The pituitary gland, also called the hypophysis, regulates many other endocrine glands through its production of hormones. It is divided into the anterior and posterior pituitary. The anterior pituitary produces hormones that control growth, metabolism, reproduction, and lactation. These hormones are regulated by hypothalamic releasing and inhibiting hormones. The posterior pituitary stores and releases oxytocin and vasopressin, which are produced in the hypothalamus and travel to the pituitary via nerve fibers. Together, the hormones produced by the anterior and posterior pituitary regulate important bodily functions.

1. Pituitary Gland
DANISH HASSAN
LECTURER, UNIVERSITY OF SARGODHA

2. Pituitary Gland (Anatomy)
 Also called the hypophesis
 Measures about 1 centimeter in diameter and 0.5
to 1 gram in weight
 Lies in the sella turcica, connected to the
hypothalamus by the pituitary/hypophysial stalk.
 Physiologically, divided into two distinct portions:
1. Anterior pituitary (Adenohypophysis)
2. Posterior pituitary (Neurohypophysis)

3.  Between these is a small, relatively avascular zone
called the pars intermedia
 Almost absent in the human being but is much
larger and much more functional in some lower
animals

5. 1. Anterior
Pituitary/Adenohypophysis
 Also known as the
master gland because it
regulates many other
endocrine glands
through its hormones.
 Anterior pituitary consists
of three parts:
1. Pars distalis
2. Pars tuberalis
3. Pars intermedia

6.  Anterior pituitary has two types of cells, which
have different staining properties:
1. Chromophobe cells
2. Chromophil cells

7. 1. Chromophobe Cells
 Do not possess granules and stain poorly.
 Form 50% of total cells in anterior
 Are not secretory in nature, but are the precursors of
chromophil cells

8. 2. Chromophil Cells
 Contain large number of granules and are darkly
stained
 Form rest of 50% of anterior pitutary.
 Types:
1. Basis of staining property
2. Basis of secretory nature

9. Based on Staining Property
1. Acidophilic cells / alpha
cells
 Form 35%
2. Basophilic cells / beta
cells,
 Form 15%.
Based on the Secretory Nature
1. Somatotropes (GH)
2. Corticotropes (AcTH)
3. Thyrotropes (TSH)
4. Gonadotropes (FSH &
LH)
5. Lactotropes (Prolactin)

11.  30 to 40 per cent of the anterior pituitary cells are
somatotropes that secrete growth hormone,
 20 per cent are corticotropes that secrete ACTH.
 Each of the other cell types accounts for only 3 to
5 per cent of the total; nevertheless, they secrete
powerful hormones for controlling thyroid
function, sexual functions.

13. Regulation Of Anterior Pituitary
Secretion
 Hypothalamus controls anterior pituitary by
secreting the releasing and inhibitory hormones
(factors), which are called neuro-hormones.
 These hormones from hypothalamus are
transported anterior pituitary through
hypothalamo-hypophyseal portal vessels.
 Some special nerve cells present in various parts
hypothalamus send their nerve fibers (axons) to
median eminence and tuber cinereum.

14.  These nerve cells synthesize the hormones and
release them into median eminence.
 From here, the hormones are transported by
blood via hypothalamo-hypophyseal portal
vessels to anterior pituitary.

17. Releasing and Inhibitory Hormones
Secreted by Hypothalamus
 Growth hormone-releasing hormone (GHRH)
 Stimulates the release of growth hormone
 Growth hormone-releasing polypeptide (GHRP)
 Stimulates the release of GHRH and growth hormone
 Growth hormone-inhibitory hormone
(GHIH)/Somatostatin
 Inhibits the growth hormone release
 Thyrotropic-releasing hormone (TRH)
 Stimulates the release of thyroid stimulating hormone

18.  Corticotropin-releasing hormone (CRH)
 Stimulatesthe release of adrenocorticotropin
 Gonadotropin-releasing hormone (GnRH)
 Stimulatesthe release of gonadotropins, FSH and LH
 Prolactin-inhibitory hormone (PIH)
 Inhibits prolactin secretion

19. 2. Posterior
Pituitary/Neurohypophysis
 Bodies of the cells that secrete the posterior pituitary
hormones are not located in the pituitary gland.
 Large neurons, called magnocellular neurons,
located in the supraoptic and paraventricular nuclei
of the hypothalamus synthesise post pitutary
hormones.
 Hormones are then transported in the axoplasm of
the neurons
 Nerve fibers passing from the hypothalamus to the
posterior pituitary gland carry the hormones.

22. ANT PITUTARY HORMONES
1. Growth hormone (GH)
2. Thyroid-stimulating
hormone (TSH)
3. Adrenocorticotropic
hormone (ACTH)
4. Follicle-stimulating
hormone (FSH)
5. Luteinizing hormone
(LH)
6. Prolactin
POST PITUTARY HORMONES
1. Anti diuretic hormone/
Vasopressin
2. Oxytocin