Hypothalamus Flashcards
What are the anterior and postero-inferior borders of the hypothalamus?
The lamina terminalis borders the hypothalamus anteriorly.
The mammillary bodies mark the end of the hypothalamus posteriorly.
What is the blood supply of the hypothalamus?
Small perforating arteries from the circle of willis.
What is the sella turcica?
What is the tuber cinereum?
The bony identation of the anterior cranial fossa in which the pituitary gland sits.
A bulge of gray matter that sits posterior to the optic chiasm.
Lateral Preoptic Nucleus
Is it located anteriorly or posteriorly?
What is it derived from?
Lateral Preoptic Nucleus
Anterior (“preoptic”)
Derived from the telencephalon, unlike most of the hypothalamus.
Lateral Hypothalamic Nucleus
What functions does it regulate?
What happens when it is ablated?
Lateral Hypothalamic Nucleus
Feeding.
Ablation results in decreased appetite (anorexia).
Tuberomammilary Nucleus
What process does it regulate?
What is the chemical basis for this control?
Tuberomammillary Nucleus
Wakefullness and sleep.
The neurotransmitter is histamine.
Presumably, H1 blockers cause sedation due to effects here.
Medial Preoptic Nucleus
What process does it regulate?
Medial Preoptic Nucleus
Release of gonadotropins (GnRH), influencing the anterior pituitary to release FSH/LH.
Note: This structure is sexually dimorphic.
Suprachiasmatic Nucleus
What process does it regulate?
Suprachiasmatic Nucleus
Circadian rhythm. Note that it receives direct input from the retinas.
Anterior Hypothalamic Nucleus
What process does it regulate?
Anterior Hypothalamic Nucleus
Warmth regulation (ablation = hyperthermia).
Paraventricular Nucleus
What processes does it regulate?
Paraventricular Nucleus
- Release of vasopressin/oxytocin (magnocellular).
- Release of CRF (parvocellular).
- Regulation of ANS outflow (parvocellular).
Supraoptic Nucleus
What process does it regulate?
Supraoptic Nucleus
Release of vasopressin/oxytocin.
Note that like the magnocellular cells from the paraventricular nuclei, these nerves travel into the pituitary, and don’t rely on portal vessels.
Dorsomedial Nucleus
What process does it regulate?
Dorsomedial Nucleus
Blood pressure regulation, and maybe aggression.
Ventromedial Nucleus
What process does it regulate?
Ventromedial Nucleus
Feeding–but specifically satiety, unlike the lateral hypothalamic.
Arcuate Nucleus
What process does it regulate?
Arcuate Nucleus
Complex regulation of anterior pituitary.
Posterior Nucleus
What process does it regulate?
Posterior Nucleus
Cold sensation. Ablation results in poikilothermia.
Mammillary Body
What process does it regulate?
Mammillary Body
Since it is linked with the hippocampus as part of the Papez circuit, it is involved in memory and learning.
Describe the papez circuit, starting at the hippocampus and ending in the cingulate gyrus.
Hippocampus signals via the fornix to the mammilary bodies. These signal via the mammillothalamic tract to the anterior thalamic nuclei, and then to the cingulate gyrus.
What does the stria terminalis connect?
What is the medial forebrain bundle?
Stria terminalis connects the amygdala and hypothalamus.
Medial forebrain bundle is a fiber pathway common to many different signaling tracts.
Does the posterior pituitary involve the hypophyseal portal vessel system or the tuberoinfundibular tract?
What other pathway does it involve?
Posterior pituitary is signaled from higher structures via the tuberoinfundibular and supraopticohypophyseal tracts.
What is carried on the hypothalamospinal tract?
What can result from a lesion here?
Hypothalamospinal tract carries ANS efferents from the PVN to the spine.
Lesions can cause horner’s syndrome.
What processes are triggered by the hypothalamus to reduce temperature? To increase it?
Why does a bilateral lesion of the posterior hypothalamic nucleus cause poikilothermia rather than hypothermia?
Reduce temperature via sweating, panting, and cutaneous vasodilation. Incrase via shivering, thyroid upregulation, and cutaneous vasoconstriction.
This region also carries fibers extending from the anterior nucleus.
What three structures seem to play a role in feeding urges?
In which of these are AgRP/NPY and POMC/CART neurons found?
On which structure do those neurons synapse?
The ventromedial and lateral hypothalamic nuclei, and the arcuate nucleus too.
The arcuate nucleus.
The nucleus tractus solitarius.
Which mediates hunger: Leptin or ghrelin?
Which is secreted by adipocytes?
Ghrelin induces hunger. Leptin mediates satiety.
Leptin is produced by adipocytes when they take up metabolites.
In what patients are craniopharyngiomas found?
What symptoms are associated with them?
Newborns or young children (congenital tumor).
Bitemporal hemianopia (loss of lateral vision) due to pressure on the optic chiasm. Hypothalamic syndrome eg adiposity, diabetes insipidus, temperature dysregulation, and somnolence.
What results from a lesion of the mammillary body?
Why might alcoholics experience similar symptoms?
Lesion of the mammillary complex causes inability to form new memories (anterograde amnesia).
Chronic alcoholism results in malabsorption (or general deficiency) of thiamine, resulting in Korsakoff’s psychosis.
What is Klein-Levin syndrome?
A hypothalamic lesion, especially in young men, which causes excessive eating, sleeping, and sexual drive.
Associated with decrease in dopamine.
