Ch. 30 - Hypothalamus Flashcards
Boundaries of the HT
Rostral = Lamina terminalis
Superior = hypothalamic sulcus
Lateral = substantia inominata (front) + posterior limb of IC (back)
Medial = Third ventricle
Caudal = Tegmentum and PAG
Medial Preoptic area contains cells that make ______.
GnRH
Which HT area is “sexually dimorphic”
Medial Preoptic nucleus
The lateral zone contains what fibers?
Medial Forebrain Bundle
Nuclei in the HT lateral zone
- Lateral HT nucleus
- Tuberal Nuclei
Stimulation of the Lateral HT nucleus will result in…
Feeding behavior
Lesion causes anorexia
Tuberal nuclei location and function
Lateral Zone
- Sends releasing hormones via tuberoinfundibular tract
- Sends histaminergic input to CB
Regions of the Medial zone
Supraoptic
Tuberal
Mammillary
Tuberal region is located internal to the _____
Tuber cinereum
Where in the medial zone is the supraoptic region?
What are the nuclei of the supraoptic region?
In the rostral-most portion of the medial zone
- Supraoptic
- Paraventricular
- Suprachiasmatic
- Anterior
Function of SON and PVN?
contain oxcytocin + ADH
transmit these substances via supraoptico-hypophysial tract for release to the neurohypophysis
Location / Main function of the Anterior nucleus
Location = In the supraoptic region
Main function = Body temperature maintenence
Nuclei of the tuberal region
Ventromedial
Dorsomedial
Arcuate
Ventromedial nucleus function?
Satiety center
If stimulated = no feeding behavior
Location and function of the Dorsomedial nucleus
Location = tuberal region
Function = regulation of emotional behavior
Stimulation of dorsomedial nucleus results in…
sham rage
Arcuate nucleus function
the primary nucleus containing releasing hormones
transmitted via **tuberoinfundibular tract **and Hypophysial portal system
Mammillary region nuclei
medial
intermediate
lateral
posterior
Which mammillary nucleus is the target for the fornix? Where are these fibers coming from?
Medial mammillary nucleus
Subiculum of the hippocampus
Efferent connection of the medial mammillary nucleus?
Mammillothalamic tract
**to the Anterior Nucleus of the Dorsal Thalamus
Neurons of the periventricular zone (***not par_a_ventricular nucleus) project to the __________ via the __________
anterior pituitary via the tuberoinfundibular tract
Adopose tissue releases _____, which travels to receptors in the _____ nucleus.
Some of these neurons contain ____ and _____, while others contain ____ and _____
Leptin >> receptors in arcuate nucleus
- aMSH + CART
- NPY + AgRP
Function of aMSH and CART-containing neurons
project to LATERAL zone, PVN, and lateral horn of Sp. cord
Increases TSH and ACTH = increased metabolism and Sy tone
Decreased feeding behavior
Function of NPY and AgRP
Promotes decrease in TSH and ACTH = decreased metabolism and increased feeding behavior
Major blood supply to HT
perforating arteries of the circle of Willis
(branches of…)
A1 = anteromedial group
P1 = posteromedial group
*posterior group also gets some from thalamoperforating arteries
Fornix divisions & projections
Precommisural (small) >> Anterior HT region
Postcommissural (*large) >> *Medial Mammillary nucleus
MFB connects the…
septal nuclei
HT
Midbrain Tegmentum
Two projection systems from Amygdala to HT
- Stria Terminalis (older, goes to septal/Preoptic nuclei and Medial zone)
- Ventral Amygdalofugal pathway (new, passes under lentifurm nucleus and through substantia inominata to go to the septal/Preoptic nuclei and Lateral zone)
Mammillary peduncle connections?
originates from midbrain reticular formation
terminates in the lateral mammillary nucleus
Where do the thalamohypothalamic fibers originate from?
Dorsomedial nucleus
What is the only cortical HT connection
Corticohypothalamic fiber from the prefrontal cortex
Two origins for retinohypothalamic fibers?
- as direct axons from optic chiasm
- collaterals of retinogeniculate fibers
Major ascending efferent projection from the HT? (include branches and targets)
Mammillary fasiculus
(bifurcates into Mammillothalamic and mammillotegmental tracts)
Mammilothalamic = Anterior thalamic nucleus
Mammillotegmental = tegmental nuclei of the midbrain RF
What are the other efferent HT ascending projections?
Hypothalamo-thalamic fibers (to DM nucleus)
Hypothalamo-amygdaloid fibers (via ST and VAFP)
4 main descending HT projections
HT-spinal
HT-medullary
Dorsal Longitudinal Fasiculus
Mammillotegmental Tract
Hypothalamomedullary origin/target
HT-spinal origin/target
Both from PVN nucleus
HM = goes to solitary, dorsal vagal, and ambiguus
HS = terminates on IML neurons
DLF origin
medial HT zone
mammillotegmental tract origin
Medial Mammillary nucleus
DLF and mammillotegmental tract terminate at the _______
PAG
major function of DLF and Mammillotegmental?
indirect influence of autonomic nuclei
OT and ADH are secreted by….
They are stored in…
Magnocellular cells in PVN and SO
Stored in Herring bodies
Lesion of SO + PVN results in…
Diabetes insipidus
Tuberoinfundibular tract comes from _______ neurons
parvicellular neurons in arcuate nucleus and periventricular zone
axons of the T-I tract convey releasing hormones to the
median eminence
cutoff for classifying micro/macroademonas
1 cm
IGF1 is considered a ______
somatomedin
FSH secreting tumors only affect
menapausal women – it may shut down cycle
Prolactin release is inhibited by…
Prolactin-inhibiting factor (PIF)
activation of the Caudolateral HT produces what kind of behavior?
Anxiety-related
- increased Sympathetics
- increased aggression
- increased hunger
- increased Body Temperature
Stimulation of the Rostromedial HT produces what kind of behavior?
Contentment
- Increased Parasympathetic
- Increased Passiveness
- Increased Satiety
-
Reduced Temperature
5.
Explain Biofeedback
Some people are able to alter blood pressure/body temperature through neural mechanisms that haven’t been elucidated.
In the baroreceptor reflex, the solutary nucleus transmits to the ___________ nuclei
PVN, DM, and Lateral HT nuclei
These project back down to the dorsal vagal nuclei in the medulla
In the temperature regulation reflex, an increase in temperature will stimulate the __________ nucleus, responsible for heat dissipation
What part is responsible for heat conservation?
Rostral HT dissipates
Caudal HT is responsible for:
- heat conservation (via vasoconstriction)
- heat production (via shivering)
The water balance reflex is said to be _____.
Basic mechanism
neurohumoral
Osm is monitored by Anterior HT (near preoptic and PVN)
Output from these receptors influences ADH release
