulthood causes pituitary Mixedema
Hypersecretion of GH-
•Since birth cause Gigantism
•In adulthood it causes Acromegaly in which
disproportioned ate growth takes place. Lantern
jaw, hunch back, kyphosis are types of acromegaly
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28. 2- Prolactin (PL) or
Luteotrophic Hormone (LTH) or
Mammotrophic Hormone (MTH)
Secreted by anterior Pituitary.
Function :
This hormone develops mammary glands specially during
pregnancy
Stimulation of milk secretion (Lactation) by mammary gland.
Stimulation of synthesis of fat & lactose mammary gland.
Inhibit the action of gonadoropin (FSH, ICTH)  inhibition of
ovulation .
In males : unknown functions:--
If excess Prolactin  impotence.
Regulation of Secretion :
Prolactin Releasing Hormone (PRH).
From hypothalamus and Prolactin inhibitory Hormone (PIH)
(dopamine)
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29. 1. Normally Prolactin inhibitory Hormone (PIH) Predominates
or overbalances the effect of (PRH).
2. Prolactin Facilitated PIH from hypothalamus.
= negative feed-back mechanism to inhibit its own secret.
3. increase secretion of Prolactin in :
exercise
stress
suckling
sleep.
. Tumour of cells : Excessive secretion :
- Galactorrhea.
- Amenorrhea.
- Impotence in males.29

30. 3- Follicle cell Stimulating Hormone (FSH)
In females FSH stimulate follicle of Ovary
In Males it stimulates spermatogenesis
4- Interstitial cell Stimulating Hormone (ICSH) or
Lutenizing Hormone (LH)
In females ICSH stimulate ovulation
In Males it stimulates Interstitial cells (Cells of
Leydig), found in testis of man
Follicle cell Stimulating Hormone-
Secreted by anterior Pituitary.
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31. 5- Thyroid Stimulating Hormone (TSH)
it stimulates the Thyroid gland
6- Adeno corticotrophic Hormone (ACTH)
ACTH stimulates the Thyroid gland
7- Melanocytes stimulating Hormone (MSH)
 It is secreted by intermediate lobe.
Melanocytes are pigment cells of skin
containing Melanin. MSH stimulates melanin
to spread and darken the skin color.
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33. HORMONES OF POSTERIOR PITUITTARY
The posterior lobe of the pituitary secretes two peptide
hormones, antidiuretic hormone (ADH) and oxytocin.
The posterior pituitary hormones are initially synthesized in
the cell bodies of the supraoptic & paraventricular nuclei of
the hypothalamus, & then transported in combination with
“carrier” proteins called neurophysins down to the nerve
ending in the posterior pituitary. Stimulation of the hypothamic
nuclei initiate action potentials in their neurons, transmitted
downward along the fibers from the supraoptic or
paraventricular nuclei on reaching the nerve ending cause
release of hormone by the usual secretary mechanism of
exocytosis and is absorbed into adjacent capillaries from which
they reach the general circulation. This process is known as
neurosecretion ( hormone secreted into the circulation by nerve
cells. )
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34. Hypothalamo-hypophyseal Tract
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35. Antidiuretic Hormone (ADH) or
Vasopressin or Pitressin
Functions-
A) On the kidneys :
ADH increases the reabsorption of water by
the kidney. These reduce the excretion of
water from the body. The urine becomes
concentrated and its volume is reduced
(antidiuretic effect). It acts on the distal
portions of nephrones (in the collecting duct
and collecting tubules), increasing their
permeability to water. ADH causes opening
of many protein water channels.
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36. B) On the blood vessels
ADH is a potent vasoconstrictor. It
acts on vascular smooth muscle.
ADH in moderate concentration
has a very potent effect of
constricting the arterioles so,
increasing the arterial pressure.
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37. Control Of ADH
1. Osmotic stimuli :-
The release of ADH is controlled by a feed back
mechanism that act to maintain the plasma osmolality
close to 290 mosm/L. When the osmolarity of the plasma
is increased (as in dehydration or high salt level) the rate
of discharge of vasopressin from the posterior pituitary
increases leading to water retention by its action on the
kidney.
The change in osmolality is sensed by osmoreceptor cells
present in the hypothalamus which transmit signals to
cells secreting ADH.
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38. 2. Volume depletion
Decrease in circulatory volume and mean arterial pressure
will increase ADH.They are sensed by barorecptors in left
atrium,pulmonary veins, carotid sinus and aortic arch.
Impulses are transmitted to the central nervous system
through vagal and glossopharengal nerves.
In hemorrage, ADH is secreted in large amount.It
promotes water conservation to reestablish circulatory
volume and causes vasoconstriction to maintain blood
pressure.
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39. 3. Angiotensin II :
Acting on the brain to increase vasopressin secretion.
4. Drugs
Some drugs such as nicotine, morphine, tranquilizer and
some anesthetics lead to increase ADH secretion. Alcohol
decreases secretion of ADH.
5. Stress :
Lead to increase ADH as severe pain, trauma, exercise and
surgical operation.
Hyposecretion of ADH :
Diabetes insipidus (diuresis) is a disease caused by ADH
deficiency in which too much water is passes out with
urine (upto 30L/day). The urine in this become tasteless.
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40. OXYTOCIN or PITOCIN HORMONE
 It is polypeptide hormone secreted by hypothalamus and stored in posterior
pituitary. It is acting on the target cells by increasing the intracellular Ca++
content.
Function Of Oxytocin
1.Milk Ejection :
• It causes contraction of special smooth muscle like cells known as
myoepithelial cells that line the alveoli and ducts of the mammary gland thus
squeezing milk outwards through the nipple.
2. Contraction of smooth muscle of uterus :
• It causes contraction of the smooth muscle fibers of both pregnant or non-
pregnant uterus.
• It is used clinically for the induction of labor pain in woman at the time of
delivery (child birth) or parturition. The pain is due rhythmic contractions in
uterine wall and detachment of placenta for coming out of child from uterus.
• This hormone is also considered helpful in fertilization because during
copulation uterine contractions help sperm in reaching the oviduct to fertilize
ovum.40

41. Control Of Oxytocin Secretion
1.The sucking of the breast stimulates
touch receptors in the nipple, sensory
nerves transmit impulse upward to the
hypothalamus to cause release of
oxytocin.
2.The secretion of oxytocin is increased by
genital stimulation.
3. Fear, Pain, anxiety and alcohol cause
inhibition of oxytocin release.
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45. Pineal is found on dorsal side (Epithalamus) of
brain between optic lobes and cerebrum.
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46. Its content are like sand particles, so it is called brain sand; its
cells are called pinealocytes,; and the hormone produced is
called Melatonin which is antagonistic to MSH of pituitary.
Rats attain early sexual maturity on removal of pineal it is
therefore concluded that function of pineal is to delay sexual
maturity
Melanin
MSH
Melatonin
Light colour of skinDark colour of skin
Pineal is sensitive to light reception of eyes; due to this it is less
active in blind people, so they are said to be sexually mature at
early age.46