Book recommended: Medical Physiology by Jaypee

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