Hypothalamus and Temperature Regulation

Question 1

Anatomically, what structures surround the hypothalamus?

Answer 1

The pituitary gland is inferior to it.
The optic chiasm is anterior to it.
The mammillary bodies are posterior to it.

Question 2

True or false: the pineal gland is anterior to the thalamus.

Answer 2

False. It is posterior.

Question 3

How does the hypothalamus control the somatic motor system?

Answer 3

Via efferent projections to autonomic control areas of the cortex and brainstem motor nuclei

Question 4

True or false: parasympathetic innervation decreases the release of norepinephrine.

Answer 4

False. There is no parasympathetic innervation of the adrenal glands.

Question 5

There are two hormones made and secreted by the hypothalamus: _____________. Describe the route they take.

Answer 5

oxytocin and vasopressin; they are made in the supraoptic and periventricular nuclei and are transported through axons to the blood vessels of the posterior pituitary (this is the direct pathway)

Question 6

Visceral sensory information synapses on the _____________.

Answer 6

solitary nucleus

Question 7

What are the neural inputs to the hypothalamus?

Answer 7

Direct from the retina
Fornix projections from the hippocampus
Visceral sensation from the solitary tract
Brainstem reticular nuclei (BP)
Stria terminalis connections with amygdala
Medial forebrain bundle (connects to frontal lobe)

Question 8

What are the humoral inputs to the hypothalamus?

Answer 8

Osmolality
Temperature
Glucose concentration
Peripheral hormones

Question 9

What is the superior end of the neural tube?

Answer 9

Lamina terminalis

Question 10

What is the milk letdown reflex?

Answer 10

Stimulation of the nipples (via neural stimulation) leads to release of oxytocin and subsequent release of milk

Question 11

Decerebrating experiments in cats demonstrated that ______________.

Answer 11

they couldn’t have the full “sham rage” (arching the back, hissing) response when the brainstem was separated from the hypothalamus; in contrast, sham rage was observed excessively when the hypothalamus was left connected to the brainstem but severed from the higher brain areas

Question 12

Lesions of the ____________ lead to ravenous hunger, while lesions of the ____________ lead to lack of appetite.

Answer 12

ventromedial nuclei (in the hypothalamus); lateral hypothalamic area

Question 13

Describe the idea of the setpoint in weight (as set by the hypothalamus).

Answer 13

The hypothalamus sets weight. If you give rats a high fat diet, they’ll gain weight. If you give them back their normal diet, they’ll return to their previous weight. The inverse happens with low calorie diets.

Question 14

The _____________ nucleus coordinates the circadian rhythm.

Answer 14

suprachiasmatic

Question 15

What happens to the metabolic rate when the hypothalamus cools?

Answer 15

It increases to return the temperature of the hypothalamus back to its set point.

Question 16

The anterior hypothalamus is the _______________ center.

Answer 16

“I’m too hot” (the area that motivates you to cool off)

Question 17

The ______________ controls behavior that generate heat.

Answer 17

posterior hypothalamus

It generates vasoconstriction and shivering to warm up the body.

Question 18

Where does the PGE2 that stimulates fever come from?

Answer 18

The OVLT (organum vasculosum of lamina terminalis) – a part of the POAH – which makes it in response to IL-1

Question 19

Brown adipose tissue is important in keeping _________ warm.

Answer 19

infants and other small mammals

It does so by having its catabolism sped up when the anterior hypothalamus cools.

Question 20

The __________ divides the hypothalamus into medial and lateral sections.

Answer 20

fornix

Question 21

The hypothalamus controls the sympathetic and parasympathetic nervous systems via _______________.

Answer 21

neuronal projections to the lateral gray column (for sympathetic) and brainstem (for parasympathetic)

Question 22

Oxytocin stimulates ______________.

Answer 22

contraction of smooth muscle in the uterus and breasts

Question 23

Angiotensin II acts on the ____________ to stimulate thirst centers.

Answer 23

subfornical organ

Question 24

The arcuate nucleus is involved in _________.

Answer 24

sensing peripheral hormone levels

Question 25

The posterior hypothalamus is the ____________ center.

Answer 25

“I’m too cold” (that is, it motivates you to seek warmth)

Question 26

What is the POAH?

Answer 26

PreOptic Anterior Hypothalamus (the area that senses warmth)

Question 27

Pyrogens act on the ___________ to stimulate fever.

Answer 27

POAH; they do so by decreasing activity of the thermoreceptors (thus tricking the body into thinking it is cooler than it actually is)

Question 28

The indirect pathway controls release of _____________.

Answer 28

hormones made in the anterior pituitary

Question 29

Lesions of the anterior hypothalamus leads to ___________.

Answer 29

hyperthermia, because the body can’t sense when it’s too hot and doesn’t engage in cooling behaviors