Pituitary gland

The pituitary gland, or hypophysis, is a pea-sized gland of the endocrine system, situated at the base of the brain. As part of the HPA axis, it is regulated by the hypothalamus to produce, store, and secrete various hormones, which target other endocrine glands. The pituitary gland is sometimes referred to as the “master gland” as it regulates the function of the other endocrine glands. https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/pituitary-gland-disorders/overview-of-the-pituitary-gland

Structure and Function The pituitary gland sits at the base of the brain, underneath the hypothalamus. It is surrounded by a protective bony cavity called the sella turcica. The pituitary is divided into three distinct lobes: posterior, anterior, and intermediate. https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/pituitary-gland-disorders/overview-of-the-pituitary-gland

Posterior The posterior pituitary develops as an extension of the hypothalamus (distinct from the anterior pituitary). The posterior pituitary is largely made up of the terminals of nerve cells of the hypothalamus, as neurons in the hypothalamus project directly to the posterior pituitary. Hormones produced by the hypothalamus are stored in the terminals of hypothalamic neurons in the posterior pituitary, and are released by nerve excitation. The two major hormones stored and secreted by the posterior pituitary include: Antidiuretic hormone (ADH, also known as vasopressin) Oxytocin https://www.ncbi.nlm.nih.gov/books/NBK27/


 * include picture of each anatomical section*

Anterior The anterior pituitary is structurally distinct from the posterior pituitary. It makes up 80% of the pituitary gland, and is made up of different types of endocrine cells. These cells are classified by the hormones they synthesize and release, and are regulated by the hypothalamus via releasing and inhibiting hormones. The six major hormones of the anterior pituitary are: Growth hormone (GH) Adrenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Follicular-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin https://www.ncbi.nlm.nih.gov/books/NBK27/ https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/pituitary-gland-disorders/overview-of-the-pituitary-gland

Intermediate The intermediate lobe is present in many lower vertebrates, but is almost absent in humans. The intermediate pituitary synthesizes and secretes: Melanocyte-stimulating hormone (MSH)

Function of Hormones

Hormone Target Organ Role Growth hormone (GH) Muscular, skeletal, and fat tissue Regulates growth and physical development by stimulating muscle growth and reducing fat tissue Adrenocorticotropic hormone (ACTH) Adrenal glands Stimulates the adrenal glands to produce cortisol and other hormones Thyroid-stimulating hormone (TSH) Thyroid gland Stimulates the thyroid to produce thyroid hormone Follicular-stimulating hormone (FSH) Ovaries or testes Stimulates the ovaries to produce eggs/the testes to produce sperm, and the sex organs to produce sex hormones Luteinizing hormone (LH) Ovaries or testes Stimulates the ovaries to produce eggs/the testes to produce sperm, and the sex organs to produce sex hormones Prolactin Mammary glands Stimulates the mammary glands to produce milk Antidiuretic hormone (ADH, also known as vasopressin) Kidneys Regulates amount of water absorbed and excreted by the kidneys Oxytocin Uterus and mammary glands Causes uterus contraction during childbirth, stimulates contractions of the milk ducts in breast for breastfeeding Melanocyte-stimulating hormone (MSH) Skin and hair Stimulates the production of melanin in skin and hair, suppresses appetite, contributes to sexual arousal https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/pituitary-gland-disorders/overview-of-the-pituitary-gland

Dysfunction and Disease Dysfunction of the pituitary gland can result in overproduction or underproduction of pituitary hormones, thus having major consequences in bodily function. Conditions of pituitary malfunction include: Acromegaly -- overproduction of GH Cushing’s disease -- overproduction of ACTH GH deficiency -- underproduction of GH Syndrome of inappropriate antidiuretic hormone -- overproduction of antidiuretic hormone Diabetes insipidus -- underproduction of antidiuretic hormone Sheehan syndrome -- underproduction of any pituitary hormone Pickardt-Falhbusch Syndrome -- underproduction of any pituitary hormone aside from prolactin Hyperpituitarism (usually pituitary adenoma) -- overproduction of any pituitary hormone Hypopituitarism -- underproduction of any pituitary hormone Hypophysitis -- inflammation of the pituitary gland Autoimmune hypophysitis -- inflammation of the pituitary gland due to autoimmunity Pituitary adenoma -- noncancerous tumor of the pituitary gland https://en.wikipedia.org/wiki/Pituitary_disease