Hormones and Behavior

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Hormones and Behavior
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The Endocrine System

• hormones chemical messengers that travel
  through blood
• Produced by endocrine glands

Pineal
Works w/ nervous system
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Hormones

• Effect distant and multiple targets
• Targets are so widespread bets way of reaching is
  thru blood
• Only influence targets w/ receptor

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Neural Vs. Hormonal Communication

• Differences
• Neural fixed (telephone)
• Endocrine - broad messages (TV)
• Neural - fast (msec)
• Endocrine - slow (sec, min)

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Similarities

• Use chemical messengers
• Release chemical after stimulation
• React only w/ particular receptors
• Many different types of neurotransmitters and
  hormones

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Hormones Important for Many Aspects of Behavior

• Homeostasis - keeping internal environment
  constant (H2O, sugar, salt etc)
• Reproduction - child care, gender attributes etc
• Stress - emergency coping mechanisms

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Hierarchical Control of Hormones
Hormones produce behavior by targeting brain
activating neurons there.
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Self-Regulation

• Often use negative feedback - presence of hormone
  slows/stops further release of hormone

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The Main Players
See Fig 11.11 your book

• Hypothalamus
• Connections w/ many brain regions
• Regulates pituitary
• Pituitary Gland
• Regulates other endocrine glands
• 2 main subdivisions
• Endocrine (anterior)
• Neural (posterior)

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Posterior Pituitary

• Hypothalamus neural cells release hormones in
  posterior pit.
• Hormones enter blood vessels.
• 2 main hormones
• Oxytocin (reproduction/parental behv)
• Vasopressin (H2O retention/ blood pressure)

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Milk Letdown Reflex
Initially takes 30 sec, then immediate
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Anterior Pituitary

• Hypothalamic RELEASING HORMONES act on
  hormone-secreting cells in anterior pituitary
• Glandular tissue
• Synthesizes own hormones

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Control Effects of Anterior Pituitary (a few
examples)
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You see Thyrotropin-RELEASING Hormone and
Thyroid-STIMULATING Hormone

• Which structure releases what?
• What gland is effected?

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When things go Wrong!
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Hypothyroidism

• Thyroid hormones require iodine
• No iodine means no thyroid hormones, so
  hypothalamus keeps secreting TRH causing overstim
  of thyroid

TRH
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Goiter-enlargement of thyroid

• Enlarged thyroid due to
• iodine deficiency.
• Treatment - iodine in diet
• Also causes Cretinism

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Hyperpituitarism

• Before puberty giantism
• Gradual enlargement of bones due to increased
  secretions of GH after normal growth is done
• After puberty acromegaly

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Acromegaly/Giantism

• Somatostatin inhibits GH production release

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Giantism
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Acromegaly

• Excess GH after puberty
• Since growth plates of long bones already
  finished, dont get increased height
• Soft tissue enlargement
• Bony changes alter facial features
• Enlargement of body organs (multiple effects)
• Diabetes
• Hypertension
• Cardiovascular disease

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Seasonal Affective DisorderSymptoms
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Causes

• Pineal - melatonin affects hypothal. releasing
  factors
• Melatonin influences mood rhythms
• Melatonin released during dark - shorter days
  more dark periods
• Artificial light helps

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Prematurely Aging Brain?!!!

• Stress hormones influence memory (epinephrine)
• Chronic stress - adrenals release cortisol
• Multiple effects
• Neurons wither/die
• Hippocampus damage
• Premature aging of brain
• Immune problems
• GI problems