Pituitary gland one of the most important glands for health and normal biological functions inside the body. This is a very influential gland releases hormones that affect your growth as well as influencing the activities of other glands. For this reason the pituitary gland is often referred to as the master gland.Pituitary secretion is controlled by either hormonal or nervous signals from hypothalamus. Division in Two Lobes 1-Anterior pituitary (adenohypophysis) - cells secrete peptide/protein hormones 2-Posterior pituitary (neurohypophysis) - is an extension of the hypothalamus - is composed largely of the axons of the hypothalamic neurons

1. PITUITARY GLAND
Biochemistry
4th level
Asmaa Fawzy Fawaz
Aya Mohamed Hegazy
Aalaa khaled Abdallah

2. INTRODUCTION
• The pituitary gland, also known As hypophysis which is part of the
endocrine system, is a small, oval structure located just below the
hypothalamus (a region of the brain that controls an immense
number of bodily functions, is located at the base of the brain) in
bony sella turcica.
• This is a very influential gland releases hormones that affect your
growth as well as influencing the activities of other glands. For this
reason the pituitary gland is often referred to as the master gland.
• Pituitary secretion is controlled by either hormonal or nervous signals
from hypothalamus

3. Division in Two Lobes
•Anterior pituitary (adenohypophysis)
- cells secrete peptide/protein hormones
•Posterior pituitary (neurohypophysis)
- is an extension of the hypothalamus
- is composed largely of the axons of the
hypothalamic neurons

4. Posterior Pituitary Gland (or neurohypophysis)
It is largely a collection of axonal projections from the hypothalamus.
Posterior Pituitary Hormones
The posterior pituitary secretes two important endocrine hormones, namely Oxytocin
and Antidiuretic hormone.
The hormones released by the posterior pituitary are actually synthesized in the
hypothalamus by nerve signals . They migrate along nerve fibers to the posterior
pituitary, and are stored until stimulated to be released into the general circulation.
Functions of the Posterior Pituitary Gland
The posterior pituitary stores and secretes the following important endocrine
hormones: Oxytocin and Antidiuretic hormone (ADH, also known as vasopressin and
AVP, arginine vasopressin)

5. 1. Oxytoxin (OT)
Target in the body:
Uterus and Mammary gland
Effects:
aiding in uterine contractions during childbirth and stimulating the production and
release of milk(lactation)
2. Antidiuretic hormone
Antidiuretic hormone (ADH,also known as vasopressin and AVP)
vasopressin :a hormone secreted by cells of the hypothalamic nuclei and stored
in the posterior pituitary for release as necessary called "anti-diuretic hormone"
that is normally secreted by the pituitary gland.
Target in body :
Vasopressin acts on the kidneys and blood vessels.

6. Effects:.
Vasopressin helps prevent loss of water from the body by reducing urine
output and helping the kidneys reabsorb water into the body. Vasopressin also
raises blood pressure by narrowing blood vessels.
Underproduction of ADH results in a disorder called
diabetes insipidus characterized by inability to concentrate
the urine and, consequently, excess urination
leading potentially to dehydration.
Classification of the posterior pituitary :
varies, but most sources include the three regions below:
Pars nervosa, also called the neural lobe or posterior lobe,
constitutes the majority of the posterior pituitary
and is the storage site of oxytocin and vasopressin.

7. ANTERIOR PITUITARY GLAND
• The major organ of the endocrine system, also called
(adenohypophysis or front lobe).
• Larger than posterior lobe.
• Composed of three parts:
Pars distalis&pars intermedia&pars tuberalis
• Function: Secretion of polypeptideprotein
hormones,seven hormones that regulate several
physiological processes, including stress, growth,
reproduction and lactation.

8. Regulation of anterior petituiry gland
• The anterior pituitary is regulated by the hypothalamus
which is stimulated by negative&positive feedback from
these target organs.
• Target cell stimulate Hypothalamus positively or negatively
,then Neurosecretory cells in hypothalamus release
hormones (releasing or inhibiting) which go to anterior gland
through blood vessels called (hypothalamo-hypophysial
portal vessels) and stimulate it to further produce or inhibit
the production of the corresponding hormone.

