Neuro 40: Hypothalamus

lateral terminalis (anterior end of the third ventricle) and anterior commissure

what is the anterior/rostral boundary of the hypothalamus?

posterior commissure, PAG, and tegmentum of the midbrain

what is the posterior/caudal boundary of the hypothalamus?

hypothalamic sulcus and ventral thalamus

what is the superior boundary of the hypothalamus?

optic chiasm, infundibular stalk, median eminence and mammillary body

what is the inferior boundary of the hypothalamus?

posterior limb of internal capsule and optic tract

what is the lateral boundary of the hypothalamus?

inferior portion of the third ventricle

what is the medial boundary of the hypothalamus?

1. periventricular

2. medial

3. lateral

what are the three longitudinal areas of hypothalamic neurons

medial

which hypothalamic area/zone can be further divided into anterior, middle (tuberal) and posterior groups?

anterior, medial zone

what area/zone of the hypothalamus: preoptic nucleus (PON)

anterior, medial zone

what area/zone of the hypothalamus: paraventricular nucleus (PVN)

anterior, medial zone

what area/zone of the hypothalamus: anterior hypothalamic nucleus (AHN)

anterior, medial zone

what area/zone of the hypothalamus: supraoptic nucleus (SON)

anterior, medial zone

what area/zone of the hypothalamus: suprachiasmatic nucleus (SCN)

middle/tuberal, medial zone

what area/zone of the hypothalamus: dorsomedial hypothalamic nucleus (DMN)

middle/tuberal, medial zone

what area/zone of the hypothalamus: ventromedial (hypothalamic nucleus (VMN)

middle/tuberal, medial zone

what area/zone of the hypothalamus: arcuate nucleus (ARC)

posterior, medial zone

what area/zone of the hypothalamus: posterior hypothalamic nucleus (PHN)

posterior, medial zone

what area/zone of the hypothalamus: mammillary nucleus (MNu)

periventricular zone

what area/zone of the hypothalamus: periventricular nucleus (periVN)

internal carotid artery

the hypothalamus receives blood supply from the circle of willis except for ?

1. ACA

2. PCA

3. anterior communicating

4. posterior communicating

what is the blood supply to the hypothalamus?

1. hippocampus

2. septal area

3. amygdala

where locations in the limbic system does the hypothalamus receive afferent input from?

fornix

how does the hippocampus of the limbic system send afferent info to the hypothalamus

medial forebrain bundle

how does the septal area of the limbic system send afferent info to the hypothalamus?

1. stria terminalis

2. ventral amygdalofugal pathway

how does the amygdala of the limbic system send afferent info to the hypothalamus

1. limbic system (hippocampus, septal area, amygdala)

2. midbrain PAG

3. thalamic hypothalamic fibers

4. retinohypothalamic fibers

5. mammillary peduncle

6. monoaminergic pathways

what is the afferent input to the hypothalamus (6)?

pituitary gland

where do the hypothalamohypophyseal tract and tuberoinfundibular tract project?

1. parasympathetic nervous system:

   1. nucleus tractus solitarius (NTS)

   2. nucleus ambiguus

   3. dorsal vagal nucleus (DVN)

where does the hypothalamomedullary tract project to?

sympathetic nervous system: intermediolateral cell column (IML)

where does the hypothalamospinal tract project to?

magnocellular neurons (SON and PVN)

what type of hypothalamic neurons project to the posterior pituitary gland?

supraoptic (SON) and paraventricular nucleus (PVN)

where are hypothalamic magnocellular neurons that project to the hypothalamohypophyseal tract located?

hypothalamohypophyseal tract (supraopticohypophyseal tract)

what tract do magnocellular neurons (SON and PVN) project?

AVP (ADH) and oxytocin

what hormones are produced by magnocellular neurons (SON and PVN) in the hypothalamohypophyseal tract?

hypothalamohypophyseal tract (supraopticohypophyseal tract)

what tract is stimulated in response to an increase in ECF osmolarity?

hypothalamohypophyseal tract (supraopticohypophyseal tract)

what tract is stimulated suckling on the nipple by a baby and functions to stimulate uterine contraction and milk ejection

parvocellular neurons

what hypothalamic neurons project to the tuberoinfundibular tract?

tuberoinfundibular tract

what hypothalamic tract projects to the anterior pituitary gland?

tuberoinfundibular tract

what tract for thyroid and gonad stimulation?

tuberoinfundibular tract

what tract for milk production?

tuberoinfundibular tract

what tract for growth and cortisol production?

false (axonal transport → median eminence → long portal veins → anterior pituitary gland)

T/F: parvocellular neuronal axons project directly to the anterior pituitary gland?

true

T/F: magnocellular neuronal axons project directly to the posterior pituitary gland

median eminence

parvocellular neurons project here to release the releasing or inhibiting hormones into the vessels of the hypophyseal portal system

solitary nucleus (NTS)

what receives afferent info from the baroreceptors in the baroreceptor reflex?

1. nucleus ambiguus (nAmb) → inhibitory preganglionic parasympathetic fibers to the heart through vagus nerve

2. CVLM → inhibitory to RVLM

where does the solitary nucleus (NTS) project?

excitatory to intermediolateral cell column (IML)

what is the output of the RVLM

inhibitory to the RVLM

what is the output of the CVLM

1. stimulate NTS

2. stimulates nAmb and CVLM

3. nAmb inhibitory via vagus nerve to heart (parasymp) and CVLM inhibitory to RVLM

4. RVLM decrease stimulation to IML

5. IML decrease sympathetic ganglia = parasympathetic activated

explain the BR response when BP increases

1. NTS not stimulated

2. nAmb and CVLM not stimulated

3. no inhibition to RVLM

4. RVLM stimulates IML

5. IML preganglionic sympathetic neurons project to sympathetic ganglia -> heart and BV

explain the BR response when BP decreases

vasovagal response

hypothalamic modulation affect on the BR reflex when an intense emotion can cause the blood pressure to drops and causes the person to faint

preoptic nucleus (PON)

acts as a heat loss center and temperature sensor; sends efferents to the skin and subcutaneous vessels to increase sweat production and vasodilation to release excess heat

increase

the preoptic nucleus (PON) increases its firing rate in response to a __________ in body temperature

posterior hypothalamus (PHN)

heat conservation center that increases heat production of the body by increasing metabolic rate (brown fat in babies) and shivering

decrease

the posterior hypothalamus (PHN) increases its firing rate in response to a __________ in body temperature

PHN and PON

which hypothalamic nuclei work reciprocally to control core body temperature

preoptic nucleus (PON)

receives afferent from the skin, allowing it to preemptively modulate the body’s thermoregulatory mechanisms in response to a change in ambient temp in a feed-forward manner even before the core temp change

fever

occurs do to a change in the body’s perceives temperature set points, often due to infection