Transcript Chapter3Notes

Chapter 3 Notes
The Endocrine System
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The Endocrine system sends chemical
messages called hormones to the brain.
The Endocrine System consists of glands that
secrete substances, called hormones, into the
blood stream.
These hormones stimulate growth and many
kinds of reactions, such as changes in activity
levels and moods.
The Hypothalamus
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This is in your brain and it directs the pituitary
gland, which is the “master gland”
The pituitary gland secretes a large number of
hormones which carry messages through the
blood stream
These hormone messages carry information to
the organs that regulate storing of nutrients,
growth and reproduction.
The Thyroid Gland
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Produces the hormone thyroxine. Too little
thyroxine makes people feel lazy and lethargic
which is a condition called hypothyroidism.
Too much thyroxine causes people to lose
weight and become overactive. This is known
as hyperthyroidism.
Adrenal Glands
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Become active when you are frightened or
angry. They secrete adrenaline. This prepares
your body to handle emergencies.
Heredity Debate
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Heredity is the transmission of genes from
parent to child. Nature vs. Nurture asks the
question “ Do people learn to be good athletes,
or are they born that way?” and “Do people
learn to do well in school, or are they born
good at it?”
In the past, one way to study genes and
heredity was by studying twins. This is still
used today to conduct research.
Look on page 73.
Twin studies
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Identical twins develop from a single fertilized
egg and share the same genes.
Fraternal twins develop from two separate
eggs and their genes are not more similar than
those of brothers or sisters.
Read the page 72 and 73 to learn more about
several studies that have been conducted with
twins