The hypophysial portal system carries gonadotropin-releasing hormone (GnRH) from the hypothalamus to the anterior pituitary. It stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary.
The anterior pituitary produces and secretes its own hormones in response to releasing hormones from the hypothalamus, while the posterior pituitary stores and releases hormones produced by the hypothalamus. The anterior pituitary is derived from glandular tissue, while the posterior pituitary originates from neural tissue.
The master of the anterior pituitary gland is the hypothalamus. It secretes releasing and inhibiting hormones that control the release of hormones from the anterior pituitary gland.
Hypothalamus
The anterior pituitary is controlled by the hypothalamus, which releases hormones that stimulate the anterior pituitary to release its own hormones. The anterior pituitary itself is not contained within a particular gland, but is connected to the hypothalamus via the pituitary stalk.
The mechanism of transportation from the hypothalamus to the anterior pituitary gland is through a system of blood vessels called the hypothalamic-pituitary portal system, which connects the two structures. Hormones synthesized in the hypothalamus are released into these blood vessels and then travel to the anterior pituitary gland where they can regulate the secretion of pituitary hormones.
The hypothalamus regulates the release of hormones from the pituitary gland, not organs.
Oxytocin is secreted by the posterior pituitary and is peptide/water-soluble. It stimulates contractions during childbirth and milk secretion during nursing.
The hypothalamussecretes Corticotropin releasing hormone which stimulates the anteriorpituitary to secrete A.C.T.H. (Adrenocorticotrophic) hormone, which in turn stimulates the adrenal cortex to produce cortisone.
The anterior pituitary is connected to the hypothalamus through a network of blood vessels called the hypothalamic-hypophyseal portal system. This system allows hormones produced by the hypothalamus to be transported directly to the anterior pituitary where they can regulate the release of pituitary hormones into the bloodstream.
Adrenocorticotropic hormone (ACTH) is released by the anterior pituitary gland in response to corticotropin-releasing hormone (CRH) released by the hypothalamus. ACTH stimulates the release of cortisol from the adrenal glands in response to stress.
Luteinizing hormone (LH) release by the anterior pituitary is primarily stimulated by the gonadotropin-releasing hormone (GnRH) produced by the hypothalamus. GnRH is released in a pulsatile manner, which triggers the anterior pituitary to secrete LH, along with follicle-stimulating hormone (FSH). Additionally, the levels of sex steroids, such as estrogen and testosterone, can modulate the release of LH, particularly in feedback mechanisms during the menstrual cycle or in response to reproductive cues.