Hypothalamus Flashcards
What is the function of the hypothalamus?
Homeostasis
- maintain physiological homeostasis (feeding, thirst, salt, thermoreg, sleep, sickness)
- species survival
- primarily by the autonomic nervous system
- controls direct function (HR, respiration..) and then also indirectly control through the endocrine system (through the pituitary) and also, consciously control through the limbic system.
Three controls:
- autonomic nervous system
- endocrine
- limbic control
What is the function of the suprachiasmatic nucleus?
Biological clocks- circadian and circannual.
Uses VP and VIP
What is the function of the arcurate nucleus?
Releasing hormones from the anterior pituitary.
Affected by stress (increased CRH, prolactin, GnRH and GH).
uses a lot of hormones and NT
What is the function of paraventricular nucleus?
Vagus and Parasympathetic
Ant/Post pituitary hormones; ANS via DMV-vagus solitary tract, interomediolateral cell column, venrolateral medulla and locus ceruleus.
What is the function of mammillary nucleus?
Memory (from hipppocampus via fornix).
Projects to brainstem, reticular formation and anterior thalamic nucleus.
What are the three monoamine of importance to the hypothalamus?
Dopamine, Serotonine, Norepinepherine
What are the two principle dopaminergic systems in the brain?
Nigrostriatal and mesolimbic:
Basal ganglia- dopa
Mesolimbic system has cells in the ventral tagmentum that send projections to the hypothalamus, mostly through the medial forebrain bundle
Lot to do with motivational components for movements (strong inhibitor)
Much more specific than NE and serotonin (because they go throughout the cerebral cortex and cerebellum).
NE:
Found in: locus ceruleus (of greatest importance to the hypothalamus), course through the dorsal tegmental bundle to the hypothalamus and other limbic structures; join up fiber bundles and enter the hypothalamus through the median forebrain bundle.
- important for sleep cycle (orexin = arousal)
Serotonin:
two ascending groups of serotonergic cell bodies found in the dorsal and medial raphe nuclei. Enter the lateral hypothalamic area through the median forebrain bundle.
- MODULATORY effect
- strong influence on pain modulation
-majority of time inhibitory
Big outputs:
- wide spread cortex
through the anterior thalamic nucleus, back to the cingulate gyrus
Mammillary bodies:
function primarily in recollective memory, and also, serve to aid in spatial memory, integrating the role of olfaction in to our memory
At least two projections:
- Mammilothalamic tract (ascending- part of Papez)
- Mamillotegmental tract (descending)
Which of the pituitaries has direct release of hormones?
Posterior pituitary.
-Hypothalamus has an axon going into the
There is an indirect control of hormones via the anterior pituitary. Control pathway still in the hypo but because AP came from a different embryological pathway, it stimulates its release. (extra level of control)
What nuclei control the release of the posterior pituitary hormones (oxytocin and vasopresin)?
Magnocellular: paraventricular and supraoptic neurosecretory cells.
cell bodies in hypothalamus, with axons projects down to the blood supply in posterior pituitary.
What nuclei control the release of the anterior pituitary hormones?
Parvocellular neurosecretory cells, which stimulate the release of hypophysiotropic hormones, which then stimulate/inhibit tropic hormones the AP hormone release.
What is the idea behind servomechanism?
FEEDBACK mxn
Most hypothalamic controls work through servomechanism:
hypo determines the proper set point… then it has control mechanisms to increase/decrease that function…it also has a way to measure.
The set point could be altered or changed by external stimuli.
