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How does the Hypothalamus control endocrine function?
- Receives sensory input from various organ systems
- Directs pituitary gland secretion of various "releasing hormones"
- Pituitary gland stimulates hormone secretion from the major endocrine organs of the body
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What hormones is the pancreas associated with?
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What hormones are the Parathyroid glands associated with?
Parathyroid hormone
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What hormones are the adrenal glands associated with?
- Cortisol
- Aldosterone
- Epinephrine
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What hormones is the Thyroid gland associated with?
Tri-iodothyronine-T3, Thyroxine - T4, calcitonin
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What hormones are the gonads associated with?
- Estrogen, progesterone
- Testosterone
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How does the basic endrocine signaling system work?
- Regulated secretion of hormones
- Diffusion of hormones through the systemic circulation
- Diffusion of hormones out of the vasculature, to the target cell
- Binding to specific hormone receptor on cell
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Most endocrine system utilize what feedback?
Negative feedback loop
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What is physiologic response-driven feedback?
Hormone production is inhibited by change in physiologic parameter
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What are some examples of a physiologic response-driven feedback?
- Blood glucose
- Blood Ca2+
- Blood osmolarity
- Blood Na+, K+, H+
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How does endocrine axis-driven feedback work?
- Hypothalamus secretes releasing hormones
- Releasing hormones stimulates secretion of tropic hormones (from pituitary glands)
- Tropic hormones stimulate release of hormones from peripheral endocrine glands
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Neural input provides stimulus for secretion of:
hypothalamic-releasing hormones
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Daily rhythm of hormone release occurs due to input from the:
Suprachiasmatic nucleus
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What does the Pineal gland do?
Secretes melatonin in cyclical fashion to inform the system of the light-dark cycle
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Systemic and psychological stress also stimulates what?
Endocrine system
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What are the three types of hormones released?
- Proteins & polypeptides
- Steroids
- Tyrosine derivatives - amines
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What three things does the hormone type determine?
- Mode of transport
- Binding to target cell
- Action on target cells
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Protein/peptide and amine hormones are produced and stored where?
in intracellular vesicles
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Steroid/thyroid hormones are produced from what?
Cholesterol
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Steroid/thyroid hormones circulate how?
Bound to plasma protein
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What do protein-bound hormones allow for?
- Provides a reservoir of circulating hormones
- Increases the half-life of hormones
- Controls movement of hormones into target cells
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Binding of cell membrane receptors (proteins, peptides, catecholamines) activates what?
Intracellular 2nd messenger system that stimulates target cells
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Binding to intracellular receptors (steroid hormones) activates what?
Binds to DNA and stimulate/repress transcription
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Binding to nuclear receptors (thyrod hormones) affects what?
Directly affects gene transcription to promote metabolic activity of cells
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Thyrotropin releasing hormone (TRH) stimulates what?
Release of TSH
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Gonadotropin releasing hormone (GnRH) stimulates what?
release of FSH/LH
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Corticotropin-releasing hormone (CRH) stimulates what?
release of ACTH
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Growth hormone-releasing hormone (GHRH) stimulates what?
Release of GH
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Where is Oxytocin released from?
- paraventricular nucleus of hte hypothalamus
- -Stimulates breast duct contraction (milk ejection)
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Where is ADH released from?
supra-optic nucleus of the hypothalamus
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What are some facts about the anterior pituitary (adenohypophysis)?
- Contains a collection of tropic hormone-releasing cells
- Each hormine is secreted by only one type of cell
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What are some facts about hte posterior pituitary (neurohpophysis)?
- Distal continuation of the hypothalamus; modified neurons
- Nuclei of the hypothalamus secrete hormone and sore them in axon terminals of the posterior pituitary
- Hormones are released upon appropriate stimulation
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Name the 6 pituitary hormones
- ACTH - adrenocorticotropic hormone
- TSH - thyrod-stimulating hormone
- FSH - follicle-stimulating hormone
- LH - Leutenizing hormone
- GH - growth hormone
- PRL - prolactin
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What do somatotropes do?
Release GH
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What do cotricotropes do?
Release ACTH to stimulate release of adrenal hormones
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What do thyrotrops do?
Release TSH to stimulate release of thyroid hormones (T3/T4)
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What do gonadotrops do?
Release FSH and LH to stimulate sex steroid release from gonads
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What do lactotropes do?
Release PRL to stimulate milk production
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