Which statement best describes the characteristics of hormones secreted from the pituitary gland?

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Quizplus · Accepted Answer

11ecba2d_0fdb_567d_a3bf_9fd302ff77dd_MD0008_00 The pituitary gland is a small structure that sits inside a bony cavity below the hypothalamus at the base of the brain. It is attached to the hypothalamus via the pituitary stalk and can be divided into two separate lobes: The anterior lobe is made up of glandular tissue that synthesizes and secretes follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), growth hormone (GH), β-endorphins, and prolactin. The synthesis and secretion of hormones from the anterior pituitary is controlled primarily by neurohormones released from hypothalamic neurons. These regulatory neurohormones are secreted into the hypophyseal portal system, a network of small blood vessels that enables small quantities of hormones secreted from the hypothalamus to directly reach the anterior pituitary without being diluted in the circulation. The posterior lobe, made up of axonal projections from the hypothalamus, stores and secretes the hormones oxytocin and vasopressin (also called antidiuretic hormone [ADH]). Posterior pituitary hormones are synthesized in hypothalamic neurons and then transported down the axon to the axon terminals in the posterior pituitary, where they are stored. The secretion of stored hormones from the posterior pituitary is mediated by action potentials that cause exocytosis of neurosecretory vesicles. (Choices B and C) Hormones can be classified by their modes of actions. Tropic hormones regulate the secretion of other hormones by acting on other endocrine glands. In contrast, direct or nontropic hormones act directly on nonendocrine tissues to cause physiological end points. The anterior pituitary releases both tropic (FSH, LH, ACTH, TSH) and direct (GH, prolactin, endorphins) hormones, whereas the posterior pituitary releases direct hormones (oxytocin, ADH). (Choice D) The secretion of hormones from the anterior pituitary is mediated by regulatory neurohormones released into the blood by hypothalamic neurons. In contrast, the secretion of stored hormones from the posterior pituitary is induced by depolarization of the nerve terminals. Educational objective: The synthesis and secretion of hormones from the anterior pituitary is regulated by the release of neurohormones into the blood from neurons located in the hypothalamus. In contrast, posterior pituitary hormones are synthesized in hypothalamic neurons and undergo anterograde axonal transport to the posterior pituitary. The secretion of stored posterior pituitary hormones from the axon terminals is mediated by depolarization of the nerve terminals.

Which Statement Best Describes the Characteristics of Hormones Secreted from the Pituitary