16 Motivation Hunger

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16 Motivation (Hunger)

• Long-Term Regulation of Eating
• Short-Term Regulation of Eating
• Eating Emotions
• Control of Thirst
• Discussion

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I. Long-Term Regulation of Eating

• A. Homeostasis
• 1. Balance between intake, use, storage of
  nutrients
• 2. Maintains nutrients within normal range

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I. Long-Term Regulation of Eating

• B. Hypothalamus lesions (rats)
• 1. Lateral hypothalamic lesions causes
  anorexia (16.5)
• a. decr appetite
• b. hunger center
• 2. Ventromedial hypothalamic lesion
• causes overeating and obesity
• a. satiety center

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I. Long-Term Regulation of Eating

• C. Leptin (ob gene)
• 1. Released by adipocytes
• 2. Incr leptin
• a. targets arcuate nucleus (hypothalamus)
  (16.6)
• b. ?appetite

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I. Long-Term Regulation of Eating

• C. Leptin
• 2. Incr leptin
• b. incr secretion of TSH ACTH by
  pituitary induced by paraventricular nucleus
• 1) incr metabolic rate of body (16.7)

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I. Long-Term Regulation of Eating

• C. Leptin
• 2. Incr leptin
• c. incr sympathetic activity (16.6)
• 1) arcuate paraventricular nuclei
• 2) incr metabolic rate of body
• d. decr appetite (arcuate -gt lat.
  hypothalamus)

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I. Long-Term Regulation of Eating

• C. Leptin
• 3. Mechanism of decr leptin (16.8)
• a. stim another area of arcuate nucl
• b. inhibit TSH ACTH from pituitary by
  effect on paraventric nucl

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I. Long-Term Regulation of Eating

• C. Leptin
• 3. Mechanism of decr leptin (16.8)
• c. activate parasympathetic div
• d. stimulate feeding behavior

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I. Long-Term Regulation of Eating

• C. Leptin
• 4. Lateral hypothalamus (16.6)
• a. input from leptin-sensitive cells of
  arcuate nucleus
• b. output to widespread areas of brain
  including cerebral cortex (motivation?)

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II. Short-Term Regulation of Feeding

• A. Hunger phases
• 1. Mental
• a. stim by sight and smell
• b. activates parasympathetic system
  (pathway?)
• 2. GI system
• a. chew, taste, swallow
• 3. Absorption
• a. nutrients transported in blood

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II. Short-Term Regulation of Feeding

• B. Satiety
• 1. Distension of stomach wall
• a. vagal sensory fibers to solitary nucleus
  tract (taste input)
• 2. CCK (cholecystokinin)
• a. secreted by cells in intestine
• b. stimulates vagal n -gt sense of satiety

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II. Short-Term Regulation of Feeding

• B. Satiety
• 3. Insulin
• a. insulin levels inversely related to
  blood glucose
• b. insulin is satiety signal
• c. action similar to leptin
• (?blood glucose, ?insulin, ?appetite (arcuate, LM
  nucleus)

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III. Eating Emotions (Motivation)

• Not well understood
• A. Mesocorticolimbic DA System
• 1. Ventral tegmental area to ventral forebrain
  (16.14)
• 2. Pleasure center (?)
• 3. Desire/want feelings?

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III. Eating Emotions (Motivation)

• A. Mesocorticolimbic DA System
• 4. Addiction
• a. heroin nicotine target VTA (box 16.3,
  p 541)
• b. cocaine targets nucleus accumbens
  (ventral forebrain)

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III. Eating Emotions (Motivation)

• B. Serotonin (15.12)
• 1. Levels incr with ingestion of CHO
• 2. Incr 5HT elevation of mood
• 3. Incr 5HT suppress appetite
• 4. Decr 5HT depression
• 5. Decr 5HT decr satiety

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IV. Control of Thirst

• A. Volumetric Thirst
• 1. Hypovolemia decr blood vol (16.16)
• a. decr blood flow in kidney
• b. incr renin (angiotensinogen -gt
  angiotensin)
• c. incr angiotensin II
• d. acts on subfornical organ
  (telencephalon)
• e. stimulates hypothalamic magnosecretory
  cells

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IV. Control of Thirst

• A. Volumetric Thirst
• 2. Hypovolemia (16.16)
• a. decr BP
• b. mechanoreceptors in bl vs heart send
  signals to hypothalamus
• 3. Hypovolemia stimulates sympathetic system
  to constrict bl vs
• 4. Hypovolemia incr thirst via lateral
  hypothalamus

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IV. Control of Thirst

• B. Osmometric Thirst (16.17)
• 1. Hypertonic blood
• 2. Cellular water loss (osmosis)
• 3. OVLT (organum vasculosum of the lamina
  terminalis)
• a. stimulates magnocellular neurons to
  secrete vasopressin
• b. stimulates osmometric thirst

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IV. Control of Thirst

• C. Diabetes insipidus (16.17)
• 1. Loss of vasopressin secreting neurons
• 2. Xs loss of water through kidney
• 3. Incr thirst
• 4. Incr urine
• 5. Treatment vasopression

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V. Discussion

• Mind-Body questions.
• How is conscious control of eating influenced by
  value judgements?

Peter Paul Reubens 1577-1640
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V. Discussion

• How is eating influenced in anorexia? Bulimia
  nervosa? Dieting? Self-image? Advertising?
  Culture?

19th century Russian beauty vs. 20th century
Calvin Klein beauty
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V. Discussion

• Additional factors related to hunger.
• Taste pleasure
• Sensory stimulation vision, smell
• ?
• Effect of constipation on mood (?)