Hypothalamus and Pituitary

Hypothalamus (brain)

The hypothalamus is the command centre of the endocrine (hormone) system - it links the nervous system with the endocrine system via the pituitary gland which can then initiate a response via other target tissues.

A hormone is a signalling molecule produced by a gland, transported via the blood to their target sites to regulate processes within the body (physiological and behavioural regulation - reproduction, digestion, metabolism - Insulin). Hormones bind to receptors on their target tissues - initiating a cellular response.

Anterior Pituitary - manufactures hormones - secretion of these hormones is regulated by hormones released from the hypothalamus.

Posterior Pituitary - does not produce hormones but stores and secretes (after signals from the hypothalamus) the hormones of the hypothalamus.

Oxytocin - stimulates uterine contractions during childbirth and associated with breast milk ejection when the newborn begins suckling.

Antidiuretic Hormone (ADH/vasopressin) - released in response to high solute concentration in the blood (high blood osmolarity) target the tubular cells of the kidney (nephrons) to increase water reabsorption. At high concentrations ADH constricts blood vessels - increased blood pressure - by increasing peripheral resistance.

Alcohol and caffeine inhibit the release of ADH - leading to increased urine production

Growth hormone (GH/somatotropin) - promotes protein synthesis and tissue building. Release of GH is controlled by Growth hormone releasing hormone (GHRH) from the hypothalamus.

GH also stimulates the liver to break down glycogen to glucose which is deposited in the blood - diabetogenic effect.

Thyroid stimulating hormone (TSH) - regulates the activity of the thyroid gland. Released from the pituitary in response to the release of thyroid-releasing hormone (TRH) from the hypothalamus.

Adrenocorticotropic Hormone (ACTH) - stimulates the adrenal cortex (Adrenal glands above the kidneys) to release corticosteroid hormones (cortisol). Release of ACTH is controlled by the release of corticotropin-releasing hormone (CRH) from the hypothalamus.

Follicle Stimulating Hormone and Luteinizing Hormone (FSH, LH) - control the development and regulation of the reproductive system. Secretion is regulated by Gonadotrophin Releasing Hormone (GnRH).

Prolactin - promotes lactation in women and the development of mammary glands during pregnancy. Release stimulated due to prolactin releasing hormone (PRH) from the hypothalamus.

https://courses.lumenlearning.com/suny-ap2/chapter/the-pituitary-gland-and-hypothalamus/