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16 Cards in this Set
- Front
- Back
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Where is pineal gland located? Its also called ___?
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located in dienchephalon
aka epithalamus |
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What two cell types does it contain?
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Pinealocytes
Glial cells |
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What are pinealocytes-- generally
sensitive to what? |
neurons, arranged in clusters
sensitive to light and receive SNS innervation |
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Glial cells of pineal
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similar to pituicytes, fcn as supportive stromal cells
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What is brain sand
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calcium rich particles that accumulate in pineal gland with age
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What does pinealocyte convert?
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its a neuroendocrine transducer-- converts neuronal input (light/lack of light) into endocrine output
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What else does pinealocyte contain? and its classified as what?
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brain peptides
classified as an APUD cell |
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In pineal, light controls the production of which two biogenic amines?
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Serotonin
Melatonin (specific to pineal) |
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Neuronal pathway of light transduction
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Stimulus from retinal ganglion cells-->suprachiasmatic nucleus of HT-->via pineal nerve to SC (IML column)-->via sympathetic preganglionics to Superior cervical ganglion-->pinealocyte
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What does pinealocyte do under influence of light?
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produces serotonin
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What does pinealocyte do in absence of light?
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Serotonin is converted to melatonin:
Serotonin-->N-acetyl serotonin via N-acetyl transferase N-acetyl serotonin-->melatonin via hydroxyindole-o-methyl transferase so serotonin by day, melatonin by night |
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Two types of pineal-driven rhythms?
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circadian (24 cycle)
ultradian (occur monthly/seasonally/ or annually) |
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What things does circadian rhythm control?
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Body temp
WBC count Mitotic activity in epithelia Secretion of ACTH and cortisol Resonsiveness to drugs |
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Two types of ultradian rhythms
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lunar (eg, mentrual)
seasonal (eg, animal breeding cycles) |
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Melatonin function
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major impact is inhibitory--
its antigonadotropic (LH/FSH): prevents onset of puberty controls onset of gonadal activity in seasonal breeders also, regulates secretion of anterior and posterior lobe hormones in pituitary |
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What evidence is there that humans (depending on where they live) may tend toward seasonal breeding?
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-test and LH levels increase in spring (USA)
-contraception rates incr in spring months (England) -this effect not seen presently, because of contraception, diet, fertility? |
