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Flashcards in Hypothalamus and Temp Regulation Deck (23)
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1

Hypothalamus

Bridge structure that sits in brain and modulates visceral motor, somatic motor, neuroendocrine, and behavioral responses

Homeostasis and emotional expression for survival of individual and species

Between optic chiasm and mamillary bodies

2

How does the hypothalamus regulate the autonomic and somatic motor systems?

Efferent projections to:
•autonomic centers and preganglionic neurons
•motor nuclei in brainstem

3

How does the hypothalamus regulate the endocrine system?

2 ways:

Direct (oxytocin and vasopressin): via the paraventricular nucleus and supraoptic nucleus

Indirect (releasing and inhibiting factors): Control release of anterior pituitary hormones from glandular cells (LH, GH, ACTH, PRL,TSH, FSH)

4

Neural inputs to hypothalamus

direct input from retina

processed sensory information from limbic areas (hippocampus and amygdala)

visceral sensation via nucleus of the solitary tract

5

Humoral inputs to hypothalamus

temperature
osmolality
glucose
peripheral hormones

6

Regions with fenestrated capillaries (no Blood Brain Barrier):

OVLT (organum vasculosum lamina terminalis)
subfornical organ
posterior pituitary
median eminence

7

OVLT

No blood brain barrier
Near lamina terminalis
Sensitive to osmolarity of blood

8

Subfornical organ

No blood brain barrier
Responsive to chemical composition of blood

9

Milk letdown

Lag in time from baby rat suckling for milk and actual change in pressure (milk letdown)

Because neural input but humoral output

10

How does the hypothalamus recruit motivated behavior pathways?

projections to the limbic system:
amygdala, hippocampus, etc.

11

Sham rage

Experiments doing transsections of the brain reomving cerebrum, but leaving hypothalamus intect:
Normal cat-like sham rage response (also get rage response more easily)

If remove hypothalamus in addition to cerebral cortex: no sham rage response

12

Pair bonding in prairie voles

Hypothalamus regulates posterior pituitary with regulates this pair bonding

13

Control of body temperature

Hypothalamus

Anterior hypothalamus: “I’m too hot area” Lesion - hyperthermia

Posterior hypothalamus: Heat generating mechanisms Lesion - hypothermia

14

Preoptic Anterior Hypothalamus (POAH)

"I'm too hot area"
Depends on temp of blood running through brain (directly senses blood temp); also gets input from skin
Hypothalamic warm sensors
Causes heat loss through vasodilating skin and sweating

15

Fever

Still regulated by hypothalamus but higher "set point" for body temp

16

Pyrogens

Cause fever
Exogenous (bacteria or virus) and Endogenous (Cytokines, IL1 for ex)

17

Posterior hypothalamus

Doesn't directly sense temp of brain; gets input from skin receptors

18

How is fever generated?

Cytokines are released and then sensed by the OVLT which then stimulates the POAH thermoreceptors through prostaglandins to increase their tempertaure setpoint, causing vasoconstriction, shivering, and fever.

19

Brown adipose tissue

Heat generation in infants and baby mammals
Usually not much in adult mammals
UCP1
Increased in most humans in winter
Increased in response to NE signaling from hypothalamus

20

Water regulation

Hypothalamus
pOsm=295mosm/kg H2O
Regulate intake through thirst
Regulate output through vasopressin (ADH)

21

Body weight homeostasis

Hypothalamus
Lesions can make people lose appetite or have too much appetite
Short-term regulation of feeding behavior

22

Circadian Rhythms

Suprachiasmatic nucleus in hypothalamus regulates endogenous circadian rhythm
Light/dark can influence cycle
Also input from peripheral clocks and transcriptional autoregulatory feedback loops

23

Tumor in pituitary could do what

Endocrine problems: reproduction (pregnancy lactation), regulation of body temp, regulation of body weight, water balance and BP

Vision problems