What contributes to the posterior/mammillary region of the hypothalamus?
posterior hypothalamic nucleus (PMH)
mammillary bodies/nuclei (MAM)
Which statement is false?
B. the anterior hypothalamus senses heat loss and initiates heat conservation while the posterior hypothalamus senses heat increase and
starts heat loss behavior
(the anterior hypothalamus senses heat increase and initiates heat loss behavior while the posterior hypothalamus senses heat loss and
starts heat conservation)
True or false: the infundibular nuclei of the hypothalamus is the same as the arcuate nucleus
What are the functions of the anterior/supraoptic hypothalamic nuclei?
preoptic nucleus: water intake, sleep, have parvocellular cells
suprachiasmatic: circadian rhythms, retina input (b/c on top of optic chiasm), sexual behavior (?)
supraoptic: oxytocin, ADH production
anterior hypothalamic: temperature (heat loss), sleep-waking, have parvocellular cells
paraventricular: oxytocin, ADH production, have parvocellular cells
Which hypothalamic nuclei has connections to both the anterior and posterior pituitary thus regulating endocrine functions and also controls the ANS via "regular" neurons that send axons down to brainstem and spinal cord neuron targets?
paraventricular nucleus (in anterior/supraoptic region of hypothalamus)
What are parvocellular cells?
they are small cells within (hypothalamic) nuclei that control endocrine secretion of anterior pituitary cells by secreting releasing or inhibitory factors
e.g. growth hormone, LH, FSH, ACTH, TSH
What are magnocellular cells?
magnocellular cells are large cells in (hypothalamic) nuclei that secrete ADH and oxytocin from posterior pituitary gland
found in supraoptic and paraventricular hypothalamic nuclei
Which hypothalamic nuclei have magnocellular cells?
What are the functions of the middle/tuberal hypothalamic nuclei?
dorsomedial hypothalamus: feeding, rage
ventromedial hypothalamus: feeding (satiety center), rage, has parvocellular cells
infundibular/arcuate: endocrine control (e.g. senses decreased sex hormones), has parvocellular cells
(tuberomammillary nucleus: sleep/waking)
What would happen to a mouse's appetite if it had a bilateral lesion through its ventromedial hypothalamic nuclei?
the mouse would never feel satiated; it would continually eat
Where are the brain "centers" that contribute to the sensation of satiety and decrease appetite?
posterior lobe/neurohypophysis origin: dragged down hypothalamus
What hormones does the anterior pituitary secrete? What structure controls their secretion?
the hypothalamus controls their secretion
In what two ways does the hypothalamus control the pituitary gland?
hypothalamo-hypophyseal TRACT: axons of cells in the SO and PV nuclei transmit signals to blood vessels in the neurohypophysis
hypothalamo-hypophyseal PORTAL SYTEM: hypothalamic controlling factors are released onto a private venous portal system (at level of median eminance) that transmits signals to the adenohypophysis, where receptor cells are located
What factors does the posterior pituitary release into the bloodstream? What are their target organs?
oxytocin: smooth muscle of uterus (parturition), breast (lactation)
What affect does alcohol have on ADH levels and what are the consequences of this change, if any?
alcohol inhibits release of ADH (antidiuretic hormone)
the change in blood osmolarity is sensed by the hypothalamus, which triggers the kidney tubules to increase urination
a person becomes flooded with uninhibited diurectic signals --> uninhibited increased urination
What is the effects of diabetes insipidus on ADH levels and what are its associated symptoms?
diabets insipidus reflects a marked decrease in ADH levels
symptoms: increased thirst and drinking, increased urination of vast quantities of dilute urine
Describe the hypothalamus-pituitary-axis pathway that controls ACTH release.
note negative feedback on two levels
(side note: adrenal cortex is backup to ANS activated in prolonged stress response)
What are some parasympathetic innervated structures in the brainstem?
DMNX (dorsal motor nucleus of Vagus)
Where are some sympathetic innervated structures of the ANS in the spinal cord?
lateral horn in T1-L2
Through which two tracts does the hypothalamus regulate the autonomic nervous system?
dorsal longitudinal fasciculus: (through brainstem) parasympathetic preganglionic cells in brainstem
hypothalamo-spinal tract: (through brainstem) sympathetic preganglionic cells in lateral horn of spinal cord (T1-L2)
most of both tracts originate in the PV nucleus
In the context of acting as the "head ganglion" of the ANS, what are the inputs and outputs of the hypothalamus?
-viscera (afferents via CN X, IX to caudal solitary nucleus)
-autonomic centers in brainstem
-parasympathetic cranial nerve motor nuclei
-sympathetic spinal cord motor nuclei
Hypo controls ans for homeostasis and for emotional expression, therefore needs visceral inputs and external world inputs—and then sends outputs to ans—to parasympathetic neurons, to sympathetic neurons and to brainstem ANS coordinating centers
What are the (preganglionic) parasympathetic nuclei in the brainstem and the (preganglionic) sympathetic nuclei in the spinal cord?
dorsal motor nerve of vagus (DMNX)
interomedial lateral (IML) column in lateral horn in thoracic cord (T1-L2)
lateral horn in sacral cord (giving rise to pelvic splanchnic nerves)
What will damage to one side of the hypothalamus cause if the lesion is at the level where the ANS and PNS are lateralized?
a. there will be no clinical presentation, must have bilateral damage to hypothalamus to cause noticeable effects
b. unilateral, contralateral loss of ANS function
c. bilateral loss of ANS function
d. unilateral, ipsilateral loss of ANS function
True or False: On their way to the spianl cord from the hypothalamus, only branches from the dorsal longitudinal fasciculus terminate on nuclei in the brainstem (e.g. DMNX).
Some branches of the descending hypothalamo-spinal tract terminate on nuclei in the brainstem as well as branches from the DLF.
Choose correct word: (Descending/Ascending) fibers drive sympathetic motor nuclei in interomedial lateral (IML) horn/column.
Descending fibers drive sympathetic motor nuclei in interomedial lateral (IML) horn/column.
What are the symptoms of Horner's Syndrome? Why would a hemisection of the spinal cord at the thoracic level be a possible cause of Horner's Syndrome?
Horner's Syndrome: ("Horny PAMELa"): Ptosis, Anhydrosis, Miosis (pupil constriction), Excess mucous, Loss of ciliospinal reflex (also vasodilation)
A hemisection of the spinal cord at the thoracic level would be a possible cause of Horner's syndrome because the sympathetic fibers from the hypothalamus (hypothalamo-spinal tract) travel through the lateral funiculus of the spinal cord and synapse on the interomedial lateral horn (IML) and a hemisection through the cord would cause signal blockage to sympathetic system targets
Trick with horner’s is to remember that the block can be along the length of the pathway: centrally from hypothalamus through brainstem to cord, or peripherally from cord to chain, to superior cervical ganglion to carotid plexus to target in head.
Which of the following is regulated in some way by the hypothalamus?
E. all of the above
What 2 major cerebral arteries are in close proximity to the hypothalamus?