BMB 3 - The Hypothalamus; Neurobiology of Stress

Question 1

Which organ is largely the main driver of homeostasis (homokinesis)?

Answer 1

The hypothalamus

Question 2

Name the main functions of the hypothalamus.

Answer 2

TAN HATS

Thirst and water balance

Adenohypophyseal control

Neurohypophyseal control

Hunger regulation

Autonomic control

Temperature control

Sexual urges

Question 3

Name the five anterior group nuclei of the hypothalamus.

Answer 3

Preoptic n.

Suprachiasmatic n.

Supraoptic n.

Paraventricular n.

Anterior n.

Question 4

Name the three tuberal group nuclei of the hypothalamus.

Answer 4

Arcuate

Ventromedial

Dorsomedial

Question 5

Name the two posterior group nuclei of the hypothalamus.

Answer 5

Posterior

Mamillary

Question 6

Name the major lateral group nuclei of the hypothalamus.

Answer 6

Lateral n.

Question 7

What regions of the hypothalamus do the lateral nuclei cover?

Answer 7

Spans anterior, tuberal and posterior hypothalamus

Question 8

Name the anterior group nuclei of the hypothalamus that are involved in thermoregulation.

Answer 8

Preoptic n.

Anterior n.

Question 9

Name the anterior group nuclei of the hypothalamus that are involved in water balance and osmotic regulation.

Answer 9

Supraoptic n.

Paraventricular n.

Question 10

Name the anterior group nuclei of the hypothalamus that are involved in circadian rhythm regulation.

Answer 10

Suprachiasmatic n.

Question 11

Name the tuberal group nuclei of the hypothalamus that are involved in regulating energy balance and feeding.

Answer 11

Arcuate n.

Question 12

Name the tuberal group nuclei of the hypothalamus that function(s) as an integration center for thermoregulation.

Answer 12

Dorsomedial n.

Question 13

Which hypothalamic nuclei send info. to the dorsomedial nuclei in order to manage thermoregulation?

Via what structure?

Answer 13

The preoptic and anterior n.;

the medial forebrain bundle

Question 14

What function is performed by the lateral nuclei of the hypothalamus?

Answer 14

Regulation of energy balance and feeding

Question 15

What is the function of the fornix?

Answer 15

To take information to the mamillary bodies

Question 16

What is the function of the medial forebrain bundle?

Answer 16

To connect the anterior / preoptic nuclei with the dorsomedial nuclei

Question 17

The superior hypophyseal arteries branch off the ___________s and form a capillary plexus with venules which connect to the pituitary gland.

Answer 17

The superior hypophyseal arteries branch off the internal carotids and form a capillary plexus with venules which connect to the pituitary gland.

Question 18

In order to affect the hypothalamic-hypophyseal portal system, hormones/factors are released from the ____________ of the hypothalamus to enter the primary plexus.

Answer 18

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.

Question 19

The supraoptic and paraventricular nuclei send axons to the neurohypophysis via the _________________.

Answer 19

The supraoptic and paraventricular nuclei send axons to the neurohypophysis via the supraopticohypophyseal tract.

Question 20

True/False.

Osmoreceptors in the hypothalamus detect hyperosmolar states (e.g. in dehydration) and stimulate ADH release and water retention.

Answer 20

True.

Question 21

The ___________ and ___________ induce drinking behavior when stimulated by angiotensin II (ex.: during hypovolemic conditions due to dehydration or hemorrhage).

Answer 21

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).

Question 22

Which portion of the hypothalamus controls parasympathetic activity?

Answer 22

The anterior hypothalamus

Question 23

Which portion of the hypothalamus controls sympathetic activity?

Answer 23

The posterior hypothalamus

Question 24

Which hypothalamic nuclei are the primary integrative centers for energy balance?

Answer 24

The arcuate nuclei

Question 25

Inhibition of which hypothalamic nuclei will lead to a loss of appetite?

Answer 25

Lateral n. ## Footnote *('**L**acks hunger when destroyed')*

Question 26

Inhibition of which hypothalamic nuclei will lead to a large increase in appetite?

Answer 26

Ventromedial n. | ('**V**ery much hungry when destroyed')

Question 27

Stimulation of which hypothalamic nuclei will lead to an increase in appetite?

Answer 27

Lateral n.

Question 28

What are the main two substances responsible for stimulating the orexigenic neurons of the hypothalamic arcuate nuclei (and thus initiating feeding)?

Answer 28

Neuropeptide Y Agouti-related peptide

Question 29

What are the main two substances responsible for stimulating the anorexigenic neurons of the hypothalamic arcuate nuclei (and thus inhibiting appetite)?

Answer 29

Proopiomelanocortin Cocaine- and amphetamine-regulated transcript

Question 30

How do leptin and insulin exert an effect on the anorexigenic neurons of the hypothalamic arcuate nuclei?

