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17 Cards in this Set
- Front
- Back
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Cryptocrine
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a term devised to indicate that a hormone can have an effect within its own cell of production (hidden)
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Name the classic endocrine glands
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Gonads, pancreas, adrenals, thyroid, parathyroids, pituitary
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Identify more recently identified endocrine glands
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Kidneys, heart/blood, liver, brain, fat (adipose) tissue, placenta
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Name the three types of hormone
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protein/polypeptide hormones, steroid hormones, miscellaneous
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What is the pro-hormone of adrenocorticotrophic hormone (ACTH)?
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Pro-opiomelanocortin (POMC)
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Where is POMC produced and by what cells?
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Anterior pituitary gland by corticotroph cells
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Where in the cell is POMC converted to ACTH?
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Golgi apparatus
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How is ACTH released (stored or continuous)?
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Stored in vesicles and released with a stress signal (exocytosis)
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How is cholesterol transported to the adrenal cortical cells for the production of steroid hormones?
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via low density lipoproteins (LDL) as fatty acid esters, a stress stimulus drives breakdown of these esters using esterase to liberate cholesterol
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What is the rate limiting step in steroid production?
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StAR protein is used to transport cholesterol into the mitochondria where the steroid is produced (e.g. cortisol)
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How are steroid hormones released (stored or continuous)?
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Production is stimulated by a signal (e.g. stress for cortisol), but once produced the steroid diffuses across the plasma membrane and into the blood circulation.
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How are steroid hormones transported in the blood?
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On plasma proteins which can either be low affinity-high capacity (e.g. albumin), or high affinity-low capacity (e.g. GBG is a gonadal steroid binding globulin)?
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How are the levels of biologically active free steroid hormones in the blood maintained?
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Proportion of free biologically active hormone and inactive bound hormone form an equilibrium. Production of the steroid hormone can be up-regulated or down-regulated to maintain this equilibrium.
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Describe how ACTH affects its target tissues.
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Binds to ACTH G-protein linked receptor --> dissociation of G-protein activates adenylate cyclase --> cAMP --> protein kinase A --> increased StAR protein activity --> increased cortisol synthesis
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Describe how steroid hormones affect their target tissues.
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Free steroid hormones can diffuse across plasma membrane to bind to an intracellular receptor. This complex is translocated to the nucleus where it modifies protein transcription of a new protein.
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Describe how ACTH and cortisol are in a negative feedback loop
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Stress +ve ACTH
ACTH +ve cortisol cortisol -VE ACTH |
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What is the pituitary gland's alternate name and where is it located within the brain?
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aka the HYPOPHYSIS - lies at the base of the brain in the SELLA TURCICA directly under the HYPOTHALAMUS
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