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36 Cards in this Set
- Front
- Back
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Describe the "axis" concept of the pituitary
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The axis concept describes the series of feedback loops that endocrine sytem using to regulate hormone secretion
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What is the name given to the anterior lobe of the pituitary?
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adenohypophysis
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What does the adenohypophysis respond to in terms of endocrine secretion?
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responds to hypothalamic factors released into the blood from the hypothalamic nerve
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What is the name given to the posterior lobe of the pituitary?
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neurohypophysis
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What does the neurohypophysis respond to in terms of endocrine secretion?
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direct neural stimulation from the hypothalamus
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Name 6 hormones that are released by the hypothalamus that affect the secretion activity of the adenohypophysis
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-GnRH (gonadotropin releasing hormone)
-GIH (growth hormone release inhibiting hormone) -GHRH (growth hormone releasing hormone) -AVP (arginine vasopressin) -TRH (thyrotropin releasing hormone) -CRH (corticotropin-releasing hormone) |
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What does TRH do?
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thyrotropin releasing hormone stimulates the secretion of thyrotropin stimulating hormone
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What does GnRH do?
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Gonadotropin-releasing hormone stimulates the secretion of FSH and LH from gonadotrophs
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What does CRH do?
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corticotropin releasing hormone stimulates the release of ACTH, beta-lipotropin and beta-endorphins
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What does AVP do?
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arginine vasopressin helps CRH function to stimulate the release of ACTH
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What does GHRH do?
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growth hormone releasing hormone stimulates the release of growth hormone
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What does GIH do?
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growth hormone release inhibiting hormone inhibits the release of growth hormone
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Describe the c-terminal of the releasing hormone peptides
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contain an amino acid amide
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What makes TRH and GnRH different (in terms of structure) from the other releasing hormones?
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they contain a pyroglutamate
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Describe the chemical structure of AVP
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arginine vasopressin is a cyclic nonapeptide
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What is the function of AVP (other than aiding CRH)?
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arginine vasopressin is involved in water metabolism
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Name the 2 hormones that are released from the posterior pituitary
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AVP and oxytocin
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Describe the chemical structure of oxytocin
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cyclic nonapeptide
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What is the function of oxytocin?
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stimulates lactation and uterine contraction during delivery
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How are Growth Hormone and Prolactin similar?
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Both hormonal polypeptides about 190 amino acyl residues long
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Describe the mechanism of action of growth hormone
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it is a single-pass membrane receptor which dimerizes upon hormone binding. This binding stimulates a protein kinase cascade
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How are TSH, FSH, and LH similar?
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they are all glycoproteins and heterodimers consisting of an alpha and a beta subunit. The alpha subunits are all the same.
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How are TSH, FSH, and LH different?
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The beta subunits of the heterodimers are different
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What confers specificity of the glycoproteins hormones?
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the unique beta subunit
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Describe the receptors for LH, FSH, and TSH
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they are g-protein receptors (Gs) which stimulate the activity of adenylyl cyclase
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What is the target cell of growth hormone?
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all cells
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What is the target cell of prolactin?
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mammary cells
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What is the target cell of thyroid stimulating hormone?
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thyroid cells
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/What is the target cell of follicle-stimulating hormone?
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gonads
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What is the target cell of luteinizing hormone
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gonads
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What is the target cell of adrenocorticotropic hormone (ACTH)?
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adrenal gland cells
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What is the target cell of melanocyte-stimulating hormone?
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melanocytes
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What is the target cell of lipotropin?
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adipose (LIPOsuction takes out all the fat)
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What is the target cell of endotropins?
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CNS
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How are endotropins, lipotropins, ACTH and MSH similar?
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they are all derivatives of preopiomelanocortin (POMC)
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How are endotropins, lipotropins, ACTH, and MSH different?
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they are unique segments of the precursor POMC, so they differ in their cleavage sites resulting in different products.
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