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The Pituitary Gland (HYPOPHYSIS) has 2 parts, posterior and anterior, what are the names?
- neurohypophysis: Posterior Pituitary Gland
- Adenohypophysis: Anterior Pituitary Gland
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Melatonin is produced by the PINEAL GLAND: It causes?
- Mild sedative effect
- Dark exposure increases secretion of Melatonin
- Light exposure supresses secretion of melatonin
- At high enough doses can inhibit the Reproductive gonadal systems in males and females
- Levels of melatonin in blood of prepubertal children drop markedly just before the onset of puberty
- Involved with Circadian Rhythims
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HYPOTHALAMUS:
PITUITARY GLAND
PINEAL GLAND
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HYPOPHYSIS:
Posterior Pituitary Gland
Anterior Pituitary Gland
- PostPit: Oxytocin, Vasopressin
- AntPit: FSH,LH,PRL,Opiods
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The Anterior Pituitary is made up of?
- Pars Distalis (MAIN)
- pars intermedia
- pars tuberalis
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Neurosecretory neurons:
- -lie in hypothalamus
- -axons extend into posterior pituitary gland
- -synthesize large amounts of neurohormones in the cell bodies
- -neurohormones packaged into large granules and released into spaces adjacent to axon ending
- -include OXYTOCIN and VASOPRESSIN
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Effects of Oxytocin secreted by Posterior Pituitary Gland:
- -stimulates contractile cells of mammary glands so that milk can eject from nipples
- -Causes smooth muscle in uterus to contract to facilitate labor and childbirth
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effects of Vasopressin secreted by Posterior Pituitary gland:
- -Causes kidneys to retain water
- -Causes blood vessels to contrsict and blood pressure to rise
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Anterior Pituitary Gland Produces:
GH, ACTH ,TSH ,PRL, OPIODS ,FSH ,LH
- -GH: growth hormone LARGE PROTEIN stimulates growth by supporting incorporation of amino acids into proteins
- -ACTH: adreno-corticotropin hormone POLYPEPTIDE HORMONE that stimulates adrenal gland to secrete steroid hormones
- -TSH: thyrotropin Stimulates thyroid hormone to secrete thyroid hormones
- -PRL:Prolactin Supports mammary glands to become functional and secrete milk
- -OPIODS: natural pain killers
- -FSH: Follicular stimulating hormone STIMULATES ovaries to produce mature germ cells, estrogen, and stimulates testes to produce sperm
- -LH: Luteinizing Hormone STIMULATES ovaries to secrete female ssex hormones (progesterones and estrogens), induces egg release from ovary, and stimulates intersititial cells int he testes to synthesize and secrete androgens
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Hypothalamic-Anterior Pituitary Connection:
-NEUROHORMONES are released at median eminence in Hypothalamus and transported to pars distalis of anterior pituitaryvia the hypothalamo-hypophysial portal vascular system.
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RH: releasing hormone
RIH : release inhibiting hormone
INCREASES output of specific adenohypophysial hormone
DECREASES output of specific adenohypophysial hormone
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RH HORMONHYPOTHALAMUS:
GnRH
PRH
- INCREASES release of FSH and LH from adenohypophysis
- INCREASES release of prolactin from adenohypophysis
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PROLACTIN:
- -Estrogen increases the response of prolactin secreting cells in anterior pituitary
- -Prolactin supports milk synthesis in the mammary glands
- -Abnormally high levels of prolactin associated with certain types of infertility
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when estrogen and progesterone rise above the set point:
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NEGATIVE AND POSITIVE FEEDBACK IN PITUITARY FUNCTION:
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When Estrogen and Progesterone Levels are below the set point:
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ESTROGEN
>>WAY GREATER THAN SET POINT
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SUMMARY OF ESTROGEN LEVELS
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GONAD GLYCOPROTEIN HORMONES:
- GONADS release glycoprotein hormones that influence Gonadotropin secretion
- (INHIBIN) acts on pituitary to supress the secretion of FSH
- (FOLLISTATIN) binds to actifvin and blocks its action
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