Internal regulatory systems in animals

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• Internal regulatory systems in animals
• Endocrine
• Hormones secreted into blood
• Homeostasis development
• Nervous- electrical signal sent along neurons
• sensory input, motor response
• Considerable overlap between the two

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Typical regulation of hormone secretion
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Negative feedback is typical Positive feedback
occurs in specialized circumstances
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All metazoan groups have specialized secretory
cells Growth and developmental processes in
insects Controlled primarily by two
hormones ecdysone (molting hormone) juvenile
hormone- high levels suppress molting low
levels (and high levels of ecdysone) allow
development to proceed
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Sustained levels of JH prevent development
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p. 961
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Hypothalamus receives information from nervous
system Releases hormones that regulate the
pituitary gland Also releases ADH and oxytocin,
which are stored in, and released from,
the posterior pituitary
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Pineal gland- melatonin Helps maintain circadian
rhythm in non-mammal vertebrates Light
suppresses its production Seasonal breeders
melatonin suppresses gonadal activity
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Thyroid gland Development Metabolism Blood
calcium regulation Deficiencies in thyroid
levels described early (and treated early)
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Parathyroid hormone increases blood
calcium levels Why is this important?
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Two pancreatic hormones work antagonistically to
regulate blood glucose Type I and type II
diabetes
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Adrenal glands In mammals, glands have cortex
and medulla Cortex Glucocorticoids Mineralocort
icoids Androgens Medulla epinephrine norepine
phrine Regulate bodys response to stress
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Medulla responds to nervous signals heart rate,
blood pressure, contraction and dilation of
blood vessels Cortex- to endocrine regulation
(ACTH from pituitary)
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Reproductive hormones Influence growth and
development Sexual maturation Gamete formation
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Summary Hormones act on cells by binding to them
and altering their activity. Activity is
closely regulated, usually by negative feedback
mechanisms. Hormones play various roles in
growth and development, regulation of
metabolic activity, and response to
stress. Lack of hormone production or regulation
causes serious disorders.