Page 116 - Clinical Biochemistry

There are two distinct regions in the gland:
(A) The Anterior Lobe (adenohypophysis)
(B) The Posterior Lobe (neurohypophysis)
A-Hormones of the Pituitary Anterior Lobe
 The anterior lobe contains six types of secretory cells.
 All of them secrete their hormone in response to hormones reaching them from the

hypothalamus of the brain.
1-Thyroid Stimulating Hormone (TSH)
2-Follicle-Stimulating Hormone (FSH)
3-Luteinizing Hormone (LH)
4-Prolactin (PRL)
5-Growth Hormone (GH)
6-Adrenocorticotropic hormone (ACTH)
1-Thyroid Stimulating Hormone (TSH)
 TSH (also known as thyrotropin) is a glycoprotein consisting of:
(1) A beta chain of 112 amino acids.
(2) An alpha chain of 89 amino acids.
 The alpha chain is identical to that found in two other pituitary hormones, FSH and LH as

well as in the hormone chorionic gonadotropin (hcG).
 Thus it is its beta chain that gives TSH its unique properties.
 The secretion of TSH is stimulated by the arrival of thyrotropin releasing hormone (TRH)

from the hypothalamus.
 Inhibited by the arrival of somatostatin from the hypothalamus.
 As its name suggests, TSH stimulates the thyroid gland to secrete their hormones, thyroxine

(T4) and triiodothyronine (T3).
 The secretion of TSH is stimulated by the arrival of thyrotropin releasing hormone (TRH)

from the hypothalamus.
 Inhibited by the arrival of somatostatin from the hypothalamus.
 As its name suggests, TSH stimulates the thyroid gland to secrete their hormones, thyroxine

(T4) and triiodothyronine (T3).
 Normal TSH levels for adults are 0.5-5.0 mU/L.
2-Follicle-Stimulating Hormone (FSH)
 FSH is a heterodimeric glycoprotein consisting of the same alpha chain found in TSH (and

LH)