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39 Cards in this Set
- Front
- Back
Hypothalamus
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• Region of lower brain, base of the diencephalon
• Integrates nervous and endocrine systems |
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Inputs to hypothalamus from CNS
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Solitary
tract –baroreceptors; olphactory Locus coeruleus; Stress; Ventrolateral medulla Stress |
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hypothalamus
and pituitary |
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The hypothalamic-‐hypohyseal portal system
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• Directs trophic hormone delivery to the anterior pituitary
- only need a small amount of trophic hormones to get a big effect - blood flow here is slow thus small amount persists for a long time and not much is needed |
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Anterior Pituitary Hormones
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Growth
hormone |
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GH pathway
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acromegaly
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GnRH Pathway
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Prolactin Pathway
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Oestrogen increases number of prolacJn secreJng cells during pregnancy (BUT THEY ARE STILL NOT SECRETING PRL AT THIS POINT)
PIH suppresses ProlacJn release. PIH falls towards end of pregnancy, prolacJn rises Following birth oestrogen and progesterone levels fall, suckling sJmulates prolacJn release and secreJon of milk (LOSE THE PLACENTA THUS NO MORE INHIBITION BY E AND PG ANYMORE) |
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the only 2 hormones that also have inhibitory hormones from the hypothalamus
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1. Prolactin
2. GH |
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What else does prolactin suppress?
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- SUPPRESSES GnRH
- nursing one child u dont want more children - thus some cultures have a child at the breast for 5years to avoid fertility |
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HyperprolacJnaemia
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•ProlacJnoma
•Galactorrhea •Functional gonadotrophin deficiency Women = menstrual disturbance, infertility Men = erectile dysfunction, diminished libido |
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Endocrine regulation of reproductive physiology
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Endocrine regulation of male reproductive physiology
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External Influences on GnRH
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1. daily rhythms (peaks at midnight and 6am); night time penile eminence, wake up with an erection
2. annual rhythms: greater in winter, in the short day periods (EXPERIMENT WITH BEARD HAIR AND WRIGHT IN WINTER vs SUMMER) - PULSTILE RELEASE IS V>IMPORTNAT (experiment where they used high levels and nothing happenedn until they used it pulsitilty |
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LH has a direct negative feedback on GnRH
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True
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Menstrual Cycle
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Early Follicular phase
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- recuirt many follicles and then the dominant follicle takes over and the rest die (atresia)
- autocrine manner INC. # of granulosa cells - so high E with low FSH and LH due to negative feedback |
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Late follicular phase/ovulaJon
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marked sens. of hypothalamus to E, desensitised and now the E is a +ve feedback and so u get a surge of GnRH and so get a peak in LH
- LH drives ovulation i.e occyte realease, then picked up in the infundibulum |
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Luteal Phase
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suppression now with levels even lower than those in the normal early follicular phase
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Late Luteal phase/menses
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Oxytocin
and vasopressin (aka ADH) |
nonapeptides; varying by just one a.a
- both are synthesised as prohormones |
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Oxytocin Protein Structure
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Neurohypophysisis
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Oxytocin and parturition
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plasma oxytocin in the mother during labour
- most powerful contraction agent - also useful for placental ejection and stopping the bleeding -stimulates partuition - once the babies head stimulates the cervix and the process starts over |
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Oxytocin and parturition pathway
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Clinical Implications of Oxytocin during pregnancy
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- Syntocinon: used to induce labour and eject placenta
- Atosiban: OTA prevents premature birth |
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Oxytocin and lactation – let‐down reflex.
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Myoepithelial cells
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contractile and express oxytoxin receptor
- mammary lobule |
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Oxytocin During Suckling
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In-vivo bursts of supraoptic oxytocin neurons during suckling
- everytime the baby suckles, the release of oxytocin is immediate |
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Non-‐classical ac;ons of oxytocin
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- sexual arousal; the hormone of love (plays a major role in love in mena nd women but in men it also plays a major role in ejaculation). ALSO important for maternal bonding
- social dysfunction- Autism spectrum disorder (inability to respond to facial expressions and visual cues) - Schizophrenia - CV function: dec. BP |
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Water reabsorption in Kidney tubules
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Vasopressin (ADH)
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- more aquaporin-2 in the apical surface of the ducts
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Control of vasopressin secretion
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1. PLASMA OSMOLARITY: main driving force
2. Blood volume 3. BP |
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Clinical Implication of Vasopressin control
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Bedwetting: (vasopressin nasal spray
– desucopressin vasopressin is slighty higher during the night and it develops in children - diurnial rhythm of vasopressin can be used at night to avoid bed wetting (managed quite effectively) |
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Vasopressin and Ang II link
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Atrial Natriueritic Peptide
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Vaasopressin in Hypovolemic Shock
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- INC. vascular resistance
- restores BP |