Systems Biology
The anterior pituitary, located in the front of the pituitary gland, produces and releases seven hormones: FLAT PEG. The FLAT hormones are tropic hormones, including FSH, LH, ACTH, and TSH. These hormones stimulate endocrine glands to signal the release of another hormone. The PEG hormones, on the other hand, are direct hormones that target non-endocrine tissues, including prolactin, endorphins, and growth hormone.
Gonadotropin-releasing hormone (GnRH) from the hypothalamus signals the anterior pituitary to synthesize FSH and LH, hormones targeting the gonads for gamete production and testosterone synthesis. Corticotropin-releasing factor (CRF) also signals the anterior pituitary to make and release ACTH, which in turn stimulates the adrenal cortex to synthesize cortisol. Thyroid-releasing hormone (TRH) signals the anterior pituitary to make and release TSH, which stimulates the thyroid gland to make thyroid hormones.
The direct hormone prolactin is usually inhibited from production by dopamine, preventing constant lactation. Endorphins affect pain perception and euphoria, while growth hormone supports growth by altering metabolism and stimulating growth in bones and muscles. Imbalances in growth hormone during puberty can lead to gigantism (growth hormone excesss) or drawfism (growth hormone deficiency); in adults, it can result in acromegaly (growth hormone excess), leading to organs, bones, cartilage, and other tissues to increase in size.
Lesson Outline
<ul> <li>Anterior pituitary location and function <ul> <li>Located in the front of the pituitary gland</li> <li>Produces and releases seven hormones (FLAT PEG)</li> </ul> </li> <li>FLAT hormones (the tropic hormones = hormones that act on other endocrine glands) <ul> <li>Follicle-stimulating hormone (FSH)</li> <li>Leutinizing hormone (LH)</li> <li>Adrenocorticotropic hormone (ACTH)</li> <li>Thyroid-stimulating hormone (TSH)</li> </ul> </li> <li>PEG hormones (the direct hormones = hormones that target non-endocrine tissues) <ul> <li>Prolactin</li> <li>Endorphins</li> <li>Growth hormone (GH)</li> </ul> </li> <li>Hormone synthesis and release <ul> <li>Gonadotropin-releasing hormone (GnRH) signals anterior pituitary for FSH and LH synthesis</li> <li>Corticotropin-releasing factor (CRF) signals anterior pituitary for ACTH production and release</li> <li>Thyroid-releasing hormone (TRH) signals anterior pituitary for TSH production and release</li> </ul> </li> <li>Prolactin production <ul> <li>Usually inhibited by dopamine</li><ul> <li>Prevents constant lactation</li></ul> </ul> </li> <li>Effect of endorphins <ul> <li>Affect pain perception</li> <li>Affect euphoria</li> </ul> </li> <li>Growth hormone functions and imbalances <ul> <li>Supports growth by altering metabolism</li> <li>Stimulates growth in bones and muscles</li> <li>Imbalances during puberty can lead to gigantism (GH excess) or dwarfism (GH deficiency)</li> <li>Imbalances in adults can result in acromegaly (GH excess) </li> </ul> </li> </ul>
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FAQs
The anterior pituitary, also known as the adenohypophysis, plays a crucial role in the endocrine system by producing and secreting multiple hormones. These hormones regulate various processes such as growth, reproduction, and energy metabolism. FLAT PEG is a mnemonic that represents the major hormones produced by the anterior pituitary. Each letter stands for a specific hormone, as follows:F - Follicle-stimulating hormone (FSH)L - Luteinizing hormone (LH)A - Adrenocorticotropic hormone (ACTH)T - Thyroid-stimulating hormone (TSH)P - ProlactinE - EndorphinsG - Growth hormone (GH)
The hypothalamus regulates the secretion of hormones from the anterior pituitary through the hypophyseal portal system. This system consists of a network of blood vessels that connect the hypothalamus and the anterior pituitary. The hypothalamus releases specific hormones, known as releasing and inhibitory hormones, into the portal system. These hormones travel directly to the anterior pituitary, where they either stimulate or inhibit the production and release of other hormones.
These hormones secreted by the anterior pituitary have various target organs and functions:- FSH (follicle-stimulating hormone): Regulates the production of eggs in females and sperm in males.- LH (luteinizing hormone): Stimulates ovulation in females and testosterone production in males.- ACTH (adrenocorticotropic hormone): Stimulates the adrenal cortex to produce cortisol and other related hormones.- TSH (thyroid-stimulating hormone): Stimulates the production and release of thyroid hormones by the thyroid gland.- Prolactin: Promotes milk production in females post-pregnancy.- Endorphins: Act as natural pain relievers within the body.- Growth hormone (GH): Stimulates growth, cell reproduction, and cell regeneration in the body.
The production and secretion of hormones are regulated by the intricate balance between the hypothalamus and the hypophyseal portal system. The hypothalamus releases specific releasing or inhibitory hormones into the portal system, which then directly influence the anterior pituitary's hormone production. This regulatory mechanism ensures that appropriate levels of hormones are maintained, allowing the endocrine system to function optimally. Additionally, feedback mechanisms involving hormonal levels in the bloodstream also help regulate anterior pituitary hormone secretion.
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