Hypothalamus Flashcards
Main function of the hypothalamus
Maintain homeostasis
What three systems is the hypothalamus functionally related to?
Autonomic nervous system
Endocrine system
Limbic system
What are the three zones that the hypothalamus is divided into?
Periventricular
Medial
Lateral
What anatomical structures separate the medial and lateral zones?
Fornix (ventrally) and mammillothalmic tract (dorsally)
Major nuclei of Lateral zone
Lateral preoptic nucleus
Lateral Hypothalamic area
Tuberomammillary (lateral tuberal) nucleus
Function of Lateral hypothalamic area
Induces eating when stimulated
Ablation causes anorexia and starvation
Contains important peptide ntms that increase food intake
Function of Tuberomammillary Nucleus
Contains large neurons that release histamine as a ntm via axonal projections to widespread portions of the forebrain
Thought to plan an important role in attention and arousal processes
Actively inhibited during sleep
Major nuclei of the Medial zone
Preoptic Region: Medial preoptic nucleus
Anterior Region: Suprachiasmatic nucleus, Anterior hypothalamic nucleus, Paraventricular nucleus, Supraoptic nucleus
Middle Region: Dorsomedial nucleus, Ventromedial nucleus, Arcuate nucleus
Posterior Region: Posterior nucleus, Mammillary nucleus
Function of the Medial Preoptic Nucleus
Houses neurons that regular gonadotropin secretion from the adenohypothysis
Contains the interstitial nuclei of the anterior hypothalamus, only of which is sexually dimorphic and developmentally regulated by testosterone
Function of Suprachiasmatic Nucleus
Immediately dorsal to optic chasm, receives direct input from retina
Plays critical role in control of circadian rhythm
Function of Anterior Hypothalamic Nucleus
Between suprachiasmatic and paraventricular nuclei
Involved in temp regulation, contains neuron that sense warmth and initiate response to dissipate excess heat
Bilateral lesions result in hyperthermia
Function of paraventricular nucleus
Contains neurons that synthesize and release arginine vasopression, oxytocin, and CRH
Additional neurons project to interomediolateral cell column of the spinal cord (T1-L2) exciting sympathetic preganglionic neurons, as well as projections to brainstem
Function of Supraoptic nucleus
Contains neuron that synthesize AVP and oxytocin
Project to neurohypophysis where they release these hormones into circulation
Function of dorsomedial nucleus
involved in BP regulation, aggression and savage behavior result
Function of ventromedial nucleus
Inhibits the urge to eat when stimulated
Bilateral destruction results in hyperphagia
Neurons play an important role in relaying ingestion-related signals to the brainstem