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Describe the structure and function of the pituitary gland.
- Releases nine peptide hormones
- Seven from endocrine cells of the anterior pituitary (adenohypophysis)
- Called tropic hormones because they “turn on” other endocrine glands
- Two from hypothalamic axons in the posterior pituitary (neurohypophysis)
- All nine bind to membrane receptors and use cAMP as 2nd messenger
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What are the two hormones released from the anterior pituitary gland?
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
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What is the function of Thyroid-stimulating hormone (TSH)?
Stimulates release of thyroid hormones
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When is TSH stimulated to release and when does it stop releasing?
- Released in response to thyrotropin-releasing hormone (TRH) from hypothalamus
- Decreased release when thyroid hormone levels rise (negative feedback)
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What is the function of ACTH?
- Stimulates release of steroid hormones from adrenal cortex
- Specifically those that affect glucose metabolism
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ACTH is released in response to what?
corticotropin-releasing hormone (CRH) from hypothalamus
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What two hormones are released in response to gonadotropin-releasing hormone (GnRH)
- from hypothalamus?
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
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What is the function of FSH?
- Females: promotes ovarian follicle development and (in concert with LH) stimulates secretion of estrogens
- Males: promotes maturation of sperm
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What is FSH inhibited by?
inhibin (peptide released by gonads)
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What is the function of LH?
- Females: induces ovulation, promotes secretion of estrogen and progestins (e.g.,
- progesterone)
- Males: stimulates production of sex hormones (androgens), primarily
- testosterone
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What is the function of Growth Hormone (GH) ?
Stimulates cell growth and reproduction by stimulating rate of protein synthesis
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What stimulates the release of GH?
Released in response to growth hormone–releasing hormone (GH–RH) and growth hormone–inhibiting hormone (GH–IH)
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What is the function of Prolactin (PRL)?
Works with other hormones to stimulate mammary gland development and milk production
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What is PRL stimulated and inhibited by?
- Released in response to several prolactin-releasing factors
- Inhibited by prolactin-inhibiting hormone (PIH)
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What are the two hormones released by the posterior pituitary gland?
- Antidiuretic hormone (ADH)
- Oxytocin (OXT)
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ADH is also known as what?
arginine vasopressin (AVP)
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What is the function of ADH?
- Primary function is to decrease water lost from kidney
- Also causes vasoconstriction
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What causes the release of ADH and what inhibits it?
- Released in response to a variety of stimuli, Primarily increased solute concentration of blood (sensed by osmoreceptors), or a decrease in blood pressure or volume
- Inhibited by increase in extracellular fluid volume, Also inhibited by alcohol
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When is the release of Oxytocin (OXT) increased?
- Childbirth
- Nursing (suckling)
- Sexual arousal (function unknown)
- Sensory input (neuroendocrine reflex)
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OXT stimulates the contraction of what?
- Smooth muscle walls of uterus
- Mammary gland myoepithelial cells, releasing milk
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