BMB 3 - The Hypothalamus; Neurobiology of Stress Flashcards
Which organ is largely the main driver of homeostasis (homokinesis)?
The hypothalamus
Name the main functions of the hypothalamus.
TAN HATS
Thirst and water balance
Adenohypophyseal control
Neurohypophyseal control
Hunger regulation
Autonomic control
Temperature control
Sexual urges
Name the five anterior group nuclei of the hypothalamus.
Preoptic n.
Suprachiasmatic n.
Supraoptic n.
Paraventricular n.
Anterior n.
Name the three tuberal group nuclei of the hypothalamus.
Arcuate
Ventromedial
Dorsomedial
Name the two posterior group nuclei of the hypothalamus.
Posterior
Mamillary
Name the major lateral group nuclei of the hypothalamus.
Lateral n.
What regions of the hypothalamus do the lateral nuclei cover?
Spans anterior, tuberal and posterior hypothalamus
Name the anterior group nuclei of the hypothalamus that are involved in thermoregulation.
Preoptic n.
Anterior n.
Name the anterior group nuclei of the hypothalamus that are involved in water balance and osmotic regulation.
Supraoptic n.
Paraventricular n.
Name the anterior group nuclei of the hypothalamus that are involved in circadian rhythm regulation.
Suprachiasmatic n.
Name the tuberal group nuclei of the hypothalamus that are involved in regulating energy balance and feeding.
Arcuate n.
Name the tuberal group nuclei of the hypothalamus that function(s) as an integration center for thermoregulation.
Dorsomedial n.
Which hypothalamic nuclei send info. to the dorsomedial nuclei in order to manage thermoregulation?
Via what structure?
The preoptic and anterior n.;
the medial forebrain bundle
What function is performed by the lateral nuclei of the hypothalamus?
Regulation of energy balance and feeding
What is the function of the fornix?
To take information to the mamillary bodies
What is the function of the medial forebrain bundle?
To connect the anterior / preoptic nuclei with the dorsomedial nuclei
The superior hypophyseal arteries branch off the ___________s and form a capillary plexus with venules which connect to the pituitary gland.
The superior hypophyseal arteries branch off the internal carotids and form a capillary plexus with venules which connect to the pituitary gland.
In order to affect the hypothalamic-hypophyseal portal system, hormones/factors are released from the ____________ of the hypothalamus to enter the primary plexus.
In order to affect the hypothalamic-hypophyseal portal system, hormones/factors are released from the median eminence of the hypothalamus to enter the primary plexus.
The supraoptic and paraventricular nuclei send axons to the neurohypophysis via the _________________.
The supraoptic and paraventricular nuclei send axons to the neurohypophysis via the supraopticohypophyseal tract.
True/False.
Osmoreceptors in the hypothalamus detect hyperosmolar states (e.g. in dehydration) and stimulate ADH release and water retention.
True.
The ___________ and ___________ induce drinking behavior when stimulated by angiotensin II (ex.: during hypovolemic conditions due to dehydration or hemorrhage).
The subfornical organ and organum vascularum of the lamina terminalis induce drinking behavior when stimulated by angiotensin II (ex.: during hypovolemic conditions due to dehydration or hemorrhage).
Which portion of the hypothalamus controls parasympathetic activity?
The anterior hypothalamus
Which portion of the hypothalamus controls sympathetic activity?
The posterior hypothalamus
Which hypothalamic nuclei are the primary integrative centers for energy balance?
The arcuate nuclei
Inhibition of which hypothalamic nuclei will lead to a loss of appetite?
Lateral n.
(‘Lacks hunger when destroyed’)
Inhibition of which hypothalamic nuclei will lead to a large increase in appetite?
Ventromedial n.
(‘Very much hungry when destroyed’)
Stimulation of which hypothalamic nuclei will lead to an increase in appetite?
Lateral n.
What are the main two substances responsible for stimulating the orexigenic neurons of the hypothalamic arcuate nuclei (and thus initiating feeding)?
Neuropeptide Y
Agouti-related peptide
What are the main two substances responsible for stimulating the anorexigenic neurons of the hypothalamic arcuate nuclei (and thus inhibiting appetite)?
Proopiomelanocortin
Cocaine- and amphetamine-regulated transcript
How do leptin and insulin exert an effect on the anorexigenic neurons of the hypothalamic arcuate nuclei?
By stimulating synthesis of proopiomelanocortin and cocaine- and amphetamine-regulated transcript
State if each of the following is orexigenic or anorexigenic:
Agout-related peptide
Cocaine- and amphetamine-regulated transcript
Proopiomelanocortin
Neuropeptide Y
Orexigenic
Anorexigenic
Anorexigenic
Orexigenic
Which portion of the hypothalamus senses changes in osmolarity?