Answer 30

By stimulating synthesis of **proopiomelanocortin** and **cocaine- and amphetamine-regulated transcript**

Question 31

State if each of the following is orexigenic or anorexigenic: ## Footnote **Agout-related peptide** **Cocaine- and amphetamine-regulated transcript** **Proopiomelanocortin** **Neuropeptide Y**

Answer 31

Orexigenic Anorexigenic Anorexigenic Orexigenic

Question 32

Which portion of the hypothalamus senses changes in osmolarity?

Answer 32

The organum vasculosum of the lamina terminalis (**OVLT**)

Question 33

Cooling of the body is regulated by the ______________ (CNS structure).

Answer 33

Cooling of the body is regulated by the **_anterior hypothalamus_**.

Question 34

Heating of the body is regulated by the ______________ (CNS structure).

Answer 34

Heating of the body is regulated by the **_posterior hypothalamus_**.

Question 35

Which hypothalamic nuclei control thermoregulation AND sexual behavior?

Answer 35

Preoptic n.

Question 36

\_\_\_\_\_\_\_**receptors** in the preoptic and anterior nuclei (Pr-An) are connected to integrative centers in dorsomedial nuclei via the medial forebrain bundle (MFB).

Answer 36

**_Thermo_****receptors** in the preoptic and anterior nuclei (Pr-An) are connected to integrative centers in dorsomedial nuclei via the medial forebrain bundle (MFB).

Question 37

As a body's core temperature increases, what occurs in the hypothalamus?

Answer 37

The threshold for the warm-sensitive neurons is surpassed → heat disposal neurons activate → Sweating, vasodilation, panting

Question 38

As a body's core temperature decreases, what occurs in the hypothalamus?

Answer 38

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

Question 39

In general terms, what mechanisms allow for pyrogens to cause fevers?

Answer 39

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**

Question 40

What is the definition of a stressor?

Answer 40

Perturbation of the body’s homeostasis

Question 41

What are the two major modalities of stress response in terms of pathway?

Answer 41

**Reactive** stress **Anticipatory** stress

Question 42

Describe the reactive stress response in terms of how it is triggered.

Answer 42

Intrinsic pertubations of homeostasis triggered by **afferent sensory pathways**; the response is of **descending neuro-motor-endocrine pathways**

Question 43

Describe the anticipatory stress response in terms of the responses.

Answer 43

**Descending limbic system** pathways + **Descending neuro-motor-endocrine** response

Question 44

Which stress response pathway is a top-down system controlled by the limbic system and one's mental preparation for stress?

Answer 44

Anticipatory stress

Question 45

Which stress response pathway is a bottom-up system reacting to internal pertubations such as immune challenges, dehydration, hypoglycemia, pain, etc.

Answer 45

Reactive stress

Question 46

Name the three stages of general adaptation syndrome.

Answer 46

Alarm Resistance Exhaustion

Question 47

\_\_\_\_\_\_\_ stress follows an initial fight-or-flight response involving energy mobilization and rapid adaptation to environment.

Answer 47

**_Acute_** stress follows an initial fight-or-flight response involving energy mobilization and rapid adaptation to environment.

Question 48

\_\_\_\_\_\_\_\_\_ 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.

Answer 48

**_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.

Question 49

The anticipatory stress response circuit often involves which brain regions?

Answer 49

The **amygdala** (_main driver_ of HPA axis) The **hippocampus** (_inhibits_ HPA axis) The **prefrontal cortex** (_inhibits_ HPA axis)

Question 50

Which nucleus of the hypothalamus is largely involved in controlling autonomic pathways?

Answer 50

The paraventricular nucleus

Question 51

The anticipatory (psychological) stress response largely involves indirect, inhibitory limbic inputs to CRH neurons via \_\_\_\_ergic neurons from the ____ nucleus of the \_\_\_\_\_\_\_\_\_\_\_\_.

Answer 51

The anticipatory (psychological) stress response largely involves indirect, inhibitory limbic inputs to CRH neurons via **_GABA_**ergic neurons from the **_Bed_** nucleus of the **_stria vascularis_**.

Question 52

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.

Answer 52

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.

Question 53

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.

Answer 53

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.

Question 54

Name two brainstem nuclei that respond to sensory signals by sending excitatory (noradrenergic) inputs to the paraventricular CRH neurons of the hypothalamus.

Answer 54

Locus coeruleus Nucleus of the tractus solitarius

Question 55

Describe the mechanism by which glucocorticoids exert negative feedback on the HPA axis.

Answer 55

The glucocorticoids stimulate **endocannabinoids** (eCBs) release in the PVN, causing suppression of synaptic excitation to CRH neurons