10. Hormones of adenohypophysis
1. Growth hormone
2. Thyroid stimulating hormone(TSH)
3. Adrenocorticotropic hormone (ACTH)
4. Prolactin
5. Gonadotrophins:
Lutenizing Hormone (LH)
Follicle-stimulating Hormone (Fsh)
6. Beta-endorphin

11. Three distinct cell types are seen in hypophysis:
1- adenohypophysis
Acidophils (40%)
•Somatotrophs – produce growth hormone (GH)
•Lactotrophs – produce prolactin (PRL)
Basophils (10%)
•Thyrotrophs - produce thyroid stimulating hormone (TSH)
•Gonadotrophs – produce luteinizing hormone (LH) & follicle – stimulation
hormone (FSH)
•Corticotrophs – produce adrenocorticotropic hormone (ACTH)
2-neurohypophysis
Chromophobes (50%)
The major portion of the neurohypophysis contains axons from
hypothalamic neurosecretory neurons:
•Supraoptic nuclei – mainly produce antidiuretic hormone (ADH)/vasopressin (AVP)+
neurophysin
•Paraventricular nuclei – mainly produce oxytocine + neurophysin

12. 1. Growth hormone
Stimulates the growth of bones, muscle,and other organ by
increasing protein synthesis.
affects protein, fat and carbohydrate metabolism.
Too little growth hormone secretion can be the result of
abnormal development of the pituitary gland.
Release is stimulated by GHRH Growth hormone–
releasing hormone (GHRH )GHRH stimulates GH
production and release by binding to the GHRH Receptor
(GHRHR) on cells in the anterior pituitary

13. • Suppression is by GHRIH known as
growth hormone release–inhibiting
hormone (GHRIH)
• Inhibit the release of growth hormone
(GH) (thus opposing the effects of
growth hormone–releasing hormone
(GHRH))

14. Thyroid stimulating hormone
(TSH)
Stimulated by Thyroidtropin- releasing
hormone (TSH )from hypothalamus
the thyroidtropin -releasing hormone and release it into the
blood surrounding the pituitary gland, where it has its most
important action. This is to regulate the formation and
secretion of thyroid stimulating hormone in the pituitary gland,
which in turn regulates the production of thyroid hormones in
the thyroid gland
Stimulates growth and activity of the thyroid gland
When too much TSH is secreted ,it cause the thyroid gland to
enlarge and secrete too much thyroid

15. • When too much TSH is secreted ,it
cause the thyroid gland to enlarge and
secrete too much thyroid
• Inhibit by Somatostatin from
hypothalamus
• Somatostatin from the hypothalamus
inhibits the pituitary gland’s secretion
of growth hormone and thyroid
stimulating hormone

17. 3. Adrenocorticotropic hormone
(corticotrophin, ACTH)
1-Stimulated by: Corticotropin-releasing
hormone(CRH) from the hypothalamus.
Secretion is regulated by negative feedback
(Inhibit when blood level ACTH raises ).
2-Targrt: adrenal gland (cortex).
3-Action:ACTH stimulate the adrenal
gland(cortex) to secret a hormone called
glucocorticoids,The name glucocorticoid
(glucose + cortex + steroid) derived from its
role in the regulation of the metabolism of
glucose and its synthesis in the adrenal
cortex.

18. 4. Prolactin
1-prolactin is a protein hormone of
anterior pituitary gland
2-Also known as lactogenic hormone
3-Stimulated by Prolactin-releasing hormone
(PRH) from hypothalamus
4-Target cell is mammary gland
5-Stimulates the production of milk in the
breast following pregnancy.

19. 5. Gonadotrophins
1. Lutenizing Hormone (LH)
stimulated by gonadotropin-releasing
hormone(GnRH) from hypothalamus
In males, stimulates the testes to secrete testosterone
In females, stimulates release of ovum by ovary.
After ovulation,it stimulate the formation of corpus
luteum in ovary and secret hormone progesterone .

20. 2- Follicle-stimulating Hormone (Fsh)
• in male, stimulate production of sperm cells
in the testes.
• in females, stimulates maturation of ovarian
follicle and secrete estrogen by ovaries

21. 6. Beta-endorphin
1. Polypeptide hormone
2. β-Endorphin is found in neurons of the
hypothalamus, as well as the pituitary gland
3. Target: Opioid receptor
4. Effect: inhibit perception of pain