BIOL242 Pituitary Gland

BIOL242 Pituitary Gland

Function

· The pituitary is a small, bean-shaped gland located below the brain in the skull base in an area called the pituitary fossa, or sella turcica. Weighing less than one gram, the pituitary gland is often called the "master gland" since it controls the secretion of hormones.

· Hormones have a dramatic and broad range of effects on metabolism, growth and maturation, sexuality and reproduction, and other important bodily functions.

· The pituitary glandproduces several hormones:

o Prolactin: stimulates breast milk production and controls menstrual periods

o ACTH: signals the adrenal glands (situated atop the kidneys) to produce the steroid cortisol

o Growth hormone (GH): signals special liver cells to produce somatomedin-C, which is critical for body growth during childhood

o Thyroid stimulating hormone (TSH): signals the thyroid gland to produce thyroid hormone which is essential for the regulation of body metabolism

o FSH and LH: regulate hormone production by the testes (testosterone)and ovaries (estrogen, progesterone)

o ADH: stimulates the kidney concentrate the urine by taking up water back into the bloodstream

Structure

/ · Structurally, the pituitary gland is divided into a larger frontal region (adenohypophysis) and a smaller posterior region (neurohypophysis).
· The gland is connected to a region of the brain called the hypothalamus by the pituitary stalk. Directly above the pituitary gland and in front of the pituitary stalk are the crossing fibers of the optic nerves, called the optic chiasm.
· On each side of the pituitary gland is the cavernous sinus. Through each cavernous sinus runs a carotid artery that carries blood to the brain, and important nerves that control eye movements.

· Because of the close proximity of the pituitary gland to major intracranial nerves and blood vessels, as well as the vital hormonal control the pituitary gland provides, disorders of the pituitary can cause a wide spectrum of symptoms, both hormonal and neurological.

Pituitary Hormones

Listed below are the specific hormones produced by the pituitary. Hormone over production ofdeficiencies can cause a host of symptoms:

· Thyroid Stimulating Hormone (TSH):

· Stimulates the thyroid gland to release thyroid hormones.

· Control basal metabolic rate and play an important role in growth and maturation.

· Affect almost every organ in the body.

· Growth Hormone (GH): Principal hormone that regulates growth.

· Adrenocorticotropic Hormone (ACTH): Triggers the adrenal glands, which regulate stress response with the release of hormones such as cortisol and aldosterone.

· Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH): Control reproduction.

· Prolactin (PRL): Stimulates secretion of breast milk.

· Vasopressin, also called anti-diuretic hormone (ADH): Promotes water retention.

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