Nsp Week 4: Hypothalamus (Foreman)

Front 1

Which area of the hypothalamus is responsible for temperature regulation?

Back 1

Preoptic anterior area

Front 2

Which area of the hypothalamus is the feeding center?

Back 2

Lateral hypothalamic zone

Front 3

What are the two nuclei of the preoptic area?

Back 3

1. Medial preoptic nucleus (Mpoa)
2. Lateral preoptic nucleus (Lpoa)

Front 4

What are the 3 regions of the medial zone of the hypothalamus?

Back 4

1. Supraoptic region
2. Tuberal region
3. Mammillary region

Front 5

List the 4 nuclei of the supraoptic region

Back 5

(medial zone)

1. Supraoptic nucleus
2. Paraventricular nucleus
3. Suprachiasmatic nucleus
4. Anterior hypothalamic area

Front 6

Which hormones does the supraoptic nucleus contain?

Back 6

1. Oxytocin
2. ADH

Front 7

Which hormones does the paraventricular nucleus contain?

Back 7

1. Oxytocin
2. ADH
3. Corticotropin releasing hormone

Front 8

Which hypothalamic nucleus is responsible for circadian rhythms?

Back 8

Suprachiasmatic nucleus (Scn)
(supraoptic region)

Front 9

Which hypothalamic area functions in maintaining body temperature?

Back 9

Anterior Hypothalamic area (Aha)
*Also has a wide range of visceral/somatic functions

Front 10

List the 3 nuclei within the tuberal region

Back 10

(medial zone)

1. Ventromedial nucleus
2. Dorsomedial nucleus
3. Arcuate nucleus

Front 11

Where is the satiety center?

Back 11

Ventromedial nucleus
(tuberal region)

Front 12

Which area of the hypothalamus is responsible for emotional behavior and sham rage?

Back 12

Dorsomedial nucleus
(tuberal region)

Front 13

Which area of the hypothalamus is associated with body weight?

Back 13

Arcuate nucleus
(tuberal region)

Front 14

List the nuclei/areas found within the mammillary region of the hypothalamus

Back 14

1. Medial, intermediate, and lateral mammillary nuclei
2. Posterior hypothalamic area

Front 15

Which region of the hypothalamus is associated with short term memory?

Back 15

Medial, intermediate, and lateral mammillary nuclei

Front 16

Which region of the hypothalamus has emotional, cardiovascular, and analgesic function?

Back 16

Posterior hypothalamic area
(mammillary region)

Front 17

What is the function of the periventricular zone (Pevn)?

Back 17

Synthesizes hormones or factors important for body homeostasis

Front 18

Activation of which area of the hypothalamus produces behavioral contentment?

Back 18

Anteromedial hypothalamus

Front 19

Activation of which area of the hypothalamus produces anxiety?

Back 19

Posterolateral hypothalamus

Front 20

List the 3 types of thermal receptors and the fibers involved

Back 20

1. Cold receptors (A-delta)
2. Warm receptors (C-fibers)
3. Nociceptors (A-delta and C-fibers)

Front 21

Are warm and cold receptors rapidly or slowly-adapting?

Back 21

slowly adapting

Front 22

What range of temperature do warm receptors detect?

Back 22

86*F - 109*F

Front 23

Which temperature range do cold receptors detect?

Back 23

41*F - 109*F

Front 24

Which tract trasmits thermal information in the CNS?

Back 24

Lateral spinothalamic tract

Front 25

How is heat produced within the body?

Back 25

Exothermic chemical rxns
(oxidative, anaerobic)

Front 26

List 4 mechanisms of heat loss from the body

Back 26

1. Radiation
2. Convection
3. Conduction
4. Evaporation

Front 27

What are the 3 zones of thermal regulation?

Back 27

1. Vasomotor region
2. Metabolic regulation (cold)
3. Sudomotor/sweating regulation (heat)

Front 28

During mild thermal stress and mild exercise, which zone of thermal regulation functions to maintain appropriate body temperature?

Back 28

Zone of vasomotor regulation
*Increased/decreased conduction of blood through skin blood vessels

Front 29

Which zone of thermal regulation begins functioning when skin temperature falls below 88*F?

Back 29

Zone of metabolic regulation (cold

Front 30

What is the average skin temperature maintained by the zone of vasomotor regulation?

