HMB200 2014 Exam Summary Notes.pdf

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Human Biology
John Yeomans

Lecture 13 HypothalamusFeeding and Obesityhypothalamus is the main area for food intake control o before during after eatingFeeding centers Lateral hypothalamus LH Paraventricular Hypothalamus PVN Ventromedial Hypothalamus VMHBody weight influenced by fat storageinfluenced by leptin receptors o Leptin can be used to control body weightobese humans lots of fat cellshigh leptin levelsnormal level of leptin receptors o hypothalamic set point has changed o obesity due to leptin insensitivity lack of leptin receptorsFeeding LH and PVN o PVN gets input from Neuropeptide Y NPY and NE to increase feedingSatiety VMH o Serotonin decreases feeding o Want to lose weight Best way is to take serotoninobob and dbdbobob micemutation in leptin gene o fat cells cannot induce production of leptino leptin tells the brain that the animal has eatendbdb micemutation in leptin receptor gene o injecting leptin will not cureno receptors for it anywaysleptin receptors in arcuate nucleus and lateral hypothalamusboth mutations have the same symptoms obsess brain think its starvinglook for high energy food and rapid eating o when the brain thinks you are starvingshuts down body functionsenergy expenditure decreases temperature decreases reproductive hormones decrease interest decrease depressionShortTerm Feeding Signalsstomach ghrelin distention vomiting o ghrelin stomach shrunkhungryghrelin is released from walls of stomach to activate NPY neurons in the hypothalamic feeding centersfeeding induced o neural distension signal eat too much Stretch receptors on walls of stomach is activatedstop eating o vomiting eat too much Or presence of poisons VomitIntestines pancreas gall bladder hormones insulin CCK PYY336 o Insulin from the pituitary glandactivates POMCCART neurons to inhibit feeding o CCK from the GI system to stimulate digestion of fat and proteins o Ghrelin from the stomach to inhibit feeding o PYY336 from intestines to inhibit AgRPNPY which stimulates feedinginhibit feedingCritical Areas located above the pituitary arcuate nucleus highest expression of leptin receptors o 2 types of neurons project to the LH and PVN POMCCART and AgRPNPY o POMCCART inhibits feedingActivated by leptin insulin o AgRPNPY stimulates feedingActivated by ghrelinInhibited by no feeding PYY leptin insulinAgRPNeuropeptide Y powerful feeding stimulator o Made by arcuate nucleus neurons o NPY goes to LH neurons and PVN neuronsactivation of feedingLecture 14 Sex and Gender Part ISRY gene Sex Determining Region of the Y ChromosomeSingle gene results in production of testosterone in the male gonad o expression of SRY gene produces testosteronecauses male gonad to go from an undifferentiated state to differentiated o shape of gonad is altered because of SRY expressionMale gonads produce 2 hormones testosterone and AMH antimummarian hormoneresult of the SRY geneTestosterone In the BrainMALES testosterone goes to the braingets converted into estrogen by aromatasecan now act on estrogen receptorsbrain changessecondary sex characteristicso Testosterone is the most important androgen for inducing male sexual motivationFEMALES estrogen is bound by alpha feto protein in the peripherycannot get into braindoes not bind estrogen receptors in brain SDNsexually dimorphic nucleus in the preoptic area POA is changed by the arrival of testosteroneo testosterone gets converted into estrogen in the brainact on estrodial receptorscells multiplyMALES darker SDNresult of testosterone converting to estrogenbrain differentiationSDN triggers the on set of puberty AND production of hormones in the hypothalamusPrimary sex characteristics driven by SRY gonadal changes reproductive organsSecondary sex characteristics driven by hypothalamic nucleihormones changes in SDN breasts facial hair sexual behavior cognitive differencesSDN and BNST are sexually dimorphicnd2 Nervous System ChangeTestosterone in the brain changes spinal cord in malesin the spinal cord development of motor neurons bulbocarvernosus SNBOnufs nucleus is important in the sexual response for males o bulbocarvernosis muscle in the penisin the male rat changes in lumbal spinal cordEstrogen Receptors main receptors located at the basal part of the forebraintells you which areas are sexually dimorphicthe hypothalamus is most important for its connections between the mPOA and the pituitarymainly found ino medial hypothalamus o medial preoptic area mPOAtriggers puberty and sex interest o pituitaryalso found ino accessory olfactory bulb to the medial amygdalapheromonesfemale sexual response system smells males o projections from the amygdala to the BNSTgender identity and maternal behavioro periaqueductal greylordosis and analgesiasexual arousal activation pheromonesaccessory olfactory bulbmedial amygdalaBNSTinformation relayed to hypothalamus amydgalabed nucleuspreoptic pathwayEndocrinology oxytocin milk let down reflex AND can ascend and go into the amygdala and forebrain o makes mother feel bonded to childoxytocin receptors found in hypothalamus hippocampus amygdalainfluence social bondinglack of oxytocin Autismvasopressin is important for pair bonding in mice
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