The organum vasculosum of the lamina terminalis
(OVLT)
Cooling of the body is regulated by the ______________ (CNS structure).
Cooling of the body is regulated by the anterior hypothalamus.
Heating of the body is regulated by the ______________ (CNS structure).
Heating of the body is regulated by the posterior hypothalamus.
Which hypothalamic nuclei control thermoregulation AND sexual behavior?
Preoptic n.
_______receptors in the preoptic and anterior nuclei (Pr-An) are connected to integrative centers in dorsomedial nuclei via the medial forebrain bundle (MFB).
Thermoreceptors in the preoptic and anterior nuclei (Pr-An) are connected to integrative centers in dorsomedial nuclei via the medial forebrain bundle (MFB).
As a body’s core temperature increases, what occurs in the hypothalamus?
The threshold for the warm-sensitive neurons is surpassed → heat disposal neurons activate → Sweating, vasodilation, panting
As a body’s core temperature decreases, what occurs in the hypothalamus?
Temperature-insensitive neurons and cold-sensitive neurons are stimulated → neurons involved in heat retention and production are activated → shivering and nonshivering thermogenesis; increased basal metabolic rate via TRH
In general terms, what mechanisms allow for pyrogens to cause fevers?
Pyrogen can:
(1) increase the set-point of core body temperature,
(2) decrease the sensitivity of warm-sensitive neurons,
and (3) increase the sensitivity of cold-sensitive neurons
What is the definition of a stressor?
Perturbation of the body’s homeostasis
What are the two major modalities of stress response in terms of pathway?
Reactive stress
Anticipatory stress
Describe the reactive stress response in terms of how it is triggered.
Intrinsic pertubations of homeostasis triggered by afferent sensory pathways;
the response is of descending neuro-motor-endocrine pathways
Describe the anticipatory stress response in terms of the responses.
Descending limbic system pathways
+
Descending neuro-motor-endocrine response
Which stress response pathway is a top-down system controlled by the limbic system and one’s mental preparation for stress?
Anticipatory stress
Which stress response pathway is a bottom-up system reacting to internal pertubations such as immune challenges, dehydration, hypoglycemia, pain, etc.
Reactive stress
Name the three stages of general adaptation syndrome.
Alarm
Resistance
Exhaustion
_______ stress follows an initial fight-or-flight response involving energy mobilization and rapid adaptation to environment.
Acute stress follows an initial fight-or-flight response involving energy mobilization and rapid adaptation to environment.
_________ stress results from maladaptive scenarios of either continued stress or a failure to turn off the stress response, sometimes leading to PTSD, anxiety, and/or depression.
Chronic stress results from maladaptive scenarios of either continued stress or a failure to turn off the stress response, sometimes leading to PTSD, anxiety, and/or depression.
The anticipatory stress response circuit often involves which brain regions?
The amygdala (main driver of HPA axis)
The hippocampus (inhibits HPA axis)
The prefrontal cortex (inhibits HPA axis)
Which nucleus of the hypothalamus is largely involved in controlling autonomic pathways?
The paraventricular nucleus
The anticipatory (psychological) stress response largely involves indirect, inhibitory limbic inputs to CRH neurons via ____ergic neurons from the ____ nucleus of the ____________.
The anticipatory (psychological) stress response largely involves indirect, inhibitory limbic inputs to CRH neurons via GABAergic neurons from the Bed nucleus of the stria vascularis.
In inhibiting stress responses via the anticipatory pathway, the ___________ sends stimulatory (glutamate) inputs to the __________, which sends inhibitory (GABA) inputs to the paraventricular CRH neurons.
In inhibiting stress responses via the anticipatory pathway, the prefrontal cortex sends stimulatory (glutamate) inputs to the bed nucleus of the stria vascularis, which sends inhibitory (GABA) inputs to the paraventricular CRH neurons.
In stimulating stress responses via the anticipatory pathway, the ______________ sends inhibitory (GABA) inputs to the ______________, which would normally send inhibitory (GABA) inputs to the paraventricular CRH neurons.
In stimulating stress responses via the anticipatory pathway, the amygdala central nucleus sends inhibitory (GABA) inputs to the bed nucleus of the stria vascularis, which would normally send inhibitory (GABA) inputs to the paraventricular CRH neurons.
Name two brainstem nuclei that respond to sensory signals by sending excitatory (noradrenergic) inputs to the paraventricular CRH neurons of the hypothalamus.
Locus coeruleus
Nucleus of the tractus solitarius
Describe the mechanism by which glucocorticoids exert negative feedback on the HPA axis.
The glucocorticoids stimulate endocannabinoids (eCBs) release in the PVN, causing suppression of synaptic excitation to CRH neurons
