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84 Cards in this Set
- Front
- Back
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What is the hypothalamus a division of?
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The diencephalon
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What is the function of the hypothalamus?
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To maintain homeostasis by controlling three important systems
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What are the 3 systems controlled by the Hypothalamus?
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1. ANS
2. Endocrine system 3. Limbic system |
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How is the hypothalamus related to the 3rd ventricle?
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It forms the walls and floor of the third ventricle.
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What separates the hypothalamus from the overlying thalamus?
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The hypothalamic sulcus
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What is situated anterior to the hypothalamus?
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The optic chiasm and lamina terminalis
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What is situated posterior to the hypothalamus?
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The mamillary bodies
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What makes the lateral borders of the hypothalamus?
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The optic tracts
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What makes the medial order of the hypothalamus?
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The third ventricle
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Where is the hypothalamus visible from?
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Only from a ventral view
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What 4 structures can be seen from a ventral view?
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-optic chiasm
-Infundibulum -Tuber cinereum -Mammillary bodies |
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What is the infundibulum?
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The stalk of the pituitary
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What is contained in the infundibulum?
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-Portal vessels
-Important tracts connecting the hypothal to posterior pituitary |
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What is another name for the posterior pituitary?
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Neurohypophysis
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What is the anterior portion of the infundibulum called?
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The median eminence - it slightly protrudes
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What is housed within the median eminence?
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It houses hypothalamic peptidergic neurons which release regulatory factors carried by portal vessels to the anterior pituitary.
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What is another name for the anterior pituitary?
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Adenohypophysis
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What is the Tuber Cinereum?
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A bulge between the optic chiasm and mammillary bodies.
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What are the mammillary bodies part of?
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The limbic system (Papez circuit)
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What gives the highly vascularized supply to the hypothalamus?
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The circle of willis
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3 divisions of the hypothalamus:
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-Lateral
-Medial -Periventricular |
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What 2 structures separate the medial from lateral zones?
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1. Mammillothalamic tracts
2. Fornix |
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Is there a distinct division between the thin periventricular zone and medial areas?
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No
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What does the periventricular zone surround?
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The third ventricle
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What are the lateral zones comprised of?
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Loosely arranged neuronal cell groups
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What traverses the lateral zones?
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Fibers of the medial forebrain bundle
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What are the 3 major nuclei in the lateral zones?
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1. Lateral Preoptic nucleus
2. Lateral Hypothalamic Area 3. Lateral Tuberal Nucleus |
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What is the lateral preoptic nucleus derived from?
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The telencephalon
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What is the function of the Lateral Hypothalamic Area?
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It induces eating when stimulated - so you GROW LATERALLY
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What is the result of ablation of the lateral hypothalamic area?
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Anorexia and starvation
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What do neurons in the Lateral Tuberal Nucleus release? To where?
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Histamine - to widespread portions of the forebrain.
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What is the release of histamine by the Lateral Tuberal Nucleus a function of?
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Attention and arousal processes
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What do these lateral nuclei look like in general? Why?
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Speckled - because they're loosely arranged and are traversed by the medial forebrain bundle.
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What are the 4 anatomic regions of the Medial Hypothalamic Zone (from front to back)?
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1. Preoptic area
2. Supraoptic area 3. Tuberal area 4. Mammillary area |
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What is the preoptic area?
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The anterior telencephalic portion of the hypothalamus
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What nucleus is in the preoptic area? What type of neurons does it house?
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The Medial Preoptic Nucleus - contains parvocellular neuron cell bodies that send hormones to the anterior pituitary!
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What is INAH1-4?
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Interstitial cells housed in the anterior preoptic area that are sexually dimorphic.
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What regulates the development of INAH1-4 Interstitial cells?
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Testosterone - so this area is bigger in men.
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What exact hormones are sent from the Medial Preoptic Nucleus to stimulate the ant pituitary?
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GnRH - gonadotropin releasing hormones!!
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4 nuclei in the Supraoptic Area of the Medial Zone:
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1. Suprachiasmatic nucleus
2. Anterior Hypothalamic nucleus 3. Paraventricular nucleus 4. Supraoptic nucleus |
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Where is the Suprachiasmatic nucleus located?
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Just dorsal to the optic chiasm
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What gives direct input to the Suprachiasmatic nucleus?
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The retina
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What does the Suprachiasmatic nucleus play a critical role in?
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Control of Circadian Rhythmicity
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Where does the Anterior Hypothalamic nucleus lie?
