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26 Cards in this Set
- Front
- Back
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What are the 4 major fiber tracts of hypothalamus |
Fornix: hippocampus to mammillary nucleus, also to septal areas and medial basal hypothal Mammillothalamic tract: from anterior nuclear group to thalamus Stria Terminalis: an afferent pathway to hypothalamus from amygdala medial forebrain bundle: fibers from monoamine cell groups in brainstem, descending fibers from olfactory cortex to hypothalamus Mostly bidirectional |
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Efferent pathways |
Projections to cortex to mamillary bodies to brainstem - regulate sleep |
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Retinohypothalamic Tract |
Unidirectional tract originates from retinal ganglion cells comes through optic nerve, ends in SCN sends light signals to SCN to entrain biological rhythms |
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Hypothalamo-hypophysial tract |
Direct neuronal connection from hypothalamus to posterior pituitary originate in Supraoptic + paraventricular n. -magnocellular neurons Release oxytocin and vasopressin directly into the bloodstream |
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Vasopressin (ADH) |
Causes kidneys to conserve water when body is dehydrated increases blood pressure by promoting vasoconstriction CNS effects include effects on social interactions (pair bonding). projections to forebrain |
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Oxytocin |
Stimulates uterine contractions promotes lactation CNS effects include promotion of sexual and maternal behaviors -due to local release of hormones, not reentry of hormones from periphery |
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Two Types of neurohormones in the pituitary |
1. releasing/inhibiting factors (made in hypothalamus released from median eminence) that control hormone release by the anterior pituitary 2. Posterior pituitary neurohormones (made in hypothalamus, released from posterior pituitary) control functions in periphery |
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Thirst response |
Nuclei: SON, PVN. To : posterior pituitary, directly into blood stream Stimuli: dehydration/salt ingestion > high blood osmolality Sensed by: osmoreceptors Posterior pituitary: increase ADH also leads to thirst |
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Thermoregulation |
Defend against cold: heat production - shivering, increase metabolic activity heat conservation - vasoconstriction defend against hot: heat loss - sweating, vasodilation, panting Behavioral changes - change environment |
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Hypotalamic nuclei involved in temperature regulation |
Anterior hypothalamus/preoptic area - promote heat loss -median preoptic nucleus - promotes vasodilation Posterior lateral hypothalamus - implicated in heat conversation, via vasoconstriction these areas sense temperature |
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What are body processes the change body thermal mass (body temperature) |
Skin blood flow sweat rate shivering (exercise and environment are external processes) |
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Thermoneutral zone |
A range of temperatures (homeostatic range) between an upper and lower threshold between which we don't notice changes Above upper threshold, sweating occurs below threshold, shivering occurs |
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What causes hot flashes |
perimenopausal woman, have a smaller thermoneutral zone Estrogen loss shrinks the thermoneutral zone |
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What increases the temperature set point? |
Fever onset of fever - triggers shivering and vasoconstriction to conserve heat when fever breaks - triggers sweating and vasodilation to dissipate heat |
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Hypothalamic nuclei involved in feeding |
Ventromedial n. Lateral hypothalamus arcuate n. paraventricular n |
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Short term satiety signal comes from |
CCK |
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Long term satiety signal comes from |
Insulin from pancrea and Leptin from fat |
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Neurons of the Arcuate nucleus |
NPY neurons: activated by ghrelin -activation leads to increase food intake POMC neurons: activated by insulin, leptin -activation leads to decrease food intake the two neurons inhibit eachother |
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Hypothalamic nucleus involved in the regulation of biological rhythms: |
suprachiasmatic nucleus Light trains SCN to be on a schedule |
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Examples of biological functions that have daily rhythms |
Core body temperature Level of melatonin urine production cortex activity + alertness sleep/wake cycle |
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What occurs in constant dark condition? |
Free-running rhythms There is a drift, because clocks are not exact. Need to entrain with light |
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Where does SCN project? |
Dorsal Medial Hypothalamus -- will then integrate signals and spread information throughout brain -projects to lateral hypothalamus PVN |
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What cells from retina project to SCN? |
ipRGC Non-image forming retinal ganglion cells (separate from image forming ganglion cells) |
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Hypothalamic nuclei involved in sexual behaviors and reproduction |
Ventromedial n. Preoptic area |
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Hypothalamic nuclei involved in stress response |
Paraventricular nucleus |
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Parvocellular cells and the anterior pituitary |
cortex senses stress > PVN Parvocellular cells in paraventricular nuclei release CRH to the anterior pituitary, stimulating the release of ACTH >> work on adrenals corticosteroids go to body to trigger flight response negative feedback on brain |
