stimulates the release of hormone from other endocrine gland o Examples: TSH (+) release of Thyroid Hormones GnRH (+) release of gonadotropins from anterior pituitary gland 5.Where is the pituitary gland? 6.Describe the anterior and posterior pituitary gland in relation to the hypothalamus. How is each lobe associated with the hypothalamus? 1. Nerve bundle called hypothalamic - hypophyseal tract maintains connection 2. Does not produce its own hormones, but stores and releases hormones that are produced by the hypothalamus
ii. Anterior pituitary does not have direct contact with hypothalamus, but contains glandular cells that produce hormones 1. associated with hypothalamus through local network of blood vessels called the hypophyseal portal system 2. hypothalamus produces regulatory hormones that control the release of the anterior pituitary hormones a. releasing hormone : stimulates the synthesis and secretion of one or more of the hormones from anterior pituitary b. inhibiting hormone : prevents the synthesis and secretion c. the secretion of hypothalamic regulatory hormones and anterior pituitary hormones controlled by negative feedback 7.What hormones are produced in the anterior pituitary gland? 8.What is the function of each of these hormones?
1. Growth Hormone (GH) or somatotropin Function : Stimulates cell growth and replication by stimulating protein synthesis Primary target cells are skeletal muscle and bone cells, although every tissue responds to GH to some degree Production of GH regulated by: o growth-hormone releasing hormone (GHRH) and growth-hormone inhibiting hormone (GHIH) from the hypothalamus Growth-promoting effects are indirect, i.e., effects are through proteins called somatomedins o GH stimulates liver to produce somatomedins, which are released and bind to receptor sites on target cells Metabolic effects are direct o Bind at target cells and increase nutrient availability (i.e., anti-insulin effect: ↑ lipolysis and ↑ blood sugar) 2. Prolactin (PRL) Function : stimulates mammary gland development and stimulates milk production during lactation Regulation : release is regulated by prolactin-releasing hormone (PRH ) and prolactin- inhibiting hormone (PIH) from hypothalamus; neuroendocrine reflex remaining anterior pituitary hormones are called tropic hormones because they “turn on” other endocrine glands