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Just above the suprachiasmatic nucleus, and just below the PVN
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What is the Anterior Hypothalamic nucleus involved in?
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-Temperature regulation - it dissipates heat - COOLING
-Stimulatory drive of the ParaNS |
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Bilateral lesions of the Anterior hypothalamic nuclei result in:
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Hyperthermia
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What lies overtop the anterior hypothalamic nucleus?
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The PVN - paraventricular nucleus
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Why is the PVN important?
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Because it houses Magnocellular cell bodies of neurons that make and release oxytocin and ADH in the posterior pituitary
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What hormone other than ADH and Oxytocin is made in the PVN?
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CRH - corticotropin releasing hormone
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Where do non-pituitary related neurons in the PVN project?
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To the intermediolateral cell column of the SC from T1-L2
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What do the non-pituitary related neurons in the PVN do?
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Excite the sympathetic preganglionic neurons.
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Where is the Supraoptic Nucleus found?
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Just behind the suprachiasmatic nucleus (under the anterior)
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What do the neurons in the supraoptic nucleus do?
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Make/release Oxytocin and ADH
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What are the 3 important nuclei in the Tuberal (middle) area of the medial hypothalamic zone?
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-Dorsomedial nucleus
-Ventromedial nucleus -Arcuate nucleus |
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What happens when the Dorsomedial nucleus is stimulated?
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Agression and savage behavior
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What happens when the Ventromedial nucleus is stimulated?
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It inhibits the urge to eat
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So what is the Lateral Hypothalamic nucleus? What is the Ventromedial nucleus?
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Lateral = hunger center
Ventromedial = satiety |
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What does bilateral destruction of the Ventromedial nuclei cause?
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Hyperphagia and savage behavior
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Where is the arcuate nucleus located?
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In the tuber cinereum
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What is the Arcuate nucleus involved in controlling?
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The release of various anterior pituitary hormones
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What does the Arcuate nucleus play a prominent role in?
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Feeding behavior
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2 important nuclei in the Mammillary area of the medial hypothalamic zone:
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-Posterior nucleus
-Mammillary bodies |
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What is the Posterior nucleus important for?
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Thermoregulation - heat conservation and production.
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What does a bilateral lesion of the posterior hypothalamic nucleus result in? Why?
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Inability to thermoregulate at all - NOT hypothermia; because the anterior hypothalamic nucleus projects through here too.
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What is the inability to thermoregulate called?
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Poikilothermia
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What is the mammillary nucleus a component of?
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The limbic papez circuit
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What do neurons in the Mammillary nuclei recieve input from?
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The hippocampus via the fornix
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Where do the mammillary nuclei project to?
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The anterior thalamus via the mammillothalamic tract
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What will damage to the mammillary nuclei cause?
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Learning and memory deficits
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What nucleus is in the periventricular zone?
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The periventricular nucleus
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What is the periventricular one really?
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Just the layer of cells lining the wall of the third ventricle
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How many major fiber tracts run through the hypothalamus?
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Seven
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What are the major fiber tracts in the hypothalamus?
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1. Fornix
2. Mammillothalamic tracts 3. Stria terminalis 4. Medial forebrain bundle 5. Supraopticohypophyseal tract 6. Tuberoinfundibular tract 7. Hypothalamospinal tract |
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What is the fornix?
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The tract that carries input from the hippocampus to the mammillary bodies
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What is the Mammillothalamic tract?
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The projection from the mammillary bodies to the anterior thalamus - Key in the Papez circuit
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What is the Stria terminalis?
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The pathway that connects the amygdala to the medial zone of the hypothalamus
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What is the Medial forebrain Bundle?
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The MOST COMPLEX FIBER PATHWAY IN THE ENTIRE CNS!!!
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How many distinct constituent parts are within the medial forebrain bundle?
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At least 50
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Where does the Medial Forebrain Bundle pass thru the hypothalamus?
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Thru the lateral zone
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What does the medial forebrain bundle connect (rostral->caudal)
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The septal area nuclei to the brainstem.
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What is the Supraopticohypophyseal tract?
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The fibers that pass from the supraoptic SON and PVN to the posterior pituitary.
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What is the Tuberoinfundibular tract?
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The fibers that go from the arcuate nucleus to the portal system in the medial eminence (to go to anterior pituitary)
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What is the Hypothalamospinal tract?
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The axons that go from the hypothalamus to the spinal cord to drive both the SNS and PNS
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finish
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k
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