© 2009 the mcgraw-hill companies, inc. all rights reserved the endocrine system
TRANSCRIPT
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
How are the endocrine and nervous systems similar? The Endocrine System and the Nervous
System are two communication systems for sending information to and from the brain
They operate differently of course
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Introduction The endocrine system includes the organs of the body that
secrete hormones directly into body fluids such as blood Regulates chemical reaction in cells and therefore control
functions of the organs, tissues, and other cells
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target tissues
Glandssecrete
hormones
into
bloodstream
to
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What are hormones? Chemicals secreted by a cell that affect the functions of other cells How do they affect behavior? Hormones affect the growth of bodily structures (muscles and
bones), affecting what you can do physically They affect metabolic processes, influencing the amount of
energy you have Certain hormones cause the differences between boys and girls Other hormones prepare the body for action during stress Hormones also act in the brain to directly influence moods and
drives
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Hormones work like neurotransmitters in that they have a special molecular structure that match the structure of a receptor
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Hypothalamus Controls the pituitary gland It monitors the amount of hormones in the
blood Sends out messages to correct hormonal
imbalances
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Controlled by the hypothalamus Located at the base of the brain How does the pituitary gland act as the “Master
Gland?” It secretes a large number of hormones, many of
which control the output of hormones by other endocrine glands – it’s the boss of other glands
Secretes the growth hormone - GH
Pituitary Gland
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Thyroid Gland Located below the larynx (voice box) Controls how fast your body uses energy with
controls your weight…metabolism Secretes the hormone thyroxine which
controls the rate at which your body burns and uses energy
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Thyroid Gland What happens if there’s too much or too
little thyroxine? Hypothyroidism – too little; become tired Hyperthyroidism – too much; overactive,
lose weight and sleep
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ExtraParathyroid Glands
Four located on the posterior surface of the thyroid gland
Secrete parathyroid hormone (PTH) It’s responsible for bone growth and for
regulating the calcium level in body
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Adrenal Glands Located on top of each kidney Becomes active when angry or scared Secretes the hormones… Epinephrine (adrenaline) Norepinephrine (noradrenaline) Same effects as sympathetic nervous system
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Adrenal Glands
epinephrine (adrenaline) increases blood pressure, breathing rate and energy level
norepinephrine (nonadrenaline) causes the heartbeat and breathing to increase; raises blood pressure
Both generate the extra energy needed to handle a difficult situation Both can heighten emotions such as fear and anxiety Norepinephrine sends out a chemical that will clot blood faster just
in case we get cut Glands also secrete cortical steroids – help muscles develop and
cause the liver to release stored sugar when the body requires extra energy for emergencies
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ExtraOther Hormone-Producing Organs Pineal gland
Small gland Located between
cerebral hemispheres Melatonin
Regulates circadian rhythms
May play a role in onset of puberty
Thymus gland Located between
lungs Thymosin
Helps with immunity
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Pancreas Located behind the stomach Both exocrine gland and endocrine
gland Exocrine – secretes digestive
enzymes into a duct leading to the small intestine
Endocrine – secretes hormones into bloodstream
Regulates the metabolism of sugar Secretes insulin which lowers
blood sugar (used to treat Type 1 Diabetes
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The Gonads The Ovaries Reproduction in females Secrete estrogen and progesterone Their levels vary…PMS Responsible for female sex characteristics
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The Gonads Testes Testosterone important in physical development of male In prenatal period, it helps decide the sex of a fetus In adolescence, it’s important for growth of muscle and
bone along with the growth of male sex characteristics
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© 2009 The McGraw-Hill Companies, Inc. All rights reserved
Hormone versus a Neurotransmitter When a chemical is used as a
neurotransmitter, it is released right beside the cell that it is to excite or inhibit
When a chemical is used as a hormone, it is released into the blood, which diffuses it throughout the body
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