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Lecture 20

Lecture 20 - Hypothalamus & Limbic System

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Michelle French

L20 Oct 28 11 Maintenance of a stable internal body envt HypothalamusLimbic Systemcontrollermilieu intrieurprogrammer of autonomic fns product of many specific physiological control circuitsMicturitionurinationve fdbk loops Voiding bladder reflexprogrammed control hypothalmajor coordinator of homeostaticPara sacral reflex driven by bladder wall stretch controlreceptors Many levels of controlHomeostasis Pontine centers organize Hypothalamusmajor regulator of core 1Seq of relaxation of external sphincter parameters ex plasma glucose osmolality temp musclepelvic floor musclesgood since much blood around face pit hypothal sensors located wi hypothal to detect 2Continence prevents micturitionmost of changes in thesetime corrective actions initiated involving entirePAG zone selects continencemicturitionautonomic ns endocrine somatomotor exHypothal medial preoptic n amygdalareticulospinovolitional control mechslimbic frontal lobe influence PAGDetermine context of when appropriate to Hypothalamusurinate Interacts w brainstem motorautonomic centers via axonal projections usually by PAG interacts w endocrine system via pituitary body can coordinate complete physiological response to challenges to internal envtcan coordinate simultaneously in parallel systems Para efferents to bladder originate in Pituitary Bodyintermediolateral region in grey matter sameprovides an interface btwn CNSendocrine relative position of sym efferents in thoracic but not systemmany protuberants congregate in that region butnot used muchdont make a lateral horn project to bladder2 modes to communicate w hypothalmuscles cause contraction 1 axonal projections into posterior pituitarySomatic nuc under volitional control Onuf direct release of hormone from terminals into controlling external spincter all motor nuc in bloodstreamventral horn when contracts prevents urination Hormones released same way as blocks urethra must inhibit those motoneurons neurotransmitter thru bloodstream to to get mitrition need to activate set of inhibitory specific distant body parts ex ADHinterneurons in spinal cord to urinate 2 releasing hormone intermediary carried toIn ponspituitary in portal system eg CRH part of Continence centreactivates nuc of circulatory systemOnuf to prevent urinationMore common methodMicturition centreBarringtonsNeurons in hypothal go to base of hypothalprogrammingdriving urination processsecrete an intermediary releasing hormone Antagonizing centres one active at a timepicked up at capillaries at based of hypothal signals sent up in spinoreticulothalamicinfo carried short distance to pituitarytrigger about bladder state lots of info going to pontine level ndrelease of 2 hormone into bloodstreamPAGhigher up ex limbic in autonomicex CRHdetermines correct context for when turn on mitrition vs contincenceHomeostasis definition
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