Back 30

88 - 93*F

Front 31

Which zone of thermal regulation is activated when vasomotor regulation (vasoconstriction) is not sufficient to prevent excessive heat loss?

How is temperature maintained?

Back 31

Zone of metabolic regulation
(cold)

*Increased muscle activity (shivering) produces heat

Front 32

Which zone of thermal regulation is active during vigorous exercise when skin temperature rises above 93*F?

Back 32

Zone of sudomotor (sweating) regulation

Front 33

How does the zone of sudomotor regulation decrease skin temperature?

Back 33

Heat is lost by evaporation
1. Sweat rate increases
2. Peripheral vasodilation increases

Front 34

Are thermosensitive cells in the POA more active when the blood temperature is above or below the set point?

Back 34

MORE active when blood is ABOVE the set point

T(blood) > setpoint --> increased discharge rate

Front 35

How does the change in temperature set point occur?

Back 35

Pyrogens affect neurons of the hypothalamus

Front 36

How do exogenous pyrogens result in fever?

Back 36

Exogenous pyrogens --> macrophages --> IL-6 --> Prostaglandins --> hypothalamus --> increased set point --> heat production, conservation --> FEVER

Front 37

How does Aspirin lower fever?

Back 37

Inhibits synthesis of prostaglandins, which normally stimulate the hypothalamus to increase the set-point

Front 38

Describe the effects of heat stroke on body temperature

Back 38

Breakdown of temperature regulating ability-- body can no longer cool itself enough by sweating
*Elevated temperature damages neurons of the hypothalamus, so regulation fails

Front 39

What is the effect of hypothermia on hypothalamic neurons?

Back 39

Reduced core temperature will depress activity of hypothalamic neurons

Front 40

Hypothalamic control of food intake depends on which two sites?

Back 40

1. Feeding center (lateral hypothalamus)
2. Satiety center (ventromedial nucleus)

Front 41

Destruction of the lateral hypothalamus area will have what sort of consequence?

Back 41

Anorexia

Front 42

A lesion in the ventromedial nucleus of the hypothalamus will have what consequence?

Back 42

Hyperphagia

Front 43

Describe the interaction between the ventromedial nucleus and the lateral hypothalamus

Back 43

Ventromedial nucleus (satiety center) transiently inhibits the lateral hypothalamus (feeding center)

Front 44

What are the 2 hypotheses that explain satiety due to meal-related signals?

Back 44

1. Glucostatic hypothesis
(increased glucose utilization in the hypothalamus leads to satiety)

2. Gut peptide hypothesis
(Food in GI causes release of peptides that inhibit food ingestion)

Front 45

Where does the leptin receptor appear to be located?

Back 45

Arcuate nucleus

Front 46

Explain the lipostatic hypothesis of body weight maintenance.

Back 46

Leptin is synthesized and released from adipose tissue. When weight is gained over a period of a few days/weeks leptin is increased.

*Leptin activates anorexigenic factors in the arcuate nucleus and inhibits orexigenic factors in the paraventricular nuclei

Anorexigenic factors stimulate the VMN (satiety center), which inhibits the lateral hypothalamus (feeding center)

Front 47

What is the effect of insulin on the arcuate nucleus?

Back 47

Insulin inhibits NPY containing neurons in the arcuate nucleus, reducing appetite and food intake

Front 48

Increased NPY has what affect on body weight?

Back 48

Functions to increase body weight
(released in response to starvation)

Front 49

What is ghrelin?
Which cells does it excite?

Back 49

Appetite stimulating hormone, released by the stomach fundus during fasting and immediately before meals

*Excites NPY containing neurons in the arcuate nucleus

Front 50

Where are osmoreceptors located?

Back 50

Anterior hypothalamic region

Front 51

Which regions of the anterior hypothalamus are deficient in the blood-brain barrier?

Back 51

(cricumventricular organs)

1. Organum vasculosum of the laminal terminalis (OVLT)
2. Subfornical organ (SFO)

Front 52

Describe the activation pathway of ADH release

Back 52

Activation of OVLT + SFO osmoreceptors excites neurons in the paraventricular and supraoptic nuclei --> excites nerve endings in the posterior pituitary --> causes release of ADH

Front 53

Which areas of the hypothalamus are involved in the defense reaction?
Which other area of the midbrain is involved?

Back 53

1. Perifornical region
2. Lateral hypothalamus

*Dorsolateral periaqueductal gray region may be the primary integration center for this response